Mechanics, Materials Science & Engineering Journal Vol.7 2016 by MMSE Journal

Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

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Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

Sankt Lorenzen 36, 8715, Sankt Lorenzen, Austria

Mechanics, Materials Science & Engineering Journal

December 2016

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Mechanics, Materials Sciences & Engineering Journal, Austria, Sankt Lorenzen, 2016

Mechanics, Materials Science & Engineering Journal (MMSE Journal) is journal that deals in peerreviewed, open access publishing, focusing on wide range of subject areas, including economics, business, social sciences, engineering etc.

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

CONTENT I. Materials Science MMSE Journal Vol. 7 ..................................................................................... 6 An Effective Way of Obtaining Bainite Structure in Alloyed High-Strength Cast Irons. R.K. Hasanli ........................................................................................................................................ 7 Laser Metal Deposition Repair Applications for Ti-6Al-4V Alloy. L. Jyothish Kumar, C.G. Krishnadas Nair ........................................................................................................................ 13 Statistical Study of Corrosion Types in Constructions in South Region of Rio De Janeiro Brazil. Carolina Lacerda da Cruz, Thalita Gonçalves de Lima, Nilo Antônio S. Sampaio, José Wilson de Jesus Silva ..................................................................................................................................... 23 Influence of the Composition of (TlGaS2)1-х(TlInSe2)x Alloys on Their Physical Properties. Mustafaeva S.N., Jafarova S.G., Kerimova E.M., Gasanov N.Z., Asadov S.M. ................................ 33 Enhancement of Optical and Thermal Properties of γ- Glycine Single Crystal: in the Presence of 2-Aminopyridine Potassium Chloride. R. Srineevasan, D. Sivavishnu, K. Arunadevi, R. Tamilselvi, J. Johnson, S. M. Ravi Kumar .................................................................................... 39 Enhanced Mechanical Performance for Nacre-Inspired Polyimine Composites with Calcium Carbonate Particles. Si Zhang, Yanting Lv, Jiayi Li, Song Liang, Zhenning Liu ........................... 52 Study on Laser Welding Process Monitoring Method. Heeshin Knag ................................... 61 II. MECHANICAL ENGINEERING & PHYSICS MMSE JOURNAL VOL. 7 .......................................... 67 Determining Optimum Location Places for Clutch Couplings in Hydrostatic and Mechanical Transmissions of Wheeled Tractors. Taran I.O., Bondarenko A.I................................................. 68 The Evaluation of Torsional Strength in Reinforced Concrete Beam. Mohammad Rashidi, Hana Takhtfiroozeh............................................................................................................................ 75 Process Modeling for Energy Usage in “Smart House” System with a Help of Markov Discrete Chain. Victor Kravets, Vladimir Kravets, Olexiy Burov ................................................... 84 Statistical Control of the Technological Process Stability to Manufacturing Cylindrical Parts into High Series. Viorel-Mihai Nani ................................................................................................ 96 Analysis of the Time Increment for the Diffusion Equation with Time-Varying Heat Source from the Boundary Element Method. Roberto Pettres ............................................................... 110 Investigation of Energy Absorption in Aluminum Foam Sandwich Panels By Drop Hammer Test: Experimental Results. Mohammad Nouri Damghani, Arash Mohammadzadeh Gonabadi ... 122 Probabilistic Analysis of Wear of Polymer Material used in Medical Implants. T. Goswami1, V. Perel ............................................................................................................................................ 141 Mathematical Models of Hybrid Vehicle Powertrain Performance. K.M. Bas, V.V. Kravets, K.A. Ziborov, D.A. Fedoriachenko, V.V. Krivda, S.A. Fedoriachenko ........................................... 153 Optimization of Die-Sinking EDM Process Parameters in Machining OF AMMCDesirability Approach. M. Sangeetha, A. Srinivasulu Reddy, G. Vijaya Kumar ......................... 164 Analytical and Numerical Study of Foam-Filled Corrugated Core Sandwich Panels under Low Velocity Impact. Mohammad Nouri Damghani1,a, Arash Mohammadzadeh Gonabadi ..... 175 Various Comparison of Additional Conditions of Different Designed Thermal Solar Technology Systems with the Same Collector Field. Kenan Karacavuş .................................... 200 III. MACHINE BUILDING MMSE JOURNAL VOL. 7........................................................................ 208 Conceptual Model of “Lapwing” Amphibious Aircraft. Iftikhar B. Abbasov, V’iacheslav V. Orekhov ...................................................................................................................................... 209 MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

VIII. ECONOMICS & MANAGEMENT MMSE JOURNAL VOL. 7 .................................................... 222 Cost Reduction of Taxi Enterprises at the Expense of Automobile Fleet Optimization. Novytskyi А.V. 1, Melnikova Yu. I. .................................................................................................. 223 Factor Analysis of Passenger Cars Using as a Taxi. Deriugin O.V.1, Novikova О.О.1, Cheberyachko S.І ............................................................................................................................ 230 Mathematical Models Concerning Location of Vehicular Gas-Filling Stations within Cities. Kuznetsov A.P. ................................................................................................................................. 235 IX. PHILOSOPHY OF RESEARCH AND EDUCATION MMSE JOURNAL VOL. 7 ............................... 244 On Communicative Competences as a Satisfactory Solution for Masters in Engineering. K.A. Ziborov, T.A. Pismenkova, S.A. Fedoriachenko, I.V. Verner ................................................. 245 The Use of Online Quizlet.com Resource Tools to Support Native English Speaking Students of Engineering and Medical Departments in Accelerated RFL Teaching and Learning. Kh.E. Ismailova, K. Gleason, E.A. Provotorova, P.G. Matukhin ................................................... 251

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I . M a t e r i a l s S c i e n c e M M S E J o u r n a l V o l . 7

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

An Effective Way of Obtaining Bainite Structure in Alloyed High-Strength Cast Irons1 R.K. Hasanli1,a 1 – Associated professor, Dr., Azerbaijan Technical University, Baku, Azerbaijan a – hasanli_dr@mail.ru DOI 10.13140/RG.2.2.18415.23200

Keywords: high-strength cast iron, globular graphite, economical alloying, mold, heat treatment, isothermal transformations, the details of locking devices, structure, properties.

ABSTRACT. This paper describes the features of the isothermal transformation in high-strength nodular cast iron. It explores the feasibility and effectiveness of obtaining bainite structure in the cast iron economically -alloyed with Nickel, copper and molybdenum cast in metallic form by continuous cooling air.

Introduction. In the coming years, the engineering industry of Azerbaijan should significantly be improved by the quality of the products. The most effective way to solve this problem is development of advanced structural materials, used for manufacturing various parts used in Oil and Gas industry machinery. The use of high-strength cast iron with nodular graphite (ductile iron) instead of alloy steel for producing machine parts is a promising direction of materials science development in mechanical engineering. In accordance with existing manufacturing technology, critical parts of the locking devices of oilfield equipment are produced from alloyed steels and subjected to bulk quenching or normalizing, followed by nitration to provide high wear resistance and toughness. Analyses of the Bainite Structure of High-Strength Cast Irons. For ductile iron, such processing is unsuitable, as parts made from cast iron with volumetric hardening are prone to cracks. Nitrating ductile iron is also impractical due to the significant duration of the process and the fragility of the resulting surface layer [1]. To ensure high wear resistance of parts made from sparingly-alloyed high-strength cast iron there is a possibility of obtaining bainite structure through isothermal treatment or otherwise [2]. It is known that the material with the bainite structure do not inferior in the wear resistance to the nitride layer. It was indicated that the highest wear resistance, cast irons possess lower bainitic structure [3]. The strength of the isothermal heat-treated cast irons is at a high level [2]. Several works are focused on the study of methods employed for obtaining bainitic cast iron [3 7]. Technique to obtain a matrix of bainite in cast iron in the cast state is complex and requires complex alloying additions. This does not guarantee the homogeneity of the structures and have a risk of developing segregation and micro segregation of elements in the iron composition during solidification. © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

For cast irons, obtained by casting in a metal mold, this method is unacceptable, as they must undergo graphitizing annealing [6]. The experiments showed that the introduction of 1.0% Nickel, 0,5% copper and 0,5% molybdenum in the alloy, obtained by casting in the mold, leads to the formation of bainite areas in their structure even at slow (furnace and air), cooling after graphitizing annealing. This complicates the machining of castings and does not eliminate t he need to additional heat treatment [5]. More appropriate for these conditions is the method of obtaining bainite structure in cast iron via isothermal tempering [3]. It enables the formation of bainitic structure without inclusions of perlite and structurally free ferrite. However, this method requires special equipment and additional production space to accommodate the quenching baths. The complexity of the method is also due to maintaining constant bath temperature and high energy costs. For cast iron, cast in the mold, especially doped, it is possible to obtain the metal substrate bainite during continuous cooling [6]. The dopants should increase the stability of austenite in the pearlite region. It is important to understand whether it is possible at conditions of continuous cooling to obtain the bainite structure in cast iron, alloyed with Nickel, copper and molybdenum, and how homogeneous the resulting structure and properties could be. The presence of structural heterogeneity, as well as difference in proportions of phases in the matrix can significantly affect the mechanical properties of the investigated alloys. It is necessary to evaluate the degree of influence of these factors on the level of guaranteed properties of cast irons. Thus, in this work the main task was to establish the possibility of obtaining of bainite structure in alloyed Nickel, copper and molybdenum irons, featured in the metal mold during continuous cooling in air. This treatment can be carried out with the heating higher A Hc1 and higher A cK1 . Apparently, it makes no sense to carry out heating in the inter-critical region, because this can lead to increase in heterogeneity in the matrix of cast iron. In addition, it is important to ensure th e stability of the super cooled austenite in the pearlite region of decay that would be better achieved after heating above A Kc1 . In this regard, studies were chosen temperature from 870 to 930 0C. Isothermal hardening machined alloy and, for comparison, non-alloyed high-strength cast irons with nodular graphite. Samples of unalloyed iron were studied dependence of bainitic structure from the temperature of isothermal holding. At the same time, the objective was to establish a link between the original structure of the matrix and the speed and completeness of bainite transformation. The latter is important in the development of production technologies for the manufacture of castings of parts of the locking devices from ductile iron in single and metallic forms [6-8]. Temperature of austenitization was 9100C that exceeds 500C for the A cK1 investigated alloy. The exposure was 15 min, isotherm temperatures: 350, 400 and 4500C. During quenching, the samples of ferrite and pearlite cast irons were subjected to the same heating in a furnace and simultaneously transferred into the bath. Exposure in the bath was from 30 to 20 hours. After isothermal holding the samples were cooled in water. It is established that at low shutter speeds in the bath, the iron acquires high hardness, due to presence of a significant amount of martensitic, formed during cooling of the samples to the temperature isotherms in the water. The transformation of bainite in ferrite iron initially develops slower than in pearlite, as evidenced by their high hardness (see table 1). It is discovered, that the bainite transformation starts to develop intensively in the cast irons with ferrite initial structure after more than a 10-minute exposure. At temperatures of 3500C and 4000C it almost ends at 15-16 minutes (Fig.1). Cooling bath with a temperature of 3500C leads to the formation MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

of lower bainitic (Fig. 1, 2), and a temperature of 400 and 450 0C - top. Fine precipitation of carbides in the structure of samples treated at 450 0C, with the extracts of more than 16 min are clearly visible (Fig. 3-5). Table 1. Hardness (HB) high-strength cast iron, casted in a mold, after isothermal hardening. The temperature of the isothermal quenching, oC

450

400

350

isoth. holding the cast iron

30s

50s

100 s

16m

60s

90s

10m

16m

90s

120s

10m

16m

Source structure of cast iron: Pearlite

512 444

340

321

Ferritic

512 512

512

387

375

321

425

402

364

351

248 496 496

283

241 187 532

512

340

283

c) Fig. 1. The effect of time aging at 350 C for isotherm the structure of ferritic ductile cast iron: а)  isoth=2 min.; b)  isoth=10 min.; c)  isoth=16 min. х800. 0

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Fig. 2. The effect of time aging at 3500C for isotherm the structure of pearlitic ductile cast iron: А)  =2 min.; b)  =10 min.; c)  =16 min.; d)  =2 hours.

Fig. 3. The effect of exposure time with isotherm 4000C on the structure of ferritic ductile cast iron: а)  =1,5 min; b)  =10 min; c -  =16 min.; d)  =2 hours. MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Fig. 4. The effect of exposure time with isotherm 4000C on the structure of pearlite ductile cast iron: а)  =10 min; b)  =10 min.

c) Fig. 5. The influence of exposure time on the isotherm at 4500C the structure of pearlite ductile cast iron: а -  =100 sec.; b -  =16 min.; c -  =2 hours. Studies found that the initial structure of the metallic base of cast iron, cast in the mold, has a significant influence on kinetic parameters of bainite transformation. In the original ferrite matrix, the transformation is quicker and more complete than in pearlite. However, the incubation period in ferrite is more. Summary. Thus, an efficient way of obtaining Manitou patterns in the economically-alloyed iron cast in metal mold by continuously cooled air. The proposed technique provides heat treatment resulting in a rational structure and properties of ductile iron castings for the parts of the locking devices of oilfield equipment.

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References [1] V.V. Dubrov and others, The use of high-strength cast iron in valve. In proc. High-strength cast iron with nodular graphite. Kiyev, Naukova Dumka, 1998, pp. 78-81. [2] A.I. Belyakov, A.A. Belyakov, A.A. Zhukov Isothermal quenching of cast iron with nodular graphite // Blank production in mechanical engineering, 2008, No. 1, pp. 44-48. [3] A.I. Belyakov and others. Production of castings from high-strength nodular cast iron. M., Mechanical engineering, 2010, p. 712. [4] I.N. Bogachev, R.I. Mints Cavitation-erosion fracture of cast iron. Sat. Theory and practice of foundry production, Ural Polytechnic Institute, vol. 89, 1999, pp. 71-78. [5] L.P. Ushakov Wear-resistant cast iron with spheroidal graphite. M., Mechanical engineering, 2005, 153 p. [6] R.K. Hasanli, Structure and properties of ductile iron. Baku, Science, 2013, 250 p. [7] R.K. Hasanli, Peculiarities of structure and phase composition of heat-treated high-strength cast irons with nodular graphite // Journal of mechanical engineering, 2013, No. 10, pp. 31-33. [8] N.W. Ismailov, Features of producing engineering castings, using silica sand and bentonite clay in Azerbaijan // Journal of mechanical engineering 2012, No. 6, pp. 11-14. [9] E.A. Silva, L.F.V.M. Fernandes, N.A.S. Sampaio, R.B. Ribeiro, J.W.J. Silva, M.S.Pereira (2016), A Comparison between Dual Phase Steel and Interstitial Free Steel Due To the Springback Effect. Mechanics, Materials Science & Engineering Journal Vol.4, Magnolithe GmbH, doi: 10.13140/RG.2.1.3749.7205 [10] L. I. Ă&#x2030;fron, D. A. Litvinenko (1994), Obtaining high-strength weldable steels with bainite structure using thermomechanical treatment, Metal Science and Heat Treatment, Vol. 36, Is. 10, Springer, doi: 10.1007/BF01398082 Cite the paper R.K. Hasanli (2016). An Effective Way of Obtaining Bainite Structure in Alloyed High-Strength Cast Irons. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.18415.23200

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Laser Metal Deposition Repair Applications for Ti-6Al-4V Alloy2 L. Jyothish Kumar 1, a & C.G. Krishnadas Nair 2 1 – doctoral scholar, Jain University, Bangalore – 560078 2 – professor, research superviser, Chancellor, Jain University, Bangalore – 560078 a – jyothish@rapitech.co.in DOI 10.13140/RG.2.2.35949.38889

Keywords: Laser Metal Deposition, Ti-6Al-4V powder and substrate, Taguchi L9 Orthogonal array method, Process parameters.

ABSTRACT. Laser metal deposition is an additive manufacturing process, which is used to produce functional metal parts or repair existing parts. This paper focuses on deposition of Ti-6Al-4V material for remanufacturing of existing Ti6Al-4V components. Optimization of laser metal deposition process parameters is significant in achieving good metallurgical and mechanical properties such as fine grain structure and bonding strength for aerospace applications. Taguchi’s L9 orthogonal array method has been adopted to optimize the laser power, powder feed rate and scan speed. Analysis of variance (ANOVA) is used to study the effect of process parameters on the deposit and verification trial experiments were conducted to ascertain the optimum process parameters performance. Residual stress measurement results revealed that the residual stress is compressive and significantly higher in optimized test specimen with good bonding strength. The optimized results shown that enhanced properties in refurbishment of aero engine parts using Ti6Al-4V powder material.

Introduction. Laser Metal Deposition (LMD) is an additive manufacturing process, which builds 3 dimensional parts directly from CAD data. A high power laser heat source is used to create a melt pool in the substrate and powder material is fed co-axially in to the melt pool. Due to rapid cooling the molten pool solidification takes place to produce highly dense metal parts with reduced waste of material compared to conventional manufacturing process. [1] LMD is a latest technology, which is used for freeform fabrication and repair of engineering and aerospace components [2]. Kamran shah et.al [3] have studied the effects of process parameters on direct laser metal deposition of IN 718 on Ti-6Al-4V substrate by using pulsed laser heat source parameters. It was found that optimized process parameters like laser power, scanning speed and powder feed rate resulted in crack free deposition with improved mechanical and metallurgical properties. Dinda et al. [4] have investigated microstructure analysis and thermal properties of Inconel 625 process with direct metal deposition. In this study Taguchi L9 orthogonal array method was applied to evaluate the effect of process parameters on the microstructure and mechanical properties of Inconel 625 material. Ryan Cottam et al. [5] studied the laser cladding of Ti-6Al-4V powder to understand the effect of laser cladding parameters on the metallurgical properties of the material. It was observed that microstructure of Ti-6Al-4V deposit in the clad zone with optimized process parameters was refined and contributed to the good deposition strength. Qun-li et al. [6] have studied direct laser metal deposition of Inconel-718 and the effects of process parameters on rate of deposition and layer thickness. It was found that the optimized process parameters lead to directional solidification with fine martensite microstructure and increased microhardness. R. Keshavamurthy et al. [2] have carried out process parameters optimization for direct metal deposition of H13 tool steel by using Taguchi orthogonal array method of design of experiments. The effect of powder feed rate, © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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laser scan speed and laser power on the hardness of the deposit have been studied. It was found that optimum process parameters have contributed to the increased hardness of the deposit and the optimised process parameters were verified from the analysis of variance (ANOVA). Laser Metal Deposition process includes several process parameters such as laser power, scan speed, beam diameter, powder feed rate, hatch spacing, layer thickness and scanning orientation. From the above literature review, it is crucial to optimize these process parameters to achieve the desired quality characteristics of the deposited materials. In view of above, the objective of the current study is to optimize the process parameters of laser metal deposition of Ti-6Al-4V powder on Ti-6Al4V substrate using Taguchi L9 orthogonal array method to achieve maximum hardness and bonding strength. Ti-6Al-4V is having high strength to weight ratio widely used in aerospace applications such as airframe, compressor blades, vanes and discs at elevated temperature. Details of Experiments. Deposition material: Fig.1 shows the scanning electron microscope (SEM) of Ti-6Al-4V powder particles used in the current study. As shown in the Fig.1 the powder particles are spherical in shape and size distribution varies between 44-106 Âľm and the powders produced by gas atomization process. Fig.2 shows the EDS analysis of elemental composition of Ti-6Al-4V material. Table-1 shows the chemical composition of Ti-6Al-4V powder material used in the present study.

Fig. 1. Scanning electron micrograph of Ti-6Al-4V powder at 2000 X Magnification.

Fig. 2. SEM image and EDAX pattern of elemental composition.

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Table 1. Chemical composition of Ti-6Al-4V powder. Element

Percentage

0.01

0.063

0.02

0.0045

0.21

6.4

4.0

Balance

Substrate material: The substrate material used in the present study is Ti-6Al-4V plate to deposit Ti6Al-4V powder. The chemical composition of Ti-6Al-4V substrate is given in the Table. 2. Table 2. Chemical composition of Ti-6Al-4V substrate. Element

Percentage

0.0590

5.6600

90.2100

3.7200

0.1400

Planning of experiments: Using Taguchi method experiments are planned since it is a robust design method when the process is affected by several process parameters. When compared with traditional methods of experimental planning, Taguchi method helps in reducing number of experiments, cost and time. Taguchi suggested orthogonal array method, which gives different combinations of parameters and their levels for each set of experiment [7, 8]. As per Taguchi orthogonal array method complete process parameter area is investigated with least number of experiments. Design of experiments using Taguchi L9 Orthogonal array method. In the present study the best potential combination of process parameters have been determined by using Taguchi L9 orthogonal array method. Laser power, scan speed and powder feed rate have been selected as variable input process parameters and higher hardness as the desired output and quality characteristic. L9 orthogonal arrays and signal to noise (S/N) ratio are the two important tools used in Taguchi design of experiments method. The column of L9 orthogonal array represents the process parameters to optimize and the rows represents the levels of each process parameter. The mean and the variance of the output response at every parameter setting in L9 orthogonal array are later combined in to a single performance measure known as S/N ratio and the S/N ratio helps to measure quality characteristics with importance on variation [9, 10]. Minitab software (Version: 17) was used to calculate the S/N ratio using Taguchi method. Input process parameters for laser metal deposition of and their levels are shown in table. 3 and experimental plan based on Taguchi L9 orthogonal array method is shown in table. 4. In the present research work the maximum power efficiency of the Laser Metal Deposition Machine â&#x20AC;&#x201C;TRUMPF LASER CELL 1005 is 4000W. We have selected the intermediate Laser Power 2500 W, Scanning Speed 600mm/min and beam dia of 3 mm. From these parameters we have found the energy density energy Ć?d = 83.33 J/mm2 using equation (1) for good quality of deposition, which is in the workable range based on review of literature. 60 Ă&#x2014; đ?&#x2018;&#x192;

Ć?d = đ?&#x2018;&#x2018; Ă&#x2014; đ?&#x2018;&#x2030; J/mm2 where P â&#x20AC;&#x201C; is the laser power; V â&#x20AC;&#x201C; is the scanning speed or velocity; D â&#x20AC;&#x201C; is the laser beam diameter [11].

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(1)

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Using the energy density Ɛd = 83.33 J/mm2 we have designed the experiment using Taguchi’s L9 Orthogonal Array with 3 factors and 3 levels. From the design of experiments result we have selected the optimum parameters to build the test specimens. Table 3. Input process parameters and levels. Level Sl No.

Parameters

Level 1

Level 2

Level 3

Laser power (W)

2350

2500

2650

Laser scan speed (mm/min)

500

600

700

Powder feed rate (g/min)

Table 4. Experimental plan based on Taguchi L9 orthogonal array. Expt. No.

Powder Feed Rate (g/min)

Laser Power (W)

Scan Speed (mm/min)

2350

600

2500

700

2650

500

2350

500

2500

600

2650

700

2350

700

2500

500

2650

600

Laser Metal Deposition. Laser Metal Deposition of Ti-6Al-4V on Ti-6Al-4V substrate was carried out using TRUMPF LASER CELL LMD system with 4000W CO2 laser with laser beam diameter of 3mm. The deposition was carried out in argon-controlled atmosphere to avoid oxidation. Test specimens were prepared with two layer depositions with 1.2 mm layer thickness and 10 x 30 mm size as shown in Fig.3.

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

Fig. 3. Ti-6Al-4V deposition on Ti-6Al-4V substrate as per L9 orthogonal array. After deposition the samples were held in a fixture on SODICK A350 Mark 21 submerge type wire electric discharge machine (EDM) and cut in transverse direction using brass wire (dia 25µm) as a tool electrode. The sectioned samples were polished with three coarse grits (600, 800 and 1200) and final polishing media with 0.05 microns alumina powder. The polished Ti-6Al-4V samples were etched using a mixture of 8 gms KoH (Potassium Hydroxide), 10 ml H2O2 (Hydrogen Peroxide), 60 ml distilled water and it is immersed for about 20 seconds to reveal the microstructure details. Microstructure studies were carried out on metallographically polished surfaces using optical microscope of make: Nikon, Japan and model: Eclipse LV 150. Microhardness tests were conducted using Vickers microhardness tester of make: CLEMEX, Canada and the indentation was measured using CLEMEX vision PE image analyzer software. Indentations were made at 5 locations on the substrate and deposit from the interface, using a load of 100 gms for duration of 10 seconds. Hardness value of each sample is a result of the average of all five measured readings. Results and discussions. Microstructure: Fig.4 shows the microstructure of Ti-6Al-4V deposit on Ti-6Al-4V substrate. The microstructural analysis is the function of combined effect of laser power, scan speed and powder feed rate, which is depicted by using the series of optical microscope images as shown in the Fig. 4. All the images are viewed at 200X magnification. It is observed that the microstructure comprises of combination of acicular α phase (martensite) and Widmanstatten structure. Sample 7 shows that the amount of acicular α phase is more when compared to other images, which have resulted from higher, scan speed; powder feed rate and less laser power. Further, the sample 7 exhibited more hardness as reported in table. 6 due to rapid cooling of the melt pool, which resulted in formation of acicular α, phase and in general produces the α martensite microstructure [12]. This combination is imparting the better cooling effect to have acicular α phase (martensite phase). Further, all the sample reveals least porosities and no evident cracks or incoherence exists. Hardness. Table. 5 shows the hardness values of Ti-6Al-4V deposit. The minimum and maximum hardness of the samples obtained are 407.12 and 459.54 HV for the experimental samples 7 & 3 correspondingly. The fine grain size and minimum porosity attributes to the higher hardness and strength of the material. The presence of interstitial atoms and the density dislocations decides the free plastic deformation of the material, thereby improving the resistance to plastic deformation, which leads to higher hardness. [2, 13]. Analysis of S/N ratio. In the current study, hardness was considered as the quality characteristic for laser metal deposition technology. Higher value of hardness is suitable for deposition of Ti-6Al-4V; therefore, the concept of “larger-the-better” is adopted for optimization of process parameters by Taguchi L9 orthogonal array method.

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Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

Table 5. Hardness and S/N values for Taguchi L9 experiments. Expt. No.

Microhardness (HV)

S/N ratio

407.12

52.1944

436.27

52.7951

413.47

52.3289

420.80

52.4815

410.39

52.2639

442.11

52.9106

459.54

53.2465

436.04

52.7905

434.22

52.7542

As shown in the above table the best performance of the process is indicated by a higher value of S/N (Larger is better). Hence, the optimum level of the process parameters is the level of the highest S/N value.

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Fig. 4. Optical micrographs of Ti-6Al-4V deposits as per Taguchiâ&#x20AC;&#x2122;s L9 orthogonal array. (1) 2350 W, 600 mm/min, 4 g/min; (2) 2500 W, 700 mm/min, 4 g/min; (3) 2650 W, 500 mm/min, 4 g/min; (4) 2350 W, 500 mm/min, 3 g/min; (5) 2500 W, 600 mm/min, 3 g/min; (6) 2650 W, 700 mm/min, 3 g/min; (7) 2350 W, 700 mm/min, 5 g/min; (8) 2350 W, 500 mm/min, 5 g/min; (9) 2650 W, 600mm/min, 5 g/min. Powder feed rate. The effect of powder feed rate on hardness is attributed from the Fig.5 that the S/N ratio is decreasing with increase in powder feed rate up to 4 g/min and then S/N ratio is increasing with the further increase in powder feed rate at 5 g/min. Hence the optimum powder feed rate is 5 g/min. Laser power. The effect of laser power on hardness is as shown in the Fig5. It is observed that the S/N ratio is increasing with increase in laser power. This shows that the optimum laser power is 2650 W. Scanning speed. The effect of laser scanning speed on hardness is shown in the Fig.5. It is observed that S/N ratio is increasing with increase in scanning speed. This shows that the optimum scan speed is 700 mm/min. Based on the analysis of the S/N ratio, the optimized process parameters for achieving maximum hardness are powder feed rate: 5 g/min, laser power: 2650 W, Laser scanning speed: 700 mm/min.

Main Effects Plot (data means) for SN ratios Powder feed rate (g/min)

53.0

Laser power (W)

Mean of SN ratios

52.8 52.6 52.4 3 53.0

2350

2500

Scanning speed (mm/min)

52.8 52.6 52.4 500

600

700

Signal-to-noise: Larger is better

Fig. 5. Main Effects Plot for SN ratios. MMSE Journal. Open Access www.mmse.xyz

2650

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Analysis of Variance (ANOVA). The process parameters importance has been studied by analysis of variance for S/N ratio. Based on analysis of variance, each parameter contribution has been quantified under column F of Table. 6. From table 6 it clearly reveals that the F value for scan speed is very high when compared to laser power and powder feed rate. This is a clear indication that the influence of scan speed is significantly larger than the influence of laser power and powder feed rate for achieving higher hardness. Table 6. Analysis of variance for S/N ratio. Source

Degrees of freedom (DOF)

Sum of squares

Mean square

F – ratio (F)

P – ratio (P)

Powder feed rate

0.36984

0.19842

61.42

0.016

Laser power

0.00346

0.00173

0.54

0.651

Scan speed

0.55588

0.27794

86.04

0.011

Error

0.00646

0.00323

Total

0.96264

Optimized process parameter verification test. A design of experiments verification test has been carried out for laser metal deposition of two layers of Ti6Al4V on Ti6Al4V substrate under optimized process parameters to study the hardness. The obtained deposition hardness under optimized condition is 461.22 HV as shown in table. 7. It is noticed that the hardness value of the optimized condition is considerably higher than that of the deposition experiments carried out corresponding to L9 orthogonal array. The optimized sample was deposited using 2650 W laser power, 700 mm/min scan speed and 5 g/min powder feed rate. It clearly reveals that fine and consistent ‘α martensite’ microstructure may attributes to the higher hardness as shown in Fig. 6. Table 7. Optimized process parameters and Hardness. Expt. No.

Laser Power (W)

Powder flow rate (g/min)

Laser scan speed (mm/min)

Hardness (HV)

2650

700

461.22

Fig. 6. Optical micrograph of Ti-6Al-4V deposit under optimum process parameter. MMSE Journal. Open Access www.mmse.xyz

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Residual Stresses. Residual stress was measured using X-ray diffraction method. The X-ray diffraction pattern shown in Fig. 7 (a) & (b) reveals the residual stress result of Ti-6Al-4V deposits. Residual stress measurement has carried out on L9 test specimen and optimized test specimen of Ti6Al-4V deposit. It is observed that the residual stress is compressive in both L9 and optimized Ti6Al-4V specimens. The measured residual stress in L9 test specimen is -153.3 ± 21.3 MPa and -277.8 ± 20.2 MPa in optimized test specimen. This shows that the residual stress in optimized Ti-6Al-4V test specimen is significantly higher with good bonding strength.

(a)

(b) Fig. 7. Ti-6Al-4V diffraction pattern (a) L9 test specimen 1 (b) optimized test specimen. Summary. Process parameters for laser metal deposition of Ti-6Al-4V were optimized using Taguchi L9 orthogonal array method. The optimum process parameters are found to be laser power: 2650 W, powder feed rate: 5 g/min and scan speed: 700 mm/min. The optimum process parameters have been confirmed by the verification experiment conducted. X-ray Diffraction residual stress studies clearly reveal that the residual stress is compressive and significantly higher in parts deposited under optimum laser power, laser scan speed and powder feed rate. The obtained results from the optimization of process parameters could be directly used to repair complex aero engine Ti-6Al-4V parts. References [1] Imran M.K., Masood S., Brandt M., Bhattacharya S., Mazumder J., Parametric investigation of diode and CO2 laser in direct metal deposition of H13 tool steel on copper substrate. World Academy of Science and Technology 2011, 79, 437- 442

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[2] R. Keshavamurthy, Padmanav Rashmirathi, A.R. Vinod, C.K. Srinivasa, P.V. Shashikumar, Optimisation of process parameters for direct metal deposition of H13 tool steel. Advanced Materials Manufacturing & Characterisation 2013, Volume 3 Issue 2 (2013), doi: 10.11127/ijammc.2013.07. [3] Kamran Shah, Izhar Ul Haq, Shaukat Ali Shah, Farid Ullah Khan, Muhammad Tahir Khan, Sikander Khan, “Experimental study of direct metal deposition of Ti-6Al-4V and Inconel 718 by using pulsed parameters”, The Scientific World Journal, Volume 2014, doi: 10.1155/2014/841549 [4] Dinda G P, Dasgupta A K, Mazumder J, Laser aided deposition of Inconel-625 super alloy: microstructural evolution and thermal stability, Material science and Engineering, A 2009 509, 98104 [5] Ryan Cottam, Milan Brandt, Laser cladding of Ti-6Al-4V powder on Ti-6Al-4V substrate: Effect of laser cladding parameters on microstructure, Physics Proceedia 12 (2011) [323-329] W.H.Yang, Y.S.Tarng, Design optimization of cutting parameters for turning operations based on the Taguchi method, Journal of Materials Processing Technology 84 91998) 12-129 [6] Qun-li Z, Jian-Hua Y, Mazumder J, Laser direct metal deposition technology and microstructure and composition segregation of Inconel 718 super alloy, 2011, Journal of Iron an Steel Research, 18 (4),73-78 [7] W.H.Yang, Y.S.Tarng, Design optimization of cutting parameters for turning operations based on the Taguchi method, Journal of Materials Processing Technologies 84 (1980) 122-129. [8] T.P Bagchi, Taguchi Methods Explained, Printice-Hall of India, 1993 [9] Phadke, M.S. Quality Engineering Using Design of Experiment, Quality Control, Robust Design and Taguchi Method, 1998 California, Warsworth & Books. [10] Rama Rao, S. Padmanabhan.G, Application of Taguchi methods and ANOVA in ootimisation of process parameters for metal removal rate in electrochemical machining of Al/5%SiC composites, International Journal of Engineering Research and Applications (IJERA), Vol 2, Issue 3, May-Jun 2012, pp. 192-197. [11] J Jayakumar, Dr. T.Senthil Kumar, Review study of laser cladding processes on ferrous substrates, 2015, International Journal of Advanced Multidisciplinary Research, 2(6): (2015), Pages 72–87. [12] Jun Yu, Marleen Robouts, Gert Maes, Filip Motmans, Material properties of Ti-6Al-4V parts produced by laser metal deposition, Journal of physics proceedia, 39 (2012) 416-424 [13] J. Michael Wilson, Yung C.Shin, Microstructure and wear properties of laser-deposited functionally graded Inconel 690 reinforced with TiC, Journal of Surface and Coatings Technology, 207 (2012) 517-522 Cite the paper Jyothish Kumar & C.G. Krishnadas Nair, (2016). Laser Metal Deposition Repair Applications for Ti-6Al-4V Alloy. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.35949.38889

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Statistical Study of Corrosion Types in Constructions in South Region of Rio De Janeiro - Brazil3 Carolina Lacerda da Cruz1, Thalita Gonçalves de Lima1, Nilo Antônio S. Sampaio1,2, José Wilson de Jesus Silva1,3 1 – Asociação Educacional Dom Bosco, AEDB, Resende, RJ, Brazil 2 – Universidade do Estado do Rio de Janeiro, UERJ, Resende, RJ, Brazil 3 – Centro Universitário Teresa D’Ávila, UNIFATEA, Lorena, SP, Brazil DOI 10.13140/RG.2.2.29609.60004 Keywords: corrosion, construction, corrosion inhibitors, corrosion protection, corrosion in south region. ABSTRACT. Some of the most difficult and troubling problems encountered in construction are those caused by corrosive processes. The corrosion processes are constituted by some material degradation, generally metallic material, by means of chemical or electrochemical actions of environment in which the material are and can or cannot be combined with mechanical stress. Corrosion is present in the materials in general. Their deterioration is caused by such physicalchemical interaction between the material and the corrosive environment where it causes major problems in several activities. In order to prevent material losses, anticorrosive techniques are used which include coatings, medium modification techniques, anodic and cathodic protection, and corrosion inhibitors such as the organic compounds use. This article analyses the statistical study of corrosion types in construction in south region of Rio de Janeiro, Brazil.

Introduction. The financial losses by processes of degradation and structures corrosion of metal and concrete in an engineering work are generally very high. Surveys have found that the annual corrosion cost in the United States is about 3.1% of GDP, amounting to about 276 billion [1]. While in Brazil, this cost is about 3.5% of GDP. Corrosion may be defined as a deterioration process of the material that produces harmful and undesirable changes in the structural elements, since the corrosion product is an element different of the original material, making the alloy loses its essential qualities, (such as mechanical strength, elasticity, ductility, aesthetics) [2]. Corrosion can focus on several materials types, whether metallic or non-metallic and root causes of this deterioration are different taking into account the material and the medium. All these processes are of spontaneous nature, which occur with greater or lesser speed and intensity. The speed at which corrosion proceeds is given by the total mass of material removed in a given area during a given time. Some factors help to influence this speed, such as corrosive medium, temperature and speed effect [3]. There are some protection mechanisms whose purpose is to increase the structure life. Corrosion resistance increase by means of anticorrosive protection practices adopted in the design phase is one of the most important control forms. This resistance increase can be achieved by adopting practices that minimize the corrosion problems or using anticorrosive protection techniques [4]. For metal structures protection it is traditional to use organic paints, metallic and non-metallic coatings, which are usually effective against the corrosion process however this effectiveness will depend on some factors such as application method, environment, exposure time to weather and more. © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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For reinforced concrete structures in which their physical properties are result from combination of resistance to compression of concrete itself and high tensile strength which is given to the steel. Concrete consists of cement, aggregates, water and additives, therefore the defects of each of these materials may influence unfavorably on the most important characteristics of the concrete: mechanical strength, stability and durability. These three characteristics are related to a number of factors among which we highlight the homogeneity and compactness [5]. In addition to structural advantages that result from combination of both materials, the concrete acts as a physical barrier of reinforcement in relation to environment and have chemical characteristics that provide the steel excellent corrosion protection. However, in the course of time it was proved that reinforced concrete also deteriorated by both degradation process of concrete itself and by corrosion of its armor. If the concrete coating on the armor is not maintained in good condition one cannot expect a good performance of reinforced concrete, Fig. 1. Its deterioration may be caused by cracks, mechanical erosion, freezing, acid attack, attack by sulfates, alkali-aggregate reaction, biological attack, desalination [6]. Due to the environment in which it will exercise its activity, a structure can require chemical and physical protection, produced by a good compact and waterproof coating. Furthermore, a structure may require additional protections, which can act directly on steel, as in the case of cathodic protection, electroplating and coating with synthetic resins or on the concrete, as with the corrosion inhibitors and the resin or asphaltic paints [7].

Fig. 1. Steel structure. Materials and methods. For metallographic analysis, cylindrical samples of CA 50 rebar were used. The sample was mechanically polished using SiC paper (80-1200). The electrochemical study was initiated by analyzing potential measurements on open circuit. For this purpose, it was used a conventional thermostated glass cell, Fig. 2, and a reference electrode of Ag/AgCl KCl sat. As electrolyte, it was prepared an aqueous solution from sodium chloride (NaCl) 2.0 and 4.0 g/L. The equipment used was an AUTOLAB coupled with a computer for control and data processing, Fig. 3. Prior to each measurement the alloy surface had to be finely polished, free of scratches when viewed under a microscope. MMSE Journal. Open Access www.mmse.xyz

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The electrochemical cell used in the test is composed of three electrodes: the polished steel surface was the working electrode; as an auxiliary electrode it was used a Pt mesh; as a reference electrode the Ag|AgCl|KClsat. and a beaker where sodium chloride is placed [8]. The equipment used in the experiment was a potentiostat/galvanostat AUTOLAB (brand: Eco Chemie B.V., Utrecht, Netherlands, model PGSTAT302). The samples were previously sanded with sandpaper SiC immediately before the test then being washed with distilled water and then were immersed in the test solution, thereby initiating polarization [9]. The tests were repeated twice per solution.

Fig. 2. Conventional electrochemical thermostatically cell of borosilicate glass.

Fig. 3. AUTOLAB coupled to a computer. Results and discussion. In this topic it is presented and discussed the experimental results of corrosion tests of the materials described in this work. In the figure below (Fig. 4), the curve representing the open circuit potential [10] is presented as a function of time for the steel samples studied and tested in a NaCl solution, 2.0 and 4.0 g/L at room temperature. The open circuit potential evaluation provides a comparison of corrosive material in MMSE Journal. Open Access www.mmse.xyz

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different media, so that the higher the value of this potential, the greater its corrosion resistance in the medium considered. It is emphasized that this potential is a thermodynamic factor and is related to the tendency for corrosion to occur, i.e. with the Gibbs free energy. According to figures (Fig. 5 and 6), a typical active state behavior was observed by the potential descending with time. Variation in solution concentration produced a significant difference (~ 0.08 V) between the two measurements when the OCP value approaches the steady state, indicating that the change in chloride ions concentration turns the medium more oxidizing.

E (v) vs. Ag|AgCl|KClsat.

Fig. 4. OCP curves for CA-50 steel in two concentrations of chloride ions.

-0,3 -0,4

NaCl 2,0 g/L NaCl 4,0 g/L

-0,5 -0,6 -0,7 -0,8 -0,9 -8

-7

-6

-5

-4

-3

-2

Log (I / A cm )

Fig. 5. Tafel curves obtained after 3 immersion hours of steel in chloride medium.

E (v) vs. Ag|AgCl|KClsat.

1,2 Tafel Curva CP

0,9

NaCl 2,0 g/L

0,6 0,3 0,0 -0,3 -0,6 -0,9 -8

-7

-6

-5

-4

-3

-2

Log (I / A cm )

Fig. 6. Comparison between potentiodynamic profiles of a Tafel curve and a CP curve obtained in NaCl 2.0 g/L medium. MMSE Journal. Open Access www.mmse.xyz

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For this type of steel, the electrochemical mechanism of corrosion process originates in the form of localized corrosion (crevice) usually associated with electrolyte stagnation conditions in microenvironments where there is hindrance or difficulty to the spread of chemical species. The solution within the crack is deoxygenated due to initial corrosion that consumes, through cathodic process, the oxygen in solution: O2 + 2H2O + 4e 4OH-. The oxygen diffusion rate into the crack is not fast enough to replenish the oxygen consumed in the cathodic process. The cathodic process moves out of the crack where oxygen is plentiful. There is separation of anodic and cathodic regions. The ferrous ions are formed within the crack (Fe Fe ++ + 2e-) and hydroxyls in oxygenated regions. The ferrous ions undergo hydrolysis (Fe ++ + H2O Fe (OH) + + H+) and decrease the pH within the crack. Due to the current flow and mass transport phenomena, aggressive ions migrate under the influence of electrostatic field into the crack, and are concentrated there, causing great changes in chemical conditions. As a result there is the iron hydroxide (II), white color, which due to the oxidation process is turned slowly into iron hydroxide (III), which has a brown-orange coloration according to the iron content (III) .When this type of coloring appears in structures (concrete and steel), it indicates that they are suffering corrosion. The oxidized iron assumes that color and begins to crumble. In the affected areas, the metal will lose density and, if the process is not contained, it can reach the full degradation. The curve corresponding to the steel in NaCl 2.0 g/L, Fig. 5, was overlapped with the anode region of a CP curve obtained under the same experimental conditions as Fig. 6, to verify the repeatability in the current response during the scan of potentials of electroactive area and also to illustrate the active steel behavior in chloride medium within a wide potentials range, shown by the presence of positive hysteresis and the absence of a passivation region in the reverse scan, showing a generalized corrosion process. In the investigated pH range (between 5.0 and 6.0 before and after corrosion tests) the anodic reactions involve the formation of complex ions of Fe (II) and Fe (III) and possible precipitation Fe(III) hydroxide. Statistical study. Corrosion in civil construction is directly linked to its increase. The civil construction industry in Brazil grew above GDP in the period 2010-2013, Fig. 7. The civil construction is a featured segment in south economy in Rio de Janeiro, being responsible for almost 25% of new jobs in recent years [11].

Fig. 7. Civil Construction in Brazil grew above the GDP in the period 2010 to 2013.

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This growth was due to the need for improvements in the country boosted, for example, by the World Cup, 2016 Olympics in Rio de Janeiro with the need for Brazil in infrastructure, the Accelerated Program for Growth (PAC, in Portuguese) and the program called "My house, my Life" (Minha Casa, Minha vida - in Portuguese) sponsored by a federal bank. The State Government, by means of the Department of Highways and Roads (DER, in Portuguese), made in the last two years important interventions on state roads which have improved the population routine. Counties of state south were Rio Claro, Miguel Pereira and Barra do Pirai that have received improvements to their roads (paving, drainage and coasting building and extending bridges). This year, it was given to paving the RJ-151, between Visconde de Mauá and Campo Alegre. With investments of US$ 2.25 million, the work included paving, drainage, earthworks, rock blasting and track enlargement of the RJ-151, and an extension of 8.4 km. Even with Brazilian economy slowdown, the companies located in the South of Rio de Janeiro - region integrated by counties like Resende, Itatiaia, Porto Real and Volta Redonda - proceeding with their investment plans of more than US$ 3.75 billion for the period 2010-2016. It is projects like the new Nissan plant in Resende, of US$ 0.8 billion, and the expansion of the plant of PSA Peugeot Citroën, in Porto Real, US$ 1.16 billion. The number does not consider the works of Angra 3, which has received US$ 0.88 billion this year. The construction industry is one of the sectors of the economy of most impact on employment and population welfare. Investments in infrastructure and housing demand large volumes of steel (rebar for reinforced concrete CA60, CA50 and CA25, latticework frames, brackets, etc.) The civil construction shows its importance also in the economic and social aspect. Thus, the amounts of activities are part of the construction production cycle that serves the consumer goods and services for other sectors. In addition, the civil construction, from the social point of view, is a great capacity to generate jobs and labor, direct labor and indirect absorption mainly little and unskilled. The performance of construction is influenced directly and strongly by the performance of the economy, Figs. 8 to 15 [12-15].

Fig. 8. Growth (%) of establishments number by sectors of IBGE (Brazilian Institute of Geography and Statistics, in Portuguese) in the Mid-Paraíba region of Rio de Janeiro (2011).

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Fig. 9. Growth of Establishments number by IBGE Sectors in the South Central Region of the State of Rio de Janeiro (2011).

Fig. 10. Growth (%) of Establishments Number by IBGE sectors in the Costa Verde region of Rio de Janeiro State (2011).

300% 250% 200%

150% 100% 50%

-50% -100%

Porto Real Itatiaia Pinheiral Resende Quatis Volta Redonda Barra Mansa Barra do Piraí Rio Claro Piraí Valença Rio das Flores Três Rios Sapucaia Paty do Alferes Paraíba do Sul Engenheiro Paulo de Frontin Mendes Vassouras Miguel Pereira Areal Comendador Levy Gasparian Paraty Angra dos Reis Mangaratiba

00%

Fig. 11. Establishment numbers in some cities in the southern state.

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Fig. 12. Distribution (%) of Employees Number by Counties of Fluminense South Central Region of Rio de Janeiro State / IBGE Sectors (2011).

Fig. 13. Distribution (%) of Employees Number by Counties of Middle Paraiba Region of Rio de Janeiro State / IBGE Sectors (2011).

Fig. 14. Distribution (%) of Employees Number by Counties in Costa Verde region in Rio de Janeiro State / IBGE Sectors (2011).

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0.25 0.2 0.15 0.1 0.05 0

Fig. 15. Numbers of employees in some cities in the southern state. Summary. With the end of the work, it is presented by means of researches and tests, the causes of corrosion of the studied area, which are directly influenced by the location in which the buildings are, influenced by salt spray and different climates present throughout southern Rio de Janeiro. With the construction boom, it tends to be more careful with concrete for durability achieve as much as possible. References [1] Koch, G. H., Brongers, M. P., Thomson, N. G., Virmanio, Y. P., & Payer, J. H. (2005). Cost of corrosion in the United States. Handbook of environmental degradation of materials, 3-24. [2] OLIVARI, G. (2003). Patologia em edificações. São Paulo: Universidade Anhembi Morumbi. [3] V. GENTIL - Corrosão. Rio de Janeiro: LTC – Livros Técnicos e Científicos Editora, 1994. [4] Portella, K. F., Garcia, C. M., Vergés, G. R., Joukoski, A., Freire, K. R. R., & de PCorrea, A. (2006). Desempenho físico-químico de metais e estruturas de concreto de redes de distribuição de energia: Estudo de caso na região de Manaus. Química Nova, 29(4), 724. [5] Cánovas, M. F. (1988). Patologia e terapia do concreto armado. Pini. [6] Hoar, T. P., & Mears, D. C. (1966, October). Corrosion-resistant alloys in chloride solutions: materials for surgical implants. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences (Vol. 294, No. 1439, pp. 486-510). The Royal Society. [7] Marino, C., & de Titânio, Ó. A. (1997). um estudo do crescimento e estabilidade em meio ácido. 1997. 135f (Doctoral dissertation, Dissertação (Mestrado em Físico-Química)–Universidade Federal de São Carlos, São Carlos). [8] Silva, L. L. G. (2001). Eletrodos em diamante CVD para estudos eletroquímicos. Eletrodos em diamante CVD para estudos eletroquímicos. [9] de Macena Rezende, D. (2014). ESTUDO DA FRAGILIZAÇÃO PELO HIDROGÊNIO NO AÇO SUPER 13Cr MODIFICADO (Doctoral dissertation, Departamento de Engenharia Metalúrgica e de Materiais da Escola Politécnica, Universidade Federal do Rio de Janeiro). [10] Greaney, M. J., Das, S., Webber, D. H., Bradforth, S. E., & Brutchey, R. L. (2012). Improving open circuit potential in hybrid P3HT: CdSe bulk heterojunction solar cells via colloidal tertbutylthiol ligand exchange. Acs Nano, 6(5), 4222-4230. MMSE Journal. Open Access www.mmse.xyz

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[11] Lins, L. M., Salerno, M. S., Araújo, B. C., Gomes, L. A. V., Nascimento, P. A. M. M., & Toledo, D. (2014). Escassez de engenheiros no Brasil? Uma proposta de sistematização do debate. Novos Estudos-CEBRAP, (98), 43-67. [12] Sociais, R. A. D. I. Ministério Do Trabalho E Emprego (RAIS/MET). 2006-2011. Base de Dados. [13] Sawacha, E., Naoum, S., & Fong, D. (1999). Factors affecting safety performance on construction sites. International journal of project management, 17(5), 309-315. [14] Porter, M. (2003). The economic performance of regions. Regional studies, 37(6-7), 549-578. [15] Leiblein, M. J., Reuer, J. J., & Dalsace, F. (2002). Do make or buy decisions matter? The influence of organizational governance on technological performance. Strategic management journal, 23(9), 817-833. Cite the paper Carolina Lacerda da Cruz, Thalita Gonçalves de Lima, Nilo Antônio S. Sampaio, José Wilson de Jesus Silva (2016). Statistical Study of Corrosion Types in Constructions in South Region of Rio De Janeiro – Brazil. Mechanics, Materials Science & Engineering, Vol 7. doi: 10.13140/RG.2.2.29609.60004

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Influence of the Composition of (TlGaS2)1-х(TlInSe2)x Alloys on Their Physical Properties4 Mustafaeva S.N.1,a, Jafarova S.G. 1, Kerimova E.M. 1, Gasanov N.Z. 1, Asadov S.M.2 1 – Institute of Physics, National Academy of Sciences of Azerbaijan, AZ–1143, G. Javid Pr., 131, Baku, Azerbaijan 2 – Institute of Catalysis and Inorganic Chemistry, National Academy of Sciences of Azerbaijan, AZ–1143, G. Javid Pr., 113, Baku, Azerbaijan a – solmust@gmail.com DOI 10.13140/RG.2.2.29609.600

Keywords: TlGaS2, TlInSe2, alloys physical properties, roentgensensitivity, photoresistors.

ABSTRACT. The single crystals of (TlGaS2)1-х(TlInSe2)х (х = 0–0,5) solid solutions have been grown up. The photoelectric, roentgendosimetric, dielectric and optical characteristics of the (TlGaS 2)1-х(TlInSe2)х solid solutions with various compositions have been determined. The maximum and spectral range of photosensitivity were found to redshift as x increases from 0 to 0.5. Both the photo- and roentgensensitivity of the solid solutions are higher than those of pure TlGaS2. The nature of dielectric losses and the hopping mechanism of charge transport in the (TlGaS 2)1-х(TlInSe2)х solid solutions were established from the experimental results on high-frequency dielectric measurements. The temperature dependences of exciton peak position for various compositions (x = 0-0.3) are investigated in 77-180 K temperature interval. It was established that with increasing x in (TlGaS2)1-х(TlInSe2)х solid solutions the width of their forbidden gap decreases.

PACS: 71.20.Nr; 71.35.Cc; 72.15.Rn; 72.20.Ee; 72.20.Jv; 72.30.+q; 72.40.+w; 73.20.At Introduction. Ternary layer-chain TlGaS2 and TlInSe2 single crystals exhibit high photo- and roentgensensitivity making them well-suited for photoresistors and roentgendetectors [1-4]. The study of physical properties of the TlGaS2, TlInSe2 compounds and solid solutions on their base are very important for establishing the relations between their compositions and properties. This offers the possibility of controlling the band gap, energy position of emission bands and electrical conductivity of such semiconductors. In [5-7] the results of investigation of ac – electric and dielectric properties of TlGaS2, TlInSe2 and diluted (TlGaS2)1-х(TlInSe2)х solid solutions (x = 0.005 and 0.02) are given. The purpose of present work was to investigate the influence of (TlGaS2)1-х(TlInSe2)х solid solutions compositions (x = 0-0.5) on their photo- and roentgensensitivity, ac – electric, dielectric and optical properties. Experiment. The synthesis of (TlGaS2)1-х(TlInSe2)х solid solutions was carried out in an ampule evacuated to pressure 10-3 Pa. The ampule was fabricated from a fused silica tube. In this case, (TlGaS2)1-х(TlInSe2)х samples were prepared through the interaction of initial components (TlGaS2 and TlInSe2). In order to prevent the ampule filled with reactants from explosion, the furnace temperature was raised to the melting temperature of selenium (T = 493 K) and the ampule was held at this temperature for 3h. Then, the furnace temperature was raised to T = 1080 K at a rate of 50 K/h and the ampule was held at this temperature for 4 h, after which it was cooled to 300 K at a rate of 20 © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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K/h. Phase purity of (TlGaS2)1-х(TlInSe2)х was established by differential thermal analysis and powder X-ray diffraction. Each sample was used as the charge for Bridgman crystal growth. The crystal data for (TlGaS2)1-х(TlInSe2)х are presented in the Table 1. Table 1. Crystal data for TlGaS2 and (TlGaS2)1-х(TlInSe2)х. Solid solution composition

а(Å)

b(Å)

c(Å)

, deg

Sp.gr.

TlGaS2

10.40

15.17

100.06

P21/n

(TlGaS2)0.9(TlInSe2)0.1

10.40

15.18

100.06

P21/n

(TlGaS2)0.8(TlInSe2)0.2

10.41

15.18

100.06

P21/n

(TlGaS2)0.7(TlInSe2)0.3

10.43

15.181

100.06

P21/n

(TlGaS2)0.6(TlInSe2)0.4

10.435

15.20

100.06

P21/n

(TlGaS2)0.5(TlInSe2)0.5

10.452

15.245

100.06

P21/n

The spectral characteristics were recorded with a GIBI-TIBI potentiometer; the samples were illuminated with a 400-W incandescent lamp through a DMR-4 monochromator. In roentgendosimetry measurements, we used a URS-55 X-ray generator. The variation in sample resistance under X-ray irradiation was followed with an R-4053 bridge. X-ray dose rates were measured with a DRGZ-02 dosimeter. Measurements of the dielectric properties of (TlGaS2)1-х(TlInSe2)х (x = 0.1; 0.2) single crystals were performed at fixed frequencies in the range 5×104–3.4×107 Hz by the resonant method using a TESLA BM560 Qmeter. The single-crystal samples for dielectric measurements had the form of planar capacitors normal to the C- axis of the crystals, with silver-paster electrodes. The thickness of the crystal samples was 90–120 µm, and the area of the capacitor plates was 8×10-2–2×10-1 cm2. All dielectric measurements were performed at T = 300 K. The accuracy in determining the resonance capacitance and the quality factor Q=1/tanδ of the measuring circuit was limited by errors related to the resolution of the device readings. The accuracy of the capacitor graduation was ±0.1 pF. The reproducibility of the resonance position was ±0.2 pF in capacitance and ±(1.0–1.5) scale divisions in quality factor. The largest deviations were 3–4% in ε and 7% in tan δ. Optical absorption spectra were measured using samples in the form of platelets 10–100 µm thick, cleaved from the single-crystal ingots. Light was incident along the normal to the layers of the samples, that is, along the crystallographic axis C of the crystals. Optical transmission spectra were measured as functions of temperature using an experimental setup built around a KSVU-6M system and UTREKS helium cryostat, which ensured temperature stabilization with an accuracy of ± 0.01 K. The setup included an MDR-6 double monochromator and FEU-100 photomultiplier tube. The spectral resolution of the experimental configuration was = 2 Å. Results and discussion. We measured the spectral dependences of photoconductivity and photosensitivity Rd/Rph (Rd is the dark resistance, and Rph is the resistance of the sample under abovegap illumination) at a steady illumination, as well as the roentgensensitivity and other photoelectric parameters. Table 2 and fig.1 give the photoelectric properties of the (TlGaS 2)1-х(TlInSe2)х solid solutions.

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Table 2. Photoelectric and roentgendosimetric characteristics of the (TlGaS2)1-х(TlInSe2)х solid solutions. Solid solution composition TlGaS2 (TlGaS2)0.9(TlInSe2)0.1 (TlGaS2)0.8(TlInSe2)0.2 (TlGaS2)0.7(TlInSe2)0.3 (TlGaS2)0.6(TlInSe2)0.4 (TlGaS2)0.5(TlInSe2)0.5

∆λmax, µm 0.46-0.57 0.50-0.62 0.55-0.66 0.59-0.71 0.64-0.76 0.69-0.81

Rd, Ohm (3-5)×1010 (1-2)×1010 (3-4)×109 (2-3)×108 (1-2)×107 (3-5)×106

Rd/Rph at 200 lx 5-8 10-25 15-30 21-37 23-42 25-46

K, min/R 0.063-0.159 0.075-0.178 0.089-0.198 0.098-0.213 0.107-0.219 0.142-0.252

From fig. 1 one can see, that the photosensitivity maximum (λmax) linearly shifts from 0.50 to 0.73 µm as x increases from 0 to 0.5. This shift is associated with a decrease in the band gap with increasing x. Increasing x leads to a redshift of the sensitivity range ∆λ and a considerable rise in Rd/Rph at 200 lx. For example, the Rd/Rph of (TlGaS2)0.5(TlInSe2)0.5 is 5 to 6 times greater than that of pure TlGaS2 (table 2). The rise in Rd/Rph with increasing x is apparently related to an increase in both the lifetime and mobility of the photogenerated carriers.

Fig. 1. Composition dependence of the photosensitivity maximum in (TlGaS2)1-х(TlInSe2)х solid solutions. Roengenosensitivity K of (TlGaS2)1-х(TlInSe2)х was characterized by relative change in conductivity per unit dose rate,

K 

 E ,0

0  E

(1)

where 0 – is the conductivity of the unirradiated crystal; ∆E,0 = E – 0 is the change in the conductivity under X-ray irradiation with dose rate E (R/min). Table 2 lists K values at accelerating voltages from 25 to 30 keV and dose rates from 0.75 to 10 R/min. One can see that the K of (TlGaS2)1-х(TlInSe2)х solid solutions exceeds that of pure TlGaS2. As the TlInSe2 content increases, K rises to 0.142–0.252 min/R at x = 0.5. MMSE Journal. Open Access www.mmse.xyz

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We measured also the electric capacitance of (TlGaS2)0.9(TlInSe2)0.1 and (TlGaS2)0.8(TlInSe2)0.2 samples in the frequency range 5×104–3.4×107 Hz. Using the measured capacities of these samples, we calculate the permittivity ε at different frequencies. The ε values of (TlGaS2)1-х(TlInSe2)х single crystals vary from 9.5 to 12.7 for x = 0.1 and from 9.8 to 11.6 for x = 0.2 over the entire frequency range studied, with no significant dispersion (the ε of TlGaS2 single crystal, as it was shown in [5], varies from 26 to 30 at f = 5×104–3×107 Hz). In contrast to what was reported for TlGaS2 [5], the frequency dependences of the loss tangent for the (TlGaS2)1-х(TlInSe2)х (x = 0.1; 0.2) single crystals have maxima, which points to relaxation losses [8]. The ac-conductivity of investigated samples varies as f 0.8 at f = 5×104–2×106 Hz for x = 0.1 and at f = 5×104–6×106 Hz for x = 0.2. At more high frequencies ac(f) – dependence of these crystals was superlinear (~f 1.4). The ac~ f 0.8-dependence indicates that the mechanism of charge transport is hopping over localized states near the Fermi level [9].

   3  ac ( f )   e 2 kTNF2 a 5 f ln ph  96  f 

(2)

where e – is the elementary charge; k – is the Boltzmann constant; NF – is the density of localized states near the Fermi level; a = 1/α – is the localization length, α is the decay parameter of the wave function of a localized charge carrier, ψ ~ e-αr; νph – is the phonon frequency. Using expression (2), we can calculate the density of states at the Fermi level from the measured values of the conductivity σac(f). Calculated values of NF for (TlGaS2)1-х(TlInSe2)х solid solutions (x = 0.1; 0.2) single crystals were given in Table 3 (localization radius is chosen as 14 Å, in analogy with the TlGaS2 single crystal [5]). Table 3. Parameters of (TlGaS2)1-х(TlInSe2)х single crystals obtained from high- frequency dielectric measurements. Crystal composition TlGaS2 (TlGaS2)0.9(TlInSe2)0.1 (TlGaS2)0.8(TlInSe2)0.2

NF, eV-1cm-3 2.1×1018 6.8×1018 7.7×1018

τ, s 2×10-6 9.8×10-7 3.3×10-7

R, Å 103 98 90

Nt, cm-3 4.2×1017 5.1×1017 6.5×1017

According to the theory of hopping conduction we calculate the mean hop distance (R) and mean hop time (τ) in an applied ac-electric field using the formula [9]:

 1   ph exp  2R 

(3)

where R – is the average hopping distance.

R

1  ph ln 2 f

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(4)

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

These values also are presented in the table 3. Knowing NF and R from [9]:

4 3 E R NF  1 3 2

(5)

We estimate energetic scattering of trap states near the Fermi level (E): E = 0.075 eV for x = 0.1 and 0.085 eV for x = 0.2. Evaluated concentrations of deep traps determining the ac-conductivity of (TlGaS2)1-х(TlInSe2)х single crystals ( Nt  N F  E ) are given in last column of the table 3. It is seen from the table 3 that with increasing of x from 0 to 0.2 in (TlGaS2)1-х(TlInSe2)х single crystals the values of NF and Nt increased, but R decreased. Optical properties of (TlGaS2)1-х(TlInSe2)х (x = 0–0.3) single crystals have been studied in 77–180 K temperature interval. The thicknesses of crystals under study were 20–50 µm. Light was incident on the crystals in direction parallel to their crystallographic axis C. The present data on the optical properties of the (TlGaS2)1-х(TlInSe2)х demonstrate that, at temperatures from 77 to 180 K crystals have an absorption band near fundamental absorption edge, which is due to transitions to a direct exciton state. We examined the temperature dependence of the energy position of the exciton peak for (TlGaS2)1-х(TlInSe2)х crystals in the temperature range 77– 180 K (fig. 2). It is seen that the peak position of the exciton band of (TlGaS 2)1-х(TlInSe2)х solid solutions has a positive temperature coefficient. Given that the exciton energy is a weak function of temperature, this indicates that the band gap of (TlGaS2)1-х(TlInSe2)х crystals increases with temperature.

Fig. 2. Temperature dependences of the energy position of the exciton peak at the absorption edge of (TlGaS2)1-х(TlInSe2)х solid solutions: (1) x = 0; (2) x = 0.02; (3) x = 0.1; (4) x = 0.2; (5) x = 0.3. The temperature variation of the band gap of semiconductors Eg, is known to be determined by a combined effect of the thermal expansion of their lattice and electron-phonon interaction. Semiconductors rarely have a positive temperature coefficient of their band gap. In particular, such an experimental fact in TlGaS2 and TlGaS2-based single crystals [10, 11] is thought to be caused by the significant contribution of the thermal expansion of their lattice to the temperature variation of Eg. Thus, the TlGaS2 and (TlGaS2)1-х(TlInSe2)х crystals were found to be similar in the structure of their absorption edge, formed by direct interband transitions. MMSE Journal. Open Access www.mmse.xyz

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Summary. The results of photoelectric, roentgenodosimetric and high-frequency dielectric measurements on obtained (TlGaS2)1-х(TlInSe2)х solid solutions provided an opportunity to increase photo- and roentgenosensitivity, to determine the mechanism of dielectric losses and charge transport, and also to evaluate the density of localized states at the Fermi level, the average time of charge carrier hopping between localized states, average hopping distance, scattering of trap states near the Fermi level and concentration of deep traps responsible for ac-conductivity. The temperature dependences of exciton peak position for (TlGaS 2)1-х(TlInSe2)х solid solutions were investigated in 77–180 K temperature interval. It is established that the edge of optical absorption of these solid solutions is formed by straight line exciton with the positive temperature coefficient. References [1] Mustafaeva, S.N., Kerimova, E.M., Ismailova, P.G., and Asadov, M.M., Roentgendosimetric characteristics of detectors on the base of TlGaS2〈Yb〉 single crystals, Fizika, 2004, no. 4, p. 108. [2] E.M. Kerimova, S.N.Mustafaeva, Yu.G.Asadov, R.N.Kerimov. Synthesis, growth and properties of TlGa1– xYbxS2 crystals, Crystallography Reports, 2005, V.50, Suppl. 1, P.S122–S123. [3] S.N. Mustafaeva, Photoelectric and x-ray dosimetric properties of TlGaS2〈Yb〉 single crystals Physics of the Solid State, 47, 2015 (2005), doi:10.1134/1.2131137 [4] S.N. Mustafaeva, E.M. Kerimova, M.M. Asadov, R.N. Kerimov, Roentgenodetectors on the base of TlInSe <Li+>, Fizika, Vol. 9, 62 (2003). [5] S.N. Mustafaeva, Frequency dispersion of dielectric coefficients of layered TlGaS single crystals Physics of the Solid State, Vol. 46, 1008 (2004). [6] S.N. Mustafaeva, Frequency dependence of real and imaginary parts of complex dielectric permittivity and conductivity of TlInSe single crystal at relaxation processes, Journal of Radioelectronics, 7, 8 (2013). [7] Mustafaeva, S.N. Frequency effect on the electrical and dielectric properties of (TlGaS2)1- x(TlInSe2)x (x = 0.005, 0.02) single crystals, Inorg Mater (2010) 46: 108. doi:10.1134/S0020168510020032 [8] V.V. Pasynkov, V.S. Sorokin, Materials of electron techniques, Sankt-Petersburg- Moscow, 2004.368 p. [9] N. Mott and E. Davis, Electron processes in noncrystalline materials, Clarendon Press, Oxford, 1971. 472 p. [10] Mustafaeva, S.N., Asadov, M.M., Kyazimov, S.B. et al. T-x phase diagram of the TlGaS2-TlFeS2 system and band gap of TlGa1 − xFexS2 (0 ≤ x ≤ 0.01) single crystals, Inorg Mater (2012) 48: 984. doi:10.1134/S0020168512090117. [11] Mustafaeva, S.N., Asadov, M.M., Kerimova, E.M. et al. Dielectric and optical properties of TlGa1−xErxS2 (x = 0, 0.001, 0.005, 0.01) single crystals, Inorg Mater (2013) 49: 1175. doi:10.1134/S0020168513120121 Cite the paper Mustafaeva S.N., Jafarova S.G., Kerimova E.M., Gasanov N.Z., Asadov S.M. (2016). Influence of the Composition of (TlGaS2)1-х(TlInSe2)x Alloys on Their Physical Properties. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.29609.600

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Enhancement of Optical and Thermal Properties of γ- Glycine Single Crystal: in the Presence of 2-Aminopyridine Potassium Chloride5 R. Srineevasan1,а, D. Sivavishnu1, K. Arunadevi1, R. Tamilselvi1, J. Johnson1, S. M. Ravi Kumar1 1 – P. G & Research Department of Physics, Government Arts College, Tiruvannamalai, 606603, India а – rsrinee61@gmail.com DOI 10.13140/RG.2.2.33138.654

Keywords: slow evaporation, single crystal, NMR spectrum, TGA-DTA, SHG efficiency. ABSTRACT. In this research paper, an overview of polymorph γ-form glycine single crystal crystallization in the presence of 2-aminopyridine potassium chloride as an additive at an ambient temperature by slow evaporation solution growth technique (SEST) has been presented. FTIR and NMR studies confirm the presence of functional groups in the grown crystal. In the UV–Visible NIR optical absorption spectral studies from 200 nm to 900 nm, the observed 0% absorption with lower cutoff wave length at 240 nm and high band gap (5. 5eV) enabled enhanced linear optical properties. Powder XRD study confirms crystalline nature of the grown γ-glycine crystal. The single crystal XRD study shows that the grown crystal possesses hexagonal structure and belongs to space group P31 with the cell parameters a=7. 09 Å; b=7. 09; c=5. 52 Å; α = β = 90˚; and γ = 120˚. Thermal studies have been carried out to identify the elevated thermal stability and decomposition temperature of the grown sample. Dielectric studies of as grown γ-glycine crystal exhibit low dielectric constant at higher frequencies, which is most essential parameters for nonlinear optical applications. Enhanced SHG efficiency of the grown crystal was confirmed by the Kurtz powder technique using Nd:YAG laser and found 1. 6 times greater than that of inorganic standard potassium dihydrogen phosphate.

1. Introduction. Highly polarizable conjugated system of organic molecule possesses non-centro symmetry structure and the inorganic molecule (anion), linking through hydrogen bond with organic molecule (cation) yields strong mechanical and high thermal stability [1, 2]. Molecular charge transfer induced in semiorganic complex by delocalized π electron, such that moving between electron donor and electron acceptor which are in opposite sides of the molecules [3, 4]. In the base acid interaction of organic and inorganic molecules, there is a high polarizable cation derived from aromatic nitro systems, linked to the polarizable anion of inorganic molecules through hydrogen bond network yields a noncentrosymmetric structural systems and this hydrogen bonding energy between organic and inorganic molecules made the dipole moment in parallel fashion ensures the increase of second harmonic generation activity [5]. The structures of 2-aminopyridine complexes have already been studied by Chao and his co-workers [6]. In recent years metal organic complexes have been played reasonable attention in advancement of technology [2,7]. Growth of 2-aminopyridine complex crystals is widely used in the rapid advancement in technology, such as ultra-fast phenomena, optical communication and optical storage devices , frequency doublers and optical modulators [8]. Optical properties of 2-aminopyridine complexes and their suitability for optoelectronic devices have been reported [9-14]. Metal organic nonlinear optical crystals possess good second harmonic generation efficiency, hence rich demand in optical storage devices, color display units and optical communication systems [7]. Recent research focus is on designing of new materials capable of attaining SHG processes by strong interaction with an oscillating field of light. Amino acids with ionic salt complex crystals have been investigated and recognized as materials having good nonlinear optical properties [1,3,15-17]. In this present work, synthesis and crystallization of glycine into γ© 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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form glycine in the presence of aqueous solution 2-aminopyridine potassium chloride and their suitability for device fabrication with various enhanced optical and thermal properties are reported. 2. Experimental Procedure 2. 1 Material synthesis The title compound was synthesized by taking analytical grade glycine, 2-aminopyridine and potassium chloride in the stoichiometric ratio (1:1:1) with Millipore water of resistivity 18. 2 megaohm. cm-1 as a solvent. In this synthesis, protonation of nitrogen in pyridine ring facilitates hydrogen bonding interaction between potassium chloride and glycine such that 2-aminopyridine is linked to the metal K+ ion through pyridine ring nitrogen, rather than amino group nitrogen leaving (Cl)- ion [18]. C5 H6 N2 + KCl + NH2 CH2 COOH → [(K+) + C5H6N2 COOCH2 NH2 (Cl)–] [(2-aminopyridine) + (potassium chloride) + (glycine)]→ [(γ-glycine crystal)] Amino group hydrogen in 2-aminopyridine coordinates through hydrogen bond with carboxylic groups of monoprotonated glycinium ion. Stacking of γ- glycine crystal one over the other is shown in figure 1.

Fig. 1. Scheme of as grown γ-glycine crystal. 2. 2 Solubility study of γ-glycine in the presence of 2-aminopyridine potassium chloride Solubility is an important parameter, which dictates the crystal growth process. The solubilities of the title compound in aqueous medium were estimated in the temperature range between 25 and 50˚C. Neither a flat nor a steep solubility curve and less viscous solution enabling the faster transfer of the growth units by diffusion of the title compound, enables the growth of bulk crystals from solution. Variations in solubility at different temperatures is plotted in figure 2. The moderate variations in solubility indicate the reasonable growth rate of title compound along all crystallographic directions. MMSE Journal. Open Access www.mmse.xyz

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2-APKCG

Solubility (g/100 ml)

16 14 12 10 8 6 4 2 25

Temperature ( C)

Fig. 2. Solubility curve of title compound at different temperatures. 2. 3 Crystal Growth The prepared mother solution was stirred vigorously for 4h using magnetic stirrer. High degree of purification of synthesized salt was achieved by successive recrystallization process. Synthesized saturated solution was filtered using filter paper of micron pore size. The filtered solution was pored in different petri dishes and covered with porous paper for slow evaporation. After a time span of 15 days, quality crystals of average size 13mm x 12mm x 3mm were harvested. The grown crystal is shown in figure 3.

Fig. 3. Grown γ-glycine crystal. 3. Results and discussion The as grown γ-glycine crystal was subjected to FTIR analysis using PERKIN ELMER SPECTRUM RX1 Fourier Transform infrared spectrometer. 1H NMR and 13C NMR spectroscopic studies were done by a Bruker Advance III 500MHz FTNMR spectrometer using D2O as solvent to identify the functional groups. The transmission behavior was studied by using LAMBDA-35 UV-VIS Spectrophotometer. Single crystal and powder XRD analysis were carried out on a PHILIPS X PERT MPD system. TGA and DTA analysis were carried out using NETZSCA STA 409 instrument at a heating rate of 20°C min-1 from ambient to 500°C. Dielectric studies were carried out by using HIOKI 3532 HiTESTER LCR meter. The NLO efficiency of the grown crystal was tested by KURTZ powder technique using Nd: YAG laser of wavelength 1064 nm. MMSE Journal. Open Access www.mmse.xyz

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3. 1 Fourier Transform Infrared (FTIR) analysis The as grown γ-glycine crystal was subjected to FTIR analysis by KBr pellet technique in the wavelength between 4000 and 400 cm-1. The recorded absorption spectrum of title compound confirms the presence of various functional groups and their frequency assignments are shown in figure 4. The doublet frequency 928. 06 and 888. 46 cm-1 clearly shows the γ- glycine formation [19]. The vibrational frequencies are assigned with structure as shown in Table 1. Table 1. Frequency of the vibrations and their assignment of as grown γ-glycine crystal. Frequency in wave number (cm-1)

Assignment of vibration NH3+ Stretching

3105. 77 2887, 2604

Aliphatic CH2 Stretching NH3+ Stretching

1586. 84

NH2+ Bending

1492. 95

COO - Symmetric Stretching

1327. 82

CH2 Twisting

1126. 21

NH2+Rocking

1041. 67

C-N Stretching

928. 06

CH2 Rocking

888. 46

C-C-N Symmetric Stretching

683. 10

COO - Bending

502. 87

COO - Rocking

3500

3000

2500 2000 Wavenumber cm-1

1500

Fig. 4. FTIR spectrum of the grown γ-glycine crystal. C:\Documents and Settings\All Users\Desktop\MEAS\.5

srini 7

Instrument type and / or accessory

1000

502.87 452.34 412.37

683.10

928.06 888.46

1041.67

1126.21

1393.84 1327.82

1492.95

1586.84

2171.48

2360.74

2604.48

2887.67

3105.77

Transmittance [%] 50 60 70

100

2171. 48

500

19/12/2011

Page 1/1

3.2 NMR spectrum H NMR and 13C NMR analysis of the as-grown γ-glycine crystal were shown in figure 5 & 6. 1H NMR spectrum of as-grown γ-glycine crystal showed multiple peak signals at δ 3. 461 to 3. 445 ppm (quartet or triplet) corresponds to protons of methylene group (CH2) and peak at δ 4. 678 ppm due to amino group protons (NH2). 13C NMR spectrum of as-grown γ-glycine crystal showed peaks at δ 41. 1

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429 ppm and δ 172. 41 ppm corresponding to methylene carbons and carbonyl carbon respectively. All the above results support the true chemical reactions in the formation of the γ-glycine crystal.

Fig. 5. 1H NMR of γ-glycine crystal.

Fig. 6. 13C NMR of γ-glycine crystal. 3.3 UV- Visible spectral analysis The optical properties of the crystals are mainly depending on the interaction between crystal and components of electric and magnetic fields of the electromagnetic wave. UV-Visible absorption spectrum of the grown crystal recorded in the wave length range 200-900 nm was shown in figure 7. The grown crystal has good transmission (100%) in UV, Visible and IR region. This highest transmission percentage (100%) clearly shows the intrinsic property of amino acid and their defect less nature of the grown γ-glycine crystal [20]. The absorption spectrum shows that the grown crystal has lower cut off wavelength at 240 nm and this characteristic is most favorable for nonlinear optical materials. Lower cut off wavelength value of the γ-glycine crystal (240nm) is compared with Glycine potassium chloride (GPC), Serine sodium chloride (SSC), Bis glycine Maleate, Pure Glycine, Glycine potassium sulphate (GPS), and Glycine picrate as shown in Table 2. This observed decreasing lower cutoff wavelength value of the as grown crystal is due to the addition of 2-aminopyridinium potassium

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chloride. Hence the lower cut off wave length of as grown crystal can be suitably used for optoelectronic application in the UV, Visible and IR range. Table 2. Comparison of cutoff wave length. Crystals Name

Cutoff wave length(nm)

GPC

295

SSC

300

Bis glycine Maleate

330

Pure Glycine

346

GPS

384

Glycine picrate

450

γ- glycine crystal*

240

*present work 3.5

Absorbance (a.u)

3.0 2.5 2.0 1.5 1.0 0.5 0.0 200

300

400

500

600

700

800

900

Wavenumber (nm)

Fig. 7. UV-Visible absorption spectrum of grown crystal of γ-glycine. Since optical properties of the crystals are governed by the interaction between the crystal and the electric and magnetic fields of the electromagnetic wave, transmittance (T) was used to calculate the absorption coefficient (α) using the formula:

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300

200

(alpha.hv) .ev .mm

250

150

100

Eg=5.5 ev

0 1

hv ev

Fig. 8. Plot of hυ versus (αhυ)2 of as grown γ-glycine crystal.

Where t is the thickness of the sample. The optical band gap (Eg) was evaluated from the transmission spectra and the optical absorption coefficient (α) near the absorption edge is given by [21]. αhυ=A(hυ-Eg)1/2 where A – constant; Eg – the optical band gap; h – the Plank’s constant; υ – the frequency of the incident photons. The graph drawn between hυ (E=hυ) and (αhυ)2 is used to estimate the direct band gap value of the grown crystal as shown in figure3. 5. The band gap of γ-glycine single crystal was estimated by extrapolating the linear portion near the onset of absorption edge to the E=hυ axis. From the figure 8, the optical band gap value is calculated to be 5. 5 eV. The wide band gap of the as grown γ-glycine crystal confirms the 100% transmittance in the UV-vis-NIR region and less defect concentration of the grown crystal [22]. The observed lower cutoff wavelength 240 nm of the as grown γ-glycine due to the addition of 2-aminopyridinium potassium chloride leads to an increase in the band gap of the grown γ-glycine crystal 5. 5 eV. Intraction of electromagnetic wave with high band gap materials ( ˃ 1 eV known as Wide-bandgap) create a bound electron–hole pair, which can permit devices to operate at much higher voltage, temperature and frequency applications. Also this high band gap material brings the electronic transition in the range of the energy of visible light as light-emitting diodes even blue LEDs or even produce ultraviolet LEDs with wavelengths down to 200–250 nm and lasers. 3.4 Powder XRD studies The grown γ-glycine crystal crushed to a uniform powder and subjected to powder x-ray diffractrometer with CuKα (λ=1. 540598 Å) radiations for structural analysis study. The powder form sample was scanned over the range 10-45˚ at the rate of 2˚/min. The indexed powder XRD pattern of grown crystal is shown in figure 9. Peaks in the XRD without any broadening confirm that the grown sample is higher order of crystalline nature. MMSE Journal. Open Access www.mmse.xyz

(102)

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600

(031)

2-APKCG

400

(211)

(300)

(002) (112)

(210)

(002)(201) (201)

(112)

(120)

100

(200) (111)

(110)

(100)

(002)

(012)

200

(101)

300

(010)

(001)

(011)

Intensity (a.u)

500

0 10

Diffraction angle,2 (deg)

Fig. 9. Powder XRD pattern of as grown crystal γ-glycine. 3.5 Single crystal XRD analysis Single crystal X-ray diffraction analysis confirms the hexagonal structure of the γ-glycine crystal with space group P31. The unit cell parameters of the grown γ-glycine are a = 7.09Å; b = 7.09Å; c = 5.52Å; α = β = 90˚; γ = 120˚ and volume of the unit cell was found to be 278 Å3. These values are in-line with the literature values [23-25]. Further, it is evident that the presence of 2-aminopyridine potassium chloride in the aqueous solution, without enter into the grown crystal lattice, yields the polymorph form γ-glycine, as a physical change. 3.6 Thermal analysis Thermo gravimetric (TG) and Differential thermal analysis (DTA) gives information regarding phase transition, water of crystallization and different stages of decomposition of the crystal. Samples of γglycine crystals were weighed in an Al2O3 crucible with a microprocessor driven temperature control. TGA and DTA curves of grown crystals were recorded in nitrogen atmosphere between ambient temperature to 500˚C shown in figure 10. There is no weight loss up to 216.6˚C indicating that there is no inclusion of solvent (water) in the crystal lattice. The thermogram reveals that the major weight loss (42. 4%) starts at 216.6˚C and continues up to 484.4˚C with 1.255mg (57. 6%) as residue. The nature of weight loss indicates the decomposition of the material. Below 484.4˚C no weight loss was observed. DTA curve shows that the decomposition point of as grown γ-glycine crystal is 270˚C. This decomposition point was compared with the decomposition point of pure γ-glycine crystal (246˚C) and γ-glycine synthesizes in the presence of different additives are shown in Table 3. 3. 7 Dielectric studies Cut and polished samples were used as a dielectric material, which is placed between two copper electrodes of parallel plate capacitor. To ensure the good electrical conductivity to electrodes graphite was coated on opposite side of the sample.

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216.6Cel 2.838mg

1.583mg 2.800 55.4%

95.0

484.4Cel 2.600 2.838mg

30.00 90.0

85.0

2.400

20.00 80.0

2.200 10.00

70.0

2.000

TG mg

DTA uV

TG %

75.0

609uV.s/mg 65.0 0.00

1.800

60.0

55.0

1.600 -10.00

50.0

45.0

1.400 -20.00

484.4Cel 1.200 1.255mg 100.0

200.0

300.0

400.0

500.0

Temp Cel

Fig. 10. TGA& DTA graph of as grown γ-glycine crystal. Table 3. comparison of decomposition point. γ-glycine crystal

Decomposition point

In the presence of CoCl

116. 86 ˚C [26]

In the presence of CaCl2

265 ˚C [27]

In the presence of AgNO3

208 ˚C [28]

In the presence of Li NO3

195 ˚C [29]

In the presence of LiBr

200 ˚C [30]

In the presence of NH3

145. 7 ˚C [31]

In the presence of NaNO3

256 ˚C [32]

In the presence of MgCl2

213 ˚C [33]

In the presence of KCl

170 ˚C [34]

In the presence of KF

259 ˚C [25]

In the presence of HF

240 ˚C [35]

In the presence of H3PO3 &

51 ˚C [36]

In the presence of H3PO3 + Urea

155 ˚C [36]

In the presence of C5H6N2+KCl (present work)

270 ˚C

The capacitance of the grown crystal was measured in the frequencies range between 500H Z to 5MHZ for different temperatures. The formula used to calculate dielectric constant is, Ɛr= Ct/ƐOA where C – is the capacitance; t-thickness of the sample; MMSE Journal. Open Access www.mmse.xyz

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Ɛo – the permittivity of the free space and A-the area of cross section. The graph shown in fig 8, shows the variation of Ɛr Vs frequency for the grown γ-glycine crystal at different temperature. The dielectric constant value increases at low frequency region and then dielectric constant value decrease with the increasing frequency. The Ɛr value reached the least value of about 250 at the applied frequency of 2 KHZ and the value remains constant for further frequency. A similar trend was observed for all the recorded temperatures and is compared with previous research report which is shown in table 4. Among the all four polarizations, electronic and space charge polarizations are predominant in the low- frequency region. The characteristic of low dielectric constant at higher frequency evident that the γ-glycine possesses an improved optical quality with lesser defects and this dielectric property is most important for nonlinear optical materials and their applications. 7000 o

40 o 45 o 50 o 55 o 60

6000

Dielectric Constant r

5000

C C C C C

4000 3000 2000 1000 0 2

Log f

Fig. 11. Dielectric behavior of γ-glycine crystal. Table 4. Comparision of dielectric constant. Crystal

Dielectric constant

2APTZS

2.5[37]

2APKSNG

3.5[38]

3.8 NLO studies In order to confirm the NLO property, powdered sample of grown crystal was subjected to KURTZ and PERRY powder technique, which is a powerful tool for initial screening of the materials for second harmonic generation (SHG) [39]. The beam of wave length λ =1064 nm from Q-switched Nd:YAG laser was made to fall normally on the prepared powdered sample of grown γ-glycine crystal, which was packed between two transparent glass slides. Suitable solution (CuSO4) was used to absorb the transmitted beam and the optical second harmonic signal was detected by a photomultiplier and displayed on CRO. Here powder form of KDP crystal of identical size to grown γ-glycine crystal powder particles were used as standard in the SHG measurement. The SHG behavior was confirmed from the emission of bright green radiation (532nm) by the sample. The measured amplitude of second harmonic green light for as grown γ-glycine crystal was 14.9mJ as against 8.8mJ of KDP and 8.9mJ of UREA. MMSE Journal. Open Access www.mmse.xyz

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The enhanced powder SHG efficiency of as grown γ-glycine crystal is about 1.65 times that of KDP and 1.63 times of UREA. This value is relatively high when compared to the SHG values reported for γ-glycine crystals grown with other additives and comparision is given in Table 5. This enhanced lasing performance of as grown γ-glycine crystal is due to the additive influence of 2aminopyridinium potassium chloride. The good second harmonic generation efficiency of as grown γ-glycine crystal in the presence of 2-aminopyridine potassium chloride attests, that the grown crystal is a potential candidate for nonlinear optical applications. Table 5. Comparision of SHG efficiency of γ-glycine crystals. γ-glycine crystal

# SHG efficiency

In the presence of NaF

1.3[40]

In the presence of NaOH

1.4[40]

In the presence of NaCl/KCl

1.5[41]

In the presence of NaCH2COOH

1.2[41]

*In the presence of C5H6N2+KCl

1.65

*Present work, # With reference to KDP Summary. We have successfully grown polymorph γ-form of glycine single crystals by slow evaporation solution growth technique at ambient temperature. FTIR & NMR spectral studies confirm that 2-aminopyridine potassium chloride not entered into the crystal structure, but they inhibit the growth of polymorph form γ-glycine. UV –Visible spectral studies show that it has the wide range of transmission from 240nm to 900nm with cut off wave length 240 nm and the observed high transmittance percentage (100%) from 240 nm clearly indicates that the grown crystal possessing good optical transparency for second harmonic generation of Nd:YAG laser and attests the enhancement of optical prpperties. Powder and single crystal XRD studies reveal that the grown γglycine crystal is having higher order of crystallinity. Thermal studies show the sample is thermally stable up to 270°C (elevated temperature) and this makes the grown crystal’s suitability for possible application in laser, where the material is required to with stand high temperatures. Dielectric studies of grown crystal confirm the improved optical quality. NLO studies of the grown sample show that the enhanced SHG efficiency is greater than KDP (1. 65 times) and Urea (1.63 times) crystals. The grown title compound was possessing various enhanced properties such as wide transparency range with 100% transmission, low dielectric constant value at higher frequency and hence improved optical quality with lesser defects and elevated decomposition temperature (270˚C) with greater SHG efficiency as that of KDP suggest that the grown γ-glycine crystals in the presence of 2-aminopyridine potassium chloride is a promising materials for optoelectronic applications. Acknowledgements The authors would like to thank Professor Dr. R. Jayavel, Director, Academic Research and Professor, Centre for Nanotechnology, Anna University, Chennai, for their providing facilities and the corresponding author thanks the UGC for providing financial support through Minor Project (No: F. MRP-5978/15/(MRP/UGC-SERO). References [1] S. Debrus, H. Ratajczak, J. Venturini, N. Pincon, J. Baran, J. Barycki, T. Glowiak, A. Pietraszko, Novel nonlinear optical crystals of noncentrosymmetric structure based on hydrogen bonds interactions between organic and inorganic, Synthetic Metals 127 (2002) 99 – 104.

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[2] Ch. Bosshard, K. Sutter, Ph. Pretre, J. Hulliger, M. Florsheimer, P. Kaatz, P. Gunter, organic Nonlinear optical materials, Gordon and Breach, Basel,1995. [3] M. C. Etter, J. Chem, Phy. 95 (1991) 4601. [4] C. B. Aakeroy, P. B. Hitchcock, B. D. Moyle, K. R. Seddon, J. Chem. Soc., Chem. Commun. (1989)1856. [5] C. B. Aakeroy, P. B. Hitchcock, B. D. Moyle, K. R. Seddon, J. Chem. Soc., Chem. Commun. (1992) 553. [6] M. Chao, E. Schemp and R. D. Rosenstein, Acta cryst. B31, (1975). 2922-2924 [7] D. S. Chemla, J. Zyss(Eds), Nonlinear optical optical properties of organic molecules and crystals, Academic press, New York,1987. [8] Yari S. Kivshar, Optics Express, 16, (2008)22126-22128 [9] B. K. Periyasamy, R. S. Jebas, and B. Thailampillai, Materials Letters, 61 (2007) 1489-1491. [10] K. P. Bhuvana, S. Robinson and T. Balasubramanian, Cryst. Res. Technol,45 (2010) 299-302 [11] Z. kotler, R. Hierle, D. Josse, J. Zyss, R. Masse, J. Opt. Soc. Am. B9(1992) 54 [12] Y. Lefur, M. Bagiue-Beucher, R. Masse, J. F. Nicoud, J. P. Levy, Chem. Mater. 8 (1996) 68. [13] H. Ratajczak, J. Baran, J. Barycki, S. Debrus, M. May, A. Pietraszko, H. M. Ratajczak, A. Tramer, J. Mol. Struct. 555 (2000) 149 [14] H. Ratajczak, , S. Debrus, M. May, J. Barycki, J. Baran, Bull. Pol. Acad. Sci. Chem. 48 (2000) 189. [15] Katsuyuki Auki, Kozo Pagano, Yoichi Iitaka, Acta Crystallogr. B 27 (1971) 11. [16] C. Razzetti, M. Ardoino, L. Zanotti, M. Zha, C. Paorici, Cryst. ResTechnol. 37(2002) 456 [17] R. Bairava Ganesh, V. Kannan, R. Sathyalakshmi, P. Ramasami, Mater. Lett. 61, (2007)706 [18] P. Andreazza, D. Josse, F. Lefaucheux, M. C. Robert, and J. Zyss (1992) Phys. Rev. B 45, 7640. [19] M. Narayan Bhat, S. M. Dharmaprakash, J. Crystal Growth. 236 (2002) 376 [20] R. Shanmugavadivu,G. Ravi, A. Nixon Azariah, j. phys. chem. solids 67 (2006) 1858. [21] N. Ashour, S. A. El-Kadry, Mahmoud, Thin Solid Films 269 (1995) 117–120. [22] K. Gupta Manoj, Sinha Niahi, Kumar Binay, Phys. B Condens. Matter 406 (2011) 63–67 [23] T. P. Srinivasan, R. Indirajith, R. Gopalakrishnan, J. Cryst. Growth 318 (2011)762-767. [24] S. Sankar, M. R. Manikandan, S. D. G. Ram, T. Mahalingam, G. Ravi, J. Cryst. Growth 312 (2010)2729-2733. [25] G. R. Dillip, P. Raghavaiah, C. Madhukar Reddy, G. Bhagavannaraya, V. Ramesh Kumar, B. Deva Prasad Raju, Spectrochimica Acta Part A 79 (2011) 1123-1127. [26] Jain John, P. Christuraj, K. Anitha, T. Balasubramanian "Materials Chemistry and Physics” Volume 118, Issues 2–3, 15 (2009) pp. 284–287. [27] M. Iyanar, J. Thomas Joseph Prakash, C. Muthamizhchelvan, S. Ponnusamy “Journal of Physical Sciences” Vol. 13 (2009) pp. 235-244. [28] C. Sekar, R. Parimaladevi “Journal of Optoelectronics and Biomedical Materials” Vol. 1, Issue 2, (2009), pp. 215–225. [29] R. Ashok Kumar, R. Ezhil Vizhi, N. Vijayan and D. Rajan Babu. , “Physica B” Volume 406, (2011) Pages 2594-2600. MMSE Journal. Open Access www.mmse.xyz

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[30] Balakrishnan, T., Ramesh Babu, R. and Ramamurthi, K. “Spectrochim. Acta Part A”Vol. 79(2008)pp. 1114-1118. [31] S. A. Martin Britto Dhas, S. Natarajan “ Optics Communications” Vol. 278, Issue 2, 15 (2007) pp 434–438. [32] J. Thomas Joseph Prakash, M. Lawrence, J. Felicita Vimala , M. Iyanar “Journal of Physical Sciences”, Vol. 14, 2010, 219-226. [33] G. R. Dillip, G. Bhagavannarayana, P. Raghavaiah, B. Deva Prasad Raju“Materials Chemistry and Physics” Volume 134 Issue 1 (2012)pp 371–376. [34] C. Sekar, R. Parimaladevi Spectrochimica Acta Part A, 74 (2009) 1160–1164. [35] K. Selvaraju, R. Valluvan, S. Kumararaman “Materials Letters” Vol. 70, Issue 23 (2006) pp 2848-2850. [36] S. Kalainathan, M. Beatrice Margaret, “Materials Science and Engineering: B” Vol. 120 (2005) pp. 190-193. [37] R. Srineevasan, R. Rajasekaran, “Journal of Molecular Structure”Vol. 1048 (2013) pp. 238-243. [38] R. Srineevasan, R. Rajasekaran, “JOAM” Vol. 16 (2014) pp. 65-69. [39] S. K. Kurtz and T. T. Perry, J. Appl. Phys. 39, (1968). 3798. [40] M. Narayana Bhat, S. M. Dharmaprakash, J. Cryst. Growth 242 (2002) 245. [41] K. Ambujam, S. Selvakumar, D. Prem Anand, G. Mohamed, P. Sagayaraj, Cryst. Res. Technol. 401 (2006) 671. Cite the paper R. Srineevasan, D. Sivavishnu, K. Arunadevi, R. Tamilselvi, J. Johnson, S. M. Ravi Kumar (2016). Enhancement of Optical and Thermal Properties of γ- Glycine Single Crystal: in the Presence of 2-Aminopyridine Potassium Chloride. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.33138.654

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Enhanced Mechanical Performance for Nacre-Inspired Polyimine Composites with Calcium Carbonate Particles6 Si Zhang1, Yanting Lv1, Jiayi Li1, Song Liang1,a and Zhenning Liu1,b 1 – Key Laboratory of Bionic Engineering (Ministry of Education), College of Biological and Agricultural Engineering, Jilin University, Changchun, Jilin 130022, P. R. China a – songliang@jlu.edu.cn b – liu_zhenning@jlu.edu.cn DOI 10.2412/mmse.81.85.882

Keywords: mechanical properties, polymer composites, polyimine, calcium carbonate (CaCO3), bio-inspired, reinforcement, nacre.

ABSTRACT. Polyimine is a novel functional thermoset material with several attractive functions. Yet the mechanical properties of polyimine-based composites have been rarely investigated. In this work, calcium carbonate (CaCO3), a cheap and commonly used reinforcing material, has been chosen as the reinforcing filler to form composites with polyimine through heat-pressing under mild conditions to mimic natural nacre. Elemental mapping shows that CaCO 3 particles are evenly distributed in the continuous network of the polyimine matrix. Then thermal analyses and mechanical measurements of hardness, tensile strength, toughness, bending strength, and impact strength have been conducted to characterize the properties of the resultant polyimine composites. The fracture surfaces of the specimens after tensile testing have also been examined by scanning electron microscopy (SEM). The polyimine composites with CaCO 3 particles demonstrate remarkable enhancement on multiple mechanical features, especially on tensile properties. More importantly, the polyimine composites fabricated with 6 wt% of CaCO 3 particles show simultaneous increases of tensile strength and toughness, which are 56% (from 35.75 to 55.79 MPa) and 110% (from 112.82 to 236.54 MJ/m3) respectively in comparison with the polyimine matrix. The work presented herein affords a facile and low-cost approach to enhance the mechanical properties of polyimine material for more practical applications.

Introduction. Reinforced polymer composites have attracted broad interest in recent years owing to their enhanced performance compared to the respective polymer matrix [1-10]. To this end, fillers such as calcium carbonate, zirconia, hydroxyapatite, have been added at low content to various polymers [11], and the resultant composites have demonstrated superior mechanical properties to meet different industrial demands [12]. Polyimine, also called Schiff base polymer, is a novel thermoset material with advantages of self-healing, recyclability and environmental friendliness. Moreover, such a material is often malleable at ambient conditions, holding a good promise for a range of industrial applications including automobile, electronics, medical, etc. [13-19]. However, reinforced polyimine composite has been rarely explored. Nacre, composed of inorganic particles (mainly of calcium carbonate, CaCO3) and biopolymers, is widely considered as a gold standard for the engineering of bionic composite with excellent strength and toughness [20]. It has been proposed that the CaCO3 platelets in natural nacre function to deflect cracks and mitigate localized stress [20]. Hence, a variety of polymer composites reinforced by CaCO3 particles have been prepared, which have exhibited remarkable improvements in mechanical properties such as tensile strength, stiffness, impact strength, bending strength and toughness [11, 12, 21-27].

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Inspired by natural nacre, we have envisioned that CaCO3 can be used as the reinforcing phase to enhance the mechanical performance of polyimine. Herein, the polyimine composites with varied contents of CaCO3 have been fabricated by heat-pressing the mixed powder of polyimine and CaCO3 particles. The resultant composites formed by imine metatheses have demonstrated simultaneous enhancements for both tensile strength and toughness, which are 56% and 109% respectively for the composite with 6% of CaCO3. A different optimal level of CaCO3 particles is required to achieve best performance for bending and impact resistance. The possible reinforcing mechanism is also discussed. Materials and Methods Experimental material. All the chemicals including terephthalaldehyde, diethylenetriamine, and triethylene tetramine were purchased from Aladdin Industrial Inc. (China). CaCO3 was purchased from Sinopharm Chemical Reagent Co., Ltd (China). All reagents were used as received without further purification. Preparation. The polyimine (PI) matrix was synthesized with terephthalaldehyde, diethylenetriamine, and triethylene tetramine according to the literature [18]. The obtained PI was milled into powder by pulverizer (QE-1OO, Yili Ltd., China), and then sifted by an 80-mesh sieve. The PI powder and CaCO3 particles were mixed by a ball miller for 1 hour. Then the mixed powders were heat-pressed by a thermocompressor (JYP-20) under 9 MPa at 80 °C to form polyimine composites. Characterization. A Rockwell hardometer (XHQ-150, Shanghai, China) was used to measure the hardness. Tensile tests and bending tests were performed with a Universal Testing Machine (Instron 1121, UK) according to ASTM standard D638 and D5023, respectively. The effective dimension for tensile test sample is 5 x 2 x 2 mm and the effective dimension for bending test sample is 35 x 5 x 4 mm. The crosshead speed for tensile tests and bending tests is 1 mm/min. The toughness was calculated by integrating the area of stress-strain curves. The impact strength was measured on a Charpy impact tester (XJ-40A, Wuzhong, China) with effective sample dimension of 35 x 5 x 4 mm. All the mechanical tests were carried out at room temperature. The average of at least 3 independent measurements was obtained for all mechanical characterization and the P value was calculated by the Student’s t-test. The differential scanning calorimetry (DSC) measurement was performed with a DSC instrument (Q20, TA, USA) in the temperature range of 30-150 °C at a heating rate of 5 °C /min. The thermogravimetric analysis (TGA) was conducted with a thermogravimetric analyzer (Q600, TA, USA) in the temperature range of 23-800 °C at a heating rate of 10 °C /min. Morphology characterization and elemental mapping. The tensile fracture surfaces of PI matrix and composites were observed by a scanning electron microscope (XL-30 ESEM FEG, FEI, USA). The elemental mapping was performed on Genesis 2000 (EDAX Company). Results and Discussion. The polyimine (PI) was synthesized according to the literature [18]. The sizes of PI powder and additive CaCO3 particles were measured as about 122±21 μm and 1.2±0.4 μm in diameter by Scanning Electron Microscopy (SEM) (Figure 1b and 1a). The PI composites with calcium carbonate (CaCO3) particles (PI-CC) were prepared by heat-pressing (80 °C, 9 MPa) the mixed powder of PI and CaCO3 particles (Figure 1e). The weight percentages of CaCO3 particles in the composites were 3%, 6%, 9%, 12% and 15%, which were subsequently denoted as PI-CC-3, PICC-6, PI-CC-9, PI-CC-12, and PI-CC-15 respectively. The original fracture SEM micrograph and elemental mapping micrograph were performed to verify the distribution of CaCO3 particles in the PI matrix (Figure 1c and 1d, the image was obtained with PI-CC-6). The yellow and green dots in the mapping graph (Figure 1d) represent calcium (corresponding to CaCO3) and nitrogen (corresponding to PI), respectively. SEM image of the fracture surface (Figure 1c) shows there are smooth areas with clear boundaries, among which rough areas exist. Comparing the SEM image with the corresponding elemental mapping graph, (Figure 1d) it is found the smooth areas contain only the PI, while the MMSE Journal. Open Access www.mmse.xyz

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rough areas consist of both PI and CaCO3. The existence of pure PI areas suggests that the CaCO3 particles can hardly penetrate into the PI powders during the heat-pressing. The distribution of CaCO3 particles among the pure PI areas proves that these particles work as the fillers in the composite matrix as our expectation.

Fig. 1. SEM micrographs of raw materials powder including CaCO3 particles (a) and PI (b). Fracture SEM micrograph (c) and elemental mapping (d) of Ca and N for the PI composite filled with 6 wt% CaCO3 particles. The yellow and green dots in (d) represent calcium and nitrogen, which indicate distribution of CaCO3 particles in the composite of PI-CC-6. Schematic illustration for preparing PI composite is shown in (e). Next, a range of mechanical measurements including hardness, tensile, bending, and impact strengths have been conducted to characterize the CaCO3-enhanced PI composites together with the control of PI matrix. It has been found that introducing CaCO3 into PI matrix results in little change of the overall hardness as the hardnesses of the composites remain comparable to that of the PI matrix (Table 1). MMSE Journal. Open Access www.mmse.xyz

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The tensile property measurement for the PI composites reveals a similar trend with a maximum value at 6 wt% of CaCO3 particles in terms of tensile strength, toughness, tensile modulus, and elongation at break (Figure 2 and Table 1). Specifically, the tensile strength exhibits a gradual increase from 35.75 MPa for the PI matrix to 55.79 MPa for the PI composite with 6 wt% of CaCO3 particles, which has been enhanced by 56% (Figure 2a and Table 1). Meanwhile, the toughness has also shown an increase of 109% from 112.82 MJ for the PI matrix to 236.54 MJ for the PI composite with 6 wt% of CaCO3 particles (Figure 2b and Table 1). Increasing the CaCO3 content beyond 6% results in a decline of tensile performance. The enhancement of tensile strength and toughness is significant (P<0.05) for most pairwise comparison among the samples (Figure 2c). It’s worth noting that for most composite materials, it is hard to achieve simultaneous improvements on tensile strength and toughness [28, 29]. Yet the PI composite with 6 wt% of CaCO3 particles exhibits an excellent integration of tensile strength and toughness showing the peaks for both. The rationale underlying such an interesting finding requires further investigation. The fracture surfaces of the PI matrix and the reinforced composites were examined by scanning electron microscopy (SEM) to reveal the possible rationale for the observed trend in tensile property measurement (Figure 3). Overall, “river-pattern” streaks can be observed in the micrographs of all these samples, suggesting a nature of brittle fracture. Moreover, the micrographs of the composites (Figure 3b-3d) exhibit some granules, which are likely to be CaCO3 particles, since they are absent in the image of the PI matrix (Figure 3a) and more granules can be found as the content of CaCO3 in the composite increases. In particular, the micrograph for PI-CC-15 (Figure 3d) shows a rougher surface covered by the granules, suggesting that high level of CaCO3 content may cause the agglomeration of CaCO3 [27] and therefore result in markedly reduced tensile strength and toughness as shown in Figure 2. Table 1. Mechanical properties for PI and PI composites with CaCO3.

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Fig. 2. The tensile strength (a) and toughness (b) of PI composites with different CaCO 3 contents. Both tensile strength and toughness show a maximum value at the CaCO3 content of 6 %. The statistical significance (P<0.05) for the pairwise comparison of tensile strength (dots) and toughness (stars) among the PI composites with different CaCO3 contents (c). The dotted boxes highlight the significance of property enhancement for the composite with CaCO3 content of 6%.

Fig. 3. SEM micrographs of PI (a) and PI composites with various contents of CaCO3: 3% (b), 6% (c) and 15% (d). MMSE Journal. Open Access www.mmse.xyz

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It should be noted that the maximum for tensile modulus and elongation at break also coincide at the composite of PI-CC-6 (Table 1), which agrees with the observation for tensile strength and toughness. Together, the results of tensile property measurement and SEM imaging indicate that a low level of CaCO3 particles, likely around 6%, can yield a better dispersion in the PI matrix without evident agglomeration and lead to more interfacial interaction between the matrix and the filler. As a consequence, the composite of PI-CC-6 demonstrates the highest tensile performance among the PI composites evaluated. As suggested by previous reports of artificial nacre [20], it is proposed herein that the CaCO3 particles, when added to the matrix at an optimal amount, can function to disperse localized stress by crack deflection and prevent slippage by mineral bridging.

Fig. 4. The bending strength (a) and impact strength (c) of PI composites with different CaCO3 contents show maximum values when CaCO3 content is 3% and 9%, separately. The statistical significance (P<0.05) for the pairwise comparison of bending strength (b) and impact strength (d) among the PI composites with different CaCO3 contents. The dotted boxes in (b) and (d) highlight the significance of property enhancement for the composite with CaCO3 content of 3% and 9% for bending strength and impact strength respectively. Furthermore, the bending strength and impact strength of the PI composites with CaCO3 particles were measured to see whether these properties can also be enhanced. The bending strength displays a peak value for PI-CC-3 (Figure 4a), whereas the impact strength shows a maximum for PI-CC-9 (Figure 4c). The increases are 19% for bending strength (from 44.2 MPa for the PI matrix to 52.7 MPa for PI-CC-3) and 13% for impact strength (from 6.87 kJ/m2 for the PI matrix to 7.78 kJ/m2 for PI-CC-9) (Table 1). The significance of the pairwise comparison for bending strength and impact strength is shown in Figure 4b and 4d respectively. These results suggest that a different optimal level of CaCO3 particles is required to achieve best performance for these mechanical properties. Due to the rigid nature of CaCO3 particles, it is reasonable that less CaCO3 particle is needed to obtain the MMSE Journal. Open Access www.mmse.xyz

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optimal bending strength and more for the optimum of impact resistance, compared to the tensile enhancement. Yet, the reinforcing mechanism is possibly similar to that of tensile enhancement, i.e. by crack deflection, interlocking and mineral bridging. It should be noted that, similar to the case of tensile properties, over-dosing use of CaCO3 particles also results in a decline of bending and impact resistance, likely also because of agglomeration of CaCO3 particles.

Fig. 5. The DSC (a) and TGA (b) curves of PI matrix and PI composites with various CaCO3 contents. Thermal analyses of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed to assess the thermal properties of the composites (Figure 5). Addition of CaCO3 particles incurs a slight increase on the glass transition temperature (Tg) of the PI composites compared to the matrix (from 62 °C to 65 °C) in DSC plots (Figure 5a). Figure 5b shows the weight loss of various samples with increasing temperature. The PI matrix and composites initiate degradation at similar temperature. Yet, the PI composites with more content of CaCO3 particles (e.g. PI-CC-15) retain higher weight percentage under the temperature higher than 400 °C, which may be contributed by two factors. First, CaCO3 is thermally table till 800 °C. Thus the PI composite containing higher weight percentage of CaCO3 particles will result in more inorganic residuals. Second, the dispersed CaCO3 particles could also enhance the thermal stability of PI composites via a mechanism of heat buffering and re-distribution. Summary. Inspired by natural nacre, a series of PI composites filled with CaCO3 particles have been successfully prepared under mild conditions. The resultant composites demonstrate a range of mechanical enhancements including tensile strength, toughness, bending strength, and impact strength, which are 56%, 109%, 19%, and 13% at the respective maximum values, compared to the PI matrix. Interestingly, simultaneous improvements of tensile strength and toughness have been observed for the PI-CC-6 composite, indicating an excellent balance of tensile strength and toughness reinforcement at the optimal amount of CaCO3. Yet, lower level of CaCO3 content is required to achieve the best bending performance and higher level for impact resistance, suggesting that an optimal content shall be determined base on the individual case of application. Furthermore, the incorporation of CaCO3 particles can also enhance the thermal stability of the PI composites. Together, this work demonstrates that the mechanical properties of PI matrix can be enhanced by CaCO3 particles, affording a facile and low-cost approach to reinforce PI for more applications. Acknowledgements This work was supported by National Natural Science Foundation of China (51375204) and Jilin Provincial Science & Technology Department (20140101056JC). The authors thank Prof. Wei Zhang from University of Colorado at Boulder for the discussion of polyimine synthesis.

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References [1] D.S. Lobanov, V.E. Vildeman, A.D. Babin, M.A. Grinev, Experimental Research Into the Effect Of External Actions and Polluting Environments on the Serviceablity of Fiber-Reinforced Polymer Composite Materials, Mechanics of Composite Materials, 2015. 10.1007/s11029-015-9477-8 [2] Y. Şahin, H. Mirzayev, Wear Characteristics of Polymer -Based Composites, Mechanics of Composite Materials, 2015. 10.1007/s11029-015-9525-4 [3] B. Kord, A. Sheykholeslami, A. Najafi, Effect of Nanoclay on the Flexural Creep Behavior of Wood/Plastic Composites, Mechanics of Composite Materials, 2016. 10.1007/s11029-016-9543-x [4] W. Sitticharoen, A. Chainawakul, T. Sangkas, Y. Kuntham, Rheological and Mechanical Properties of Silica-Based Bagasse-Fiber-Ash-Reinforced Recycled HDPE Composites, Mechanics of Composite Materials, 2016. 10.1007/s11029-016-9594-z [5] N. Phongam, R. Dangtungee, S. Siengchin, Comparative Studies on the Mechanical Properties of Nonwoven- and Woven-Flax-Fiber-Reinforced Poly(Butylene Adipate-Co-Terephthalate)-Based Composite Laminates, Mechanics of Composite Materials, 2015. 10.1007/s11029-015-9472-0 [6] Z.F. Zhang, X. Hu, The Effect of Addition of SiO2 on the Mechanical Properties of PBO-FiberFilled HDPE Composites, Mechanics of Composite Materials, 2015. 10.1007/s11029-015-9508-5 [7] H. Javed, M. Islam, N. Mahmood, A. Achour, A. Hameed, N. Khatri, Catalytic growth of multiwalled carbon nanotubes using NiFe2O4 nanoparticles and incorporation into epoxy matrix for enhanced mechanical properties, Journal of Polymer Engineering, 2016. 10.1515/polyeng-2015-0137 [8] N. Khun, P. Loong, E. Liu, L. Li, Enhancing electrical and tribological properties of poly(methyl methacrylate) matrix nanocomposite films by co-incorporation of multiwalled carbon nanotubes and silicon dioxide microparticles, Journal of Polymer Engineering, 2016. 10.1515/polyeng-2014-0346 [9] H. Zengin, E. Bayir, G. Zengin, Solution properties of polyaniline/carbon particle composites, Journal of Polymer Engineering, 2016. 10.1515/polyeng-2015-0091 [10] S. Das, S. Basak, M. Bhowmick, S. Chattopadhyay, M. Ambare, Waste paper as a cheap source of natural fibre to reinforce polyester resin in production of bio-composites, Journal of Polymer Engineering, 2016. 10.1515/polyeng-2015-0263 [11] Y.W. Leong, M.B. Abu Bakar, Z. Ishak, A. Ariffin, B. Pukanszky, Comparison of the mechanical properties and interfacial interactions between talc, kaolin, and calcium carbonate filled polypropylene composites, Journal of Applied Polymer Science, 2004. 10.1002/app.13542 [12] M.A. Ghalia, A. Hassan, A. Yussuf, Mechanical and thermal properties of calcium carbonatefilled PP/LLDPE composite, Journal of Applied Polymer Science, 2011. 10.1002/app.33570 [13] K.C. Gupta, A. Kumar Sutar, C.C. Lin, Polymer-supported Schiff base complexes in oxidation reactions, Coordination Chemistry Reviews, 2009. http://dx.doi.org/10.1016/j.ccr.2009.03.019 [14] R. Kitaura, G. Onoyama, H. Sakamoto, R. Matsuda, S. Noro, S. Kitagawa, Immobilization of a Metallo Schiff Base into a Microporous Coordination Polymer, Angewandte Chemie, 2004. 10.1002/ange.200352596 [15] W. Luo, Y. Zhu, J. Zhang, J. He, Z. Chi, P.W. Miller, L. Chen, C.Y. Su, A dynamic covalent imine gel as a luminescent sensor, Chemical communications, 2014. 10.1039/c4cc05120c [16] M.G. Schwab, B. Fassbender, H.W. Spiess, A. Thomas, X. Feng, K. Müllen, Catalyst-free Preparation of Melamine-Based Microporous Polymer Networks through Schiff Base Chemistry, Journal of the American Chemical Society, 2009. 10.1021/ja902116f [17] Y. Sun, Y. Sun, Q. Pan, G. Li, B. Han, D. Zeng, Y. Zhang, H. Cheng, A hyperbranched conjugated Schiff base polymer network: a potential negative electrode for flexible thin film batteries, Chemical communications, 2016. 10.1039/c5cc09662f MMSE Journal. Open Access www.mmse.xyz

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[18] P. Taynton, K. Yu, R.K. Shoemaker, Y. Jin, H.J. Qi, W. Zhang, Heat- or water-driven malleability in a highly recyclable covalent network polymer, Advanced materials, 2014. 10.1002/adma.201400317 [19] J.M. Whiteley, P. Taynton, W. Zhang, S. Lee, Ultra-thin Solid-State Li-Ion Electrolyte Membrane Facilitated by a Self-Healing Polymer Matrix, Advanced materials, 2015. 10.1002/adma.201502636 [20] Q. Cheng, M. Wu, M. Li, L. Jiang, Z. Tang, Ultratough Artificial Nacre Based on Conjugated Cross-linked Graphene Oxide, Angewandte Chemie, 2013. 10.1002/ange.201210166 [21] S. Abdolmohammadi, S. Siyamak, N.A. Ibrahim, W.M. Yunus, M.Z. Rahman, S. Azizi, A. Fatehi, Enhancement of mechanical and thermal properties of polycaprolactone/chitosan blend by calcium carbonate nanoparticles, International journal of molecular sciences, 2012. 10.3390/ijms13044508 [22] A. Chatterjee, S. Mishra, Rheological, thermal and mechanical properties of nano-calcium carbonate (CaCO3)/Poly(methyl methacrylate) (PMMA) core-shell nanoparticles reinforced polypropylene (PP) composites, Macromolecular Research, 2013. 10.1007/s13233-013-1049-y [23] H. He, K. Li, J. Wang, G. Sun, Y. Li, J. Wang, Study on thermal and mechanical properties of nano-calcium carbonate/epoxy composites, Materials & Design, 2011. 10.1016/j.matdes.2011.03.026 [24] L. Jiang, J. Zhang, M.P. Wolcott, Comparison of polylactide/nano-sized calcium carbonate and polylactide/montmorillonite composites: Reinforcing effects and toughening mechanisms, Polymer, 2007. 10.1016/j.polymer.2007.11.001 [25] B. Kord, Effect of Calcium Carbonate as Mineral Filler on the Physical and Mechanical Properties of Wood Based Composites, World Applied Sciences Journal, 2011. 10.1007/s11029-0169543-x [26] J.Z. Liang, D.R. Duan, C.Y. Tang, C.P. Tsui, D.Z. Chen, Tensile properties of PLLA/PCL composites filled with nanometer calcium carbonate, Polymer Testing, 2013. 10.1016/j.polymertesting.2013.02.008 [27] J. Liang, L. Zhou, C. Tang, C. Tsui, Crystalline properties of poly(L-lactic acid) composites filled with nanometer calcium carbonate, Composites Part B: Engineering, 2013. 10.1016/j.compositesb.2012.09.086 [28] W. Cui, M. Li, J. Liu, B. Wang, C. Zhang, L. Jiang, Q. Cheng, A Strong Integrated Strength and Toughness Artificial Nacre Based on Dopamine Cross-Linked Graphene Oxide, ACS Nano, 2014. 10.1021/nn503755c [29] S. Gong, W. Cui, Q. Zhang, A. Cao, L. Jiang, Q. Cheng, Integrated Ternary Bioinspired Nanocomposites via Synergistic Toughening of Reduced Graphene Oxide and Double-Walled Carbon Nanotubes, ACS Nano, 2015. 10.1021/nn503755c Cite the paper Si Zhang, Yanting Lv, Jiayi Li, Song Liang, Zhenning Liu (2016). Enhanced Mechanical Performance for Nacre-Inspired Polyimine Composites with Calcium Carbonate Particles. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.81.85.882

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Study on Laser Welding Process Monitoring Method7 Heeshin Knag1, a 1 – Korea Institute of Machinery and Materials, Daejeon, Korea a – khs@kimm.re.kr DOI 10.2412/mmse.00.05.997

Keywords: process, inspection, defect, monitoring, laser.

ABSTRACT. In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load: 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The remote laser welding system with laser scanner system is used to increase the processing speed and to improve the efficiency of processes. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity by using UV and IR sensor. This paper proposes the quality monitoring method and the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

Introduction. Laser welding is one of the important technologies used in the manufacturing of lighter, safer automotive bodies at a high level of productivity; to that end, the leading automotive manufacturers have replaced spot welding with laser welding in the process of car body assembly. Korean auto manufacturers are developing and applying the laser welding technology using a high output power Nd:YAG laser and a 6-axes robot [1,2]. The conventional spot resistance welding used in the car body assembly process has been an obstacle to car design and manufacturing due to the limited applicability and lower welding efficiency resulting from the geometry and welding characteristics of spot welding machines. As such, the automotive industry has been trying to develop new welding and joining technologies [3-5]. This study was conducted to develop a remote car body laser welding technology, a welding quality inspection technique, and a robot control. In particular, due to the characteristics of laser welding where the laser beams have to be directed perpendicularly to the welding surface - it is very difficult to instruct the robot to direct the laser beam perpendicularly on to a curved surface. Indeed, many studies have been performed to improve the speed of the robot laser welding process and the quality of welding parts [6,7]. In this study, these problems were addressed by applying the remote laser welding method and the quality monitoring method. Experimental equipment. Figure 1 shows a schematic block diagram and the developed system of the entire remote laser welding control system. The beam from the laser generator is transmitter via an optical fiber to the welding head at the end of the robot's arm. The laser welding can be achieved by manipulating the axes of the robot system. The laser generator used was 1.6 kW fiber laser system and the robot system was the 6 axes Industrial robot of payload 130 kg. To conduct a basic study of the weldability of the remote laser welding system, butt welding and lap welding were conducted with common steel plates and galvanized plates. The weld joints were inspected and tested for tensile © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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strength to determine the optimal welding parameters. In order to devise a technique of measuring the quality of the laser welding on a real-time-basis, basic experiments were conducted with a technique capable of determining the quality of welding by monitoring plasma and temperature. Pattern welding tests were conducted to examine the accuracy of the entire remote laser welding system.

Fig. 1. The robot-based remote laser welding system. Table 1. Core units of remote laser welding system. Laser source

1.6kW high-power fiber laser Collimation, Bean expander/

Focusing unit

Image transfer optics, F-theta lens

Scanning unit

XY 2 axes scanner 6 axes Industrial Robot

Handling system

(payload: 130kg)

Workpiece device

Jig, Clamping

Position sensing, process monitoring

CCD vision, Optical emission monitoring

Main control

PC-based controller

Test results. Figure 2 shows the process sequence of quality monitoring system for remote laser welding. During laser welding on a real-time-basis, basic tests were conducted to develop a technique which facilitates the evaluation of weld quality by monitoring plasma and temperature. Tests were conducted using an Nd:YAG laser and a fiber laser. To monitor weld quality using plasma flux intensity, the initial criteria of plasma intensity - which itself determines the critical weld quality -

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needs to be determined. When the plasma intensity lies between the maximum and minimum values of the standard range as Figure 3 (a), the weld quality can be judged to be acceptable.

Fig. 2. Process sequence of quality monitoring system.

(a)

(b)

Fig. 3. The results of fiber laser quality monitoring in butt joint; (a) reference curves from results of welding test, b) monitoring test by using reference curves. Figure 4 shows the results of plasma monitoring test. In the Nd:YAG laser tests, stainless steel specimens were welded at laser powers of 3 kW. One UV-type and two IR-type sensors were used in the tests conducted to detect plasma intensity. Three holes measuring 2 mm in diameter were machined into steel sheets to test whether it was possible to identify defective parts in which no plasma could be generated due to potential defects in the machining. In addition, steel wire measuring 2 mm in diameter was attached to the steel sheets - perpendicular to the welding direction - to test MMSE Journal. Open Access www.mmse.xyz

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whether changes in the generation of plasma caused by changes in the laser's focal length could be detected. The applied welding conditions were laser power of 3 kW and a welding speed of 3 m/min. Figure 5 shows the results of the welding test to find the optimal welding conditions by using a fiber laser. Figure 6 and figure 7 show the test results of the welding quality monitoring using a fiber laser on the basis of the test results of the Nd:YAG laser. The fiber laser was tested at from 400 W to 1,600 W power using UV and IR sensors. The results were obtained by scanning the steel sheet many times with the laser scanner of the remote laser welding system. The plasma and temperature signals could be detected at the appropriate values, confirming that real-time-based quality monitoring can be implemented.

(a)

(b)

Fig. 4. The results of plasma intensity detection using an Nd:YAG laser;(a) welding specimen, (b) the graph of monitoring signal. Mpa 450 400 350 400W

300

600W

250

800W

200

1000W 1200W

150

1400W 100

1600W

50 0 1

1.5

6 m/min

Fig. 5. Results of UTM test in butt joints (steel plate coated with zinc).

(a)

(b)

Fig. 6. The cross-sections of laser welding specimens; (a) cross-sections of lapped joints, (b) fracture shape of laser welding in lapped joints. MMSE Journal. Open Access www.mmse.xyz

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(a)

(b) Fig. 7. The experimental results of quality monitoring during remote laser welding for a circle pattern; (a) shielding gas( nitrogen), good weld, (b) no shielding gas, error.

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Summary. The remote laser welding robot system was built on the basis of the interfacing between the laser system and the industrial robot system. Using the remote laser welding system, butt and lap welding of common and galvanized steel sheets were conducted and the tensile strength of the samples was tested to determine the optimal welding parameters. The remote laser pattern welding tests were conducted and the weld joints and defects were analyzed. During the laser welding, the plasma intensity signals were measured and analyzed to assist the development of a technique which enables evaluation of the quality of laser welding in real time. On the basis of the remote laser welding quality tests, the lap welding of galvanized steel sheets and the algorithms for evaluating the quality of laser welding will be tested in further studies. References [1] F. Coste et al., A Rapid Seam Tracking Device for YAG and CO2 High-Speed Laser Welding, Proc. ICALEO 85, 1998, 217-223. [2] T. Eimermann, Hem Flange Laser Welding, 25th ISATA Symposium, No. 921089, Florence, Italy, June, 1992. [3] E. Beyer, A. Klotzbach, V. Fleischer, and L. Morgenthal, Nd:YAG-Remote Welding with Robots, Proceedings of Lasers in Manufacturing, 2003, 367-373. [4] A. Klotzbach, V. Fleischer, L. Morgenthal, and E. Beyer, Sensor guided remote welding system for YAG-laser applications, Proceedings of Lasers in Manufacturing, 2005, 17-19. [5] M. W. de Graaf, R. G. K. M. Aarts, J. Meijer, and J. B. Jonker, Robot-sensor synchronization for real-time seam-tracking in robotic laser welding, Proc. 23rd Int. Cong. On Applications of Lasers and Electro-Optics, 2004, 1301. [6] P. Aubry, F. Coste, R. Fabbro, and D. Frechett, 2D YAG welding on non-liner trajectories with 3D camera seam tracker following for automotive applications, Laser Appls. Auto Industry, Section F-ICALEO, 2000, 21. [7] E. Beyer, and P. Abels, Process Monitoring in Laser Materials Processing, Laser Advanced Materials Processing (LAMP92), 1992, 433-438. [8] Hee-shin Kang, Jeong Suh, Taik-Dong Cho. Study on quality monitoring of laser welding, 2009 IEEE International Symposium on Industrial Electronics, DOI: 10.1109/ISIE.2009.5217434 Cite the paper Heeshin Knag (2016). Study on Laser Welding Process Monitoring Method. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.00.05.997

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II. Mechanical Engineering & Physic s M M S E J o u r n a l V o l . 7

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Determining Optimum Location Places for Clutch Couplings in Hydrostatic and Mechanical Transmissions of Wheeled Tractors 8 Taran I.O.1,a, Bondarenko A.I.2 1 – Department of Transport Management, National Mining University, Dnipro, Ukraine 2 – Department of Automobiles and Tractor Industry, National Technical University "Kharkiv Polytechnic Institute", Kharkiv, Ukraine a – taran_70@mail.ru DOI 10.13140/RG.2.2.35672.90888

Keywords: wheeled tractor, hydrostatic and mechanical transmissions, clutch coupling, emergency braking.

ABSTRACT. Using a technique of Hooke-Jeeves, constructed partial criteria, and determined generalized criterion in terms of emergency braking of wheeled tractors the paper determines optimum location place for clutch couplings in hydrostatic and mechanical transmissions of wheeled tractors operating by means of “input differential” and “output differential” schemes. Recommendations concerning changes in relative parameter to control hydraulic machines with hydrostatic and mechanical transmission in the process of emergency braking of wheeled tractors to maintain working capacity of transmissions have been formulated.

Introduction. Agroindustrial complex is among the most important economic sectors; food safety of any country depends heavily on its level of development and functioning. Constant increase in overall agricultural production and violent annual fluctuations in transport needs are those prerequisites stipulating rural use of wheeled tractors. Striving for stepless speed variation and moving force and improving ergonomic properties while performing various technological operations have become the key reasons to increase world output of wheeled agricultural tractors with hydrostatic and mechanical transmissions (HSMT). Statement of the problem. Acceleration of wheeled tractors has extremely aggravated the problem of safety maintenance in braking mode. Despite the sufficient popularity of HSMTs in tractor industry current designs of transmissions of the type require further improvement. In the first instance it concerns the following: load reduction on both hydraulic portion and components of mechanical portion in the process of braking as incorrect location place of coupling will result in sharp increase of values of angle velocities of HSMT chains in the process of emergency braking and neglecting rules of changes in parameters to control hydrostatic drive (HSD). Analysis of the research and publications. The problem of positive-displacement hydromachines and HSDs design, development and analysis of HSMTs for both wheeled and crawler tractors, lorries, combines, road-building machines, and mine diesel locomotives is highlighted in papers by world and domestic scientists [1-10]. The majority of the papers proposes structure and design parameters for two-flow HSMTs. They formulate recommendations concerning the choice of service braking and

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emergency braking implementation technique for wheeled tractors with stepless transmissions; however, authors appeal to their own designing experience only and use heuristic approach [4, 8]. Recently there is a tendency to use standard two-flow HSMTs in agricultural tractors. Range of their application increases as well as in the number of tractor models as in the power to be transmitted. Designs of HSMTs have a tendency to raise power transmitted mechanically and to decrease the number of frictional multidisk clutches. As a result, there is a decrease in the number of ranges (subranges) and complex mechanical parts [2]. However, the problem of defining optimum clutches location place in HSMTs of wheeled tractors is not covered. The problem solving. Series of perspective tractor schemes have been developed on the basis of the complex statistic analysis of HSMTs [10]. Maximum transmission efficiency is 0.82-0.88 depending upon a scheme. They served as a basis for defining optimum clutches location place in HSMTs. The research was done on the basis of emergency braking of the wheeled tractors case when engine is kinematically broken from the drive wheels in different alternatives of clutch location places: right behind the engine (alternative 1); within mechanical branch of closed circuit of HSMT (alternative 2); within hydraulic branch of closed circuit of HSMT in front of HSD (alternative 3); within hydraulic branch of closed circuit of HSMT behind HSD (alternative 4) (Figures 1 and 2). Emergency braking has been considered as it is the case when release of drive portions and loose portions of clutches (that is power flow break off) takes place. Specifically area of power flow break off effects on values of angular velocities of HSMT chains having certain limitations (angular velocity of satellites gears, shafts of hydromachines etc.).

а)

Fig. 1. Alternatives to locate clutches within structural HSMT schemes with input differential: а) is alternative 1; b) is alternative 2; c) is alternative 3; d) is alternative 4; 1 is internal combustion engine; 2 is a clutch; 3 is planetary gear set (k is transmission ratio of planetary gear set); 4 is HSD; 5 are wheels; 6 are reduction units (i is transmission ratio of reduction unit).

Optimization problem is solved to determine optimum location place for clutches in HSMT and rules to change relative parameters to control HSD (e(t)) in the context of emergency braking exercising a significant influence on operating ability of transmission. MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

To estimate braking efficiency in the process of optimization it is expedient to use braking path as a factor. It is recommended to estimate trajectory controllability according to deviation of tractor from predetermined trajectory. To estimate performance figures of HSMT it is expedient to use power parameters (working pressure difference in HSD P max ) and kinematic ones (angular velocity of satellites s

max

, angular velocity of hydraulic pump shaft 1 max and hydromotor as well as difference

between values of angular velocities of driving clutch shaft and driven clutch shaft  max ). Boundary values P max , 1 max , and 2 max depend mainly on design features of HSD; they are listed in specifications of hydromachines being indicated as P* , 1* , and 2* . P* means maximum pressure within induction pipe of HSD. Allowable value of angular velocity of satellites does not depend upon transmission parameters. However, it has its own limitation (i.e. 600 rad/s to be s max  600 ); it is indicated as s* . Maximum allowable difference between angular velocities of driving clutch shaft and driven clutch shaft indicating as  * depends on clutch type, its design parameters etc.

а)

Fig. 2. Alternatives to locate clutches in structural schemes of HSMT with output differential (symbols are similar to those in Fig. 1).

Then, if tractor applies the brakes within curved road section (driven wheels are fixed at the level of 50 right after the start of braking process), generalized criterion is  S g (e(t ))   P(e(t )) max  Pp   1 (e(t )) max    (e(t ))  K  (e(t ))  Z1  1    Z 2  1  max *   Z 4  1      Z3  1  * *  Sg   P 1*       (1)   2 (e(t )) max   s (e(t )) max    (e(t )) max   Z5  1    Z 6  1    Z 7  1    Z   P ( )  Z V  PV (V ), * * 2 s  *      

where i and  j – are weight coefficients ( i is a value before partial criteria,  j is a value before penalty functions); MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 * S g (e(t )) and S g – are real value of braking path and its allowable value;

max (e(t )) – is a value of maximum tractor deviation from predetermined trajectory after full braking;

* – is boundary value of deviation of tractor from predetermined trajectory; P(e(t )) max – is maximum of real value of working pressure difference in HSD; Pp – is intake pressure; its value is equal to that one produced by delivery pump;

P* – is allowable pressure value within induction pipe of HSD;

1 (e(t )) max , 2 (e(t)) max , and s (e(t )) max – are maximums of real value of angular velocity of hydraulic pump shaft, hydraulic motor, and satellites respectively;

1* , 2* , and s* – are allowable values of angular velocity of hydraulic pump shaft, hydraulic motor, and satellites respectively;

 (e(t )) max – is maximum of real difference value between angular velocities of driving clutch shaft and driven one;

 * – is allowable difference value between angular velocities of driving clutch shaft and driven one;

P ( ) – is penalty function reducing generalized criterion value when rotational directions of driving clutch shaft and driven clutch shaft differ; PV (V ) – is penalty function reducing generalized criterion value if difference being greater than allowable value between real velocity of tractor V and its ideal velocity Ve (which should be available at the moment relying on e value) is appeared. Penalty function P ( ) is defined as follows

  (e(t )) max , if z1  z 2  0 and z1  z 2   ** ; 1  ** P ( )    0, if     0 and      ** or     0 , z1 z2 z1 z2 z1 z2 

(2)

where  ** – is difference value between angular velocities of driving clutch shaft and driven clutch shaft being compensated at the expense of damping fluid properties and discharges to HSD;

z1 , z 2 – are angular velocity of driving clutch shaft and driven clutch shaft. Penalty function PV (V ) is defined as follows

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 Ve  V , if Ve  V  V ; 1  PV (V )   V  0, if V  V  V , e 

(3)

where V – is allowable difference between real tractor velocity V and Ve velocity, which should be available at the moment relying on e value. Value of weight coefficient is very important for generalized criterion value. Considering that partial criteria are equivalent and vary within almost comparable ranges, values of all weight coefficients are taken equal to 1/7. Expediency of such choice has also been confirmed by basic research. Rule of e(t ) variation in the process of emergency braking is perfect when K (e(t )) is maximally close to 1. In turn, penalty functions P ( ) , PV (V ) are equivalent and vary within comparable ranges; however when  and V are out of allowable range it is proposed to take values of all weight coefficients as equal to 105 before penalty functions. Thus, while determining  and V within determined range effect on a value of generalized criterion is equal to zero ( Z  P ()  ZV  PV (V )  105  0  105  0  0 ); and in the process of leaving the range a value of penalty function together with weight coefficient experiences jump-type decrease. In this context a value of generalized criterion is decreased as well. While determining e, error is 0.01 (in the braking process, simulation interval was taken as 0.005 sec and determination of e optimum value took place; its correction was performed within the next stage). In this context not maximum but current values of indices were substituted into numerators of expression (1). That made it possible to obtain new K (e(t ))ti values after each 0.005 sec and finally optimum rule of e(t ) change. However, value K (e(t )) from expression (1) is more informative as it takes into consideration not current values but maximum ones from the whole braking process; that is why obtained “optimum rule of e(t ) change for the given braking case” was given not maximum

K (e(t ))ti max value from the whole obtained set K (e(t ))ti , but K (e(t )) involving maximum values of factors which had been determined after full stop of tractor as complete situation concerning changes in each parameter during braking process was available. Optimization process is limited by consideration of tractor braking from the velocity of 60 km/h on a road surface with dry asphalt and snow. In the process of emergency braking when kinematic separation of engine from driving wheels takes place, operating ability of transmission is possible if only correct area of power stream breakage is selected to be correct area of engine separation from driving wheels. As a result of optimization problem (1) – (3) solution involving Hooke-Jeeves technique it has been determined that from the viewpoint of braking process dynamics and generalized criterion values clutching in HSMD is: • in terms of input differential it is recommended to locate it either behind engine or within hydraulic branch of closed HSMD circuit before HSD (neither alternative has evident advantage); • in terms of output differential it is preferable to locate clutch within hydraulic branch of closed HSMD circuit before HSD, another alternative being less advantageous is its location within mechanical branch of closed circuit. If the requirements cannot be met (depending upon design features) it is located behind the engine. Use of optimization theory in the process of basic research made it possible to determine that each HSMD scheme has its own optimum rule of changes in relative parameters of HSD control in terms of emergency braking of wheeled tractors with stepless HSMDs when kinematic separation of engine MMSE Journal. Open Access www.mmse.xyz

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from driving wheels takes place. Braking process when values of control parameters correspond to changes in real velocity of tractor is the closest to optimum one. The analysis of the proposed rule in comparison with optimum one (for the schemes considered) has proved that difference in values of generalized criteria is not more than 6.9%. It has been identified that in case of emergency braking of tractor in terms of kinematic disconnection of engine from driving wheels changes of HSD control parameters to improve operating ability of HSMD should be performed automatically meeting the requirements of real tractor velocity changes. Moreover, application of the rules allows a driver stopping emergency braking at any stage and continuing movement or acceleration of tractor to execute the manoeuvre without any negative consequences; that will make it possible to improve sufficiently traffic safety level. The implementation technique is permitted to be used in terms of service braking: kinematic disconnection of engine from driving wheels is maintained and rule of brake pedal pressing may be in any form without time limits, however a driver will have extra stress which cannot favour his intensive and long-term employability. As a rule, the technique is not applied as service one in the context of current tractors with HSMT. If in terms of emergency braking when kinematic disconnection of engine from driving wheels it is technically impossible to change parameters to control HSD according to changes in real tractor velocity (as it is connected with considerable complication of transmission control system) following requirements shall be subject to compulsory implementation: • braking of tractor lasts up to full stop; • parameters of HSD control while braking remains invariable; moreover, they correspond to the value they had at the initial braking stage; • when full stop of a tractor takes place, HSMT control system should provide automatically changes in HSD control parameters to be in accordance with zero velocity of tractor movement. Summary. It has been proved that in the process of emergency braking when kinematic disconnection of engine from driving wheels takes place, operating ability of transmission is maintain if only correct area of power stream breakage has been chosen, i.e. correct area of disconnection of engine from driving wheels. The optimization problem solution has helped determine that from the viewpoint of braking process dynamics and generalized criterion values, it is recommended to locate HSMT clutch with input differential either behind engine or within hydraulic branch of short circuit in front of HSD (neither alternative is advantageous); in the context of HSMT with output differential it is preferable to locate clutch within hydraulic branch of closed circuit behind HSD. It has been determined that in case of emergency braking of tractor when engine is disconnected from driving wheels, changes in parameter values to control HSD to maintain operating ability of HSMT should be performed automatically meeting changes in real tractor velocity. Use of the recommendations helps a driver stops emergency braking at any stage without any negative consequences and continues movement or acceleration of tractor to execute the maneuver; that will make it possible to improve sufficiently traffic safety level. References [1] Bondarenko, A.I. (2015) Scientific Basis of the Theory of Vehicles Braking With Stepless Hydrostatic Mechanical Transmissions // Austrian Journal of Technical and Natural Sciences, «East West» Association for Advanced Studies and Higher Education GmbH. Vienna (Austria). – # 1 – 2. – Pp. 124 – 127.

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[2] Bondarenko, A.I. (2014), Samorodov, V.B. Features of Power Flow Distribution in a Closed Circuit of Hydrostatic Mechanical Transmissions // Zbior Raportow Naukowych. Wykonane na Materiałach Miedzynarodowej Naukowo-Praktycznej Konferencji «Inżynieria i Technologia. Osiągnięć, Projekty Hipotezę», 29 – 30 December 2014, Krakow, Poland / Sp. z o.o. «Diamond Trading Tour». – Warszawa: Wydawca: Sp. z o.o. «Diamond Trading Tour», 2014. – Pp. 59 – 70. [3] Bondarenko, A.I. (2014), Mittsel, M.O., Kozhushko, A.P. Laboratory Stand for Research of the Workflow in Hydrostatic Mechanical Transmissions // Materials of the IX International Research and Practice Conference «European Science and Technology», 24 – 25 December 2014, Munich, Germany / «Strategic Studies Institute». – Munich: «Strategic Studies Institute», 2014. – Vol. II. – Pp. 289 – 295. [4] Bondarenko, A.I. (2015) Dynamics of the braking process wheeled tractors with hydrovolumetricmechanical transmission: Monograph. – Kharkiv: published by «Fedorko». – 220 pp. [5] Samorodov, V.B., Taran, I.A. (2012) Analysis of the distribution power flow considering the efficiency of hydraulic continuously variable two-flow hydrovolumetric-mechanical transmission with differential output // The bulletin of the National Technical University "KhPI". – Vol. 64. – Pp. 3 – 8. [6] Taran, I.O. (2012) Laws of power transmission on branches of double-split hydrostatic mechanical transmissions // Naukoviy visnyk NGU. – Dnipropetrovsk: SHEI «NMU». – #2. – Pp. 69 – 75. [7] Taran, I.O. (2013) System of integral stochastic criteria for transmissions of transport vehicles // Naukoviy visnyk Khersons’koi derzhavnoi mors’koi akademii. – Kherson: Kherson state maritime academy. – # 2 (9). – Pp. 277 – 283. [8] Taran, I.O. (2012) Transmission of mine locomotive: Monograph. – Dnipropetrovsk: published by SHEI «NMU». – 256 pp. [9] Taran, I.O. (2013) Automated analysis of the distribution of power flow transmission locomotive // Ugol’ Ukraine. – #12. – Pp. 34 – 38. [10] Samorodov, V.B., Bondarenko, A.I. (2014) synthesis of hydrostatic mechanical transmission of wheeled tractors for agricultural purposes // Eastern European Scientific Journal: Düsseldorf (Germany): Auris Verlag. – # 6. – Pp. 280 – 284. [11] Taran I.O., Kozhushko A.P., Substantiating of Rational Law of Hydrostatic Drive Control Parameters While Accelerating of Wheeled Tractors with Hydrostatic and Mechanical Transmission, Mechanics, Materials Science & Engineering Journal, Vol. 6, Magnolithe GmbH, Austria, DOI: 10.13140/RG.2.1.3590.9362 [12] Hao Sun, Harald Aschemann, Robust Inverse Dynamics Control for a Hydrostatic Transmission with Actuator Uncertainties, 6th IFAC Symposium on Mechatronic Systems, IFAC Proceedings Volumes, Volume 46, Issue 5, 2013, Pages 116-124, DOI: 10.3182/20130410-3-CN-2034.00032 [13] Horst Schulte, Control-oriented modeling of hydrostatic transmissions considering LEAKAGE losses, 3rd IFAC Workshop on Advanced Fuzzy and Neural Control, IFAC Proceedings Volumes, Volume 40, Issue 21, 2007, Pages 103-108, DOI: 10.3182/20071029-2-FR-4913.00018

Cite the paper Taran I.O. & Bondarenko A.I. (2016). Determining Optimum Location Places for Clutch Couplings in Hydrostatic and Mechanical Transmissions of Wheeled Tractors . Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.35672.90888 MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

The Evaluation of Torsional Strength in Reinforced Concrete Beam9 Mohammad Rashidi1, Hana Takhtfiroozeh2 1 –Department of Civil Engineering, Sharif University of Technology, Tehran, Iran 2 –Department of Civil Engineering, Building and Housing Research Center, Tehran, Iran DOI 10.13140/RG.2.2.16568.75521

Keywords: torsional strength, concrete beam, transverse and longitudinal bars, reinforcement.

ABSTRACT. Many structural elements in building and bridge construction are subjected to significant torsional moments that affect the design. A simple experiment for the evaluation of the torsional strength of reinforced concrete beams as a one of this structural elements is presented in this research. The objective of this experiments would be the role of transverse and longitudinal reinforcement on torsion strength. Four beam test samples has been tested with the same length and concrete mix design. Due to the fact, that the goal of this experiment is to determine the effect of reinforcement type on torsion strength of concrete beams; therefore, bars with different types in each beam have been applied. It was observed that the ductility factor increases with increasing percentage reinforcement from the test results. It should be also noted that transverse bars or longitudinal bars lonely would not able to increase the torsional strength of RC beams and both of them can be essential for having a good torsional behaviour in reinforced concrete beams.

Introduction. The interest in gaining better understanding of the torsional behaviour of reinforced concrete (RC) members has grown in the past decades. This may be due to the increasing use of structural members in which torsion is a central feature of behaviour such as curved bridge girders and helical slabs. The achievements, however, have not been as much as those made in the areas of shear and bending. Dealing with torsion in today’s codes of practice is also very primitive and does not contain the more elaborate techniques. Predictions of current standards for the ultimate torsional capacity of RC beams are found to be either too conservative or slightly risky for certain geometry, dimensions and steel bar sizes and arrangements. Torsional moments in reinforced concrete are typically accompanied by bending moments and shearing forces. However, simplified methods in design codes are based on a simple combination of the pure shear methods and pure torsion methods. In the ACI code [1], the effects of the torsional moment are accounted for by superimposing the amount of transverse and longitudinal steel and the intensity of the shearing stresses required for torsion resistance to those required for shear resistance. The Canadian code [2] assumes a similar interaction and further superimposes the effects of torsion and shear on the longitudinal strain indicator required in the design solution. Moreover, interaction surfaces between shearing and axial forces and bending moment such as those suggested by Elfren et al. [3] and Ewida and McMullen [4] are still of practical importance. The use of such interaction surfaces and the use and development of the code equations require knowledge of the pure torsional strength of reinforced concrete. Rahal and Collins [5] assigned the methods available for computing the torsional capacities to two main categories. Methods in the first category use semi-empirical equations chosen to fit available experimental data. The strength of these methods comes generally from their simplicity. Methods in the second category use procedures based on more rational models such as the space truss model. These models are generally more time demanding, but their strength comes from their 9

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rationality and their ability to give the engineer a feel for the behavior of the structural member designed. A recently developed simplified model [6] was shown to be an accurate and rational tool for calculating the shear strength of membrane elements subjected to shear. Similar to the General Method [7], this model is based on the equations of the MCFT. The MCFT is a powerful rational model capable of calculating the full response of sections subjected to shear, axial load, and bending and torsional moments [8, 9, and 10]. The new model was able to cast the results of the rational MCFT into a simple procedure. The applicability of the model was extended [11] to cover beams subjected to shearing and axial forces and bending moments. The effects of axial forces and bending moments on the shear strength were accounted for by a simplified superposition procedure. This paper extends the effect of reinforcement type on torsion strength of concrete beams. The objective of this experiments would be the role of stirrups and longitudinal reinforcement on torsion strength. Four beam test samples has been tested with the same length and concrete mix design. The reinforcement of this samples has been different ranging from without reinforcement to complete reinforcement. Materials and methods. Four experimental beam samples, without reinforcement, with just transverse reinforcement, with just longitudinal reinforcement, and both transverse and longitudinal reinforcement, has been tested to gain bending moment, cracking moment and ultimate bending moment. Appropriate torsional results originated from this experiment give us an information about the effect of reinforcement on Reinforced Concrete Beams. The considered mix for the samples has been shown in table 1 below. According to the instructions, coarse aggregates have been sieved via a 2-cm sieve. Also, the samples considered in construction are three cylindrical samples in 30×15 cm dimensions and four beams samples in 60×10×10 cm dimensions.

Table 1. The considered mix for the samples. Part

Weight Ratio (kg/m3)

Cement

500

Sand

800

Gravel

800

Water

220

Total

2320

Due to the fact, that the goal of this experiment is to determine the effect of reinforcement type on torsion strength of concrete beams; therefore, bars with different types in each beam have been applied. The ends of the beam has been used metal cube to avoid crunch of beams end [12]. In addition, in ends of beam, longitudinal as well as transverse reinforcement has been used to a distance of 10 cm. After reinforcement of samples according to figures 1 to 4, the stages of concreting and curing of concrete shall be conducted and then the samples shall be examined after 28 days of curing. Dimensions of cylindrical samples and beam samples are also shown in table 2 and 3 respectively.

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Fig.1. Samples No. 1, without longitudinal and transverse reinforcement.

Fig.2. Samples No. 2, just longitudinal reinforcement.

Fig.3. Samples No. 3, just transverse reinforcement

Fig.4. Samples No. 4, both longitudinal and transverse reinforcement. Table 2. Dimensions of Cylindrical Samples. Sample No.

The Average Diameter (Cm)

The Average Height (Cm)

15.1

30.3

15.2

30.1

15.0

30.2

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Table 3. Dimensions of the Beam Samples. Sample No.

Length (Cm)

Width (Cm)

Height (Cm)

60.10

9.99

10.11

60.05

10.02

10.03

60.30

10.01

10.02

60.25

9.98

10.08

It should be noted, that the compressive strength test of the samples shall be conducted after cappingthe goal of which is to create a flat surface on the sample. All the beams, which were experimented on, were 60 centimetres long, they were placed on a 55centimetre- wide support and were loaded and tested. Two concentrated symmetrical loads, which were 25 centimetres away from each other were used for loading purposes. The weight of the rods, which are placed on the beam, was 37.8 kg. The used bars in this experiment are of type A2 and the current strength of 300 MPa. The loading model of the beams can be seen in figure 5.

Fig. 5. The loading model of the beam.

Torsion in the international Standards. Provisions for torsional design of reinforced concrete members appear in majority of international standards of concrete design. While these provisions are conceptually similar, they contain variations that produce different results. Provisions of some of the more well-known standards are reviewed here in this section. Australian Standard (AS3600). According to the Australian standard for concrete structures, AS3600, the ultimate strength in pure torsion, Tuc, for a beam without closed ties can be calculated as Tuc = J t (0.3√ f'c) where f'c – is the compressive strength of concrete at 28 days; Jt – is the torsional rigidity of the cross-section. MMSE Journal. Open Access www.mmse.xyz

(1)

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This torsional rigidity for a rectangular cross-section with dimensions x×y (where x<y) can be determined as 0.4 x2 y. For beams with closed ties, the ultimate torsional strength, Tus, is

Tus = f ys (Asw / s) 2 At cotθ t

(2)

where At – is the area enclosed by the centre lines of longitudinal bars Figure 6; s – is the centre-to-centre spacing of stirrups, fys – is the yield strength of stirrups, Asw – is the cross-sectional area of stirrups, tθ – is the crack angle which can be taken as 45° or can vary linearly between 30° when T∗=φTuc and 45° when T∗ =φTu.max. There are T∗ –is the factored design torque, Tuc – is the ultimate torsional strength of a beam without torsional reinforcement, and φ is equal to 0.7. The term Tu.max is the ultimate torsional strength of a beam limited by web crushing failure and can be obtained from Tu.max=0.2f'cJt. This is a simple equation to evaluate Tu.max. Other more complicated equations have been presented in the literature but not adapted by the standard. For example, Warner et al. [13] present Tu.max as

Fig. 6. The cross-section of a rectangular reinforced concrete beam

(3) Where Aoh is the area enclosed by the centre line of the exterior closed ties and ph is the perimeter. AS3600 suggests that the total longitudinal steel area, As, shall be obtained by

As = (f ys / f y) (Asw / s ) ut cot2 θt

Where ut – is the perimeter of At (in Eq. (4)); MMSE Journal. Open Access www.mmse.xyz

(4)

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f y – is the yield strength of longitudinal reinforcement. Furthermore, according to this standard, the spacing of stirrups shall not be greater than the lesser 0.12ut and 300 mm. British Standard (BS8110). The British standard for reinforced concrete structures, BS8110, indicates that the additional stirrups required to resist torsion in addition to what is required for shear shall be calculated from

Asv / s > Tus / 0.8 x 1 y 1 (0.87 f ys )

(5)

Where Asv – is the area of the two legs of stirrups at a section; x1 and y1 – are the centre to center of the shorter and longer legs of stirrups, Figure 1. Moreover, BS8110 suggests that additional longitudinal reinforcement As due to torsion should be provided as calculated by

As > Asw f ys (x 1 + y 1) / s f y

(6)

This standard emphasises that the spacing of stirrups should not exceed the smallest of x 1, y1 / 2 or 200mm. BS8110 only allows the use of its provisions for torsional design when the yield stress of reinforcement is not more than 460MPa. ACI Standard (ACI318-02). ACI318-02 calculates the ultimate torsional strength of reinforced concrete beams as

Tus = f ys (Asw / s) 2 Ao cot θ t

(7)

Where Ao – is the gross area enclosed by the shear flow path, which can be taken equal to 0.85Aoh. Aoh – is the area enclosed by the centre of stirrups. ACI allows the crack angle θt of non-prestressed or low-prestressed members to be taken as 45°. Eq. (8) is based on the assumptions that all of the external torque is resisted by reinforcement and concrete resistance is negligible; that the concrete carries no tension; that the reinforcement yields, and that the concrete outside the stirrups is relatively ineffective. The standard also indicates that the additional longitudinal reinforcement (As) required for torsion shall not be less than the value obtained from the following equation

As = (f ys / f y) (Asw / s) u t cot2 θ t

(8)

ACI318-02 recommends that the transverse torsional reinforcement (stirrup) shall be anchored by a 135° standard hook around a longitudinal bar and the spacing of transverse torsion reinforcement MMSE Journal. Open Access www.mmse.xyz

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shall not exceed the smaller of ph/8/8 or 12'' (≈304mm). European Standard. According to the European Standard (Eurocode 2), three different ultimate values should be calculated and the minimum chosen. The first value is related to the stirrups contribution to the torsional resistance which can be calculated as

Tu (1) = f ys (Asw / s) 2 Ak cot θ t

(9)

Where Ak is the area enclosed by the centre-lines of the effective wall thickness. The effective wall thickness, tef, can be calculated as A/u where A is the total area and u is the perimeter of the crosssection. The second value of the torsional strength corresponds to the longitudinal bars as

Tu (2) = f y (As /uk) 2 Ak tan θ t

(10)

Where uk is the perimeter of the area Ak. Torsional capacity of the concrete struts is the third value. It can be derived from

Tu (3) = 2v fck Ak tef sin θt cos θt

(11)

Where fck – is the compressive strength of concrete, and ν can be taken as 0.6(1− fck / 250). The least of these three values is the torsional strength of the member. The European Standard also indicates that the variation of crack angle is in the order of 2.5 ≤ cot θt ≤ 1 but can be taken as θt =45°. Canadian Standard. The method of calculating torsional strength of reinforced concrete beams in the Canadian Standard, CSA, is similar to ACI. In addition, CSA advises that the stirrups must be anchored by 135° hooks, the nominal diameter of the bar or tendon shall not be less than s/16, and the total area of longitudinal bars required around the section, Al, (with a spacing not exceeding 300 mm) shall be calculated from At ph / s, where At is the area of a stirrup, ph is the perimeter of the centre line of the stirrups, and s is the spacing of stirrups. In the above mentioned standards, the method of evaluating the ultimate torsional capacity of reinforced concrete beams is similar. ACI standard for this experiment which is more prevalent in the vast majority of countries has been used . Discussion of test results. A simple test for calculating the torsional strength of reinforced concrete beams was experimented with two concentrated symmetrical loads presented in figure 5. As can be seen in figure 6 the failure of beams is shown and subsequently the results of tests including sample rotation, momentum of the cross-section, crack momentum and ultimate momentum of the cross section is presented in table 5.

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Fig. 6. Failure of beams.

Table 5 indicates that the crack momentum of all samples was 5870 Kg.cm according to equation 12.

Tcr = 4 √f’c Ac2 / Pc

(12)

Where Ac – is the area of beam cross-section; Pc – is the perimeter of the beam. Ultimate momentum of the cross-section in sample No. 1 is equal to its crack momentum because this sample was not reinforced by longitudinal and transverse bars. However, this amount has been increased with the enhancement of reinforcement especially in the sample of 4. Moreover, the ductility of beams, if the rotation of samples increase in results, will grow. It was observed that the ductility factor increases with increasing percentage reinforcement. As can be seen in the test results in sample No. 4 with transverse and longitudinal bars the torsional strength and ductility of beam have been increased 95% and 50% respectively in comparison with sample No. 1. In addition, it was noticed that sample No. 3 with just transverse bars had a more torsional strength compared to sample No. 2 with just longitudinal strength and it was concluded that transverse bars play an important role in torsional strength of Reinforced Concrete Beams. The results of experiment shows that the momentum of cross-section in sample No. 3 is 11500 Kg.cm, while this amount for sample No.2 would be 8500 Kg.cm. It should be also noted that transverse bars or longitudinal bars lonely would not able to increase enough the torsional strength of RC beams and both of them can be essential for having a good torsional behaviour in reinforced concrete beams.

Table 5. The Results of the Experiment. Sample No.

Sample rotation (Degree)

Momentum of the Cross- Section (Kg.cm)

8.16

7850

5870

8.78

8500

5870

6500

9.16

11500

5870

8320

12.20

15250

5870

10200

Crack Ultimate Momentum of Momentum the Cross- Section (Kg.cm) (Kg.cm)

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Summary. A simple experiment for the evaluation of the torsional strength of reinforced concrete beams is presented in this research. The following conclusions were drawn from the studies on reinforced concrete beams:  It was observed that the ductility factor increases with increasing percentage reinforcement. The torsional strength and ductility of the sample with transverse and longitudinal bars have been increased 95% and 50% respectively in comparison with sample without reinforcement.  The transverse bars play an important role in torsional strength of Reinforced Concrete Beams compared to longitudinal bars.  It should be also noted that transverse bars or longitudinal bars lonely would not able to increase the torsional strength of RC beams and both of them can be essential for having a good torsional behaviour in reinforced concrete beams. References [1] ACI. Building code requirements for reinforced concrete (ACI 318-95) and commentary (ACI 318 R-95). Committee 318, American Concrete Institute (ACI), Detroit, Mich. 1995. [2] CSA. Design of concrete structures for buildings. Standard A23.3-94, Canadian Standards Association (CSA), Rexdale, Ont. 1994. [3] Elfren, L., Karlsson, I., and Losberg, A. Torsion–bending– shear interaction for concrete beams. ASCE Journal of the Structural Division, 100(8): 1657–1676, 1974. [4] Ewida, A.A., and McMullen, A.E. Torsion–shear–flexure interaction in reinforced concrete members. Magazine of Concrete Research, 23(115): 113–122, 1981. [5] Rahal, K.N., and Collins, M.P. Simple model for predicting torsional strength of reinforced and prestressed concrete sections. ACI Structural Journal, 93(6): 658–666, 1996. [6] Rahal, K.N. Shear strength of reinforced concrete: Part I: Membrane elements subjected to pure shear. ACI Structural Journal, 97(1): 86–93, 2000a. [7] AASHTO. AASHTO LRFD bridge design specifications, SI units, first edition, American Association of State Highway and Transportation Officials (AASHTO), Washington D.C. 1994. [8] Vecchio, F.J., and Collins, M.P. The modified compression field theory for reinforced concrete elements subjected to shear. ACI Journal, 83(2): 219–231, 1986. [9] Collins, M.P., and Mitchell, D. Prestressed concrete structures. Prentice Hall, Inc., Englewood Cliffs, N.J. 1986. [10] Rahal, K.N., and Collins, M.P. The effect of cover thickness on the shear and torsion interaction — An experimental investigation. ACI Structural Journal, 92(3): 334–342, 1995a. [11] Rahal, K.N. Shear strength of reinforced concrete Part II: Beams subjected to shear, bending moment and axial load. ACI Structural Journal, 97(2), 2000. [12] Mohammad Rashidi & Hana Takhtfiroozeh. Determination of Bond Capacity in Reinforced Concrete Beam and Its Influence on the Flexural Strength. Mechanics, Materials Science & Engineering Vol. 6, 2016. doi: 10.13140/RG.2.2.18300.95361 [13] Warner, R.F., Rangan BV, Hall AS, Faulkes KA. Concrete structures. Longman, South Melbourne, 1998. Cite the paper Mohammad Rashidi, Hana Takhtfiroozeh (2016). The Evaluation of Torsional Strength in Reinforced Concrete Beam. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.16568.75521

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Process Modeling for Energy Usage in “Smart House” System with a Help of Markov Discrete Chain10 Victor Kravets1,a, Vladimir Kravets2, Olexiy Burov3 1 – National Mining University, Dnipro, Ukraine 2 – Dnipropetrovsk National University of Railway Transport, Dnipro, Ukraine 3 – Jack Baskin School of Engineering, University of California-Santa Cruz, CA, USA a – prof.w.kravets@gmail.com DOI 10.13140/RG.2.2.34948.32643

Keywords: smart house, Markov discrete chains, possible states, transition probabilities matrix, transition costs matrix, mathematical expectations of transitions costs, cost of Markov random process.

ABSTRACT. Method for evaluating economic efficiency of technical systems using discrete Markov chains modelling illustrated by the system of "Smart house", consisting, for example, of the three independently functioning elements. Dynamic model of a random power consumption process in the form of a symmetrical state graph of heterogeneous discrete Markov chain is built. The corresponding mathematical model of a random Markov process of power consumption in the "smart house" system in recurrent matrix form is being developed. Technique of statistical determination of probability of random transition elements of the system and the corresponding to the transition probability matrix of the discrete inhomogeneous Markov chain are developed. Statistically determined random transitions of system elements power consumption and the corresponding distribution laws are introduced. The matrix of transition prices, expectations for the possible states of a system price transition and, eventually, the cost of Markov process of power consumption throughout the day.

Introduction. The issue in question relates to the problem of smart house engineering for establishing controlled process of energy usage. In this research area, there are such works as [1-3]. In this problem, the leading role belongs to establishing a mathematical model of random processes of energy usage by essential appliances, the model being adequate to physical picture. In order to establish a mathematical model for the problem in question, fundamental results of probability theory and mathematical statistics [4-6], operational research [7], especially Markov random processes theories [8,9] are used. Exploring dynamics of energy usage process in residential house implies also working out an appropriate dynamic model, process scheme, method for modeling process, computation algorithm and an appropriate software package. Dynamic model for energy usage process. Typical residential house (set of rooms) is being explored. Its essential services are provided with a help of several electrical appliances. It means that a technical system consists of N independently functioning subsystems (elements). For example, let us suppose for the sake of simplicity the in the considered household there are three ( N  3 ) elements: refrigerator ( e1 ), microwave oven ( e2 ), light source ( e3 ). It is to mention that generalizing the

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problem with bigger number of elements ( N  3 ) is trivial and is related only to the mathematical formulation volume. It is evident that the energy usage process is periodical, its period ( T ) being set objectively as twentyfour hours. Thus, for the initial approximation it is logical to set the step volume ( t ) of discrete time as equal to one hour ( t  1 ). That is, discrete moments of time when random system transition from one stage to the other one are found as:

tk  k 1, where k  1, 2,3,..., 24. It is to mention that during the period t there should be no more than one switching on or off for system’s elements. It is evident that for the periodic random process of switching on and off t must not exceed the period or be the period’s multiple. It may be that, depending on the statement of technical problem being solved, it is appropriate to select the volume of step t depending on discrete time k , i.e., t  k  . Step volume grounding constitutes a problem apart being solved depending on a particular technical problem, either heuristically or with a help of mathematical estimation [10]. In total, the step volume is defined by the problem’s solution’s precision and the calculations’ volume. We assume that each of three elements can be in one of two possible states: − on-mode denoted with

;

− off-mode denoted with

In a process of independent functioning of each v  th element of engineering system in discrete moments of time k the following random transitions are taking place: On-mode is kept, that is r  k 

. This random event is defined with the probability r  k  . From on-mode to an off-mode, that is r  k 

. This opposite random event is defined with a probability r  k  and, consequently,

r  k   r  k   1.

From off-mode to an on-mode, that is v  k 

. This random transition is defined with the probability v  k  . An off-mode is kept, that is MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

v  k 

. This opposite random event is defined with the possibility of non-recovery v  k  , and, consequently,

v  k   v  k   1. Quantitatively, the probabilities of random transitions r  k  , r  k  , v  k  , v  k  are found as a result of statistical processing the possessed experimental data:

r  k  

n  k 

N  k 

r  k  

;

m  k  v  k   ; M  k 

n  k 

N  k 

;

m  k  v  k   . M  k 

 Here n  k   a number of transitions of   element on k  stage from on-mode to an on-mode;

n  k   a number of transitions of   element on k  stage from on-mode to an off-mode; m  k   a number of transitions for   element on k  stage from an off-mode to an onmode;

m  k   a number of transitions of   element on k  stage from an off-mode to an off-mode; N  k   a number of cases when   element at the beginning of k  stage is found in an onmode;

M  k   is a number of cases when   element at the beginning of k  stage is found in an off-mode. Here at the beginning of k  th and the following (k  1)  stage, there are evident equities: N  k   n  k   n  k  ; M  k   m  k   m  k  ; N  k  1  n  k   m  k  ; M  k  1  n  k   m  k  .

It is to mention that the volume of the main entity or the survey scope, i.e., the number of days when the genuine experiment was conducted, does not depend on discrete time k , element number  and is a defined, whole number, constant:

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N  k   M  k   const.

In the process of energy usage by engineering system in general, each of three independently functioning elements is passing randomly from an on-mode to an off-mode and vice versa. Possible states for engineering system are found with a help of states’ diagram or with generating function [6] in quantity found as 23 :

S1 

S8 

S2 

S7 

S3 

S6 

S4 

S5 

The sequence of random events related to the abrupt transitions of engineering system throughout the mentioned eight possible discrete states in defined discrete time moments is a random process which happens in Markov discrete chain [8, 9]. To illustrate the dynamics of engineering system’s transitioning throughout probable states, the states’ symmetric graph is convenient:

Fig. 1. Symmetric graph of probable states.

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Here the number of peaks and curves (transition probabilities) on the graph is found as 23  8; 223  64. The provided graph and an appropriate nonhomogeneous Markovian discrete chain constitute the dynamic model of energy usage process for the examined engineering system. Mathematical model for Markov random process of energy usage. Mathematical model for Markov random process of energy usage is made in conformity with provided above graph of conditions of nonhomogeneous Markovian discrete chain and has the form of recurrent matrix formula: P81  k  1  P(88)  k   P(81)  k  , k  1, 2,3,..., 24.

Here a column matrix of probability P81  S j  k  1 of eight conditions S j

 j  1, 2,3,...,8

for

engineering system on the following  k  1  stage is defined according to the column matrix P81  S j  k  of system’s states’ probability on the previous k  stage and square matrix P88  k  of

transitional probabilities. It is to mention that the iteration process can begin with any reliably known step k0 : P81  S j  k0  . The elements of transitional probabilities square matrix P88  k  , relevant to the curves of graph of Markov discrete chain's states, are defined as transitional probabilities with the use of statistically obtained probabilities of system’s elements’ transitions r  k  , r  k  , v  k  ,

v  k  , i.e., p11  r1 r2 r3 p12  r1 r2 r3

p21  r1 r2 v3 p22  r1 r2 v3

p31  r1 v2 r3 p32  r1 v2 r3

p41  v1 r2 r3 p42  v1 r2 r3

p13  r1 r2 r3 p14  r1 r2 r3 p15  r1 r2 r3

p23  r1 r2 v3 p24  r1 r2 v3 p25  r1 r2 v3

p33  r1 v2 r3 p34  r1 v2 r3 p35  r1 v2 r3

p43  v1 r2 r3 p44  v1 r2 r3 p45  v1 r2 r3

p16  r1 r2 r3 p17  r1 r2 r3

p26  r1 r2 v3 p27  r1 r2 v3

p36  r1 v2 r3 p37  r1 v2 r3

p46  v1 r2 r3 p47  v1 r2 r3

p18  r1 r2 r3

p28  r1 r2 v3

p38  r1 v2 r3

p48  v1 r2 r3

p51  r1 v2 v3

p61  v1 r2 v3

p71  v1 v2 r3

p81  v1 v2 v3

p52  r1 v2 v3 p53  r1 v2 v3 p54  r1 v2 v3

p62  v1 r2 v3 p63  v1 r2 v3 p64  v1 r2 v3

p72  v1 v2 r3 p73  v1 v2 r3 p74  v1 v2 r3

p82  v1 v2 v3 p83  v1 v2 v3 p84  v1 v2 v3

p55  r1 v2 v3 p56  r1 v2 v3 p57  r1 v2 v3

p65  v1 r2 v3 p66  v1 r2 v3 p67  v1 r2 v3

p75  v1 v2 r3 p76  v1 v2 r3 p77  v1 v2 r3

p85  v1 v2 v3 p86  v1 v2 v3 p87  v1 v2 v3

p58  r1 v2 v3

p68  v1 r2 v3

p78  v1 v2 r3

p88  v1 v2 v3

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where on each k  step of discrete time the following conditions are met: 8

 p  k   1, i  1, 2, 3, 4,...,8 , j 1

and also

 P  S  k   1 , j

j 1

i.e., the totals of matrix columns P88  k  , P81  S j  k  , P81  S j  k  1  are normalized. Thus, a random process of energy usage by the examined engineering system is modeled with the nonhomogeneous Markovian discrete chain described with a recurrent matrix formula represented in detail in the following way: P1  k  1 P2  k  1 P3  k  1 P4  k  1 P5  k  1 P6  k  1 P7  k  1 P8  k  1



p11

p21

p31

p41

p51

p61

p71

p81

p12 p13

p22 p23

p32 p33

p42 p43

p52 p53

p62 p63

p72 p73

p82 p83

p14 p15 p16

p24 p25 p26

p34 p35 p36

p44 p45 p46

p54 p55 p56

p64 p65 p66

p74 p75 p76

p17 p18

p27 p28

p37 p38

p47 p48

p57 p58

p67 p68

p77 p78

P1  k  P2  k  P3  k 

p84 P4  k   . p85 P5  k  p86 P  k  6 p87 P k 7  p88 P8  k 

Energy usage transitional chains of “Smart house” system In a similar way, with a help of statistical method, random prices of energy usage by  th element on k  th step with a time period t (depending on discrete time) are found:

c  k   l  k  

  n  k   t  n  k 

  m  k   t  m  k 

;

c  k   l  k  

  n  k  

;

  m  k  

t  n  k 

t  m  k 

Here   n  k  is a cost of energy usage by  −th element in cases when there are random transitions from on to on state statistically found as n  k  ;

  n  k  is a cost of energy usage by  −th element in cases when there are random transitions

from on to off state statistically found as n  k  ;

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  m  k   is a cost of energy usage by  −th element in cases of random transitions from off

to on state statistically found as m  k  ;

  m  k  − is a cost of energy usage by  −th element in cases of random transitions from off

to off state statistically found as m  k  .

Random transitional chains of turning energy supply on C and off L for the system “Smart house” constitute the following discrete laws of distribution: C  k  c  k  c  k  R  k  r  k  r  k 

L  k 

;

l  k 

V  k  v  k  v  k 

;

  1, 2,3 . Respective mathematical expectations of discrete random transitions for energy usage on time interval t depend on discrete time k and are found as:

M C  k   c  k   r  k   c  k   r  k  ; M L  k   l  k   v  k   l  k   v  k  . The elements of square matrix C88  k  for expected transitions of “Smart house” system throughout

possible states  S1, S2 , S3 , S4 , S5 , S6 , S7 , S8  are found according to a worked out square matrix of transitional probabilities P88  k  and are the following: c11  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c12  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ;

c13  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c14  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c15  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c16  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c17  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ; c18  k   r1  k   r2  k   r3  k   c1  k   c2  k   c3  k  ;

c21  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ; MMSE Journal. Open Access www.mmse.xyz

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c22  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ; c23  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ;

c24  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ; c25  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ;

c26  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ; c27  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ;

c28  k   r1  k   r2  k   v3  k   c1  k   c2  k   l3  k  ; c31  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ;

c32  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ; c33  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ;

c34  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ; c35  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ;

c36  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ; c37  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ;

c38  k   r1  k   v2  k   r3  k   c1  k   l2  k   c3  k  ; c41  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ;

c42  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ; c43  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ;

c44  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ; c45  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ;

c46  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ; c47  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ; MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

c48  k   v1  k   r2  k   r3  k   l1  k   c2  k   c3  k  ; c51  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ;

c52  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c53  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ;

c54  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c55  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c56  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c57  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c58  k   r1  k   v2  k   v3  k   c1  k   l2  k   l3  k  ; c61  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c62  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c63  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c64  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c65  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c66  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c67  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c68  k   v1  k   r2  k   v3  k   l1  k   c2  k   l3  k  ; c71  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ; c72  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ; c73  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ; c74  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ;

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c75  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ; c76  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ;

c77  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ; c78  k   v1  k   v2  k   r3  k   l1  k   l2  k   c3  k  ;

c81  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c82  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ;

c83  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c84  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c85  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c86  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c87  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  ; c88  k   v1  k   v2  k   v3  k   l1  k   l2  k   l3  k  .

Mathematical expectations for costs of “Smart house” system’s transitions from different states. Mathematical expectations of “Smart house” system’s transitions from eight possible states are found with a help of mathematical expectations for energy usage transitional costs M C  k  ,

M L  k  for each of three elements [6]:

M S1  k   M C1  k   M C2  k   M C3  k  ;

M S5  k   M C1  k   M L2  k   M L3  k  ;

M S2  k   M C1  k   M C2  k   M L3  k  ;

M S6  k   M L1  k   M C2  k   M L3  k  ;

M S3  k   M C1  k   M L2  k   M C3  k  ;

M S7  k   M L1  k   M L2  k   M C3  k  ;

M S4  k   M L1  k   M C2  k   M C3  k  ;

M S8  k   M L1  k   M L2  k   M L3  k  ,

or with a help of transitional prices’ matrix C88  k  , as a total of its columns’ elements: 8

j 1

M S1  k    c1 j  k  ; M S5  k    c5 j  k  ; M S2  k    c2 j  k  ; M S6  k    c6 j  k  ;

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 8

j 1

M S3  k    c3 j  k  ; M S7  k    c7 j  k  ; M S4  k    c4 j  k  ; M S8  k    c8 j  k  .

The obtained mathematical expectations of costs for “Smart house” system’s transitions from each possible state constitute a row matrix: M 18  k   M S1  k  M S2  k  M S3  k  M S4  k  M S5  k  M S6  k  M S7  k  M S8  k  ,

corresponding to a column matrix P81  k  of these states’ probabilities. “Smart house” system’s states’ identification in discrete time according to the energy usage level. Mathematical expectations for the cost of “Smart house” system’s wandering throughout possible states depending on discrete time k are found as: M  k   M 18  k   P81  k  .

Then, the cost of energy usage by “Smart house” system on time interval t is found with a help of formula

  k   M  k   t.

The total value of Markov energy usage process on finite set of steps k0 , constituting twenty-four hours is estimated as a total of k0

  k0     k . k 0

Summary. The mathematical models of stochastic processes of failures, recoveries of a broad class of systems described by discrete asymmetric Markov chains were developed. The algorithms to assess the economic efficiency of systems modeled by discrete asymmetric Markov chains are proposed. Mathematical models of stochastic processes and algorithms for evaluation the economic efficiency of systems are presented in matrix dorm and adapted to use of computer technology. Generalization of the offered algorithm for bigger number of elements in the system is a trivial one. The difficulties related to the awkwardness of the required mathematical operations are overcome with a help of advanced software development and modern computing hardware usage. References [1] G. W. Hart, Nonintrusive appliance load monitoring, Proceedings of the IEEE, vol. 80, no. 12, Dec. 1992, pp. 1870-1891.

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[2] M. Weiss, A. Helfenstein, F. Mattern, T. Staake, Leveraging smart meter data to recognize home appliances, Proceedings of the IEEE International Conference on Pervasive Computing and Communications (PerCom 2012), Lugano, Switzerland, March 2012, pp. 190-197. [3] Alan P. Rossiter (Editor), Beth P. Jones (Editor), Energy management and efficiency for the process industries, AICHE Inc., John&Sons Inc., Hoboken, New Jersey, 2015, 400 p., ISBN: 978-1118-83825-9. [4] B. Ayyub, R. Mccuen, Probability, statistics & reliability for engineers, CRC Press, New York, 1997, 663 p. [5] A. Birolini, Quality and Reliability of Technical Systems: Theory, Practice, Management, Edition Springer, 2004. DOI: 10.1007/978-3-642-97983-5. [6] V. Kravets, Vl. Kravets, O. Burov, Reliability of Systems. Part 1. Statics of Failures. Lap Lambert Academic Publishing, Omni Scriptum GmbH & Co. KG., 2016. [7] E.S. Ventcel', Issledovanie operacij [Operations research], Moscow, Sovetskoe radio Publ., 1972, 552 p. [in Russian]. [8] E.S. Ventcel', L.A. Ovcharov, Theory of random processes and its engineering application, Moscow, Nauka Publ., 1991, 384 p. [9] V. Kravets, Vl. Kravets, O. Burov, Reliability of Systems. Part 2. Dynamics of Failures. Lap Lambert Academic Publishing, Omni Scriptum GmbH & Co. KG., 2016. [10] V.A. Kotelnikov, R.A. Silverman, Theory of optimum noise immunity, New York, Dover Publ., 1968, 140 p. [11] Victor Kravets, Vladimir Kravets & Olexiy Burov (2016). Matrix Method for Assessing Economic Efficiency of Systems Simulated with Asymmetric Markov Discrete Chains, Automation, Software Development & Engineering Journal, ISSN 2415-6531 Cite the paper Victor Kravets, Vladimir Kravets, Olexiy Burov (2016). Process Modeling for Energy Usage in “Smart House” System with a Help of Markov Discrete Chain. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.34948.32643

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Statistical Control of the Technological Process Stability to Manufacturing Cylindrical Parts into High Series11 Viorel-Mihai Nani1, 2, a, b 1 – Research Institute for Renewable Energy, Politehnica University of Timisoara, G. Muzicescu Street, no. 138, 300774, Timisoara, Romania 2 – Faculty of Engineering, University ″Ioan Slavici″ of Timisoara, Paunescu Podeanu Street, no. 144, 300568, Timisoara, Romania a – viorelnani@yahoo.com b – viorel.nani@upt.ro DOI 10.13140/RG.2.2.33528.65284

Keywords: statistical control limits, arithmetic mean, standard deviation, fraction of probable defective parts, technological process stability.

ABSTRACT. This paper presents a calculation algorithm for verifying on-line of the manufacturing process stability in large and mass series of some cylindrical parts from axes type. Through experimental investigations, we conducted a statistical control on a sample parts batch to determine the machining accuracy of some checking turret lathes. In the first phase, we performed a statistical analysis of the technological process preceding the manufacture of cylindrical parts in large and mass series. For checking the normality assumption of the deviations for parts machined, we established the main statistical parameters as being arithmetic mean and standard deviation. With these parameters, I could calculate the fraction of probable defective parts. In the second phase, we determined the control limits for the arithmetic mean and standard deviation. With these parameters I could pursue in chronological order the actual achievement of the workpiece size. In this way, I could check the technological process stability on-line for well-defined period’s time, between two successive adjustments of the machine-tools.

Introduction. Following the actual technological manufacturing process of the cylindrical parts from the axes type, these will have deviations from the dimensional accuracy and geometric shape [2 and 7]. The main factors contributing to the processing deviations emergence are [1, 6, 8 and 9]: the geometrical inaccuracy of machine-tools; the imprecision of the measuring instruments used; the fastener imprecision of workpiece and of the cutting tools; the wear of cutting tools; the variation and modification during the cutting process the thermal parameters for machine tools, fastener devices, workpiece and cutting tools; the elastic deformation of the technological system; the unevenness of cutting depth; the variation of internal stresses into the processing material. The manufacture type and the causes producing these deviations, determine the check method for the machining process stability. Into the large and mass series production case, it uses exclusively a statistical analysis [1, 3, 5, 6, 11 and 12]. Being a section of this analysis, the statistical control is carried out on a sample of representative parts, considered as a standard. Thus, both during the manufacturing process and after its completion [2, 4, 6, 7, 8 and 13], batches of 100 pieces are taken to be checked individually. The statistical analysis of the measurement results provides information

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about the technological process stability. But the timeframes needed to process the experimental data can adversely influence the productive capacity, with negative effects on manufacturing costs. In paper we propose an active statistical control of the machining accuracy, conducted on-line during the technological process. The experimental investigations demonstrated the supercomputing capacity of relevant information in connection with possible trends of disturbance/impairment or decreasing the manufacturing accuracy [9, 10, 12 and 14]. In this way it was possible to correct operative the technological process without interrupting the manufacturing cycle, for it to be stable over time and to avoid the emergence of non-conforming parts. Investigations were conducted over some cylindrical parts of the axes type which have been manufactured in high series on a checking turret lathe. The schematic diagram is shown in Figure 1.

2 A

III

II 1

IV1 3 4

Câ&#x20AC;&#x201C;Hexagon turret is rotated to 900 in vertical plan

E 8 D 5

Fig. 1. The principle scheme of the testing plant. The blank denoted by A has the shape of a long cylindrical bar. This one it is operated in a primary rotational movement I with the help of a gripping device D. The metal cutting of the blank takes place in a sequential cycle of movements II - III - IV/IV1 - V/V1, using tools which are adjusted to dimension. A positioning device B includes a running center 1, and a buffer brake 2 as a plug. Another device C as a hexagon turret contains a specified number of tools for each technological operation. Thus: a necking tool 3 for grooving; a facing tool 4 for frontal lathing one end; a center drill 5; a hook tool 6 for exterior lathing; an angle cutting tool7 for beveling at 450 and a parting tool 8. Another device E ensures the working advance of the blank A for processing new parts. The technological itinerary it is: (1) the blank is fixed into D by movements II; (2) the blank into the rotation movement I is actuated; first, are processed the clean-frontal one end and the centering hole, with the help of the tools 4 and 5; (3) the device D releases the blank A which it is driven by device E up to contact with the buffer (plug) 2; (4) the device B, through the movements IV - IV1, ensures a supplementary support for the blank A by the means of running center 1, after which it takes place processing the exterior cylindrical surfaces with the help of the hook tool 6, through the movements V - V1; (5) is continue processing of the two channels by means of the necking tool 3, after which the MMSE Journal. Open Access www.mmse.xyz

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954

edges are beveled at 450 with the angle cutting tool 7; (6) the workpiece fall off by means of the parting tool 3 and the technological cycle stands ready to start again. The main statistical parameters. The main statistical parameters that characterize a certain size X from a controlled parts series [1, 4, 6 and 15], can be grouped as follows: 1 Parameters of general trend, giving information on adjustments made: 1.1 The unweighted arithmetic mean of the sampling fraction string x ; for a discrete distribution, it is calculated using the relationship:

x

 i 1

xi n

(1)

where xi – the actual size of the controlled parts in their manufacturing order I from the sampling fraction string n; n – number of parts constituting the controlled sample size 1.2 The median of the sampling fraction string M e , i.e. the value for which the frequencies having smaller or higher values than herself are equal, and calculate with the relationship: - For an uneven number n of ordered parts ascending, n = 2k + 1:

M e  xk  1

(2)

- For an even number n of ordered parts ascending, n = 2k

Me 

xk  xk  1 2

(3)

where k = 1, 2, 3, … 1.3 The modal value of the sampling fraction string M 0 , which is the characteristic value with the highest frequency, and calculate with the relationship

M 0  x  3 (M e  x )

(4)

1.4 The central value of the sampling fraction string x c , which calculate with

xc 

xmax  xmin 2

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2 The parameters of scattering, giving indications about the processing accuracy: 2.1 Dispersion of the sampling fraction string  2 , which is calculated for the discrete distributions using formula:

  2

f j .(x j  x )2

j 1



(6)

where fj – the frequency values the same rank j 2.2 The standard deviation of the sampling fraction string  , which is given by the square root of dispersion:



f j .( x j  x ) 2

j 1



(7)

2.3 The amplitude of the sample fraction string D, is calculated as the difference between highest and the lowest value measured: D  xmax  xmin

(8)

Statistical control of processing accuracy. We supposed that on the dimensional dispersion of the measured semi-products, acts only random variables as accidental factors [1, 5, 7, 9 and 15]. Moreover, we supposed that a predominant influence no factor hasn’t; in this case, the random variable it is subject to a normal distribution law (Laplace and Gauss) and its function has the form:

F ( x) 

 2









( x  x)2 2 2

dx ,

(9)

where x and  are distribution parameters (arithmetic mean and standard deviation). Statistical control was performed during the technological process and includes the following sequence: (1) statistical analysis of the technological process before application the control; (2) development of data sheet for control; (3) performing the proper statistical control; 1 Statistical analysis – it applies before using statistical control [1, 9, 12, 14 and 15]. Statistical analysis aims evaluation of the technological process stability as well as the statistical parameters determination. With the help of these parameters it will perform control in the event that manufacturing process is stable and is conducted normally. The analysis steps are the following: (1) conducting the survey on a representative group of parts (usually 100 pcs, processed successively); (2) the preparation of the time graphic; (3) the variability study of the technological process; (4) independence checking of results achieved; (5) checking of the normality assumption; (6) calculating the fraction of probable defective parts and drawing conclusions about technological process. MMSE Journal. Open Access www.mmse.xyz

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2 The control data sheet – practically, here are identified the nonconformities and it is detected the time of onset of perturbations in the technological process by recording and interpreting the variations statistical parameters as well the values characteristic compared to some control limits [2, 5 and 13]. Mainly, are used two statistical parameters: one for tendency (when adjustments are made), and the other for scattering (when accuracy repairs are made). According to these parameters, the following more common methods are used: (1) method of arithmetic mean and the standard deviation; (2) method of arithmetic mean and the amplitude; (3) method of the median and of the amplitude. 3 Performing the proper statistical control - according to the chronological criterion, to well-defined timeframes, samples of parts are taken. After that, the two select statistical parameters should be determined [2, 3 and 13]. If they it falls between the established control limits, the technological process takes place normally and can it continue. When one of the parameters is outside the control limits, means the technological process is unstable (adjustments and/or repairs are needed) and requires stopping the machine-tools for detecting and removing the causes. The parts which were processed during the timeframe from the preceding sample verification they will be rigorously controlled, piece by piece, because appeared rejects. The technological process can continue after remedying the nonconformities. Statistical control of the technological process stability. Application to manufacturing cylindrical parts. The work drawing of the cylindrical parts is shown in Figure 2. These parts are used for the closure devices of the tarpaulins on TIR-s. Heat treated at 28-32 HRC, the parts are made from quality steel 3C45 (SR EN 10083-1.2). The market demands require machining some axes in batches of 40 000 pcs/month. From functionally, is important to ensure the assembly quota of

1.2

0.8

Ф9.8

Ф7.4

Ф10

Ф12+0.045

Ф10

Ф7.4

Ф9.8

 120 0.045 mm. The sharp edges are beveled to 0.5 x 450.

1.2

Fig. 2. The work drawing of the axes. The experimental tests were based exclusively on the active control of the assembly quota during  0.045

processing (Φ120 mm). The statistical parameters used were the arithmetic mean x and standard deviation σ. With the help of these parameters, we calculated the specific control limits, valid for machining of the cylindrical parts indicated in Figure 2. The sampling on-line to well defined timeframes, the measuring of the functional quota and the automatic processing of the values effective measured provides important information about the stability of the technological process. 1 Statistical analysis of the technological process before application the statistical control 0.045

1.1 Conducting the survey - we determined actual values xi of the controlled size N  Φ120 for a number n = 100 pcs, in the order of their processing. The measurement results were recorded in the data sheet which is shown in Table 1. For measurements, we used a micrometer with dial comparator heaving a measuring field 0 – 25 mm and 0.002 mm division value. MMSE Journal. Open Access www.mmse.xyz

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Table 1. The effective values measured for a batch n = 100 pcs in the successive processing order. No.

No.

crt.

/mm/

crt.

/mm/

crt.

/mm/

crt.

/mm/

12.010

26.

12.016

51.

12.022

76.

12.014

12.006

27.

12.018

52.

12.024

77.

12.022

12.008

28.

12.022

53.

12.020

78.

12.024

12.004

29.

12.012

54.

12.020

79.

12.016

12.012

30.

12.026

55.

12.018

80.

12.020

12.016

31.

12.014

56.

12.022

81.

12.020

12.002

32.

12.008

57.

12.016

82.

12.028

12.008

33.

12.014

58.

12.018

83.

12.018

12.016

34.

12.016

59.

12.022

84.

12.022

10.

12.014

35.

12.010

60.

12.020

85.

12.026

11.

12.010

36.

12.018

61.

12.030

86.

12.024

12.

12.006

37.

12.022

62.

12.024

87.

12.020

13.

12.012

38.

12.012

63.

12.014

88.

12.018

14.

12.004

39.

12.020

64.

12.020

89.

12.030

15.

12.010

40.

12.012

65.

12.022

90.

12.022

16.

12.008

41.

12.014

66.

12.018

91.

12.028

17.

12.016

42.

12.028

67.

12.028

92.

12.020

18.

12.014

43.

12.020

68.

12.020

93.

12.024

19.

12.012

44.

12.026

69.

12.024

94.

12.034

20.

12.020

45.

12.022

70.

12.016

95.

12.018

21.

12.026

46.

12.018

71.

12.022

96.

12.026

22.

12.018

47.

12.016

72.

12.024

97.

12.020

23.

12.002

48.

12.020

73.

12.018

98.

12.022

24.

12.014

49.

12.020

74.

12.020

99.

12.032

25.

12.010

50.

12.012

75.

12.020 100. 12.024

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1.2 The time graphic - allows the formulation some comments on the dynamic stability of the technological process. The measurement results are shown in Figure 3 in a rectangular axis system. xi (10-3 mm) 35 30 25 20 15 10

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Order number

Fig. 4. The time graphic of the measurement results. On the ordinate is plotted the effective value of the controlled size N denoted xi, and on abscissa is the order number of the measured piece, of 5 in 5 in the strict order of processing. Analyzing the time graphic, it can be noted a slight upward trend in the effective size of the measured quota. This we explain by the pronounced wear of the tool edge, when is freshly sharpened, and due to thermal instability of the technological system in the beginning period of the machining. 1.3 Variability study of technological process - consists into determining the distribution law of actual 0.045

values N  12 0 of the measured parts. From statistically, is identifies the effective values measured xmax and xmin and then it calculate the amplitude D, using equation (8). In this case: D = 12.034 – 12.002 = 0.032 mm The amplitude D it is divided into k = 5 equal intervals, and the effective values of the measured parts contained in each interval, form a class; we highlight that each class includes and the values which are equal to the lower limit of interval. For each class, it determine the mean value x j and the absolute frequency mj, where j = 1, 2, …, 5 represents the order number of class. The distribution parameters ( x and  ) is calculated, where the measured values are grouped in classes of equal amplitudes, with the following relationships:

m xcd

j 1

 xj  c    d    n

(10)

Respectively

xj  m j   j 1  d n 1 5

 d

c    

n c  x   n  1  d 

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where d – the amplitude of class (d = 0.007); c – the mean value with the greatest frequency (c = x10= 12.020) To simplify the calculation for determining the distribution parameters, Table 2 was prepared. Table 2. The items for calculating the statistical distribution parameters (arithmetic mean and standard deviation). No. Class limits class I II III IV V

12.00012.007 12.00712.014 12.01412.021 12.02112.028 12.02812.035

xj  c d

 xj  c  m j .  d   

12.0035

- 2.357

- 14.142

33.332

12.0105

- 1.357

- 21.712

29.463

12.0175

- 0.357

- 16.065

5.735

12.0245

0.643

16.075

10.336

12.0315

1.643

13.144

21.595

∑ = - 22.70

∑ = 100.461

Substituting the values obtained into above relations (10 and 11), we obtain the following distribution parameters:

x  12.020  0.007 x

 22,70  12.020  0.007 x 0.227  12.018 mm 100

Respectively

  0.007

100.461 100  12.020  12.018   x  99 99  0.007 

 0.007 1.01475  0.08245  0.00676

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The histogram of distribution in a system of rectangular axis, where on ordinate is the absolute frequency of class mj, j = 1, 2, …, 5 and on abscissa the order number of the class, is shown in Figure 4. mj 40 30 20 10

III

D = 0.032

xmin = 12.002

No. class

xmax = 12.034

Fig. 4. Histogram of the absolute frequencies. 1.4 Checking of the normality assumption To check the concordance between the experimental distribution and a certain theoretical distribution, we calculated [9, 10, 11 and 15]:

  2

(m j  n p j ) 2

j 1

n pj



(12)

and we compared this value with the critical value established into statistical tables, where pj is the probability calculated on basis of the theoretical distribution so that the characteristic size to have a value within the interval j. For this purpose, for simplify the analytical calculations, we drawn up Table 3. In this table, the minimum number of classes was originally 10. But, by merging with the adjoining classes [1 and 10] we reached 8 classes because absolute frequency of the values from extreme classes was lower than 5 (we had 4 in first class, respectively 2 in the tenth class). Values of function Ф(zj) can be found into mathematical tables and the probabilities pj are set as follows [2, 7, 12, 13 and 14]:

p1   ( z1 )  0.5 p j   ( z j )   ( z j 1 ) p k  0.5   ( z k 1 ), where k – the class number (k = 1, 2, … , 8);

 ( z j ) - Laplace’s function.

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Table 3. Items for calculation of the parameter χ2. No. crt. 1.

Class limits

-∞ - 12.0084

zj 

( z j )

xi  x d

12.0084

- 1.37

12.0084–12.0116

12.0116

- 0.91

12.0116-12.0148

12.0148

- 0.46

4. 5. 6. 7. 8.

12.0148-12.0180 12.0180-12.0212 12.0212-12.0244 12.0244-12.0276 12.0276- +∞

12.0180 9 12.0212 28 12.0244 20 12.0276 5 +∞ 8 ∑ = 100

0 0.46 0.91 1.37 +∞

m j  n p j 2

m j  n p j 2 n pj

0.4147 0.3186 0.1772 0 0.1772 0.3186 0.4147 1 ∑=1

0.0853

2.1609

0.2533

0.0961

2.2521

2.2114

0.1414

0.7396

0.0523

0.1772 0.1772 0.1414 0.0961 0.0853

76.0384 105.6784 34.3396 21.2521 0.2809 ∑ = 17.4446

4.2911 5.9637 2.4285 2.2114 0.0329

If the actual and theoretical statistical distribution are into accordance, the calculated size  calc will 2

not exceed a critical value  crit . The critical value is appropriate to risk of order I(α) and to the degrees 2





number of freedom ν. The risk of order I(α) is determined in such a way that P  calc   crit   . 2

Really, for the degrees number of freedom ν = 10 - 3 = 7 (it’s was determined in accordance with the extreme classes that have mj<5, as well the statistical parameters - arithmetic mean x and standard deviation  2 - which were calculated based on observed data) and for the risk of the order 0.001  p  0.0024  0.02 with α = 0.01, we obtained

2  crit  18.5 . This value is obviously greater

than the size calculated  calc  17.446 . 2

Therefore, for experimental data resulting from measuring the functional quota of the axes N, we admit the normality assumption and we accept that the statistical distribution unfolds normally. 1.5 Calculating the fraction of probable defective parts The fraction defective or the percentages of probable rejected parts, represent probability that the characteristic value xi to exceed the limits of tolerance field and it is calculated with [3, 4, 9, 11, 12 and 14]:

p  1   ( zs )   ( zi )

(14)

Ts  Tc

(15)

where:

zs 



and z i 

Ti  Tc



where Ts and Ti – upper respectively lower limit of the specified tolerance field; Tc – center of the specified tolerance field; Ф(zs) and Ф(zi) – Laplace’s function values.

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Substituting the known values, both those provided in the work drawing, and those obtained by effective measurements, we obtain:

zs 

0.045  0.0225 0  0.0225  3.33  3.33 , respectively z i  0.00676 0.00676

Substituting the values for the arguments, zs and zi, and knowing that Ф(-z) = Ф(z), we obtain the following values for Laplace’s function:

 ( z s )   ( zi )  0.4988 Consequently, the fraction of probable defective parts it is: p  1  0.4988  0.4988  1  0.9976  0.0024

Since 0.001  p  0.0024  0.02, the scattering field of the random variables xi is approximately equal to the specified tolerance field in the work drawing. Under these conditions, the technological process is carries out normally and it is controllable in statistical terms. 2 Statistical control based on arithmetic mean and standard deviation For the checking efficiency of manufacturing process stability of the parts type axes, it is accepted that the further controlled sample, is n = 5 pcs. The timeframe between two successive samples, depending on the production volume, is [2, 10. 11 and 14]:

It 

60 nM pm

min

(16)

where pm –production rhythm /pcs/hour/; M – the mean number of parts processed between two successive adjustments /pcs/ From technical documentation resulted that the time norm to the axes processing on turret lathes is 1.25 min/pcs and the average number of machined parts between two successive adjustments is 500 pcs. With this information, the timeframe between two successive adjustments of the machine-tool is:

It 

60 45

5 x 500  62.5 min

Thus, at intervals of 62.5 minutes, are taking samples how many 5 pcs. For each sample, we calculate the arithmetic mean and standard deviation, with relations:

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xi 

1 5



j 1

xij , respectively  i 

1 5

 x 5

j 1

 xi



(17)

where i – represent the sample’s rank; j – the part number in the order of processing (j = 1, 2, … , 5) Under these conditions, the control limits for arithmetic mean was calculated depending on the standard deviation σ for the fraction of probable defective parts 0.001  p  0.0024  0.02 using the relationships [1, 7, 10, 11 and 14]: Lci x  Tc  A  , respectively Lcs x  Tc  A 

(18)

where Tc – center of the specified tolerance field; A – coefficient calculated from statistical tables for risk of the order I(α) and the argument z Therefore, the effective values of the control limits for arithmetic mean are:

Lci x  0.0225  1.431 x 0.00676  0.013 , respectively

Lcs x  0.0225  1.431 x 0.00676  0.032 In order that the machined parts to be accepted, the first time it is need that each tool be adjusted to dimension, so that the scattering field center of errors to overlap with the middle of the tolerance field. Namely, by software, the tool edges are adjusted to quota 12.0225 mm. If for each sample of 5 pcs consecutive machined, the arithmetic mean is located within the limits of 0.013 mm and 0.032 mm, then the machine tool is properly adjusted and the technological process is stable. Control limit for the standard deviation is established in function by the size of the fraction of probable defective parts so that the risk of order I(α) to be as small as:

Lc  G 

(19)

where G – coefficient calculated from statistical tables for risk of the order I(α) Consequently, the effective value of the control limit for standard deviation is:

Lc  2.12 x 0.00676  0.014 If for each sample of 5 pcs consecutive machined, the standard deviation is less than the control limit σ ≤ Lcσ ≈ 0.014, then tool ensures the processing accuracy, and the technological process is stable. 3 Performing the proper statistical control MMSE Journal. Open Access www.mmse.xyz

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During the manufacturing process of each batch of 40 000 pcs, at time intervals of 62.5 minutes, it is extract on-line a sample of 5 pcs successively processed under practically identical conditions. With these samples values, we can calculate the arithmetic mean and standard deviation for the functional quota N, using relationships (17). The calculated values are then compared with control limits established by relations (18) and (19). If the calculated statistical parameters fall between the control limits, then technological process is stable and the machined parts are appropriate. Discussions and conclusions. The experimental researches have constituted the background of a verification algorithm on-line of the technological process stability for manufacturing cylindrical parts on turret lathes. Has been designed a predictive model for operating data and/or technological parameters, which was based on the evolution analyze of statistical parameters. It is not important how was made the sampling of operative data. The parts can be actively controlled, during processing or manually, at certain timeframe. Thus, based on the anticipated results determined by calculating the arithmetic mean and standard deviation on samples of 5 pcs collected to preset timeframes, we can formulate the following conclusions: - if x i and  i are in the established control limits, it is considered that the technological process is carried out normally and the processed parts are appropriate with the technical documentation; - if x i exceeds one of limit but  i is below the limit established, means that the adjustment of machine-tool has been affected; in this case, it stops the turret lathe for restoring the adjustment, and the processed parts in the timeframe from the previous control they will check piece by piece; - if  i exceeds the limit established, regardless the arithmetic mean’ position toward its control limits, means that was affected the precision of machine-tool; the checking turret lathe it stops and by the appropriate maintenance program (current repairs and/or major repairs) it is brought to normal parameters of geometric precision; the processed parts in the timeframe from the previous control they will check piece by piece, also; The importance of verification algorithm lies in that enables, among others, determination on-line of the instability trend of the technological process. In this way, we can take action to prevent any disturbances of machine-tool leading to the appearance of defective parts and stop the production (small adjustments, compensation the tool's wear or changing some worn parts of machine-tool etc.). References [1] Baran T., Statistical methods for analysis and quality control production, Didactic and Pedagogic Publishing House, Bucharest (1979) [2] Draghici G., Concept machining processes, Polytechnic Publishing House, Timisoara (2005) [3] Falsone G., Settineri D., Explicit solutions for the response probability density function of nonlinear transformations of static random inputs, Probabilistic Engineering Mechanics;33 (79):85 (2013), 10.1016/j.probengmech.2013.03.003 [4] Falsone G., Settineri D., On the application of the probability transformation method for the analysis of discretized structures with uncertain proprieties, Probabilistic Engineering Mechanics, 35, 44–51 (2014), doi: 10.1016/j.probengmech.2013.10.001 [5] Grigoriu M., R.V. Field Jr., A two-step method for analysis of linear systems with uncertain parameters driven by Gaussian noise, Probabilistic Engineering Mechanics, 34, 200–210 (2013), doi: 10.1016/j.probengmech.2013.10.003 [6] Nani V.M., Statistical control of processing prismatic pieces on grinding machines, Measurement, 47, 516 - 520 (2014), doi: 10.1016/j.measurement.2013.09.033 MMSE Journal. Open Access www.mmse.xyz

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[7] Pau V., Bagiu L., David I., Technical Measurements, Printech Publishing Bucharest (1999) [8] Ramamoorthy B., Radhakrishnan V., Weckenmann A., Knauer M., Geus D.A., Improvement of machining accuracy on a CNC lathe through error prediction and compensation, in: XV IMEKO World Congress, June 13–18, Osaka, Japan (1999) [9] Renata T., Barros e Vasconcellos, Marcello L.R. de Campos, Error analysis in high-accuracy digital measurements, Measurement, 45, 819-832 (2012) [10] Vizireanu D.N., Halunga S.V., Simple, fast and accurate eight points amplitude estimation method of sinusoidal signals for DSP based instrumentation, Journal of Instrumentation, 7 (04), P04001 (2012), doi: 10.1088/1748-0221/7/04/P04001 [11] Vizireanu D.N., Preda R.O., "Is "five-point" estimation better than "three-point" estimation?", Measurement, 46, 840 – 842 (2013) [12] Vratislav H., Analysis of basic probability distributions, their properties and use in determining type B evaluation of measurement uncertainties, Measurement, 46, 16-23 (2013), doi: 10.1016/j.measurement.2012.09.006 [13] Weckenmann A., Estler T., Peggs G., McMurtry D., Probing systems in dimensional metrology, CIRP Annals – Manufacturing Technology, 53 (2), 657–684 (2004) [14] Xiang Y.B., Liu Y.M., Application of inverse first-order reliability method for probabilistic fatigue life prediction, Probabilistic Engineering Mechanics, 26, 148–156(2011) [15] Yazhou Xu, Fatigue reliability evaluation using probability density evolution method, Probabilistic Engineering Mechanics, 42, 1–6 (2015), doi: 10.1016/j.probengmech.2015.09.005 Cite the paper Viorel-Mihai Nani (2016). Statistical Control of the Technological Process Stability to Manufacturing Cylindrical Parts into High Series. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.33528.65284

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Analysis of the Time Increment for the Diffusion Equation with Time-Varying Heat Source from the Boundary Element Method12 Roberto Pettres1, a 1 – Federal University of Parana, Program of Pos-graduate in Numerical Methods in Engineering. Curitiba, Brazil. a – pettres@ufpr.br DOI 10.2412/mmse.8.968.954

Keywords: Boundary Element Method, diffusion equation, time increment, transient analyses.

ABSTRACT. In this paper a Boundary Element Formulation for the one-dimensional transient heat flow problem is presented. The formulation employs a time-independent fundamental solution; consequently, a domain integral appears in the integral equations, which contains the potential time derivative and the time-dependent heat source term of the governing equation. Linear elements are used for the domain discretization. The time marching scheme is implemented with finite difference approximations. The performance of the formulation was assessed comparing the numerical results with an analytical solution. Convergence of the numerical results is evaluated with varying size time-increment during analysis.

1. Introduction. The first records dealing with the origin of the Boundary Element Method (BEM) date from the year 1823, in a publication by the Norwegian mathematician Niels Henrik Abel on the tautochronous problem ('equal time') [1]. In this work, Abel portrayed to the method as a technique based on integral equations to solve problems based on partial differential equations. This method received attention from several researchers and it took another eight decades of studies for the method to receive the first classical theory of integral equations developed by Fredholm in 1903 [2]. Still in the twentieth century, several authors used the technique of integral equations and made important contributions to the evolution of the method, being called the Boundary Element Method from the works of Brebbia [3], which presented a formulation based on integral equations and in tecniques of weighted residues. Nowadays, the BEM has been used to solve a growing number of problems in solids mechanics, electromagnetism, heat diffusion [4], among others, and in certain formulations, it ends up counting on the coupling of other numerical methods, such as the Finite Differences Method (FDM) [5]. In this work, coupled to the BEM, the FDM is used to solve the heat diffusion equation with a heat generation term variable in time and a study is performed on the convergence behavior of formulation when using variables time increment values, counting on a fundamental solution independent of time. At the end of the work the results are presented. 2. Mathematical and Geometric Model. The mathematical model chosen for this study is Diffusion Equation with a source term, given by (eq. (1)) [6]:

 2u ( x, t ) 

1 du ( x, t )  F ( x, t ) k dt

x  ,   [ 0 L ]; k  thermal conductivity; t  0

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The geometric model is a unidimensional bar of unit length with a variable heat source in time, under the boundary conditions given in (2) and (3) and initial in (4). Essentials ^

u ( x, t )  u ( x, t )

(2)

Naturals ^

q( x, t )  q( x, t )

(3)

Initials ^

(4)

u ( x,0)  u

2.1 Problem formulation from BEM. Being u an approximate solution to the problem, which does not meet the boundary conditions, two types of residues or errors are generated: i) in  (domain): _ _

1 d u ( x, t )     2 u ( x, t )   F ( x, t )  0 k dt

(5)

ii) in  (contour): _

   u u  0

(6)

iii) in  (contour):

   q q  0 q

The basic sentence of weighted residues is written as:

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 _   _ ^ _ _ ^ 1 d u ( x, t )  2_   F ( x, t ) w d   u  u  w    q  q  w   0    u ( x, t )  k dt         

(8)



The weighting functions w , w and w , can be chosen conveniently, aiming to simplify the problem. Integrating the integral containing the Laplacian twice by parts (8), obtains: L

d 2w du dw 0  u( x, t ) w dx  0 u dx2 dx  w dx 0  u dx 0 _

(9)

Replacing (9) in (8): _ x L

L _

d 2w du u 0 dx 2 dx  w dx

xL

x 0

dw 1 du u  w dx  dx x0 0 k dt

(10)

x L

_ ^ _ _ ^    F ( x, t ) w dx   u  u  w   q  q  w 0     0 x 0 x L L

Making

du  q dx

and at some time w  

dw dx



and w  w in (10), obtains the resulting equation called

inverse formulation of weighted residues:

L _

d 2w 1 du u 0 dx 2 dx  0 k dt w dx  0 F ( x, t ) w dx  

(11) 

u w x  L  u w x 0  q w x  L  q w x 0  0 Using and applying the properties of the Dirac Delta function [6] to match the differential (12), can obtain the effect at the x field point of a concentrated source applied at the  source point. Then, substituting (12) into (11), obtain the equation (13): d 2w dx 2

  ( , x)

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 L _

1 du   u  ( , x) dx   w dx   F ( x, t ) w dx  k dt 0 0 0 

(13) 

u w xL  u w x0  q w xL  q w x0  0

In the BEM, the weighting function w is the solution of the equivalent singular problem, that is, the Green function [7] for the differential operator. Thus, w  u * ( , x) called the fundamental solution, can be interpreted as the effect at the field point x of a concentrated source applied at the  source point. For the one-dimensional case, the fundamental solution [8] is given by:

u * ( , x) 

| x  | 2

(14)

Replacing (14) in (13), obtain:



 ^ ^  1 du u ( , x)    w dx   F ( x, t ) w dx  u w x  L  u w x  0  q w x  L  q w x  0 k dt 0 0

(15)

Making u  u ( x, t ) and q  q( x, t ) in (15) and defining and defining the essential contour conditions according to (16), obtain the constitutive equation of the BEM (17) for the proposed problem.

u(0, t )  u( L, t )  0

1 du ( x, t ) | x   | | x  | | x  | xL u ( , t )    dx   F ( x, t ) dx  q( x, t ) x  0 k 0 dt 2 2 2 0 L

(16)

(17)

In the first integrating of equation (17) a temporal derivative is present. As the fundamental solution used in this work is independent of time, it is necessary to use some technique or numerical model for the process of march in time. 2.2 Numerical model of march in time. Several approaches have been proposed for the application of the BEM in parabolic problems, where it is used as solution of the equivalent singular problem, a solution independent of time. In this type of formulation, it is necessary to use advance in time methods, because of the integral that contains the differential term in time. Among the commonly used methods, coupled to the BEM is the Finite Differences Method (FDM). The coupling of the FDM and the BEM was first proposed by Brebbia [3] for the diffusion equation, implemented and investigated by Curran, Cross and Lewis [9], who found that this method produces only accurate results if the approximation used for time derivative presents precision. Curran, Cross and Lewis investigated the use of a higher-order approximation for time derivative, concluding that the use of this approach improved the accuracy of the method, but led to a deterioration in the convergence behavior of the model. MMSE Journal. Open Access www.mmse.xyz

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2.2.1 Numerical model of advance in time using FDM. The FDM has the purpose of obtaining the rate of variation from one instant to the next, being an approximation to the value of the derivative at the point when t becomes extremely small. Thus, the derivative at time present in equation (17) is approximated by the quotient of the variation of the potentials by the corresponding time interval, according to equation (18).

du ( x, t ) u ( x, t  t )  u ( x, t )  dt t

(18)

Replacing (18) in (17), obtain:

u ( , t )  

1 u ( x, t  t )  u ( x, t ) | x   | dx  k 0 t 2 L

| x  | | x  | xL   F ( x, t ) dx  q ( x, t ) x  0 2 2 0 L

(19)

Using the approximation from the FDM the original equation becomes an equation with solution obtained iteratively, for a number n of iterations over time. The term source F (x, t) also evolves in time, presenting a contribution portion of the problem domain that causes influence in the contour. For an internal solution where the evaluated point belongs to the domain, it is possible to determine the solution from equation (19) counting with domain cells due to integrals in   0 L. Thus, from the integral equation (19) arrive at a system of linear algebraic equations by the discretization of the domain in cells. The contour integrals are transformed into sums of integrals on each cell, passing to a solution in terms of the nodal points. 2.3 Domain discretization. Divided into cells  the domain  (Figure 1), is possibile obtain a representation of this domain in an exact or approximate form, depending on the coincidence or not of the nodes and the approximate function chosen for each cell.

Fig. 1. Domain discretization. Each cell  associates one or more points called "functional nodes" or "nodal points" and the values of the associated variables are called "nodal values". Throughout each cell the problem variables are approximated by polynomial (constant, linear, quadratic, ...) functions that are defined as a function of the number of nodal points chosen (1, 2, 3, ...).

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In this work was opted for linear approximation functions, assuming that the variation from one node to the next, presents a linear behavior and the functions are defined according to equations (20) and (21) and illustrated by Figure 2.

i  1 

i 1 



(20)





(21)



Fig. 2. Linear approximation functions. By approaching the geometry of  in linear cells, one can discretize the domain exactly by matching to coincide the i + 1 node of the cell  with node i of cell  +1. 2.4 Linear equations sistem. Discretizing the equation (19) and transforming in a summation of functions, have:

 ui    ui 1 t

x L

 x 0

1 NC L | x   |  ui    i i 1  dx    k j 10 2t ui 1 t t

1 NC L | x   |  ui  NC L | x   | | x   |  qi     i i 1  dx      F dx    k j 10 2t 2 2 qi 1 t ui 1 t j 10

x L

(22)

x 0

Grouping similar terms and using matrix notation, one can write equation (22) as follows:

H u m 1  H u m  G q m  F

(23)

Where H and G are matrices with contour coefficients, M is a vector containing the contributions of F(x, t) and so of derivative in the next time step (m+1) and D is the vector containing the derivative MMSE Journal. Open Access www.mmse.xyz

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in the current step (m). The vectors M and D represent the influence due to the domain integrals in (22). From the initial conditions of the problem, u (x,0) it is known, can use equation (23) to obtain the solution of the problem advanced in time by making m 1  m  t as a pseudo-initial condition for the next time step. Taken t as a time-forward constant, the matrices H and G and the vectors M and D are assembled, storing the subsequent calculations in the iterative process. 2.4.1 Numerical solution with advance in time. To obtain the solution of the problem, consider the contribution of all the cells in the assembly of the system of equations formed according to equation (23). The boundary conditions can be applied to form a solution system this way: A x m1  y

(24)

where A – is the coefficient matrix containing terms relative to the matrices H, G and vector M;

x m1 – is the vector of unknown nodal values at the moment t m1 ; y –is a vector constructed from known values of the previous time step containing the contributions of vector D. For a problem with time-dependent boundary conditions, the solution needs to be reformulated and updated at each time step. This update can be performed using as initial pseudo-conditions, the conditions obtained after the moment an internal solution is constructed, repeating the process at each iteration of t m1 . This time-advance procedure only involves integrating the domain at a given time, so ideally a domain integral only needs to be calculated once. For a problem with time-independent boundary conditions, as addressed by this work, at each step of m 1 time, it is only necessary to upgrade t and resolve the system to x m1 . However, in the present model, only the essential contour conditions, potential condition, remain constant, since the natural conditions, flow condition, are time dependent, being recalculated at each iteration by updating the model. From (24) obtain the vector of unknowns x is:

x  A 1 y

(25)

After the determination of the vector of unknowns, can obtain the variables in points belonging to the domain of the problem. 3. Computational implementation. The formulation adopted was implemented in commercial software Matlab R2011. In the simulations, the following initial condition was used:

u( x,0)  0

(26)

The coefficient of thermal conductivity was defined as k  1 , 100 time steps and the term source was defined by equation (27).

F ( x, t )  et

(27)

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The size of the time increment t was initially defined by the stability criterion, which is relative t to the domain cell size  and thermal conductivity coefficient k of the material, which, according to [10], is defined as follows:

tc 

 2 2k

(28)

where t c –is the critical time increment. 4. Results. The initial results obtained were compared to the analytical solution of the problem, which according to [6] is given by:

u ( x, t ) 





2 1 1 sin n x / L  e t  e ( nk / L ) t 2  n1,3,... n n k / L   1





(29)

In order to obtain the level of correlation between the numerical and analytical results, a statistical inference study was performed and the correlation coefficient R2 (Pearson's square) was calculated between the two solutions.

Fig. 3. Comparison between the analytical solution and the BEM for potential (a) and for flow (b). Results showed that for the proposed problem, the relation presented in (28) produces accurate results for the flow values, R2 = 1, but satisfactory for the potential values, R2 = 0.97806. Analysing both results, it is observed that the model's response is accurate when points belonging to the contour are analysed (where the flows are obtained), because it deals only with contour values, as the name of the method suggests, already for the calculated potential At one point in the domain, the model has a small error. This type of error is related to the size of the time increment t , the type of approximation MMSE Journal. Open Access www.mmse.xyz

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function used for the cells and their dimensions (length), requiring a specific time interval for the process of diffusion of heat throughout the cell extension (Figure 4).

Fig. 4. Insufficient time increase (1) for heat diffusion and sufficient (2). Figure 4 illustrates two cases of the heat diffusion process. In case (1), it is observed that only part of the cell was influenced by the heat diffusion. This is because the established model uses a discrete time interval, suddenly stopping the heat flow, causing the diffusion process to be insufficient, since it does not count on the total dissipation of such energy on the whole cell, adding error in the integration stage of the Cells. In case (2), it is observed that the relationship between the length of the domain cell  and the size of the time increment t was adequate and sufficient for the process of diffusion of heat in the cell. In this way, chooses to determine the increment of time that would provide the highest level of correlation between the numerical and analytical response (R2 = 1). For this, the size of the increment of time in the interval was varied t c / 4  t  2 t c , adding 0.01 to each iteration. The results obtained in this analysis are illustrated by Figure 5:

Fig. 5. Time increment analysis. MMSE Journal. Open Access www.mmse.xyz

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According to [10], the higher the values used to t , the greater will be the local truncation errors associated to temporal discretization, a fact that is observed in the previous figure for the highest values of t . However, for this one-dimensional analysis, the increase in theoretical time ( t  0.125 ), including smaller values to the same, presented results lower than the one obtained numerically ( t  0.17361), based on the values obtained for R2 = 0.97806 and R2 = 0.98456 respectively. This result expresses the convergence behaviour of the proposed mathematical model, indicating that there is a maximum limit value of correlation between the numerical and analytical solution, associated to the increment of time that represents the lowest error level of the formulation. Values for the thermal conductivity coefficient of material k between 0.2 and 2 were tested, with some cases shown in Figure 6. The convergence of the model was obtained using k = 1.6, with the result R2 = 0.99635 when using the increase of numerical time in relation to the theoretical that presented for this estimator the value 0.99634 as illustrated by Figure 7 (b).

Fig. 6. Time increment analyses to k = 0.2 (a), k = 0.5 (b) and k = 1.0 (c).

Fig. 7. Time increment analyses to k = 1.5 (a), k = 1.6 (b) and k = 1.7 (c). Figure 7 (c) shows that, for values of k > 1.6, the theoretical increment presents better results by reference to the coefficient R2.

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For the proposed formulation, the correlation level between the variables is higher when using a relatively higher time increment than the theoretical one, being limited by the set illustrated by Figure 8 (a), in analyzes where the coefficient of thermal conductivity of the material belongs to the range 0.2  k  1.6.

Fig. 8. Analysis of the time increment: (a) set of values for t and (b) ampliation of the image of the set. Figure 8 (b) illustrates the limit for k (1.6), indicating that for the k > 1.6 values, the time increment that presents the best results is the theoretical time increment, the t numeric of the set being limited by the line in red. Summary. The results obtained for the proposed problem indicated that theoretically proposed values for time increment provide solutions with a reasonable correlation level when analysing a point belonging to the domain. It was also verified that, for the proposed formulation, the level of correlation between the variables can be higher when using a relatively higher time increment than theoretical in analyses where the coefficient of thermal conductivity of the material belongs to the range 0.2  k  1.6, Making the mathematical model more efficient and presenting a lower level of error. The highest level of correlation obtained was 0.99635 with the use of time increment equal to 0.078616 of the numerical model, being higher than the value 0.99634 obtained from the theoretical time increment, 0.078125, when using k = 1.6. For analyses in which k > 1.6, it was verified that the use of theoretical time increment presents better results and it is suggested its use in applications where k is defined in such a way. Also, from these results, this work demonstrates the effectiveness of the BEM for the proposed problem and the potential of the use of the fundamental solution independent of time for the transient case. References [1] Simmons, G. F. (1987). Calculus with Analytical Geometry – Vol. 2. McGraw Hill. [2] Jacobs, D. (1979). The State of the Art in Numerical Analysis, Academic Press, New York, USA. [3] Brebbia, C. A. (1978). The boundary element method for engineers. Pentech Press, London. MMSE Journal. Open Access www.mmse.xyz

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[4] Pettres, R.; Lacerda, L. A.; Carrer, J.A.M. (2015) A boundary element formulation for the heat equation with dissipative and heat generation terms. Engineering Analysis with Boundary Elements, vol. 51, Feb., pp 191-198. [5] Kreyszig, E. (2006). Advanced Engineering Mathematics 9th Edition. Wiley, Ohio. [6] Greenberg, M. D. (1998). Advanced Engineering Mathematics (2nd Edition). Prentice-Hall, New Jersey. [7] Application of Green’s Functions in Science and Engineering (1971).. Prentice-Hall, New Jersey. [8] Vladimirov, V. S. (1979). Generalized Functions in Mathematical Physics. Nauka Publishers, Moscow. [9] Curran, D. A. S., Cross, M. and Lewis, B. A. (1980). Solution of parabolic differential equations by the boundary element method using discretisation in time - Applied Mathematical Modelling, vol. 4, pp 398–400. [10] Wrobel, L. C. (1981). Potential and Viscous Flow Problems Using the Boundary Element Method, U.K. Ph.D. Thesis, University of Southampton. Cite the paper Roberto Pettres (2016). Analysis of the Time Increment for the Diffusion Equation with Time-Varying Heat Source from the Boundary Element Method. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.8.968.954

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Investigation of Energy Absorption in Aluminum Foam Sandwich Panels By Drop Hammer Test: Experimental Results13 Mohammad Nouri Damghani 1,a, Arash Mohammadzadeh Gonabadi1,b 1 – Department of mechanical engineering, Semnan University, Semnan, Iran a – mnoori@semnan.ac.ir b – arash_mg@semnan.ac.ir DOI 10.2412/mmse.6.953.525

Keywords: sandwich panel, metal foam, impact, energy absorption, drop hammer, dynamic load, experimental method.

ABSTRACT. The sandwich panel structures with aluminum foam core and metal surfaces have light weight with high performance in dispersing energy. This has led to their widespread use in the absorption of energy. The cell structure of foam core is subjected to plastic deformation in the constant tension level that absorbs a lot of kinetic energy before destruction of the structure. In this research, by making samples of aluminum foam core sandwich panels with aluminum surfaces, experimental tests of low velocity impact by a drop machine are performed for different velocities and weights of projectile on samples of sandwich panels with aluminum foam core with relative density of 18%, 23%, and 27%. The output of device is acceleration‐time diagram which is shown by an accelerometer located on the projectile. From the experimental tests, the effect of weight, velocity and energy of the projectile and density of the foam on the global deformation, and energy decrease rate of projectile have been studied. The results of the experimental testes show that by increasing the density of aluminum foam, the overall impression is reduced and the slop of energy loss of projectile increases. Also by increasing the velocity of the projectile, the energy loss increases.

Introduction. Sandwich panels with composite face sheets and foam core are widely used in lightweight constructions, especially in aerospace industries due to their advantages over the conventional structural constructions, such as high specific strengths and stiffness and good weight saving [1]. An early study [2] has indicated that using composite materials instead of aluminium for the face sheets results in higher performance and lower weight. In the meanwhile, as a new multifunctional engineering material, aluminium foam has many useful properties such as low density, high specific stiffness, good impact resistance, high energy absorption capacity, easy to manufacture into complex shape, and good erosion resistance [3, 4], so it is usually used as core material of sandwich panels. However, it has also been found that composite sandwich panels are susceptible to impact damage caused by runway debris, hailstones, dropped tools and so on [2]. The resulting impact damage to the sandwich panel ranges from face sheet indentation to complete perforation, with the strength and reliability of the structures dramatically affected. Unlike for their solid metallic counterparts, making predictions of the effects of low-velocity impact damage are difficult and are still relatively immature. Hence, the behaviour of sandwich structures with aluminium foam core under low-velocity impact has received increasing attention. Recently, a number of studies have shown that localized impact loading on a sandwich structure can result in the generation of local damage, which can lead to significant reductions in its load-carrying capacity [5]. Investigations have been carried out on sandwich panels with foam core under quasistatic and impact loadings to explore the perforation energy absorbing mechanisms, mostly on sandwich structures with polymeric foam cores [6–8]. Wen et al. [6] have analysed marine sandwich construction and they have identified the major energy absorbing modes as fragmentation under the © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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penetrator and global panel deformation. Mines et al. [7] conducted a series of quasi-static perforation tests and low-velocity impact tests on square panels based on polymer composite sandwich structures. They suggested that higher impact velocities tend to increase the energy absorption, which is attributed to an increase in the core crush stress and skin failure stress at high strain rates. More comprehensive and detailed summaries of previous experimental studies can be found in a thorough review article of the impact response of sandwich structures given by Abrate [8]. While polymeric foams have been applied for many years, metallic foams have gained a signiďŹ cant and growing interest for applications in sandwich structures currently, for the reason that in comparison with polymer foams they exhibit excellent recycling eďŹ&#x192;ciency, high speciďŹ c stiďŹ&#x20AC;ness, good thermal conductivity and high melting point. Kiratisaevee and Cantwell [9] investigated the impact response of sandwich panels with ALPORASÂŽ foam cores and ďŹ ber-reinforced thermoplastic or ďŹ ber-metal laminate (FML) face-sheets. Impact tests were conducted by using a drop hammer at velocities up to 3 m/s. The resistance of these sandwich panels was found to be rate sensitive over the full range of conditions examined. Ruan et al. [10] have experimentally investigated the mechanical response and energy absorption of sandwich panels subjected to quasi-static indentation, which consist of aluminum face sheets and ALPORASÂŽ foam core. The eďŹ&#x20AC;ects of several parameters, such as face sheet thickness, core thickness, boundary conditions, adhesive and surface condition of face sheets on the mechanical response and energy absorption during indentation are identiďŹ ed. While most of the existing investigations into the impact responses of composite sandwich structures with metallic foam cores have focused on high-velocity impact [11â&#x20AC;&#x201C;16], only minimal attention has been paid on low-velocity tests, and few detailed parametric studies have been reported yet. In the present study, a series of perforation tests were conducted on the sandwich panels with an aluminum foam core and two face sheets, which were subjected to low-velocity impact. The perforation responses of the sandwich panels are investigated and the deformation and failure modes observed during perforation are described in detail. The mechanical properties and collapse mechanisms of aluminum foam sandwich panels are correlated to the physical and geometric properties of the face sheets and foam core, so the eďŹ&#x20AC;ects of face sheet thickness, core thickness and relative density, as well as the eďŹ&#x20AC;ect of impact energy on the energy absorption capacity of sandwich panels are analyzed. 1. Experimental investigation Specimens and material properties. The face sheets of sandwich panels are made of Aluminum series 1000 (AL-1000). The thickness of both face sheets (top and bottom of foam core) is 1 mm. Uniaxial tensile tests were carried out to obtain the stressâ&#x20AC;&#x201C;strain curves using the Zwick Tensile Testing Machine according to the Standard E8 in the Laboratory of Amirkabir University of Technology in Iran. Face sheets have been tested in 6 samples and 3 directions (0đ?&#x2018;&#x153; , 90đ?&#x2018;&#x153; and45đ?&#x2018;&#x153; ). Figures 1 and 2 demonstrate AL-1000 samples, top face sheet and Testing Machine. Also, Table 1 gives material properties for the face sheets and they are averaged from a number of repeated tests at strain rate of 10â&#x20AC;&#x201C;3/s. It should be noted that the surface of the laminates is marked by coding number such as â&#x20AC;&#x153;Front AL 1100 1mmâ&#x20AC;?, so the visual patterns are not the actual named. The aluminum foam used as the core material in the experiments is a closed-cell foam with the average cell size of approximately 2â&#x20AC;&#x201C;5 mm, which is produced by ALPORAS method using Al (A356/ SiCp) as base materials.

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(a)

(b)

(c) Fig. 1. (a) Al samples before tensile test. (b) Al samples after tensile test. According to E8 Standard (c) top face sheet.

Fig. 2. ZWICK TENSILE TESTER, Laboratory of the Amirkabir University of Iran. Table 1. Properties of the face sheets Material property

σY (MPa)

E(GPa)

value

117

0.3

ρ(kg/m3 ) 2700

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σu (MPa) 124

εD (MPa) 0.2

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Foam core samples shown in Figure 3 were used in the uniaxial compression tests and the average values of their mechanical properties with three relative densities, are shown in Table 2. Two different thicknesses of aluminum foam cores, namely 20 and 30 mm, were used to investigate the effect of foam core thickness. A commercial two-component impact-resistant adhesive SA102 was used to glue the face sheets and the foam core. Great attention has been given to achieve the perfect bonding between face sheets and foam core for a satisfactory structural performance, so the debonding effect will not be considered in this study. The final sandwich panel specimens are square plates with 20 × 20 × 22 mm3 and 30 × 30 × 32 mm3 in dimensions. To ensure the repeatability of the tests, three specimens were tested for each selected case. Table 2. Aluminium foams material properties Parameters Relative Density

Type 3 27%

Type 2

Type 1

23%

18%

Young’s modulus (GPa) yield stress (MPa) plateau stress (MPa) densification ratio ‫چگالی‬ Poisson’s ratio

1800 5.2 5.4 0.52 0.3

1660 4.6 4.7 0.5 0.3

1500 3.6 3.8 0.5 0.3

Fig. 3. Samples of Aluminum Foams with different relative densities. Quasi-static tests. To determine the level to which dynamic behavior should be considered under low-velocity impact, the sandwich panels were first tested under quasi-static loading for subsequent comparison with the impact loading cases. A ZWICK test system in the Engineering and Material Testing Center, Amirkabir University, was used to perform the quasi-static perforation. Specimens were fully clamped along all edges using two steel frames with a span of 100 × 100 mm2 , leaving an exposed square in the center. The main projectile is conical-nosed and two different projectiles with identical diameter of 40 mm were used for comparison in this study. One is a flat-ended projectile and the other is a hemispherical-nosed projectile. The geometry and dimensions of projectiles are shown in Figure 4. A constant crosshead speed of 1.2 mm/min was applied to load the samples until full failure and the force-displacement histories were recorded. Figure 5 shows the behavior of the Foam after the Compression test.

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Fig. 4. Zwick Compression Tester, quasi static test.

Fig. 5. Behavior of the Foam after the Compression test. Low-velocity impact tests. Low-velocity impact tests were conducted on a drop weight machine (Drop Hammer). The specimens were impacted at various energy levels in order to achieve different damage levels. The impact mass was varied from approximately 14 to 35 kg and the drop height ranged between 50 mm and 200 mm. An accelerometer was embedded inside the hammer just above the impactor tip to get the velocity and displacement history. For more details, the reader is referred to Reference [17]. An important issue in measuring the mechanical properties of foams is the effect of the specimen size, relative to the cell size. The size effect is also particularly important for foam core sandwich panels, as in some components the foam core may have dimensions of only a few cell diameters. As for sandwich beams with laminate skins and foam core, the size effect has already been experimentally demonstrated for shear failure in four-point bending [18]. The size effect can be avoided if the foam plate has at least eight cell diameters in thickness [19]. However, the thin and stiff face sheets will give a better distribution of load throughout the area when subjected to loads, which would lead to a lower localized mean load and diminish the size effects. 2. Experimental Results. In this section the damage of sandwich specimens composed of two 1 mm thick Aluminum faces and an Aluminum foam-core by the projectile is studied and the effect of various parameters such as impact velocity and core density on the amount of energy absorbed by the specimen are characterized. A rigid striker is used to simplify the model of impact test. The procedure of impact is the penetration of the rigid striker to the Aluminum plate or its foam. in all steps of the experiments, after the falling of projectile from the impact machine, the accelerometer measures the projectile acceleration during the energy imposition to the specimen and returning back. The Graph software is used to calculate the area under the acceleration vs. time curve to obtain the velocity vs. time curve and recalculate the area under the velocity vs. time curve to obtain the time-variation of displacement. By multiplying the mass of projectile to its acceleration one can obtain the impact force and by computing the area MMSE Journal. Open Access www.mmse.xyz

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under the force vs. time curve the impact energy would be obtained. The energy absorbed by the specimen and the depth of indentation play an important role in study of the impact phenomenon. The amount of absorbed energy by the structure can be used as a criterion for its performance. Absorbed energy by the target during the impact Ep equals the change of kinetic energy before and after the impact: (1)

1 1 mpVi 2 ď&#x20AC; mpVr 2 ď&#x20AC;˝ Ep 2 2 In which đ?&#x2018;&#x2030;đ?&#x2018;&#x2013; and đ?&#x2018;&#x2030;đ?&#x2018;&#x; are the contact velocity and the return velocity of projectile, respectively. Effect of impact velocity

A rigid projectile (with radius of 60 mm, height of 200 mm and mass of 25 kg) is dropped with different velocities and hits the sandwich specimen with dimension of 30x30x32. The relative density of foam is 0.18. So by changing the height from which the projectile is dropped one can controls its velocity according to Eq. (2). Experiments are done according to Table 3.

v ď&#x20AC;˝ 2 gh

(2)

Table 3. Specifications of prepared samples for the study of the effect of impact velocity Projectile

Falling

Radius (mm)

Height (mm)

200

110

#Test

Mass (kg) Rate of density (%)

Thickness (mm)

Figs. 6(a-d) show pictures of the specimen before and after the experiments. Plots of timeacceleration, time-velocity, time-displacement, force-displacement, energy-displacement, and timeenergy for each test are presented in Figs. 7-12, respectively. As shown in Fig. 8 with the increasing the impact velocity, the projectile acceleration tends to increase with time. As depicted in Fig. 9 the projectile velocity gets down with time in a rather linear manner. Also Fig. 10 shows that the depth of specimen crushing has a linear relation with the height of projectile falling. As shown in Fig. 11 the kinetic energy of projectile is in a linear relation with its displacement. Fig. 12 shows that the rate of energy loss is increased with increasing the impact velocity.

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(a)

(b)

(c) Fig. 6. Pictures of: (a) untested specimen, (b) specimen after the 1st experiment, (c) specimen after the 2nd experiment, (d) specimen after the 3rd experiment.

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Fig. 7. Variation of projectile force in terms of its displacement.

Fig. 8. Time-variation of projectile acceleration.

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Fig. 9. Time-variation of projectile velocity.

Fig. 10. Time-variation of projectile displacement.

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Fig. 11. Variation of projectile kinetic energy in terms of its displacement.

Fig. 12. Time-variation of projectile kinetic energy. Effect of foam-core density. In this section the effect of Aluminum foam density on the amount of energy absorbed during the impact is measured. Experiments are done according to Table 4. Figs. 13(a-d) show pictures of the specimen before and after the experiments. Figs 14-19 show the timevariation of projectile acceleration, velocity, displacement and energy as well as the variation of force and energy versus projectile displacement for each test. As expected, increasing the relative density leads to an improvement of impact strength (Fig. 14). The similar trend is observed in Fig. 15. According to Fig. 16, by increasing the core relative density, duration of crush gets shortened. Fig. 17 depicts that sandwich panels with denser core suffer less

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crush. As shown in Fig. 19 the rate of energy loss is increased with increasing the relative density of panel core. Table 4. Specifications of prepared samples for study of the foam-core density. Projectile Radius (mm)

Falling Height (mm)

Mass (kg)

110

#Test

Relative density (%) Thickness (mm)

(a)

(b)

(c) Fig. 13. Pictures of: (a) untested specimen, (b) specimen after the 4th experiment, (c) specimen after the 5th experiment.

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Fig. 14. Variation of projectile force in terms of its displacement.

Fig. 15. Time-variation of projectile acceleration.

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Fig. 16. Time-variation of projectile velocity.

Fig. 17. Time-variation of projectile displacement.

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Fig. 18. Variation of projectile kinetic energy in terms of its displacement.

Fig. 19. Time-variation of projectile kinetic energy. Effect of sandwich skin. The sandwich specimen is impacted by a rigid projectile with the properties of Table 5. Fig. 20 shows the specimen before and after the experiment. The time-variation of projectile acceleration, velocity, displacement and energy as well as the variation of force and energy versus projectile displacement is plotted in Figs 21-26. As shown in these Figures, adjoining the skins to the foam enhances the impact strength, while the total behaviours of neat foam and sandwich panel are rather the same.

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Table 5. Specifications of prepared samples for study of the effect of sandwich skin. #Test Rigid Radius (mm) 7

Falling Height Mass (kg) Rate of density (%) (mm) 200

Thickness (mm) 30

(a)

(b) Fig. 20. Pictures of: (a) untested specimen, (b) specimen after the 7th experiment.

Fig. 21. Variation of projectile force in terms of its displacement for the 7th experiment.

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Fig. 22. Time-variation of projectile acceleration for the 7th experiment.

Fig. 23. Time-variation of projectile velocity for the 7th experiment.

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Fig. 24. Time-variation of projectile displacement for the 7th experiment.

Fig. 25. Variation of projectile kinetic energy in terms of its displacement for the 7th experiment.

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Fig. 26. Time-variation of projectile kinetic energy for the 7th experiment. Summary. In this paper the behavior of Aluminum foam-core sandwich panels under the low velocity impact has studied and the effect of foam density as well as the impact velocity and the weight of projectile are investigated. Main results of the present research are as follows:  Composing of Aluminum plate and its foam to form a sandwich structure increases total rigidity of samples in comparison to its constituents and causes the structure to dissipate a major portion of the impact energy through large plastic deformations.  Increasing the relative density from 18% to 27% reduces the impact damage up to 46% as well as contact duration between the projectile and the sample.  Change in the initial energy of the projectile does not have not a noticeable effect on the time duration of contact between the projectile and the sample. It is because that with increasing the energy of the projectile the rate of its energy loss gets increased.  The destructive effect of projectile velocity is more dominant than that of its mass.  General degradation of structure is a function of the projectile energy. In another words, projectiles with different values of mass and velocity but the same initial energy will cause rather the same effect on the specimen.  The rate of energy loss of the projectile is directly dependent on its initial energy instead of its mass and velocity.  Increasing the rigidity of the structure shorten its contact duration with the projectile.  By reducing the projectile diameter and keeping constant its energy, the damage level of structure is increased. References [1] Zenkert D., 1995. An introduction to sandwich construction. Sheffield: Engineering Materials Advisory Services Ltd. [2] Abrate S. 1998. Impact on composite structures. Cambridge: Cambridge University Press. MMSE Journal. Open Access www.mmse.xyz

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[3] Gibson L.J., Ashby M.F., 1997. Cellular solids: structure and properties, 2nd edn. Cambridge: Cambridge University Press. [4] Ashby M.F., Evans A.G., Fleck N.A., et al., 2000. Metal foams: a design guide. Boston, MA: Butterworth Heinemann. [5] Hazizan M.A., Cantwell WJ., 2003, The low velocity impact response of an aluminum honeycomb sandwich structure. Compos Part B, 34 (8), 679â&#x20AC;&#x201C;687. [6] Wen H.M., Reddy T.Y., Reid S.R., et al., 1997, Indentation, penetration and perforation of composite laminate and sandwich panels under quasi-static and projectile loading. Key Eng Mater, 141-143 (1), 501-552. [7] Mines R.A.W., Worrall C.M., Gibson AG., 1998. Low velocity perforation behavior of polymer composite sandwich panels. Int J Impact Eng, 21(10), 855-879. [8] Abrate S., 1997. Localized impact on sandwich structures with laminated facings. Appl Mech Rev, 50(2), 69-82. [9] Kiratisaevee H., Cantwell W.J., 2005. Low-velocity impact response of high-performance aluminum foam sandwich structures. J Reinf Plast Compos, 24(10), 1057-1072. [10] Ruan D., Lu G., Wong Y.C., 2010. Quasi-static indentation tests on aluminum foam sandwich panels. Compos Struct, 92(9), 2039-2046. [11] Villanueva G.R., Cantwell W.J., 2004. The high velocity impact response of composite and FML-reinforced sandwich structures. Compos Sci Technol, 64(1), 35-54. [12] Hanssen A.G., Girard Y., Olovsson L., et al., 2006. A numerical model for bird strike of aluminum foam-based sandwich panels. Int J Impact Eng, 32(7), 1127-1144. [13] Zhao H., Elnasri I., Girard Y., 2007. Perforation of aluminum foam core sandwich panels under impact loading-an experimental study. Int J Impact Eng, 34(7), 1246-1257. [14] Hou W., Zhu F., Lu G., et al., 2010. Ballistic impact experiments of metallic sandwich panels with aluminum foam core. Int J Impact Eng, 37(10), 1045-1055. [15] Buitrago B.L., Santiuste C., Sanchez-Saez S., et al. 2010. Modelling of composite sandwich structures with honeycomb core subjected to high-velocity impact. Compos Struct, 92(9), 20902096. [16] Ivanez I., Santiuste C., Barbero E., et al., 2011. Numerical modelling of foam-cored sandwich plates under high-velocity impact. Compos Struct, 93(9), 2392-2399. [17] Yu J.L., Wang X., Wei Z.G., et al., 2003. Deformation and failure mechanism of dynamically loaded sandwich beams with aluminum-foam core. Int J Impact Eng, 28(3), 331-347. [18] Bazant Z.P., Zhou Y., Daniel I.M., et al., 2006. Size effect on strength of laminate-foam sandwich plates. J Eng Mater Tech, 128(3), 366-374. [19] Tekoglu C., Gibson L.J., Pardoen T., et al., 2011. Size effects in foams: experiments and model. ing Prog Mater Sci, 56(2), 109-138, doi 10.1016/j.pmatsci.2010.06.001 Cite the paper Mohammad Nouri Damghani, Arash Mohammadzadeh Gonabadi (2016).Investigation of Energy Absorption in Aluminum Foam Sandwich Panels By Drop Hammer Test: Experimental Results. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.6.953.525

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Probabilistic Analysis of Wear of Polymer Material used in Medical Implants14 T. Goswami1, V. Perel1 1 – Department of Biomedical, Industrial and Human Factors Engineering, Wright State University, 3640 Colonel Glenn Hwy, Dayton, Ohio 45435-0001, USA DOI 10.2412/mmse.7.971.990

Keywords: medical implants, wear, probabilistic analysis, reliability.

ABSTRACT. Probabilistic methods are applied to the study of fatigue wear of sliding surfaces. A variance of time to failure (to occurrence of maximum allowable wear depth) is evaluated as a function of a mean wear rate of normal wear and a size of wear particles. A method of estimating probability of failure-free work during a certain time interval (reliability) is presented. An effect of the bedding-in phase of wear on the reliability is taken into account. Experimental data for Ultra High Molecular Weight Polyethylene (UHMWPE) cups of artificial hip implants is used to make numerical calculations.

Introduction. Every year more than a million patients worldwide have a joint prosthesis implanted, the majority of which are hips and knees. The wear of artificial joints poses a particular challenge to engineers, medical scientists and clinicians, and this subject requires further development. This paper is devoted to estimation of probabilistic reliability of cups of artificial hip implants, made of Ultra High Molecular Weight Polyethylene (UHMWPE) with the use of experimental data available to the authors. During the sliding contact of surfaces, in near-surface material layers, prone to the friction damage, the stresses are distributed non-uniformly, because of discreteness of the surface contact. The actual contact area Aa is of the order 10 ÷103. Therefore, the average actual pressure pa at contact spots (defined as the ratio of the total contact force F to the actual contact area, pa = F/Aa) is 10 ÷ 103 times higher than the nominal pressure pn = F/An. Experimental and theoretical research shows that the average actual contact pressure pa does not change much upon the change of the total contact force F, but depends mainly on roughness parameters and mechanical properties of interacting surfaces [1]. This fact indicates the presence of plastic deformation in the near-surface layers of the interacting bodies. The plastic deformation causes displacement of the contact spots during the sliding contact, leading to the cyclic change of stress at points of the contacting surfaces. The cyclic variation of stress components and their high amplitude in the near surface layers (the average actual pressure pa is usually larger than the fatigue limit) causes cyclic fatigue in the near-surface layers. The fatigue damage and the resulting separation of particles of contacting surfaces occurs because of interaction of their ridges, the size and shape of which have random character. Besides, material properties in the near-surface layers can vary randomly too. Therefore the stress components in the near-surface layers and the wear depth are random functions of time. This leads to the need of using probabilistic methods to the study of wear and to the need of evaluating reliability of contacting surfaces, i.e. probability of failure-free work during a certain time interval (with failure understood as occurrence of the maximum allowable wear depth). It is established experimentally that the size of the wear particles in the fatigue wear is comparable with diameters of the contact spots, which vary from 10-6 m to

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10- 5 m [7]. More accurate experimental data on the average size of the wear particles is required for each particular contact pair. Some obvious formulas, needed for the further exposition, are đ?&#x2018;Ą

đ?&#x2018;&#x160;(đ?&#x2018;Ą) = â&#x2C6;Ť0 áş&#x2020;(đ?&#x153;?) đ?&#x2018;&#x2018;đ?&#x153;?

(1)

â&#x2C6;ž

đ?&#x2018;&#x161;áş&#x2021; â&#x2030;Ą đ??¸[áş&#x2021;(đ?&#x2018;Ą)] â&#x2030;Ą â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;ž áş&#x2020;(đ?&#x153;?)(áş&#x2020; , đ?&#x2018;Ą)đ?&#x2018;&#x2018;áş&#x2020; â&#x2C6;ž

(2) â&#x2C6;ž

đ?&#x153;&#x17D;áş&#x2021;2 (đ?&#x2018;Ą) â&#x2030;Ą đ??ˇ[áş&#x2020;(đ?&#x2018;Ą)] = đ??¸[áş&#x2020;2 ] â&#x2C6;&#x2019; (đ??¸[áş&#x2020;])2 = â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;ž áş&#x2020;2 đ?&#x2018;&#x201C;(áş&#x2020; , đ?&#x2018;Ą)đ?&#x2018;&#x2018;áş&#x2020; â&#x2C6;&#x2019; (â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;ž áş&#x2020;đ?&#x2018;&#x201C;(áş&#x2020; , đ?&#x2018;Ą)đ?&#x2018;&#x2018;áş&#x2020;)) đ?&#x2018;&#x2026;áş&#x2021; (đ?&#x153;?) â&#x2030;Ą đ??¸[áş&#x2020;(đ?&#x2018;Ą)áş&#x2020;(đ?&#x2018;Ą + đ?&#x153;?) ] đ?&#x2018;&#x;áş&#x2021; (đ?&#x153;?) = đ?&#x2018;&#x2026;

áş&#x2021; (0)

đ??¸[{áş&#x2020;(đ?&#x2018;Ą) â&#x2C6;&#x2019; đ?&#x2018;&#x161;áş&#x2021; }{áş&#x2020;(đ?&#x2018;Ą + đ?&#x153;?) â&#x2C6;&#x2019; đ?&#x2018;&#x161;áş&#x2021; } ]

(3)

(4)

(5)

After the bedding -in phase of the wear, the amount of wear can be small as compared to the maximum allowable wear depth Wm, or the bedding-in phase of the wear can be performed by a manufacturer of the implant, before its use. In this case, it can be considered that the non-linear bedding-in phase of the wear process is not present on the graph of the wear depth versus time (Figure 2), and then the reliability calculations can be done by the method, presented below.

Fig. 1. Typical phases of wear depth growth with time.

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Fig. 2. Wear depth growth with time if the bedding â&#x20AC;?in phase is absent. For the steady-state (normal) phase of wear, the wear rate áş&#x2020;(đ?&#x2018;Ą) can be treated as a stationary, ergodic random function of time, therefore the mean values (mathematical expectations) can be substituted with time-averaged quantities, leading to the formulas đ?&#x2018;&#x161;áş&#x2021; â&#x2030;Ą đ??¸[áş&#x2021;(đ?&#x2018;Ą)] =

đ?&#x153;&#x17D;áş&#x2021;2 (đ?&#x2018;Ą) â&#x2030;Ą đ??ˇ[áş&#x2020;(đ?&#x2018;Ą)] =

đ?&#x2018;&#x2021;đ?&#x2018;&#x203A;

đ?&#x2018;&#x2021;

áş&#x2021; (0) đ?&#x2018;&#x2021;đ?&#x2018;&#x203A;

= đ?&#x2018;?đ?&#x2018;&#x153;đ?&#x2018;&#x203A;đ?&#x2018; đ?&#x2018;Ą = đ?&#x2018;&#x17D;

đ?&#x2018;&#x2021;

(6) 2

đ?&#x2018;&#x203A; đ?&#x2018;&#x203A; â&#x2C6;Ť0 áş&#x2020;2 (đ?&#x2018;Ą) đ?&#x2018;&#x2018;đ?&#x2018;Ą â&#x2C6;&#x2019; (đ?&#x2018;&#x2021; â&#x2C6;Ť0 áş&#x2020;(đ?&#x2018;Ą) đ?&#x2018;&#x2018;đ?&#x2018;Ą) = đ?&#x2018;?đ?&#x2018;&#x153;đ?&#x2018;&#x203A;đ?&#x2018; đ?&#x2018;Ą đ?&#x2018;&#x203A;

1 đ?&#x2018;&#x2021;đ?&#x2018;&#x203A; â&#x2C6;Ť áş&#x2020;(đ?&#x2018;Ą)áş&#x2020;(đ?&#x2018;Ą đ?&#x2018;&#x2021;đ?&#x2018;&#x203A; 0

đ?&#x2018;&#x2026;áş&#x2021; (đ?&#x153;?) =

đ?&#x2018;&#x;áş&#x2021; (đ?&#x153;?) = đ?&#x2018;&#x2026;

1 đ?&#x2018;&#x2021;đ?&#x2018;&#x203A; â&#x2C6;Ť áş&#x2020;(đ?&#x2018;Ą) đ?&#x2018;&#x2018;đ?&#x2018;Ą đ?&#x2018;&#x2021;đ?&#x2018;&#x203A; 0

+ đ?&#x153;?) đ?&#x2018;&#x2018;đ?&#x2018;Ą

đ?&#x2018;&#x2021;

đ?&#x2018;&#x203A; â&#x2C6;Ť0 [áş&#x2020;(đ?&#x2018;Ą) â&#x2C6;&#x2019; đ?&#x2018;&#x17D;][áş&#x2020;(đ?&#x2018;Ą + đ?&#x153;?) â&#x2C6;&#x2019; đ?&#x2018;&#x17D;] đ?&#x2018;&#x2018;đ?&#x2018;Ą

(7)

(8)

(9)

For discrete experimental data, the autocorrelation function can be approximated by the autocorrelation sequence [6]. đ?&#x2018;&#x2026;(đ?&#x2018;&#x2122;) = â&#x2C6;&#x2018;đ?&#x2018; â&#x2C6;&#x2019;|đ?&#x2018;&#x2DC;|â&#x2C6;&#x2019;1 đ?&#x2018;Ľ(đ?&#x2018;&#x203A;) đ?&#x2018;Ľ(đ?&#x2018;&#x203A; â&#x2C6;&#x2019; đ?&#x2018;&#x2122;) đ?&#x2018;&#x203A;=đ?&#x2018;&#x2013; Where đ?&#x2018;&#x2013; = đ?&#x2018;&#x2122;, đ?&#x2018;&#x2DC; = 0, đ?&#x2018;&#x201C;đ?&#x2018;&#x153;đ?&#x2018;&#x; đ?&#x2018;&#x2122; â&#x2030;Ľ 0 đ?&#x2018;&#x2013; = 0, đ?&#x2018;&#x2DC; = đ?&#x2018;&#x2122;, đ?&#x2018;&#x201C;đ?&#x2018;&#x153;đ?&#x2018;&#x; đ?&#x2018;&#x2122; < 0 MMSE Journal. Open Access www.mmse.xyz

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(10a)

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and the mean wear rate can be calculated as 1

đ?&#x2018;&#x17D; = N â&#x2C6;&#x2018;đ?&#x2018; đ?&#x2018;&#x2013;=1 áş&#x2020;đ?&#x2018;&#x2013;

(10b)

If for any choice of time instants t0 < t1 < ... < tn, the random variables W(t0), W(t 1)â&#x20AC;&#x201C;W (t 0),â&#x20AC;Ś, W (t n)â&#x20AC;&#x201C; W(t n-1) are mutually independent, then the process W (t) is called the process with independent increments [8]. A process W(t) with independent increments is said to have stationary independent increments, if W(0) = 0, and the distribution of W(t + h)W(t) is independent of t for all positive h. For this process the mean value m w and the variance đ?&#x153;&#x17D;đ?&#x2018;¤2 are proportional to t [8]. If, in addition to being a stationary random process, the wear rate áş&#x2020;(t) is a highly random process, then the wear depth W(t) is a random process with stationary independent increments. In this case đ?&#x2018;&#x161;đ?&#x2018;¤ â&#x2030;Ą đ??¸[đ?&#x2018;&#x160;(đ?&#x2018;Ą)] = đ?&#x2018;&#x17D;đ?&#x2018;Ą

(11)

đ?&#x153;&#x17D;áş&#x2021;2 (đ?&#x2018;Ą) â&#x2030;Ą đ??ˇ[đ?&#x2018;&#x160;(đ?&#x2018;Ą)] = đ?&#x2018;?đ?&#x2018;Ą

(12)

where b â&#x20AC;&#x201C; is a constant. To verify that áş&#x2020;(t) is a highly random function of time, one needs to verify that the normalized autocorrelation function đ?&#x2018;&#x;áş&#x2020; (Ď&#x201E;) has a sharp spike at Ď&#x201E; = 0 that drops off rapidly to zero as Ď&#x201E; moves away from zero. The graph of the wear rate versus time [4] is presented in Figure 4. The graph of the normalized autocorrelation for the total wear rate (including bedding-in and steady-state phases of wear) is presented in Figure 5. It can be seen from this graph that at small values of time since the beginning of the wear process, the values of the autocorrelation are positive, and at large values of time Ăą negative. The negativeness of the autocorrelation means that the initial increase of the wear rate leads to decrease of the wear rate upon the wear progression. Such behaviour of the wear rate is caused by presence of the bedding-in phase. By removing the first 28 values of the wear rate (corresponding to the first 3.5 years) from the data, used to plot the graph in Figure 4, one can remove the bedding-in phase and plot the normalized autocorrelation of the steady-state wear rate (Figure 6). One can see from the Figure 6 that for the normal wear, the autocorrelation of the wear rate indeed behaves in a manner that is characteristic for a highly random process: it has a sharp spike initially, and then drops oÂ§ rapidly and oscillates near the zero value subsequently. From this follows that for the normal wear, the random process W(t) (wear depth as a function of time) is a process with stationary independent increments, for which the formulas (11) and (12) are true. Obviously, the formulas (11) and (12) cannot be applied for the wear process with the bedding-in phase present, because in this case the random function W(t) is not stationary. For the normal phase of wear, which has stationary independent increments of the wear depth W(t), the time interval to a wear depth W, Î¸(W), is also a random function of W with stationary independent increments, therefore its mean value mÎ¸ is proportional to W: đ?&#x2018;&#x161;đ?&#x153;&#x192; =

đ?&#x2018;&#x160; đ?&#x2018;&#x17D;

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(13)

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Fig. 4. Wear rate versus implantation time.

Fig. 5. Autocorrelation sequence for the total wear.

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Fig. 6. Autocorrelation sequence for the normal wear. Let us consider a time interval â&#x2C6;&#x2020;t (between instants t and t+â&#x2C6;&#x2020;t), during which one of the following events occurs: either a particle of size h is separated from the surface with probability Îł, or the particle is not separated form the surface (with probability 1â&#x20AC;&#x201C; Îł, obviously) is assumed that Îł is proportional to â&#x2C6;&#x2020;t: đ?&#x203A;ž = đ?&#x153;&#x2020;â&#x2C6;&#x2020;đ?&#x2018;Ą

(14)

The wear increment for the time interval â&#x2C6;&#x2020;t is â&#x2C6;&#x2020;đ?&#x2018;&#x160; = đ?&#x2018;&#x160;(đ?&#x2018;Ą + â&#x2C6;&#x2020;đ?&#x2018;Ą ) â&#x2C6;&#x2019; đ?&#x2018;&#x160;(đ?&#x2018;Ą)

(15)

đ??¸(â&#x2C6;&#x2020;đ?&#x2018;&#x160;) = đ?&#x203A;žâ&#x201E;&#x17D; + (1 â&#x2C6;&#x2019; đ?&#x203A;ž)Î&#x2021;0 = đ?&#x203A;žâ&#x201E;&#x17D; = đ?&#x153;&#x2020; â&#x2C6;&#x2020;đ?&#x2018;Ą â&#x201E;&#x17D;

(16)

and its mean value is

From the last equation, we have đ??¸[

Î&#x201D;W Î&#x201D;đ?&#x2018;Ą

] = đ?&#x153;&#x2020;â&#x201E;&#x17D;

or, if â&#x2C6;&#x2020;t â&#x2020;&#x2019; 0 , MMSE Journal. Open Access www.mmse.xyz

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(17)

Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

đ??¸[

đ?&#x2018;&#x2018;đ?&#x2018;&#x160; đ?&#x2018;&#x2018;đ?&#x2018;Ą

] = đ?&#x153;&#x2020;â&#x201E;&#x17D;

(18)

The left side of eq. (18) is the mean rate of wear. According to this equation, the mean rate of wear is constant, and this is a consequence of the assumption in eq. (14). Therefore, the assumption in eq. (14) is valid for the normal wear. The mean value of diÂ§erence of random variables is equal to the difference of their mean values, therefore đ?&#x2018;&#x2018;đ?&#x2018;&#x160;

đ?&#x2018;&#x2018;đ??¸[đ?&#x2018;&#x160;(đ?&#x2018;Ą)]

đ??¸ [ đ?&#x2018;&#x2018;đ?&#x2018;Ą ] =

(19)

đ?&#x2018;&#x2018;đ?&#x2018;Ą

If the wear process is modelled as separation of discrete particles, then the function Î¸(W) can be treated as a random function of the wear depth with the gamma-distribution [2]: 1

đ?&#x153;&#x2122;(đ?&#x153;&#x192;, đ?&#x2018;&#x160;) =

{Đ&#x201C;(đ?&#x2018;&#x203A;)

đ?&#x153;&#x2020; đ?&#x2018;&#x203A; đ?&#x153;&#x192; đ?&#x2018;&#x203A;â&#x2C6;&#x2019;1 exp(â&#x2C6;&#x2019;đ?&#x153;&#x2020;đ?&#x153;&#x192;) đ?&#x2018;&#x201C;đ?&#x2018;&#x153;đ?&#x2018;&#x; đ?&#x153;&#x192; â&#x2030;Ľ 0 0 đ?&#x2018;&#x201C;đ?&#x2018;&#x153;đ?&#x2018;&#x; đ?&#x153;&#x192; < 0

}

(20)

where n â&#x20AC;&#x201C; is a number of separated particles necessary for the wear depth to become equal to W. Obviously, đ?&#x2018;&#x203A;=

đ?&#x2018;&#x160;

(21)

â&#x201E;&#x17D;

In eq. (20), â&#x2C6;&#x17E;

Đ&#x201C;(đ?&#x2018;&#x203A;) = â&#x2C6;Ť0 đ?&#x2018;Ľ đ?&#x2018;&#x203A;â&#x2C6;&#x2019;1 đ?&#x2018;&#x2019; â&#x2C6;&#x2019;đ?&#x2018;Ľ đ?&#x2018;&#x2018;đ?&#x2018;Ľ

(22)

The mean mÎ¸ and the variance đ?&#x153;&#x17D;đ?&#x153;&#x192;2 of the function Î¸(W), having the gamma-distribution, is [5] â&#x2C6;&#x17E;

â&#x2C6;&#x17E;

đ?&#x2018;&#x161;đ?&#x153;&#x192; â&#x2030;Ą đ??¸[đ?&#x153;&#x192;(đ?&#x2018;&#x160;)] = â&#x2C6;Ť0 đ?&#x153;&#x192; đ?&#x153;&#x2122;(đ?&#x153;&#x192;, đ?&#x2018;&#x160;)đ?&#x2018;&#x2018;đ?&#x153;&#x192; = â&#x2C6;Ť0 đ?&#x153;&#x192; Î&#x201C;(đ?&#x2018;&#x203A;) đ?&#x153;&#x2020;đ?&#x2018;&#x203A; đ?&#x153;&#x192; đ?&#x2018;&#x203A;â&#x2C6;&#x2019;1 exp(â&#x2C6;&#x2019;đ?&#x153;&#x2020;đ?&#x153;&#x192;) đ?&#x2018;&#x2018;đ?&#x153;&#x192; = â&#x2C6;&#x17E;

â&#x2C6;&#x17E;

đ?&#x153;&#x17D;đ?&#x153;&#x192;2 â&#x2030;Ą đ??ˇ[đ?&#x153;&#x192;(đ?&#x2018;&#x160;)] = â&#x2C6;Ť0 đ?&#x153;&#x192; 2 đ?&#x153;&#x2122;(đ?&#x153;&#x192;, đ?&#x2018;&#x160;)đ?&#x2018;&#x2018;đ?&#x153;&#x192; â&#x2C6;&#x2019; đ?&#x2018;&#x161;đ?&#x153;&#x192;2 = â&#x2C6;Ť0 đ?&#x153;&#x192; 2

đ?&#x2018;&#x203A;

(23)

đ?&#x153;&#x2020;

đ?&#x2018;&#x203A; 2

đ?&#x2018;&#x203A;

đ?&#x153;&#x2020;đ?&#x2018;&#x203A; đ?&#x153;&#x192; đ?&#x2018;&#x203A;â&#x2C6;&#x2019;1 exp(â&#x2C6;&#x2019;đ?&#x153;&#x2020;đ?&#x153;&#x192;) đ?&#x2018;&#x2018;đ?&#x153;&#x192; â&#x2C6;&#x2019; (đ?&#x153;&#x2020; ) = đ?&#x153;&#x2020;2 Î&#x201C;(đ?&#x2018;&#x203A;)

(24)

If the size h of the particles, separated from the surface, is very small, then the number n of the separated particles for a given wear depth W is very large. With a large number n in the gammadistribution (20), the distribution becomes symmetrical and tends to the form [2]

đ?&#x153;&#x2122;(đ?&#x153;&#x192;, đ?&#x2018;&#x160;) =

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039; â&#x2C6;&#x161;đ?&#x2018;&#x203A;/đ?&#x153;&#x2020;2

đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? [â&#x2C6;&#x2019;

đ?&#x2018;&#x203A; (đ?&#x153;&#x192;â&#x2C6;&#x2019; )2 đ?&#x153;&#x2020;

2đ?&#x2018;&#x203A;/đ?&#x153;&#x2020;2

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147

]

(25)

Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

i.e. the distribution becomes normal with the mean value đ?&#x2018;&#x203A;

đ?&#x2018;&#x161;đ?&#x153;&#x192; â&#x2030;Ą đ??¸[đ?&#x153;&#x192;(đ?&#x2018;&#x160;)] =

(26)

đ?&#x153;&#x2020;

and the variance đ?&#x2018;&#x203A;

đ?&#x153;&#x17D;đ?&#x153;&#x192;2 â&#x2030;Ą đ??ˇ[đ?&#x153;&#x192;(đ?&#x2018;&#x160;)] = đ?&#x153;&#x2020;2 =

đ?&#x2018;&#x161;đ?&#x153;&#x192; đ?&#x153;&#x2020;

(27)

where, according to eq. (18) đ?&#x153;&#x2020;=

đ??¸[áş&#x2021;(đ?&#x2018;Ą)] â&#x201E;&#x17D;

đ?&#x2018;&#x161;áş&#x2021;

â&#x201E;&#x17D;

đ?&#x2018;&#x17D;

=â&#x201E;&#x17D;

(28)

So, đ?&#x153;&#x17D;đ?&#x153;&#x192;2 =

đ?&#x2018;&#x161;đ?&#x153;&#x192; đ?&#x153;&#x2020;

đ?&#x2018;&#x161;

đ?&#x153;&#x192; = đ?&#x2018;&#x17D;/â&#x201E;&#x17D;

(29)

where, according to eq. (13), đ?&#x2018;&#x161;đ?&#x153;&#x192; =

đ?&#x2018;&#x160; đ?&#x2018;&#x17D;

Substituting eq. (13) into eq. (29), we find â&#x201E;&#x17D;

đ?&#x153;&#x17D;đ?&#x153;&#x192;2 = đ?&#x2018;&#x17D;2

(30)

where h is a mean size of a particle, separated from the surface, and a is the mean rate of the steadystate (normal) wear. Introducing notations 1

â&#x201E;&#x17D;

đ?&#x153;&#x2021; = đ?&#x2018;&#x17D; , đ?&#x153;&#x201A; = đ?&#x2018;&#x17D;2

(31)

we will write eqs. (13) and (30) as đ?&#x2018;&#x161;đ?&#x153;&#x192; = đ?&#x153;&#x2021;đ?&#x2018;&#x160; , đ?&#x153;&#x17D;đ?&#x153;&#x192;2 = đ?&#x153;&#x201A;đ?&#x2018;&#x160;

(32)

According to eq. (25), for the normal phase of wear with stationary independent increments of W(t), the probability density of Î¸(W) can be taken as normal. MMSE Journal. Open Access www.mmse.xyz

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đ?&#x153;&#x2122;(đ?&#x153;&#x192;, đ?&#x2018;&#x160;) = đ?&#x153;&#x17D;2

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039;

đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

(đ?&#x153;&#x192;â&#x2C6;&#x2019;đ?&#x2018;&#x161;đ?&#x153;? )2

2đ?&#x153;&#x17D;đ?&#x153;&#x192;2

â&#x2C6;&#x161;2đ?&#x153;&#x2039; â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;

(đ?&#x153;&#x192;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;)2

đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

2đ?&#x153;&#x201A;đ?&#x2018;&#x160;

)

(33)

Therefore, the probability that the time to some specified wear depth W is less than some specified time interval T is

đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;) < đ?&#x2018;&#x2021;} =

đ?&#x2018;&#x2021;

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039; â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;

= â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;&#x17E; đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

(đ?&#x153;&#x192;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;)2 2đ?&#x153;&#x201A;đ?&#x2018;&#x160;

) đ?&#x2018;&#x2018;đ?&#x153;&#x192;

(34)

Then, the probability that the time to a maximum allowable wear depth Wm is less than some specifed time T (probability of failure during the time interval [0; T]) is

đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) < đ?&#x2018;&#x2021;} =

(đ?&#x153;&#x192;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;đ?&#x2018;&#x161; )2

đ?&#x2018;&#x2021;

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039; â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

= â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;&#x17E; đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

2đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

) đ?&#x2018;&#x2018;đ?&#x153;&#x192;

(35)

Performing the change of the variable in the last integral đ?&#x2018;˘=

đ?&#x153;&#x192;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

(36)

2đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

we obtain

đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) < đ?&#x2018;&#x2021;} =

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039;

đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

= â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;&#x17E;

đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

đ?&#x2018;˘2 2

đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

) đ?&#x2018;&#x2018;đ?&#x2018;˘ = Đ¤ (

â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

)

(38)

Where

Đ¤(đ?&#x2018;Ľ) =

1 â&#x2C6;&#x161;2đ?&#x153;&#x2039;

đ?&#x2018;Ľ

â&#x2C6;Ťâ&#x2C6;&#x2019;â&#x2C6;&#x17E; đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019;

đ?&#x2018;˘2 2

) đ?&#x2018;&#x2018;đ?&#x2018;˘

(39)

Then, the probability that the time to a maximum allowable wear depth Wm is larger than some specified time T (probability of failure-free work during the time interval [0; T]) is đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) > đ?&#x2018;&#x2021;} = 1 â&#x2C6;&#x2019; đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) < đ?&#x2018;&#x2021;} = 1 â&#x2C6;&#x2019; Đ¤ (

â&#x2C6;&#x161;đ?&#x153;&#x201A;đ?&#x2018;&#x160;đ?&#x2018;&#x161;

)

(40)

Now let us consider a situation in which the effect of the bedding-in phase on probability of failure is not negligible. In Figure 7, the end of the bedding-in phase coincides with the time instant t = 0, for convenience. The wear depth at the end of the bedding-in phase will be denoted as

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đ?&#x2018;&#x160;0 â&#x2030;Ą đ?&#x2018;&#x160;(0)

(41)

and it will be treated as a random quantity. Then đ?&#x2018;&#x160; â&#x2C6;&#x2014; (đ?&#x2018;Ą) = đ?&#x2018;&#x160;(đ?&#x2018;Ą) â&#x2C6;&#x2019; đ?&#x2018;&#x160;0

(42)

is the wear depth during the normal wear. The maximum allowable wear depth, measured from the beginning of the wear process (from t = t0 < 0) is denoted as Wm. The maximum allowable wear depth, measured from the beginning of the normal wear process (from t = 0) is denoted as W*m. Then đ?&#x2018;&#x160;đ?&#x2018;&#x161;â&#x2C6;&#x2014; = đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2019; đ?&#x2018;&#x160;0

(43)

Fig. 3. Illustration to reliability calculation with account of the bedding â&#x20AC;?in phase. W0 and * Wm are random quantities. The quantity Wm is not random, and the quantity W0 is random, so the quantity W*m is random. The time interval, measured from t = t0, to a predetermined wear depth W (measured from t = t0), will be denoted as Î¸(W). The function Î¸(W) is random. The time interval, measured from t = 0, to a wear depth W* (measured from t = 0), will be denoted as Î¸*(W*). The function Î¸*(W*) is random. Obviously đ?&#x153;&#x192;(đ?&#x2018;&#x160;) = |đ?&#x2018;Ą0 | + đ?&#x153;&#x192; â&#x2C6;&#x2014; (đ?&#x2018;&#x160; â&#x2C6;&#x2014; ) MMSE Journal. Open Access www.mmse.xyz

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(44)

Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954

Therefore đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) = |đ?&#x2018;Ą0 | + đ?&#x153;&#x192; â&#x2C6;&#x2014; (đ?&#x2018;&#x160;đ?&#x2018;&#x161;â&#x2C6;&#x2014; )

(45)

The length of the bedding-in time interval is usually much less than the length of the time interval of normal wear: |đ?&#x2018;Ą0 | â&#x2030;Ş đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; )

(46)

đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) â&#x2030;&#x2C6; đ?&#x153;&#x192; â&#x2C6;&#x2014; (đ?&#x2018;&#x160;đ?&#x2018;&#x161;â&#x2C6;&#x2014; )

(47)

So,

Then, the probability that the time to a maximum allowable wear depth Wm is less than some specified large time T is đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) < đ?&#x2018;&#x2021;} â&#x2030;&#x2C6; đ?&#x2018;&#x192;{đ?&#x153;&#x192; â&#x2C6;&#x2014; (đ?&#x2018;&#x160;đ?&#x2018;&#x161;â&#x2C6;&#x2014; ) < đ?&#x2018;&#x2021;}

(48)

So, with account of the bedding-in phase, i.e. considering that the maximum allowable wear depth during the normal wear, W*m, is a random quantity, the formula (38) can be substituted with the formula [8]

đ?&#x2018;&#x192;{đ?&#x153;&#x192;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; ) < đ?&#x2018;&#x2021;} â&#x2030;&#x2C6; đ?&#x2018;&#x192;{đ?&#x153;&#x192; â&#x2C6;&#x2014; (đ?&#x2018;&#x160;đ?&#x2018;&#x161;â&#x2C6;&#x2014; ) < đ?&#x2018;&#x2021;} = Đ¤ (

â&#x2C6;&#x2014;] đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;đ??¸[đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2014; ]+đ?&#x153;&#x201A;đ??¸[đ?&#x2018;&#x160; â&#x2C6;&#x2014; ] â&#x2C6;&#x161;đ?&#x153;&#x2021;đ??ˇ[đ?&#x2018;&#x160;đ?&#x2018;&#x161; đ?&#x2018;&#x161;

) = Đ¤(

đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2019;đ??¸[đ?&#x2018;&#x160;0 ])

)

â&#x2C6;&#x161;đ?&#x153;&#x2021;đ??ˇ[đ?&#x2018;&#x160;0 ]+đ?&#x153;&#x201A;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2019;đ??¸[đ?&#x2018;&#x160;0 ])

(49)

Where đ?&#x2018;Ľ

đ?&#x2018;˘2 Đ¤(đ?&#x2018;Ľ) = â&#x2C6;Ť đ?&#x2018;&#x2019;đ?&#x2018;Ľđ?&#x2018;? (â&#x2C6;&#x2019; ) đ?&#x2018;&#x2018;đ?&#x2018;˘ 2 â&#x2C6;&#x161;2đ?&#x153;&#x2039; â&#x2C6;&#x2019;â&#x2C6;&#x17E; 1

If the bedding-in phase of the wear is absent, then W0 = 0, and the formula (49) reduces to the formula (38). The probability that the time to the maximum allowable wear depth Wm is larger than some specified time T (probability of failure-free work during the time interval [0; T]) is

đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x153;&#x2021;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2019;đ??¸[đ?&#x2018;&#x160;0 ])

)

â&#x2C6;&#x161;đ?&#x153;&#x2021;đ??ˇ[đ?&#x2018;&#x160;0 ]+đ?&#x153;&#x201A;(đ?&#x2018;&#x160;đ?&#x2018;&#x161; â&#x2C6;&#x2019;đ??¸[đ?&#x2018;&#x160;0 ])

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(50)

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The mean value and variance of the wear depth at the beginning of the normal wear phase, E [W0] and D [W0], should be known from experimental data. The maximum allowable wear depth Wm is the wear depth at transition from the normal to catastrophic phase of wear, and it should be known from experimental data also. So, the formula (50) can be used for evaluating probability of failure-free work during a time interval [0; T] . For the data on wear rate of UHMWPE cups of artifficial hip joints, presented in the reference Kurtz, đ?&#x2018;&#x161;đ?&#x2018;&#x161; 2004, the mean wear rate during the normal wear is đ?&#x2018;&#x17D; = 0.159 đ?&#x2018;Śđ?&#x2018;&#x2019;đ?&#x2018;&#x17D;đ?&#x2018;&#x;; the mean value of the wear depth at the beginning of the normal wear is E [W0] = 0,35 mm ; the variance of the wear depth at the beginning of the normal wear is D [W0] = 10-4 mm2 ; the maximum allowable wear depth is Wm=1,4 mm. Taking an average size of particles, separated from the surface, as h = 10-3 mm, we find the following dependence of the probability of failure-free work of the hip joint during a time period [0; T] on the value of T (Table 1). Table 1. Value of T.

References [1] Gupta P.K., Cook N.M., Statistical analysis of mechanical interaction of rough surface, ASME, J. Lubr. Techn. F., 1972, Vol. 94, N1, pp. 14-23. [2] Gertsbakh I.B., Kordonsky Kh.B., Models of Failure. Springer, 1969 [3] Hisakado T., On the mechanism of contact between solid surfaces, Bull. ASME, 1969, Vol. 12, N 54, pp. 1528-1549. [4] Kurtz S., The UHMWPE Handbook. Elsevier, 2004 [5] Korn G.A., Korn T.M., Mathematical Handbook for Scientists and Engineers. MGraw Hill Book Company, 1961 [6] Proakis J.G., Manolakis D.G., Digital Signal Processing. Principles, Algorithms and Applications. Prentice Hall, 1996 [7] Rabinowicz E., Friction and Wear of Materials. N.Y.: Wiley, 1965 [8] Skorokhod A.V., Basic Principle and Applications of Probability Theory. Springer, 2005, DOI 10.1007/b137401 Cite the paper T. Goswami, V. Perel (2016). Probabilistic Analysis of Wear of Polymer Material used in Medical Implants. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.7.971.990

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Mathematical Models of Hybrid Vehicle Powertrain Performance15 K.M. Bas 1, V.V. Kravets 1, K.A. Ziborov 2, D.A. Fedoriachenko 3, V.V. Krivda 1, S.A. Fedoriachenko 2 1 – Automobile Sector Department, National Mining University, Ukraine 2 – Machinery Design Fundamentals Department, National Mining University, Ukraine 3 – Department of Mining Engineering, National Mining University, Ukraine DOI 10.2412/mmse.01.971.560

Keywords: hybrid powertrain, internal combustion engine, mathematical model, technology.

ABSTRACT. The structure of the hybrid powertrain includes an internal combustion engine, the electric motor/generator, electric drive, electric power converter. Electric motors of conventional design and power converting devices are described in the paper. In this paper an attention paid to the mathematical description of an internal combustion engines, as a part of hybrid powertrain component. Following the paper provides brief mathematical description of galvanic energy storage of hybrid powertrain.

Introduction. ICE (internal combustion engine) are the most common type of heat engines, in which the heat released during the combustion of fuel is converted into mechanical energy. On the fig. 1 the conventional ICE scheme is represented. The pedal is mechanically connected to the throttle. In this case, the driver controls the throttle position and thus the amount of air supplying the engine. In general, the torque depends on this parameter. Advanced technologies of ICE now have been developed to improve the efficiency of the engine and reduce emissions. Most of these technical solutions can be divided into two categories. The first category: – Mechanical throttle compounded with fuel supply system. Allows reducing emission through fuel ratio (14:1); – Fully electronically driven throttle and fuel supply system, which obtains the data from multiple sensors and adjusts fuel ratio and gearbox parameters in order to achieve maximum performance and reduce emissions.

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throttle idling valve

Pedal

cylinders outlet system

inlet system

Lambda sensor

injectors

powerâ&#x20AC;&#x201C;takeoff shaft

torgue

Fig. 1. The scheme of the internal combustion engine. The mathematical model of heat engine subsystem includes a working fluid dynamics and crankshaft subsystem dynamics. Number of air mass flowing into the inlet system ma is a function of the pressure in the system pm and throttle position angle Î¸ [3]: đ?&#x2018;&#x161;â&#x201A;?Ęš = đ?&#x2018;&#x201C;(đ?&#x153;&#x192;) â&#x2C6;&#x2122; đ?&#x2018;&#x201D;(đ?&#x2018;?đ?&#x2018;&#x161; ).

(1)

Each of the components of this equation can be represented as follows: đ?&#x2018;&#x201C;(đ?&#x153;&#x192;) = đ?&#x2018;&#x2DC;đ?&#x2018;Ąâ&#x201E;&#x17D;0 + đ?&#x2018;&#x2DC;đ?&#x2018;Ąâ&#x201E;&#x17D;1 â&#x2C6;&#x2122; đ?&#x153;&#x192; + đ?&#x2018;&#x2DC;đ?&#x2018;Ąâ&#x201E;&#x17D;2 â&#x2C6;&#x2122; đ?&#x153;&#x192; 2 + đ?&#x2018;&#x2DC;đ?&#x2018;Ąâ&#x201E;&#x17D;3 â&#x2C6;&#x2122; đ?&#x153;&#x192; 3 , đ?&#x2018;&#x201D;(đ?&#x2018;?đ?&#x2018;&#x161; ) = {

2 đ?&#x2018;?đ?&#x2018;&#x17D;đ?&#x2018;Ąđ?&#x2018;&#x161;

1, đ?&#x2018;?đ?&#x2018;&#x161; â&#x2030;¤ 0.5 â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x17D;đ?&#x2018;Ąđ?&#x2018;&#x161; â&#x2C6;&#x2122; â&#x2C6;&#x161;đ?&#x2018;?đ?&#x2018;&#x17D;đ?&#x2018;Ąđ?&#x2018;&#x161; â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x161; â&#x2C6;&#x2019; đ?&#x2018;?đ?&#x2018;&#x161; 2 , đ?&#x2018;?đ?&#x2018;&#x161; > 0.5 â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x17D;đ?&#x2018;Ąđ?&#x2018;&#x161;

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(2) ,

(3)

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where kth0 .. 3 â&#x20AC;&#x201C; constant equation; Î¸ â&#x20AC;&#x201C; throttle position angle; patm â&#x20AC;&#x201C;inlet pressure for naturally aspirated ICE; pm â&#x20AC;&#x201C; pressure in the inlet system. The dynamics of the working fluid in the inlet system can be described by the differential equation of the first order: đ?&#x2018;?đ?&#x2018;&#x161; Ęš =

đ?&#x2018;&#x2026;â&#x2C6;&#x2122;đ?&#x2018;&#x2021;đ?&#x2018;&#x161; đ?&#x2018;&#x2030;đ?&#x2018;&#x161;

â&#x2C6;&#x2122; (đ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;&#x2013; Ęš â&#x2C6;&#x2019; đ?&#x2018;&#x161;đ?&#x2018;&#x17D;0 Ęš)

(4)

where R â&#x20AC;&#x201C; gas constant; Vm â&#x20AC;&#x201C; volume of inlet system; Tm â&#x20AC;&#x201C; the temperature in the inlet system. Airflow entering the cylinders from the inlet system, mao 'is a function of the pressure in the inlet system pm and speed n of internal combustion engine: đ?&#x2018;&#x161;đ?&#x2018;&#x17D;0 Ęš = đ?&#x2018;&#x2DC;đ?&#x2018;&#x161;đ?&#x2018;&#x153;0 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x161;đ?&#x2018;&#x153;1 â&#x2C6;&#x2122; đ?&#x2018;&#x203A; â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x161; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x161;đ?&#x2018;&#x153;2 â&#x2C6;&#x2122; đ?&#x2018;&#x203A; â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x161; 2 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x161;đ?&#x2018;&#x153;3 â&#x2C6;&#x2122; đ?&#x2018;&#x203A;2 â&#x2C6;&#x2122; đ?&#x2018;?đ?&#x2018;&#x161;

(5)

where kmo0 ... 3 â&#x20AC;&#x201C; constant equation; n â&#x20AC;&#x201C; rotating speed. Block diagram corresponding to equation (1) â&#x20AC;&#x201C; (4), shown in Fig. 2.

Î¸

maĘš

maoĘš â&#x20AC;&#x201C;

pm, maoĘš

maoĘš Fig. 2. Structural scheme of ICE inlet system. Equation of the speed of crankshaft will be written as follows: đ??˝ â&#x2C6;&#x2122; đ?&#x2018;&#x203A;Ęš = đ?&#x2018;&#x2021;đ?&#x2018;&#x2019;đ?&#x2018;&#x203A;đ?&#x2018;&#x201D; â&#x2C6;&#x2019; đ?&#x2018;&#x2021;đ?&#x2018;&#x2122; where Teng â&#x20AC;&#x201C; engine torque; MMSE Journal. Open Access www.mmse.xyz

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(5)

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Tl â&#x20AC;&#x201C; reaction torque; J â&#x20AC;&#x201C; inertia momentum of the engine. The moment of the internal combustion engine can be described by the following empirical function [3]: đ?&#x2018;&#x2021;đ?&#x2018;&#x2019;đ?&#x2018;&#x203A;đ?&#x2018;&#x201D; = đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;0 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;1 â&#x2C6;&#x2122; đ?&#x2018;&#x161;đ?&#x2018;&#x17D; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;2 â&#x2C6;&#x2122; (đ??´đ??šđ?&#x2018;&#x2026;) + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;3 â&#x2C6;&#x2122; (đ??´đ??šđ?&#x2018;&#x2026;)2 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;4 â&#x2C6;&#x2122; đ?&#x153;&#x17D; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;5 â&#x2C6;&#x2122; đ?&#x153;&#x17D; 2 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;6 â&#x2C6;&#x2122; đ?&#x2018;&#x203A; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;7 â&#x2C6;&#x2122; đ?&#x2018;&#x203A;2 + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;8 â&#x2C6;&#x2122; đ?&#x2018;&#x203A; â&#x2C6;&#x2122; đ?&#x153;&#x17D; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;9 â&#x2C6;&#x2122; đ?&#x153;&#x17D; â&#x2C6;&#x2122; đ?&#x2018;&#x161;đ?&#x2018;&#x17D; + đ?&#x2018;&#x2DC;đ?&#x2018;&#x2019;10 â&#x2C6;&#x2122; đ?&#x153;&#x17D; 2 â&#x2C6;&#x2122; đ?&#x2018;&#x161;đ?&#x2018;&#x17D; (6) where ke0 ... 10 â&#x20AC;&#x201C; constant equation; ma â&#x20AC;&#x201C; the number of the working fluid in the cylinder; AFR â&#x20AC;&#x201C; the ratio of air / fuel; Ď&#x192; â&#x20AC;&#x201C; ignition timing. Variable ma is a mass of air, entering the cylinder during the inlet, which is Ď&#x20AC; radians in the first four cycles of the crankshaft. Thus, ma can be obtained by integration of air masses moving from the inlet system and resetting the integrator at the end of each cycle. Time reset integrator is variable, depending on the speed of the crankshaft. We know that in real engine there is time lag between the working fluid inlet and obtaining the moment, so the delay can be included in the model that is equal to Ď&#x20AC; to the speed of the crankshaft [4]. However, with varying integrator reset time can be approximated by the following expression: đ?&#x2018;&#x161;đ?&#x2018;&#x17D; =

đ?&#x2018;&#x161;đ?&#x2018;&#x17D;0 Ęšâ&#x2C6;&#x2122;đ?&#x153;&#x2039; đ?&#x2018;&#x203A;

(7)

where ma â&#x20AC;&#x201C; air mass entering the cylinder, g; mao â&#x20AC;&#x201C; air mass flowing from the inlet system, g / s; The block diagram is based on the equations of combustion engines, shown in the figure below. On the block diagram shows that the model of the internal combustion engine is complex and nonlinear. Simulation of internal combustion engines and engine performance. The external characteristics of the engine is the dependence of the effective power, momentum and other indicators of the engine crankshaft rotational speed at full throttle in a gasoline engine. To construct the external characteristics of the engine can be used any known empirical expression [4]. Taking some arbitrary values of speed, we can calculate the value of the effective power of the engine at different values of speed, which get a few points characteristics. It is recommended in the calculation and construction of highâ&#x20AC;&#x201C;speed external characteristics (as well as the performance further traction calculation) to select the frequency of the crankshaft of the engine in at least eight points. These points must present:

ing to the maximum motor torque. MMSE Journal. Open Access www.mmse.xyz

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The coefficients a, b, c included in the formula of Leiderman vary depending on the type and parameters of a particular engine. These values give very good agreement forms the estimated external speed characteristics of a pilot for many existing engines. In general, the coefficients a, b and c depends on the ratio of rotational speed at maximum power (nominal) and the rotational speed at maximum moment [5]. Effective power can be calculated by the following formula đ?&#x2018;&#x203A;

đ?&#x2018;&#x203A;

đ?&#x2018; đ?&#x2018;&#x2019; = đ?&#x2018; đ?&#x2018;&#x2019;đ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ â&#x2C6;&#x2122; [đ?&#x2018;&#x17D; â&#x2C6;&#x2122; đ?&#x2018;&#x203A; + đ?&#x2018;? â&#x2C6;&#x2122; (đ?&#x2018;&#x203A; ) â&#x2C6;&#x2019; đ?&#x2018;? â&#x2C6;&#x2122; (đ?&#x2018;&#x203A; ) ], (8) đ?&#x2018;

đ?&#x2018;

where n â&#x20AC;&#x201C; rotational speed of the crankshaft, rev / min nn â&#x20AC;&#x201C; rated speed, rev / min a, b, c â&#x20AC;&#x201C; coefficients of equation Nemax â&#x20AC;&#x201C; power corresponding rated speed kW. The torque can be find out by the formula Đ&#x153;Đş = 9550 â&#x2C6;&#x2122;

đ?&#x2018; đ?&#x2018;&#x2019; đ?&#x2018;&#x203A;

The fullâ&#x20AC;&#x201C;load curve of the engine shown in Figure 4.

Fig. 3. The fullâ&#x20AC;&#x201C;load curve of the engine. After calculating the external speed characteristics ICE must calculate the equations for the mathematical model of the engine. The simulation results are shown in the figure below.

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Fig. 4. The full–load curve of the ICE (simulated). It is evident that the design characteristics and external characteristics model engine speed virtually identical. Conclusion – this mathematical model can be used for the synthesis of the regulatory system. Energy model of the internal combustion engine One of the main indicators of ICE is fuel efficiency of the engine. Fuel efficiency is the set of properties that determine fuel consumption when performing transport vehicle in various conditions. The fuel efficiency of the car is largely determined by performance of the engine, as the clock fuel GT kg / h – mass of the fuel consumed in one hour and specific fuel consumption ge (g / kW × h) – the mass of the fuel consumed by one hour unit of engine power. The main meter fuel economy vehicle in our country and most European countries have fuel consumption in liters per 100 kilometers traveled path (track consumption) Qs l. The initial schedule for determining fuel consumption ge and GT are loading characteristic charts dependencies GT = f (Pe) and ge = f (Pe) when n = const. These dependencies are building sustainable mode of the engine with the same configuration it adopted high–speed characteristics [4, 5].

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Fig. 5. Loading characteristics of the engine. To calculate the cost Qs sometimes convenient to use the plot of g, by utilization of engine power. It can be obtained by loading and external characteristics of the engine.

Fig. 6. The dependence of the specific fuel consumption on engine performance. For each frequency n consumption, ge is minimum at the value and close to 100%. At low values of the coefficient and specific consumption increases by reducing engine efficiency and the deterioration of the combustion conditions and at large and (in gasoline engines) â&#x20AC;&#x201C; in connection with an enrichment fuel mixture economizer. For gasoline engines at low values of the coefficient using motor power consumption ge increased compared with the minimum several times, and at a 100% increase =10...15%. Without depending ge = f (Ne, n) use different approximate methods. Schlippe has proposed the following formula [1]:

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đ?&#x2018;&#x201D;đ?&#x2018;&#x2019; = đ?&#x2018;&#x201D;đ?&#x2018; â&#x2C6;&#x2122; đ?&#x2018;&#x2DC;Đ¸ â&#x2C6;&#x2122; đ?&#x2018;&#x2DC;đ?&#x2018;¤ where ge â&#x20AC;&#x201C; specific fuel consumption at Nemaks ky â&#x20AC;&#x201C; factor that takes into account the dependence ge = f (n) kW â&#x20AC;&#x201C; coefficient taking into account the dependence ge = f (n). To determine the approximate coefficients ky kW and can use the graphs below [6].

Fig. 7. Specific fuel consumption at different loads

Fig. 8. Specific fuel consumption at different speeds. The specific fuel consumption can be found using the formula below: MMSE Journal. Open Access www.mmse.xyz

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Mechanics, Materials Science & Engineering, December 2016 â&#x20AC;&#x201C; ISSN 2412-5954 đ?&#x2018;&#x203A;

đ?&#x2018;&#x2DC;đ?&#x2018;¤ = 0,8 â&#x2C6;&#x2122; ( ) â&#x2C6;&#x2019; đ?&#x2018;&#x203A;đ?&#x2018;

đ?&#x2018;&#x203A; đ?&#x2018;&#x203A;đ?&#x2018;

+ 1,2,

đ?&#x2018;&#x2DC;đ?&#x2018;˘ = 2,85 â&#x2C6;&#x2122; đ?&#x2018;˘2 â&#x2C6;&#x2019; 4,35 â&#x2C6;&#x2122; đ?&#x2018;˘ + 2,52. The load on the drive system depends on the resistance of the vehicle. This force depends on vehicle speed, wind speed and slope of the road, as shown below.

Fig. 9. Dependence of motion resistance on mass and velocity of vehicle.

Fig. 10. Fuel consumption simulation results.

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Fig. 11. The change in fuel consumption and torque during changes in throttle position. Map effectiveness of the internal combustion engine is presented in the figure below. Specific efficient fuel consumption is limited to the mechanical characteristics of internal combustion engines at full throttle flap.

Fig. 12. ICE efficiency map.

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Fig. 13. Fuel consumption. Summary. Obtained the dynamic and energetic models of internal combustion engine can be shared for the synthesis of the managing system of electric hybrid vehicle. References [1] Santini D., Vyas A. How to Use Life Cycle Analysis Comparisons of PHEVs to Competing Powertrains. [Електронний ресурс] / Proceedings of the 8th International Advanced Automotive Battery and Ultracapacitor Conference May 12–16, 2008, Tampa, Florida. Режим доступу: www/URL: http://www.transportation.anl.gov/pdfs/HV/501.pdf [2] Daniel Michael Lamberson, TORQUE MANAGEMENT OF GASOLINE ENGINES, A report submitted in partial satisfaction of the Requirements for the degree of Masters of Scienceс – p. 8,9. [3] Cooper, J. Furakawa, M. Kellaway, and L. Lam. “The UltraBattery– A new battery design for a new beginning in hybrid electric vehicle energy storage.” Journal of Power Sources. 2009. Vol. 188, No. 2. p. 642–649 [4] Smirnov O.P., Veselaya M.A., Bazhinova T.A (2016). Substantiation of Rational Technical & Economic Parameters of Hybrid Car, Automation, Software Development & Engineering Journal, ISSN 2415-6531. [5] Bazhynov O.V., Veselaya M.A. (2016). Intellectual Drive With Electric Engines On a Stock Car. Mechanics, Materials Science & Engineering, Vol 3. doi:10.13140/RG.2.1.3296.9369 [6] C.L. Wang, C. L. Yin, T. Zhang, L. Zhu, Powertrain design and experiment research of a parallel hybrid electric vehicle, International Journal of Automotive Technology, (2009) 10: 589. doi:10.1007/s12239-009-0069-2 [7] Andreas Lange, Ferit Küçükay, A new, systematic approach to determine the global energy optimum of a hybrid vehicle. Automotive and Engine Technology, (2016). doi:10.1007/s41104-0160011-3 Cite the paper K.M. Bas, V.V. Kravets, K.A. Ziborov, D.A. Fedoriachenko, V.V. Krivda, S.A. Fedoriachenko (2016). Mathematical Models of Hybrid Vehicle Powertrain Performance. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.01.971.560 MMSE Journal. Open Access www.mmse.xyz

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Optimization of Die-Sinking EDM Process Parameters in Machining OF AMMC-Desirability Approach16 M. Sangeetha1, A. Srinivasulu Reddy1,G. Vijaya Kumar1 1 â&#x20AC;&#x201C; M. Tech Student, Assistant Professor, Post Doctoral Fellow, S. V. University,tirupathi-517502 DOI 10.2412/mmse.7.643.887

Keywords: Metal matrix composites, Die-sink EDM, MRR, EWR, SR, Cost, Desirability Function analysis.

ABSTRACT. Metal Matrix Composites (MMCs) are one of the recent advanced materials having the properties of light weight, high specific strength and high wear resistancewhich are essential in Aircraft fittings, gears and shafts, missile parts, regulating valve parts, aerospace and defense applications. In the present work, Orthogonal Array L 27 Taguchi Experimental design is prepared using Minitab software by considering material parameters: type of the base material (Al5052, Al6082, Al7075), type of reinforcement material (FlyAsh, SiC,Al 2O3), percentage of the reinforcement(2. 5, 5%, 10%) and machining parameters current(Ip), pulse on time(T on), pulse off time(Toff),tool lifting time(TL). AMMC samples are fabricated using stir casting process and experiments have been performed on these samples by using electro discharge machining(EDM) as per Taguchi design of experiments and the responses such as Material removal rate(MRR),surface roughness(SR), and Electrode wear rate(EWR) and cost are measured. The experimental response data of electro discharge machining process is analyzed and the optimal combinations of influential parameters are determined using Desirability Function Analysis. Based on these optimum parameters combinations conformation test has been carried out and predicted results have been found to be in good agreement with experimental findings.

1. Introduction. Conventional materials have the limitations in achieving good combination of strength, stiffness, toughness and density etc. To overcome these limitations and to meet the ever increasing demand of modern day technology, composites are most promising materials of recent days. Metal matrix composites (MMCs) possess high strength, hardness, toughness, and good thermal resistance properties as compared to unreinforced alloys. Aluminium MMCs are difficult to machine by traditional machining techniques. Non-traditional machining techniques such as water jet machining, laser machining and wire EDM can be applied but these processes are mainly limited to linear cutting. Laser cutting and abrasive water jet machining had been used for machining of aluminium and MMCs and found suitable for rough cutting applications. Since the cost for using laser machining is generally prohibitive and EDM wire-cut process is not appropriate for a metal matrix composite work piece due to excessive breakage of the electrode wire, sinking EDM becomes an optimal choice for the machining of aluminium MMCs composite owing to its easy control in operation and precise criterion of high complex-shape components. 2. Literature review T. Senthilvelan [1]used EDM to machine EN8 and D3 steel materials which has wide application in Industry fields. The process parameters that have been selected are peak current, pulse on time, die electric pressure and tool diameter. The outputs responses are material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR). The Cast Copper and Sintered Powder Metallurgy Copper (P/M Copper) considered as tool electrodes. Gangadharudu Talla et al. [2] conducted experiments on aluminium/alumina MMC using EDM by adding aluminium powder in kerosene dielectric. Results ÂŠ 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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showed an increase in MRR and decrease in surface roughness compared to those for conventional machining. Mandeep Dhillon, Chandan Deep Singh, Jasvinder Singh [3] studied the optimization of EDM parameters during machining of Aluminium Alloy 7075. Four parameters namely peak current, pulse on time, duty cycle and flushing pressure are selected as input process parameters. Performance of EDM for Material removal rate (MRR), Surface Roughness (Ra) and Tool wear rate (TWR) is measured using a Copper electrode. Central composite design of Response Surface Methodology is opted for experimentation. Feng Yerui et al. [4] studied the influence of peak current, pulse duration on the surface roughness, material removal rate and material removal mode (MRD) on TiC/Ni metal ceramic processing. C. Velmurugan1 et al. [5] investigated the effect of parameters like Current(I), Pulse on time(T), Voltage(V) and Flushing pressure(P) on metal removal rate (MRR),tool wear rate(TWR) as well as surface roughness(SR) on the EDM machining of hybrid Al6061 metal matrix composites reinforced with 10% SiC and 4%graphite particles. M. Kathiresan and T. Sornakumar [6]Electrical Discharge Machining (EDM) studies were conducted on the aluminum alloy-silicon carbide composite work piece using a copper electrode. The Material Removal Rate (MRR) and surface roughness of the work piece increases with an increase in the current. The MRR decreases with increase in the percent weight of silicon carbide. The surface finish of the machined work piece improves with percent weight of silicon carbide. Gopalakannan et al. [7] performed experiments by choosing the process parameters such as pulse current, gap voltage, pulse on time and pulse off time. The Taguchi based grey relational analysis was adopted to obtain grey relational grade for EDM process with multiple characteristics namely material removal rate (MRR),Electrode wear rate (EWR)and surface roughness(SR). S. Kannan and K. Ramanathan [8] investigated the effect of current (C), pulse on-time (POT) and flushing pressure (P) on Metal removal Rate (MRR), Tool Wear Rate (TRR) during electrical discharge machining of as sintered Al-TiC MMC (5% reinforcement) was prepared by in-situ technique by synthesis route using stir casting furnace. Analysis of variance (ANOVA) was performed to find the validity of the experimental plan. S. Singh [9]applied the designs of experiments and grey relational analysis (GRA) approach to optimize parameters for electrical discharge machining process of 6061Al/Al2O3p/20P aluminium metal matrix composites. The process parameters included pulse current, pulse ON time, duty cycle, gap voltage and tool electrode lift time with three levels each. The material removal rate, tool wear rate and surface roughness were selected as the evaluation criteria, in this study. Ms. Pallavi S. Karande [10] conducted the experiments on EN-31 material with Copper as Electrode material using EDM. Various Process parameters namely Discharge Current (DC), Pulse on Time, Pulse off Time etc. have been considered. The process performance is measured in terms of Response variable like Tool Wear. Abhijeetsinh V. Makwana1, Kapil S. Banker [11] discussed the performance of die sinking EDM due to the shape configuration of the electrode. The optimization of the parameters of the EDM machining has been carried out by using the Taguchi method for design of experiments (DOE). Md. Ashikur Rahman Khan et al. [12] studied the surface finish characteristics of the machined surface in EDM on Ti-5Al-2. 5Sn titanium alloy. The microstructure of the machined surface is investigated for discharge energy and electrode materials. The peak current, pulse-on time, pulse-off time, servovoltage and electrode material (copper, copper–tungsten and graphite) are considered as process variables. Paras Kumar & Ravi Parkash [13] investigated the effect of electric discharge machining(EDM)process parameters current, pulse-ontime (Ton), pulseoff time (Toff) and electrode material on material removal rate (MRR), electrodewearrate (EWR) and surface roughness(SR)during machining of aluminium boron carbide (Al–B4C) composite. Kuldeep Ojha et al. [14] Reported research on EDM relating to improvement in MRR along with some insight into mechanism of material removal. F. Klockea, M. Schwadea, A. Klink, D. Veselovac [15] investigated the specific wear behaviour and material removal rate in detail in this paper and linked to the physical characteristics of the graphite material. In total 5 different kinds of graphite were chosen with significantly different physical characteristics concerning their specific electric resistance, thermal conductivity and grain size. The performance of each grade was evaluated in terms of material removal rate and tool wear for roughing. K. M. Patel et al. [16] investigated the EDM machinability on ceramic composite material (Al2O3–SiCw–TiC). Experiments were conducted using discharge MMSE Journal. Open Access www.mmse.xyz

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current, pulse-on time, duty cycle and gap voltage as typical process parameters. The grey relational analysis was adopted to obtain grey relational grade for EDM process with multiple characteristics namely material removal rate and surface roughness. M. M. Pawadeand, S. S. Banwait [17] reviewed that the development of die-sinking EDM within the past decades for the improvement of machining characteristics such as Material Removal Rate, Surface Roughness and Tool wear ratio. Jeevamalar and Ramabalan [18] reviewed about the Electrical Discharge Machining in which electrical energy is directly used to remove or cut the metals. . The metal is removed by electrical spark discharge between tool (Cathode) and workpiece (Anode). Electrical Discharge Machining is used in mould and die making industries, Automobile industries and making of Aerospace components. B. Venkatesh, B. Harish. [19]investigated the processing of Al/SiC by powder metallurgy method to achieve desired properties and also the results of an experimental investigation on the mechanical properties of Al/SiC are determined. A. M. S. Hamouda [20] described the processing and characterization of quartz particulate reinforced aluminium-silicon alloy matrix composite. In this regard, quartz-silicon dioxide particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand moulding process with different particulate volume fraction. The tensile strength of the composites decreases with the increase in addition of quartz particulate. R. Ramanujamet al [20]investigated the parameter optimization of end milling operation for Inconel 718 super alloy with multi-response criteria based on the Taguchi method and desirability function analysis. . 3. Design of experiments and preparation of aluminium metal matrix composites In the present work nine AMMC samples are produced using stir casting furnace as per Taguchi L27 experimental design (Table. 2) which is obtained by considering material and die sinking EDM parameters (Table 1). To produce AMMCs, the required amount of base material is poured into the graphite crucible and the temperature israised up to 900OC and allow it to maintain the same up to complete melting of base material. After melting of base metal the reinforcement particles (2. 5%,5%,10% by wt) are added graduallyinto the molten metal. Along with the particles, 2% of magnesium isalso added to the molten metal as a wetting agent. The effect of magnesium reduces the surface tension of aluminium as well as increases the wetting properties between the aluminium and reinforcement material in molten stage. In this way, mixing and dispersion time also reduce a large extent. It is possible to disperse the particles uniformly in the molten aluminium alloy after 5 minutes of stirring. Table 1. Influential parameters and their levels. Sl. no

Influential parameters

Level 1

Level 2

Level 3

Material Parameters 1

Base material (BM)

Al5052

Al6082

Al7075

Type of reinforcement material (RM)

Fly Ash

SiC

Al2O3

Percentage of particle (%RM)

2. 5

4 100 25 5

8 150 50 10

12 200 75 20

reinforcement

Die-sinking EDM Parameters 4 5 6 7

Current(I)(Amps) Pulse on time (Ton)(µs) Pulse off time(Toff)(µs) Tool lifting time(TL)(µs)

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Table 2. Taguchi design of experiments. Exp Run No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

AMMC Sample No. 1

Material parameters BM 5052 5052 5052 5052 5052 5052 5052 5052 5052 6082 6082 6082 6082 6082 6082 6082 6082 6082 7075 7075 7075 7075 7075 7075 7075 7075 7075

RM FA FA FA SIC SIC SIC Al2O3 Al2O3 Al2O3 FA FA FA SIC SIC SIC Al2O3 Al2O3 Al2O3 FA FA FA SIC SIC SIC Al2O3 Al2O3 Al2O3

%RM 2. 5 2. 5 2. 5 5 5 5 10 10 10 5 5 5 10 10 10 2. 5 2. 5 2. 5 10 10 10 2. 5 2. 5 2. 5 5 5 5

Die sinking parameters I Ton Toff 4 100 25 4 150 50 4 300 75 8 100 25 8 150 50 8 300 75 12 100 25 12 150 50 12 300 75 12 100 50 12 150 75 12 300 25 4 100 50 4 150 75 4 300 25 8 100 50 8 150 75 8 300 25 8 100 75 8 150 25 8 300 50 12 100 75 12 150 25 12 300 50 4 100 75 4 150 25 4 300 50

EDM TL 5 10 20 5 20 20 5 10 20 5 10 20 20 5 10 20 5 10 10 20 5 10 20 5 10 20 5

4. Experimentation. The experiments were conducted on compact type Diesinking-EDM machine as per the taguchi design of experiments and the experimental data is recorded in the Table 3. For these experiments, copper electrode is used and EDM oil is used as dielectric fluid.

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Fig. 1. Die sinking EDM Machine. Table 3. Experimental results. Expt. no

EWR

MRR

Process cost

(mm3 /min.)

(µm)

(Rs.)

8,1164

2,9991

4,219

766,6847

7,3588

1,7601

4,9489

1349,5366

1,1814

5,0532

4,9402

475,2602

8,8303

3,1306

4,4478

757,1636

4,5905

7,9877

4,6050

299,3395

3,9964

18,366

5,1280

130,7047

5,0045

7,1909

4,4013

327,1253

2,2267

25,4550

6,4324

94,5096

8,4285

85,3710

6,1329

28,1085

1,7367

8,9727

5,0199

257,1854

8,6933

27,9498

8,4435

85,9414

4,9565

38,6139

8,8298

62,3554

1,4249

3,5680

2,9198

662,3273

4,5593

12,042

3,4696

200,3140

4,9995

3,0239

4,2515

796,4090

2,8526

3,3258

3,8150

701,9061

4,8051

6,4011

4,8840

378,8423

3,7952

26,9494

5,9468

88,6873

5,4205

2,4795

3,2708

933,7269

5,0638

7,4035

4,6040

313,2328

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5,5754

7,3063

6,3509

316,1610

3,7939

13,3042

4,0599

175,9246

5,7060

40,2047

6,0704

59,7810

4,7450

28,5399

7,1979

85,3065

5,5338

1,8543

4,1016

1260,0380

3,5655

4,0683

4,2547

580,5867

3,2487

6,4621

5,3993

367,8497

5. Desirability functional analysis Step 1: Calculate the individual desirability index (di) for the corresponding responses using the formula proposed by the Derringer and Suich. There are three forms of the desirability functions according to the response characteristics. i. Nominal - the best: The value of Ĺˇ is required to achieve a particular target T. When the â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; equals to T, the desirability value equals to 1; if the departure of â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; exceeds a particular range from the target, the desirability value equals to 0, and such situation represents the worst case. đ?&#x2018;

Ĺˇâ&#x2C6;&#x2019;đ?&#x2018;Ś

(đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; ) , đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; â&#x2030;¤ đ?&#x2018;Ś â&#x2030;¤ đ?&#x2018;&#x2021;, đ?&#x2018; â&#x2030;Ľ 0 đ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

di =

(

Ĺˇâ&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; đ?&#x2018;Ą

{

đ?&#x2018;&#x2021;â&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

) , đ?&#x2018;&#x2021; â&#x2030;¤ Ĺˇ â&#x2030;¤ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ , đ?&#x2018;Ą â&#x2030;Ľ 0 0

ii. Larger-the better: The value of â&#x20AC;&#x2DC;Ĺˇâ&#x20AC;&#x2122; is expected to be the larger the better. When the â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; exceeds a particular criteria value, which can be viewed as the requirement, the desirability value equals to 1; if the â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; is less than a particular criteria value, which is unacceptable, the desirability value equals to 0.

di ={(đ?&#x2018;Ś

Ĺˇâ&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

đ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ â&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

đ?&#x2018;&#x;

0 Ĺˇ â&#x2030;¤ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

) , đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; â&#x2030;¤ Ĺˇ â&#x2030;¤ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ , đ?&#x2018;&#x; â&#x2030;Ľ 0 1 Ĺˇ â&#x2030;Ľ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

iii. Smaller-the better: The value of â&#x20AC;&#x2DC;Ĺˇâ&#x20AC;&#x2122; is expected to be the smaller the better. When the â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; is less than a particular criteria value, the desirability value equals to 1; if the â&#x20AC;&#x2DC;yâ&#x20AC;&#x2122; exceeds a particular criteria value, the desirability value equals to 0. In this study, â&#x20AC;&#x153; smaller the betterâ&#x20AC;? and â&#x20AC;&#x153; larger the betterâ&#x20AC;? characteristics are applied to determine the individual desirability values for minimize the TWR,SR, Process cost and maximize the MRR.

di ={(đ?&#x2018;Ś

Ĺˇâ&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ đ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; â&#x2C6;&#x2019;đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ

đ?&#x2018;&#x;

1 Ĺˇ â&#x2030;¤ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

) , đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A; â&#x2030;¤ Ĺˇ â&#x2030;¤ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x17D;đ?&#x2018;Ľ , đ?&#x2018;&#x; â&#x2030;Ľ 0 0 Ĺˇ â&#x2030;Ľ đ?&#x2018;Śđ?&#x2018;&#x161;đ?&#x2018;&#x2013;đ?&#x2018;&#x203A;

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Step 2: Compute the composite desirability (D). The individual desirability index of all the responses can be combined to form a single value called composite desirability (D) by the following Equation. D=(đ?&#x2018;&#x2018;đ?&#x2018;&#x2013; đ?&#x2018;¤1 â&#x2C6;&#x2014; đ?&#x2018;&#x2018;đ?&#x2018;&#x2013; đ?&#x2018;¤2 â&#x2C6;&#x2014; â&#x20AC;Ś . . đ?&#x2018;&#x2018;đ?&#x2018;&#x2013; đ?&#x2018;¤đ?&#x2018;&#x203A; )1/đ?&#x2018;¤ Step 3: Determine the optimal parameter and its level combination. The higher composite desirability value implies better product quality. Therefore, on the basis of the composite desirability (D), the parameter effect and the optimum level for each controllable parameter are estimated. Step 4:Obtaining optimal combination of influential factors: After determining the composite desirability the effect of each parameter is separated based on composite desirability values at different levels. The mean values of composite desirability for each level of the influential factors and the effect of influential factors on multi responses in rank wise are summarized in Table 6 Basically, larger the composite desirability(D)means it is close to the product quality. Thus, a higher value of the â&#x20AC;&#x2DC;Dâ&#x20AC;&#x2122; is desirable. From the Table 6 and fig 1, the optimal combination of influential factorsis BM3RM2%RM3I3Ton3Toff2TL3. This means Base material at level 3ie;Al7075Reinforcement material at level 2ie;SiCPercentage of Reinforcement material at level 3 ie;10,Tonat level 3 ie;300Âľs,Toff at level 2 ie;50Âľs,TLat level 3 ie;20Âľs 6. Conformation test For the obtained optimal combination, confirmation test has been conducted and compared the results (Table 6) with initial set of parameters. These results are satisfactory as the responses for optimal combination shows better performance. Table 4. Desirability indexes. Individual desirability indexes

Composite desirability

SL NO

EWR

MRR

COST

(D)

0,0933 0,0148 0,7802 0,4411

0,1924

0,0394 0,6581 0,6616

0,3619

0,0164 0,7415 0,4483

0 0,6567

0,1477 0

0,5543 0,0745 0,7149 0,7947

0,3913

0,632

0,1986 0,6264 0,9224

0,5189

0,5002

0,065 0,7493 0,7737

0,3705

0,8633 0,2834 0,4057 0,9498

0,5541

0,0525

0,3935

1 0,4563

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0,9274 0,0863 0,6447 0,8266

0,4544

0,0179 0,3132 0,0654 0,9562

0,1368

0,5065 0,4408

0,9741

0,9682 0,0216

0,5201

0,323

0,5584

0,907

0,8697

0,4824

0,5008 0,0151 0,7747 0,4186

0,2226

0,7815 0,0187 0,8485 0,4901

0,2793

0,5262 0,0555 0,6676 0,7346

0,346

0,6583 0,3013 0,4878 0,9542

0,5512

0,4458 0,0086 0,9406 0,3147

0,1836

0,4924 0,0675

0,715

0,7842

0,3695

0,4255 0,0663 0,4194

0,782

0,3102

0,6584 0,1381 0,8071 0,8881

0,5052

0,4085 0,4598 0,4669

0,976

0,5409

0,5341 0,3203 0,2761 0,9567

0,4611

0,431

0,0677

0,0716

0,6883 0,0276 0,7741 0,5819

0,3042

0,7297 0,0562 0,5805 0,7429

0,3647

0,123

0,0011

0,8

Table 5. Response Table for the Composite Desirability. Level BM

%RM

Ton

Toff

0,3042 0,2182 0,3548 0,2531 0,2595 0,2785 0,2910

0,3106 0,3828 0,2491 0,3278 0,3472 0,3487 0,2755

0,3457 0,3595 0,3566 0,3796 0,3538 0,3333 0,3940

Delta

0,0415 0,1646 0,1075 0,1265 0,0943 0,0702 0,1184

Rank

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Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 Main Effects Plot for Means Data Means

0.4

% RM

0.3

Mean of Means

0.2 5052

6082

7075

0.4

S iC

A l2O 3

2.5

5.0

Ton

10.0

Toff

0.3 0.2 4

100

150

300

0.4 0.3 0.2 5

Fig. 4. Response Graph for Composite Desirability. Table 6. Comparison of responses between AMMC with initial combination and optimal combination. Initial set of Combination Optimal combination

Combination of Controllable Parameters BM2RM2%RM2I2TON2TOFF2TL2 BM3 RM2%RM3I3TON3TOFF2TL3

COS T

Composite desirability

26,4326

7,2412

620

0,2683

45,9327

3,1243

340

0,7864

EWR

MRR

7,9244 1,3234

Improvement in composite desirability 0.5181

Summary. After analyzing the data of obtained influential factors combination, it is concluded that Rein forcement material,current and tool lifting time are the most significant parameters which influence the multi responses, % of Rein forcement material and pulse on time are the medium influenced parameters on multi responses and pulse off time, Base metal are influenced lastly the multi responses and the improvement in composite desirability is 0. 5181. From the table 6 EWR is reduced from 7. 9244 to 1. 3234,MRR increased from 26. 4326 to 45. 9327,surface roughness decreased from 7. 2412 to 3. 1243 and process cost decreased from 620 to 340 References [1] P. Balasubramanian,T. Senthilvelan “Optimization of Machining parameters in EDM process using Cast and Sinteres Copper Electrodes” Procedia Materials Science 6(2014)1292-1302 3rdInternational Conference on Material Processing and Characterization(ICMPC 2014). [2] Gangadharudu Talla,Deepak kumar sahoo,S. Gangopadhyay,C. K. Biswas “Modelling and multiobjective optimization of powder mixed electric discharge machining process of aluminium/alumina metal matrix composite Engineering Science and Technology”,An International Journal 18 (2015)369-373. [3] Mandeep Dhillon, Chandan Deep Singh, Jasvinder Singh “Evaluation and Optimization of Electro Discharge Machining parameters on Aluminium Alloy 7075”Volume1, Issue 2, 15 May- 15 August 2015 International Journal In Applied Studies And Production Management. [4] Feng Yerui, GuoYongfeng, Li Zongfeng “Experimental Investigation of EDM Parameters for TiC/Ni Cermet Machining” Procedia CIRP 42 ( 2016 ) 18 – 2218th CIRP Conference on Electro Physical and Chemical Machining (ISEM XVIII).

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[5] C. Velmurugan et al. Experimental investigations on machining characteristics of Al 6061 hybrid metal matrix composites processed by electrical discharge machining”International Journal of Engineering, Science and Technology Vol. 3, No. 8, (2011) pp. 87-101. [6] M. Kathiresan and T. Sornakumar “EDM Studies on Aluminum Alloy-Silicon Carbide Composites Developed by Vortex Technique and Pressure Die Casting” Journal of Minerals & Materials Characterization & Engineering, Vol. 9, (2010)No. 1, pp. 79-88. [7] S. Goplakannan, T. Senthilvelan and S. Ranganathan “Statistical optimization of EDM parameters on machining of aluminium Hybrid Metal Matrix Composite by applying Taguchi based Grey analysis” Journal of Scientific and Industrial Research Vol. 72,June 2013,pp. 358-365. [8] S. Kannan and K. Ramanathan “Optimization of EDM Parameter of Al/TiC Composite Using Taguchi Methodology” Middle-East Journal of Scientific Research “22 (1): 121-127, 2014. [9] S. Singh “Optimization of machining characteristics in electric discharge machining of 6061Al/Al2O3p/20P composites by grey relational analysis” International Journal of Advanced Manufacturing Technology (2012) 63:1191–1202. [10] Ms. Pallavi S. Karande, Mr. Javed S. Mujawar, Mr. V. V. Potdar “Effect of EDM process parameters on tool wear using EN 31 tool steel” Novateur publications international journal of innovation in engineering, research and technology national conference on innovative trends in engineering & technology-2016 11th & 12th march 2016 conference proceedings Issn no - 2394-36. [11] Abhijeetsinh V Makwana, Kapil S Banker “An Electrode Shape Configuration on the Performance of Die Sinking Electric Discharge Machine (EDM): A Review”Int. Journal of Engineering Research and Applications ISSN : 2248-9622, Vol. 4, Issue 11(Version - 5), November 2014, pp. 117-122. [12] Md. Ashikur Rahman Khan,M. M. Rahman K. Kadirgama “An experimental investigation on surface finish in die sinking EDM of Ti-5Al-2. 5Sn” International Journal of Advanced Manufacturing Technology(2015)77:1727-1740. [13] ParasKumarandRaviParkash “ExperimentalinvestigationandoptimizationofEDM processparametersfor machining of aluminum boron carbide(Al–B4C)composite” Machining science and technology 2016,VOL. 20,NO. 2,330–348. [14] Kuldeep Ojha et al. “MRR Improvement in Sinking Electrical Discharge Machining: A Review”Journal of Minerals & Materials Characterization & Engineering, Vol. 9, No. 8, pp. 709-739, 2010. [15] F. Klocke, M. Schwade, A. Klink, D. Veselovac “Analysisofmaterialremovalrate and electrode wear insinking EDM roughing strategies using different graphite grades” Procedia CIRP 6 ( 2013 ) 163 – 167The Seventeenth CIRP Conference on Electro Physical and Chemical Machining (ISEM). [16] K. M. Patel & Pulak M. Pandey & P. Venkateswara Rao “Optimisation of process parameters for multi-performance characteristics in EDM of Al2O3 ceramic composite” International Journal of Advanced Manufacturing Technology (2010) 47:1137–1147. [17] M. M. Pawade and S. S. Banwait “An Exhaustive Review of Die Sinking Electrical Discharge Machining Process and Scope for Future Research” World Academy of Science, Engineering and Technology International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering Vol:7, No:6, 2013. [18] Varinder Khurana, Harsimran singh sodhi, Amarjeet Singh Sandhu “The Effect of Die Sinking Process Paramters on Surface roughness of D2 Steel Using Taguchi Method” International Journal of Innovative Research in Engineering & Multidisciplinary Physical Sciences (IJIRMPS) Volume 2, Issue 3, December 2014.

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[19] B. Venkatesh, B. Harish “Mechanical properties of metal matrix composites (al/sicp) particles produced by powder metallurgy”International Journal of Engineering Research and General Science(2015) Volume 3, Issue 1, January-February. [20] A. M. S. Hamouda, S. Sulaiman, T. R Vijayaram, M. Sayuti, M. H. M. Ahmad “Processing and characterisation of particulate reinforced aluminium silicon matrix composite”Journal of achievements in Materials and Manufacturing Engineering Volume 25 issue 2 December 2007. Cite the paper Sangeetha, A. Srinivasulu Reddy, G. Vijaya Kumar (2016). Optimization of Die-Sinking EDM Process Parameters in Machining OF AMMC-Desirability Approach. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.7.643.887

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Analytical and Numerical Study of Foam-Filled Corrugated Core Sandwich Panels under Low Velocity Impact17 Mohammad Nouri Damghani1,a, Arash Mohammadzadeh Gonabadi 1,b 1 – Department of mechanical engineering, Semnan University, Semnan, Iran a – mnoori@semnan.ac.ir b – arash_mg@semnan.ac.ir DOI 10.2412/mmse.6.55.34

Keywords: sandwich panel, corrugated core, low velocity impact, corrugation, metal foam, finite element, analytical modelling.

ABSTRACT. Analytical and finite element simulations are used to predict the effect of core density on the energy absorption of composite sandwich panels under low-velocity impact. The composite sandwich panel contains two facesheets and a foam-filled corrugated core. Analytical model is defined as a two degree-of-freedom system based on equivalent mass, spring, and dashpot to predict the local and global deformation response of a simply supported panel. The results signify a good agreement between analytical and numerical predictions.

Introduction. Sandwich panels have been widely used for constructing bridge decks, temporary landing mats and thermal insulation wall boards due to better performance in comparison to other structural materials in terms of enhanced stability, higher strength to weight ratios, better energy absorbing capacity and ease of manufacture and repair. In sandwich panels, low density material, known as core, is usually adopted in combination with high stiffness face sheets to resist high loads. The main functions of core materials are to absorb energy and provide resistance to face sheets to avoid local buckling [1]. For sandwich panels having corrugated cores, it has been envisioned that this may be achieved if proper lateral support to core members against plastic yielding and buckling is supplied. To this end, recently, Yan et al. [2] inserted high porosity close-celled aluminium foams into the interstices of corrugated sandwich panels made of 304 stainless steel. A combined experimental and numerical study of the hybrid-cored sandwich was carried out under quasi-static compressive loading. It was found that the foam filling into the core of an empty corrugated sandwich could increase the compressive strength and energy absorption capacity of the hybrid sandwich by as much as 211% and 300%, respectively, and the specific energy absorption by 157%. Yan et al. [3] made theoretically and experimental studies on the behavior of sandwich beams with aluminum foam-filled corrugated cores under three-point bending. The bending stiffness, initial failure load and peak load of the sandwich structure were predicted by theoretical analysis. They concluded that the filling of aluminum foams led to dramatically increased bending stiffness, initial failure load, peak load, and sustained load-carrying capacity relative to an unfilled corrugated sandwich panel. Yu et al. [4] investigated the crushing response and collapse modes of metallic corrugate-cored sandwich panels filled with close-celled aluminum foams using Finite Elements Method. They show that at low compression velocities, the foam-filled panel was more efficient in energy absorption

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compared to the empty panel due to the lateral support provided by the filling foam against strut buckling if the foam relative density was sufficiently large. Yazici et al. [5] investigated experimentally the influence of foam infill on the blast resistivity of corrugated steel core sandwich panels and numerically through Finite Elements Method. After verifying the finite element model, numerical studies were conducted to investigate the effect of face sheet thickness, corrugated sheet thickness, and boundary conditions on the blast performance. Experimental and numerical results were found to be in good agreement with R2 values greater than 0.95. The greatest impact on blast performance came from the addition of foam infill, which reduced both the back-face and front-face deflections by more than 50% at 3 ms after blast loading at a weight expense of only 2.3%. Foam infill benefits were more prominent for Simple Supported edge case than Encastre Supported edge case. Han et al. [6] explored the physical mechanisms underlying the beneficial effect of filling aluminum foams into the interstices of corrugated plates made of stainless steel with finite element simulations. Relative to unfilled corrugated plates of equal mass, this effect was assessed on the basis of elevated peak stress and enhanced energy absorption under quasi-static out-of-plane compression. Upon validating the FE predictions against existing measurements, the influence of key geometrical and material parameters on the compressive response of foam-filled corrugated plates was investigated. Four new buckling modes were identified for foam-filled corrugations. Based upon these deformation modes of post-buckling, collapse mechanism maps were constructed. Due to the additional resistance provided by foam filling against buckling of the corrugated plate and the strengthening of foam insertions due to complex stressing, both the load bearing capacity and energy absorption of foamfilled sandwiches were greatly enhanced. In this paper, the effect of core geometry on the energy absorption of foam-filled corrugated core sandwich panels is investigated through analytical and numerical simulations. 1. Analytical study of composite sandwich panels 1.1. Static indentation Local deformation. Rigidly supported sandwich panels experience only local deformation of top facesheet. Many of the analytical methods for determining the local deformation involve Hertzian contact methods [7]. Since the local deformation causes transverse deflections of the entire top facesheet and core crushing, that Hertzian contact laws are inappropriate for finding local indentation response. Other methods for determining local deformation and core compression include modeling the top facesheet on a deformable foundation [8,9]. Turk and Hoo Fatt [10] presented an analytical solution for the local indentation of a rigidly supported composite sandwich panel by a rigid, hemispherical nose cylinder. They modelled the sandwich composite as an orthotropic membrane resting on a rigid-plastic foundation model. The solution was found to be within 15% of experimental results that involved facesheet indentations that were several times the facesheet thickness [11]. In this paper, local indentation of a sandwich panel is found by considering the elastic, perfectly plastic core as a deformable foundation for the top facesheet. Fig. 1 shows three possible regimes of top facesheet indentation: (I) plate on an elastic foundation; (II) plate on a rigid-plastic foundation; (III) membrane in a rigid-plastic foundation. When the indentation is very small and core crushing is elastic the local indentation response is found by considering a plate on an elastic foundation. As the facesheet indentation becomes larger but still less than about half of the plate thickness, local indentation response is found using a plate on a plate on a rigid-plastic foundation. If the facesheet indentation is larger than the facesheet thickness, the local indentation response is found by considering a thin membrane on a rigid-plastic foundation.

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Fig. 1. Regimes of local indentation of top facesheet. Abrate [12] gives the following expression for the local indentation of a simply supported plate on the elastic foundation

 mn 





4 P sin(    

m 1,3,... n 1,3,..

m n     )sin( )  / a 2 [ 4 ( D11m4  2( D12  2 D22 )n 4 n 4  k c )] 2 2   a 

(1)

where D ij – is the bending stiffness of the laminate face-sheet; D k c  E 33 / H – is the transverse elastic stiffness of the core.

Plate on rigid-plastic foundation. Fatt and Park [13] obtained the load-indentation by using the principle of minimum potential energy. The total potential energy  is given by   U  D V

(2)

where U – is the strain energy due to bending; D – is the work due to core crushing;

V – is the work done by the indentation force.

Assume that the local indentation is only due to bending and has the form  for 0  x 2  y 2  R 2   x R 2 y R 2  w (x , y )   [1  ( )] [1  ( )]   R   R  forR 2  x 2  y 2   2 , x  0, y  0 

where  – is the deflection under the indenter;

 – is the lateral extent of deformation; MMSE Journal. Open Access www.mmse.xyz

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(3)

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R – is the radius of the indenter.

The above function is defined only in the positive quadrant. It is assumed that the profile is symmetric with respect to both x- and y-axis. Coefficients of the above polynomial function were chosen to satisfy the boundary conditions as follows: Zero slope surrounding the projectile nose:

w w  0 x y

at 0  x 2  y 2  R2

(4-a)

Zero slope and deflection at the boundary of the deflection zone:

w w   0, x y

at x2  y 2   2

w 0

(4-b)

The strain energy due to bending of an orthotropic laminate facesheet is:

U

1  2w 2 2w 2 2w 2w 2w 2  D ( )  D ( )  2 D ( )( )  4 D ( )  dA  11 22 12 66 2 R  x 2 y 2 x 2 y 2 xy 

(5)

where D –is the laminate bending stiffness matrix,

dA  dxdy and A – is the surface area of the deformed facesheet. The integral can be approximated as 

U  2 R

 2w 2 2w 2 2w 2w 2w 2  D ( )  D ( )  2 D ( )( )  4 D ( )  dxdy  22 12 66 R  11 x2 y 2 x 2 y 2 xy 

(6)

Substituting derivatives of Eq. (3) into Eq. (5) gives

D1 2 U ( R   )2

(7)

where

D1 

16384 (7 D11  7 D22  8D66 ) 11025

D1 is the bending stiffness of the orthotropic facesheet. The work due to core crushing is also approximated by MMSE Journal. Open Access www.mmse.xyz

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 

D   qR 2  4  qwdxdy

(8)

0 0

where q – is the crushing strength of the core. Using the assumed profile in Eq. (3), one gets

D   qR 2 

256 q ( R   )2 255

(9)

The work done by the indentation force is V  P

(10)

Therefore, the total potential energy is

D1 2 256    qR 2  q( R   )2  P 2 (R   ) 255

(11)

Minimizing  with respect to  gives

P

2D1 256   qR 2  q (R   ) 2 2 (R   ) 255

(12)

Likewise minimizing P with respect to  gives

2 D1 256  q( R   ) 2 2 (R   ) 255

(13)

Eliminating the length of the deformation zone from Eqs. (11) and (12) gives the load-indentation response as

P  32

2 D1q   qR 2 255

(14)

The first term is the resistance due to facesheet bending and crushing of core outside the contact area of indenter, while the second term is due to crushing of core under the indenter. MMSE Journal. Open Access www.mmse.xyz

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Membrane on rigid-plastic foundation. The force-deformation relation is obtained as

P

8 C1q 3 2    qR 2 3

(15)

Where

  A  A 22   2A12  4A 66   C 1  8  11   45 49   The first term in Eq. (15) is the resistance due to membrane stretching and crushing of honeycomb outside the contact surface if indenter, while the second term is due to crushing of honeycomb under the indenter. Also a relation between the local indentation and the extent of deformation is given by:

 [

q(  R)4 13 ] 9C1

(16)

Global deformation. When the panel is clamped around the edges, it experiences the two types of deformations: (1) local deformation of the top facesheet into the core material,  , and (2) global panel bending and shear deformation,  . The local deformation is the local indentation of the top facesheet as the core crushes. The global deformation is understood as the bending and shear deformation of a sandwich panel that has not experienced any local facesheet indentation and core crushing. In reality both the local and global deformations are coupled. The principle of minimum potential energy is again to derive approximate solutions for simply supported panels. Functions describing the transverse deformation, W and the rotations,  and  are approximated from the exact series solution of a simply supported composite sandwich panel subjected to a point load at its center. Using the actual series solution for the deformations is not practical because a very large number of terms would have to be retained before convergence of the series solution. The resulting trial functions are as follows [14]:

2x 2 2y ) ][1  ( ) 2 ] a a for  a / 2  x  a / 2, a / 2  y  a / 2

w( x, y )  [1  (

(17)

3x x 2y  4( )3 ][1  ( ) 2 ] a a a for  a / 2  x  a / 2, a / 2  y  a / 2

(18)

3y y 2x  4( )3 ][1  ( ) 2 ] a a a for  a / 2  x  a / 2, a / 2  y  a / 2

(19)

 ( x, y )   0 [ 

 ( x, y )   0 [ 

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d d  0,  0 at the dx dy edges. In-plane deformations are assumed to be negligible with respect to the transverse deformation. Thus, the strain energy for a symmetric sandwich panel is given by: Note that these trial functions satisfy the boundary conditions, i.e., w  0,

a /2 a /2

U 4





2  D11s  2 D22s  2  w 1 w 2 s  s  ( )  D ( )( )  ( )  A [   ( ) ]  12 55 y x 2 y 2 x 2 x  2 x

w 1 w 2 1    1  A [   ( ) ]  D66s [ ( ) 2   ( )] 2 y 2 y 2 y y x 2 x s 44

(20)

 dxdy

Substituting derivatives of the expressions in Eqs. (17)-(19) into Eq. (20) gives the following expression for the strain energy: U  F12  F2 0  F3 02  F4 02  F502  F60 0

(21)

where 2240 s (A 44  A 55s ) 1575 1344 s F2  aA 44 1575 1 F3  (204a 2 A 44s  2016D 22s  2040D 66s ) 1575 1344 s F4  aA 55 1575 1 F5  (204a 2 A 55s  2016D11s  2040D 66s ) 1575 4032 s F6  (D12  D 66s ) 1575

F1 

Thus we have   F12  F2 0  F3 02  F4 0  F502  F60 0  P

(22)

Minimizing  with respect to and ensures equilibrium of the system and yields the load-indentation response. Minimizing  with respect to  gives

  2 F1  F2 0  F4 0  P  0  Likewise minimizing  with respect to  0 gives

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(23)

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  F4   2 F5 0  F6 0  0  0

(24)

Minimizing  with respect to  0 gives   F2   2 F3 0  F6 0  0 0

(25)

The global load-deflection response is found by eliminating  0 and  0 in Eqs. (24), (25). Hence: P  Kg

(26)

where

K g  [(4 F1F5  F42 )(4 F3 F5  F62 )  (2 F2 F3  F4 F6 ) ( F4 F6  2 F2 F5 )] / [2 F5 (4 F3 F5  F62 )] 1.2. Low-velocity impact on simply supported sandwich panels. The following section described simple dynamic models for the impact response of simply supported sandwich panels. Regarding to Fig. 2 the equations of motion for the 2-DOF system are (M 0  m f )(   )  P1 ( )  Qd  0

(27)

P1 ( )  Qd  ms   K gd 

(28)

and

where Q d is the dynamic crushing resistance of the core that can be experimentally evaluated. mf is the effective mass of the top facesheet, and the effective mass of the sandwich is ms . K gd is the dynamic global stiffness of the sandwich.

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Fig. 2. Discrete model of projectile impact on simply supported panel The above equations would be difficult to solve because of the nonlinear local spring response. Assume that local spring response can be linearized

P1 ( )  K1d 

(29)

where K 1d – is the dynamic local stiffness of top facesheet. Also assume again the mass of sandwich panel is negligible compared to the mass of the projectile for simplicity. Therefore Eqs. (27) and (28) simplify to M 0 (   )  K1d   Qd  0

(30)

And K1d   Qd  K gd 

(31)

Differentiating both sides of Eq. (31) twice with respect to time gives



K1d  K gd

(32)

Substituting  into Eq. (30) gives

M 0 (1 

K1d )  K1d   Qd  0 K gd

Also by differentiating both sides of Eq. (31) with respect to time and setting t  0 we obtain MMSE Journal. Open Access www.mmse.xyz

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(33)

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0 

(34)

K1d 0 K gd

According to the momentum conservation law, M 0V0  M 0 X1 where X 1 is the velocity of the upper K gdV0 facesheet obtained from X1   0  0 . Thus the initial condition is  0   (0)  and K1d  K gd  (0)  0 . The solution for  is given by:



Q Q  sin t  d cos t  d  K1d K1d

(35)

Where



K1d K gd ( K1d  K gd ) M 0

The velocity and acceleration of top facesheet is found by differentiating Eq. (35). The impact force is given by

F (t )   M 0 (   )   M 0 (1 

K1d ) K gd

(36)

The maximum impact force occurs when dF / dt  0 and is given by

Fmax 

M0 K gd

( K gd  K1d ) (Qd  )2  ( 0 K1d )2

( 02 K1d 

Qd2 2 ) K1d

(37)

Maximum impact force occurs when

tmax 



tan 1 (

 0 K1d ) Qd 

Maximum strain rate is also given by

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 max 

 cr  K tan 1 ( 0 1d ) Qd 

(39)

2. Analytical study of sandwich panels with corrugated sandwich panels. Fig. 3 shows a sandwich panel with corrugated core.

Fig. 3. Corrugated lattice sandwich structure unit cell dimensions. The core density of triangular sandwich structure are formulated respectively as [15]

c 

2t1  L sin 2

(40)

where  – is the density of the base material of the core sheets, L  H c / sin  for triangular core as in Fig. 4. Thus, the relative density for the triangular core can be expressed as [16]



2t l sin 2

(41)

Fig. 4. Geometry of triangular core. For a foam-filled corrugated core, the total average density of the sandwich core may be expressed as [2]:

total  c vc   f (1  vc )

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(42)

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where vc – is the volume proportion of the core occupied by corrugated plate;

 f – is the density of foam. Then the total average density of the sandwich core can be written as

total 

2t1 vc   f (1  vc ) l sin 2

(43)

The overall shear deflection of web-foam core is the sum of the web and foam shear deflections. Based on the static relationship [17]:

 xy   wVw   f V f

(44)

where  xy ,  w and  f – are the shearing stress of web-foam core, web and foam, respectively;

Vw and V f – the volume ratio of web and foam, respectively. The geometrical relationship:

 xy   w   f

(45)

where  xy ,  w and  f – the shear strain of web-foam core, web and foam, respectively. Using Hooke’s law, the corresponding stresses are

 xy   xy Gxy

(46)

 w   wGw  f   f Gf where Gxy , Gw and G f – the shear modulus of web-foam core, web and foam, respectively. The elastic modulus of the corrugation when loaded in x3 direction can be expressed as [18]: E3  Es  sin 4 

(47)

where Es – the Young’s modulus of the parent material. Using the same method, the effective shear modulus of the corrugated core, G1 can be expressed as

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G1 

Es  sin 2 2 Es sin 2 2 2t1vc  (   f (1  vc )) 4 4 l sin 2

(48)

For a foam-filled corrugated core the elastic modulus is given by

Etotal

2t1Es sin 4   E c vc  E f (1  vc )  vc  E f (1  vc ) l sin 2

(49)

Compressive strength,  3 as well as transverse shear strength,  1 of the corrugated core

 3   c  sin 2    c sin 2  ( 1   c

 2

sin 2w 

c 2

2t1vc   f (1  vc )) l sin 2

sin 2w(

2t1vc   f (1  vc )) l sin 2

(50) (51)

The dynamic global stiffness K gd for a simply supported sandwich panel is given by [19]:

K gd  [(4 F1F5  F42 )(4 F3 F5  F62 )  (2 F2 F3  F4 F6 ) ( F4 F6  2 F2 F5 )] / [2 F5 (4 F3 F5  F62 )] Where 2240 4t1 Es sin 4  ( vc  2 E f (1  vc )) 1575 l sin 2 1344 2t1 Es sin 4  F2  a( vc  E f (1  vc )) 1575 l sin 2 4 1 2 2t1 Es sin  F3  (204[a vc  E f (1  vc )] 1575 l sin 2 2t E sin 4  4t E sin 4  2016[ 1 s vc  E f (1  vc )]  2040[ 1 s vc  2 E f (1  vc )]) l sin 2 l sin 2 1344 2t1 Es sin 4  F4  a( vc  E f (1  vc )) 1575 l sin 2 2t E sin 4  1 F5  (204a 2 [ 1 s vc  E f (1  vc )]  1575 l sin 2 2t E sin 4  2t E sin 4  2016[ 1 s vc  E f (1  vc )]  2040[ 1 s vc  E f (1  vc )]) l sin 2 l sin 2 4032 4t1 Es sin 4  F6  ( vc  2 E f (1  vc )) 1575 l sin 2 F1 

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Thus we obtain the final stiffness

K g _ new  [(4 F1F5  F42 )(4 F3 F5  F62 )  (2 F2 F3  F4 F6 )

(53)

( F4 F6  2 F2 F5 )] / [2 F5 (4 F3 F5  F62 )] As well as the deformation, velocity and acceleration in terms of time:

 new 

Q Q  sin t  d cos t  d  K1d K1d

(54)

3. Numerical study Numerical modelling of corrugated-core sandwich panels. The corrugated sandwich panels were analysed using the explicit FE code ANSYS/LS-DYNA. The face sheets and sandwich cores were made of Al-1000 aluminum alloy. The corrugated core members were meshed by structural shell element S4R and quadratic structural element. The detailed material parameters are summarized in Tables 2 and 3. With symmetry boundary conditions, displacement controlled quasi-static uniaxial compression was applied to the top face sheet while the bottom face sheet was fixed. Upon performing a mesh sensitivity study, an element size on the order of 1.5 was shown to be sufficiently refined for ensuring the accuracy of the numerical results. The upper indenter was simulated by using eight-node solid elements, and the lower platform was defined to be rigid. An automatic surface-to-surface contact was defined between the upper indenter and the sandwich panel. Meanwhile, an automatic single surface contact was considered to simulate self-contact of core sheets during deformation. An automatic one-way surface-to-surface contact was defined between the face sheets and core members. For this reason, a speed of 2 m/s was adopted in the simulation. FE model of the triangular corrugated sandwich panel is shown in Fig. 5.

Fig. 5. Deformation and stress distribution in Finite element model of triangular corrugated sandwich panel. Numerical modeling of sandwich panels with foam core. This section is intended to give a brief review on the capabilities of LS-DYNA finite element code for simulation of impact event. The numerical simulation is used for interaction between a rigid impactor and a sandwich structure with aluminum foam-core during impact. Impactor is modeled and meshed using quad elements as shown MMSE Journal. Open Access www.mmse.xyz

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in Fig. 7. The impactor is modeled using the material type 20 (rigid). Fig. 2 shows the model of steel impactor in LS-DYNA. Material constants for the steel impactor are presented in Table 1. Table 1. Properties of steel impactor. Material property

ρ (kg/m3)

E(GPa)

σY(MPa)

Value

7800

210

0.3

400

Fig. 6. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for a triangular corrugated-core sandwich panel.

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Fig. 7. A view of steel impactor model in LS-DYNA. Plastic-kinematic model with material number 3 is used for Aluminum plate while Aluminum foam is modelled using the Deshpande-Fleck foam model by choosing material number 154 in LS-DYNA [20, 21, 22]. Fig. 8 shows the model of Aluminum plate in LS-DYNA. Material constants for the Aluminum are presented in Table 2. Fig. 9 shows the model of Aluminum foam in LS-DYNA. Material constants for the Aluminum foam are presented in Table 3.

Fig. 8. A view of Aluminum plate model in LS-DYNA. Table 2. Properties of Aluminum. Material property

ρ (kg/m3)

E(GPa)

 y (MPa)

 u (MPa)

D

Value

2700

0.3

117

124

0.2

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Fig. 9. A view of Aluminum foam model in LS-DYNA. Table 3. Properties of Aluminum foam. Relative Density Material property

(18%)

(23%)

(27%)

E (MPa)

1500

1660

1800

0.05

2.1

γ (MPa)

4.3

5.26

D

1.63

1.48

1.33

 2 (MPa)

5.5

4.6

 pl (MPa)

3.8

4.7

5.4

 cr

0.1

In some models such as Deshpande-Fleck foam model it may be not possible to reduce the step time. In order to solve this problem in LS-DYNA the element erosion method is used to remove the heavily distorted elements. Several criteria are used to this end. Although in the present work the maximum strain criterion is utilized, the maximum stress criterion is applicable. For the case of Aluminum foam the maximum strain of 0.3 is used from the experimental results [23]."MAT-adderosion" is an auxiliary tool to remove the elements of impressed region [24,25,26].

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Fig. 10. Deformation and stress distribution in finite element model of foam-core sandwich panel.

Fig. 11. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for foam-core relative density of 18%.

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Fig. 12. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for foam-core relative density of 23%.

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Fig. 13. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for foam-core relative density of 27%. Numerical modelling of sandwich panels with corrugated foam-filled core. In the case of the foam-filled panel, symmetry boundary condition was applied on the two side faces of the foam insertion. Both the front and back face sheets of the sandwich were assumed to be stiff enough to be modelled as rigid bodies. Both the corrugated core members and the filled foam were meshed by structural shell element S4R. The foam insertions, the face sheets as well as the struts were also perfectly bonded at the interface [27].

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Fig. 14. Deformation and stress distribution in finite element model of sandwich panel with corrugated foam-filled core.

Fig. 15. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for a sandwich panel with corrugated foam-filled core with relative density of 18%.

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Fig. 16. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for a sandwich panel with corrugated foam-filled core with relative density of 23%

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Fig. 17. Time-variations of impactor displacement, velocity, and acceleration, imposed force of impactor, and impactor kinetic energy for a sandwich panel with corrugated foam-filled core with relative density of 27% Summary. Analytical and numerical methods were used to characterize the failure response of foamfilled corrugated core sandwich panels under low velocity impact. A two degree-of-freedom is used to analytically predict the local and global deformation behaviour of a simply supported panel. The effect of foam-core relative density on the impact properties of sandwich panels was studied. It was shown that the impact resistance and rate of energy absorption would be increased by densifying the foam-core. Also the results revealed a good correlation between the analytical and numerical predictions. Nomenclature

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a A A ij A ijd s A 44 , A55s

b C1

C 1d D

D1d D ij D ijd

s ij

D11b

E Es

Fmax h H c

k Kg K gd

K 1d KE mf

ms M0 P P1 q qd

length of panel panel surface area laminate extensional stiffness matrix laminate dynamic extensional stiffness matrix transverse shear stiffness of sandwich width of panel static membrane stiffness of laminate dynamic membrane stiffness of laminate work in crushing core static bending stiffness of laminate dynamic bending stiffness of facesheet laminate bending stiffness matrix dynamic bending stiffness matrix sandwich bending stiffness matrix bending stiffness of the sandwich beam Young’s modulus Young’s modulus of the parent material maximum impact force facesheet thickness core thickness transverse stiffness of core global stiffness of clamped panel dynamic global stiffness of clamped panel dynamic local stiffness of top facesheet kinetic energy effective mass of top facesheet

Qd Q ij

R S t t1

t max U V V0 w w top     W x,y

 0

total dynamic core crushing strength laminate or core stiffness matrix blunt projectile radius shear stiffness of the core time ply thickness time for maximum deflection total strain energy work done by external forces projectile velocity local (top facesheet) indentation top facesheet deflection global (panel) deflection in-plane coordinates of sandwich panel shear angle along x-axis amplitude of shear angle along x-axis shear angle along y-axis amplitude of shear angle along y-axis amplitude of top facesheet velocity

 0  0   0 t 

 cr D   12b , 21b  f s total  pl

effective mass of sandwich projectile mass

Y  

indentation force

( )  d( ) / dt

initial velocity of top facesheet amplitude of global panel deformation amplitude of overall panel velocity initial velocity of panel impact duration strain critical strain densification ratio strain rate Poisson’s ratios of sandwich beam total potential energy density of facesheet density of sandwich total average density of the sandwich core plateau stress

equivalent nonlinear spring response for top facesheet deformation static crushing strength dynamic crushing strength

yield stress frequency of vibration due to impact extent of local indentation time derivative

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References [1] Wu Z., Liu W., Wang L., Fang H., Hui D., 2014. Theoretical and experimental study of foamfilled lattice composite panels, under quasi-static compression loading, Compos Part B: Eng, 60, 329340, DOI http://dx.doi.org/10.1016/j.compositesb.2013.12.078 [2] Yan L.L., Yu B., Han B., Chen C.Q., Zhang Q.C., Lu T.J., 2013. Compressive strength and energy absorption of sandwich panels with aluminum foam-filled corrugated cores, Composites Science and Technology, 86, 142-148 DOI http://dx.doi.org/10.1016/j.compscitech.2013.07.011 [3] Yan L.L., Han B., Yu B., Chen C.Q., Zhang Q.C., Lu T.J., 2014. Three-point bending of sandwich beams with aluminum foam-filled corrugated cores, Materials and Design, 60, 510-519. [4] Yu B., Han B., Ni C.Y., Zhang Q.C., Chen C.Q., Lu T.J., 2015. Dynamic Crushing of All-Metallic Corrugated Panels Filled With Close-Celled Aluminum Foams, J. Appl. Mech, 82(1), 011006. [5] Yazici M., Wright J., Bertin D., Shukla A., 2014. Experimental and numerical study of foam filled corrugated core steel sandwich structures subjected to blast loading, Composite Structures, 110, 98109. [6] Bin Han, Lei L. Yan, Bo Yu, Qian C. Zhang, Chang Q. Chen, Tian J. Lu, 2014. Collapse mechanisms of metallic sandwich structures with aluminum foam-filled corrugated cores, journal of mechanics of materials and structures, 9(4), 397-425. [7] Yang, S.H., Sun, C. T., 1981. Indentation law for composite laminates. NASA CR-165460. [8] Ericsson A., Sankar B.V., 1992. Contact stiffness of sandwich plates and application to impact problems. 2nd Int. Conf. on Sandwich Constr., Gainesville: Stockholm, Sweden. [9] Thomsen, O.T., 1995. Theoretical and Experimental Investigation of Local Bending Effects in Sandwich Plates. Composite Structures, 30(1), 85-101. [10] Turk M.H., Hoo Fatt M.S., 1999, Localized damage response of composite sandwich plates. Compos Part B: Eng, 30, 157-65. [11] Williamson J.E., Lagace, P.A., 1993. Response Mechanisms in the Impact of Graphite/Epoxy of Graphite/Epoxy Honeycomb Sandwich Panels, Proceedings of the American Society for Composites 8th Technical Conference: Composite Materials, Cleveland, OH, 287-296. [12] Abrate S., 1997. Localized impact on sandwich structures with laminated facings. Appl Mech Rev, 50(2), 69-82. [13] Hoo Fatt M.S, Park K.S. 2001, Dynamic Models for Low-Velocity Impact Damage of Composite Sandwich Panels- Part B: damage initiation, Composite Structures, 52 (3-4), 353-364. [14] Dobyns, A.L., 1981. Analysis of simply-supported orthotropic plates subject to static and dynamic loads. AIAA J. 19(5), 642-650. [15] Hou S., Zhao S., Ren L., Han X., Li Q., 2013. Crashworthiness optimization of corrugated sandwich panels, Materials and Design; 51, 1071-1084. doi 10.1016/j.matdes.2013.04.086 [16] Biagi R., Bart-Smith H., 2012. In-plane column response of metallic corrugated core sandwich panels, International Journal of Solids and Structures, 49, 3901-3914, doi 10.1016/j.ijsolstr.2012.08.015 [17] Wang L., Liu W., Wan L., Fang H., Hui D., 2014. Mechanical performance of foam-filled lattice composite panels in four-point bending: Experimental investigation and analytical modeling, Composites: Part B, 67, 270-279, doi 10.1016/j.compositesb.2014.07.003 [18] T. George, Carbon Fiber Composite Cellular Structures, Ph.D. Thesis, University of Virginia, 2014.

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[19] Hoo Fatt M.S., Park K.S., 2001. Dynamic models for low-velocity impact damage of composite sandwich panels–Part A: Deformation, Composite Structures, 52, 335-351. [20] Hanssen A.G., Hopperstad O.S., Langseth M, Ilstad H., 2002. Validation of constitutive models applicable to aluminium foams. Int J Mech Sci, 44(2), 359-406. [21] Deshpande V.S., Fleck N.A., 2000. Isotropic constitutive models for metallicfoams. J Mech Phys Solids, 48, 1253-1283. [22] Perillo M., Primavera V., 2010. Validation of Material Models for the Numerical Simulation of Aluminum Foams, 11th International LS-DYNA® Users Conference. [23] LS-DYNA Keyword user's Manual version 971, July 2006. [24] Rajendran R., Prem Sai K., 2008. Preliminary investigation of aluminium foam as an energy absorber for nuclear transportation cask, J Mater Design, 29(9), 1732-1739. [25] Rajendran R, Moorthi A, Basu S. 2009. Numerical simulation of drop weight impact behaviour of closed cell aluminium foam. J Mater Design, 30(8), 2823-2830, doi 10.1016/j.matdes.2009.01.026 [26] Mohammad Nouri Damghani, Arash Mohammadzadeh Gonabadi (2016). Investigation of Energy Absorption in Aluminum Foam Sandwich Panels By Drop Hammer Test: Experimental Results. Mechanics, Materials Science & Engineering, Vol 7. doi: http://seo4u.link/10.2412/mmse.6.953.525 [27] M. Noori-Damghani, H. Rahmani, Arash Mohammadzadeh and S. Shokri-Pour. Comparison of Static and Dynamic Buckling Critical Force in the Homogeneous and Composite Columns(Pillars). International Review of Mechanical Engineering 5, no. 7 (2011): 1208-1212 Cite the paper Mohammad Nouri Damghani, Arash Mohammadzadeh Gonabadi (2016).Analytical and Numerical Study of Foam-Filled Corrugated Core Sandwich Panels under Low Velocity Impact. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.6.55.34

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Various Comparison of Additional Conditions of Different Designed Thermal Solar Technology Systems with the Same Collector Field18 Kenan Karacavuş 1,a 1 – Asist. Prof., Edirne Technical Collage, University of Trakya, Edirne, Turkey a – kenank@trakya.edu.tr DOI 10.2412/mmse.13.44.508

Keywords: solar energy, water heating, natural circulation system, pumped circulation system, flat plate solar collector, efficiency value, moving and follow-up system, photo-controlled unit.

ABSTRACT. It is important to research, develop and disseminate new and renewable energy sources instead of fossil fuels such as fossil fuels because of the energy demands of today. The need for new and renewable energy sources and the efforts to efficiently use these resources have also been accelerated. In this study which was made for the same purpose, in the study with the solar energy, in the Edirne related climate conditions for water heating, one is a closed system with fixed angle and natural circulation, the other is the closed system consisting of closed system with photo-controlled unit. Two experimental setups were designed. In these experimental setups, instantaneous, daily and average efficiency values for both systems were determined by using two standard flatplate collectors of the same type, copper pipe, copper wing, flat plate and single glazed with equal collector area, during September, moving and follow-up system (following the sun with Photo-controlled Unit).

Introduction. In many applications made from solar energy, the conditions of operation and operation of the systems to be designed and applied are gaining importance in response to the question of how long and in which way the solar rays can be used, in consideration of the climate conditions to be applied. In order to be able to decide on applicable systems or systems that may be suitable for Edirne province climatic conditions, a "Closed System with Fixed Angle and Natural Circulation" which is a very common system applied in Edirne. Other that seem to have a high initial investment cost and thus are not very common to implement "Closed System with Moving and Follow-up system with Photo-Controlled Unit and Pumped Circulation System", these systems, which are called in September 2015 climate conditions, 1. System (First System): closed system with fixed angle natural circulation; 2. System (Second System): closed system with moving and follow-up system (following the sun with Photo-controlled Unit) and pumped circulation system. Materials If the two different systems in the experimental setup used in this study and the technical specifications of the elements forming these systems are explained in detail: 1) Closed system with fixed angle natural circulation: this system, which is called as (First System) 1st. System in the experimental setup;  2 pieces of 1930x930x85 mm size, 8 copper pipes, copper winged semiclective surface, monobloc polyurethane insulated flat-plate collector; © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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 170 lt volume, polyurethane insulated, enamelled, pressurized hot water storage (boiler);  Installation, and installation elements each insulated as a polyurethane sheath a profile skeleton providing a fixed angle (approx. 40°). The operating principle of this system is shown in Figure .1;

Fig. 1. Operating Principle of Closed system with fixed angle natural circulation. 2) Closed system with moving and follow-up system (with Photo- controlled Unit) and pumped circulation system: This system, which is named as (second system) 2nd system in experimental setup;  Flat-plate collectors of 2 pieces 1930x930x85 mm in size, with 8 copper tubes, copper wings, with a semiclective surface, monobloc polyurethane insulation;  1piece differential thermometer for circulation control in the system;  220 volts, 1 stage circulation pump with 3 speed control;  A profile stand that allows the collectors to keep the sunlight at 90 ° with 4 photocell photo control units, which can be rotated 180 ° horizontally and vertically, with collectors carrying, 2 pieces 24V 12 " dish antenna motors;  170 lt volume, polyurethane insulated, enamelled, pressurized hot water storage (boiler);  Flexible pipes and other installations, each of which is insulated with polyurethane casings. This system operation principle diagram is shown in Figure 2.

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Fig. 2. Operating Principle of closed system with moving and follow-up system (with Photo - controlled Unit) and pumped circulation system. In addition, there are 1piece self-programmed and datalogger-connected wind speed meter in the experimental setup, 1 piece solar thermometer (pyrometer) that can be connected to the datalogger, 1 piece digital thermometer connected to the datalogger that measures the ambient temperatures where the experiments are made, 7 pieces digital thermometers, which can be connected to the datalogger, were used to measure the temperature of the hot water tank (boiler), the main water temperature and the usage water temperature. All measuring instruments are digital except for 1piece analogue flowmeter which is used to adjust the flow rate of the test system and they are connected to 2 pieces dataloggers for each system. However, in order to provide the time-controlled operation of the systems and measuring instruments, one timer was used in the electrical panel of the test apparatus. Method In the experimental setup, the collector temperatures of the two systems ( t kg ), Collector outlet temperatures ( t kĂ§ ), hot water storage (boiler) temperature ( t b ), mains water temperature ( t Ĺ&#x;e ), utility water temperature ( t ks ), ambient temperature at which the experimental setup is located ( t o ), wind speed ( Vort ) After calibrating all the devices connected to 2 pieces datalogger in order to be able to determine values ( E s ) from the devices for which the values of the solar radiation per meter (m2) can be determined in advance, datalogers all the systems in the test setup, Starting from 09:00 am, which is the starting time of every day, to 1:00 hour intervals starting at 17:00. Starting from September 2015, experiments started. These 6 periodical values, which are formed every 1 hour intervals, were taken from a datalogger on a laptop computer after 17:00 hours and prepared in EXCEL and recorded for each day and every system in the experimental test protocol. [1].

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As the experiments continue during September 2015, these values are obtained by repeating for each day and processed for the test minutes. For these two systems, instantaneous efficiency values are firstly found in formula 1 [4].

a 

Qf Qsol

(1)

where Q f – the amount of useful heat to be provided by the system (kcal / day);

Qsol – amount of heat to be supplied by the system (kcal / day). The amount of heat provided by the system [4];

Q f  m.c p .(tks  tşe )

(2)

where m – daily water need to be heated in the system (kg / day); c p – specific heat of the water to be heated (kcal / kg ° C);

t ks – desired water temperature (C); t şe – mains water temperature (C).

In addition, the amount of heat that must be supplied by the system in formula 1 [4]. It is found from formula 3 [4], that:

Qsol  Es .Fk

(3)

where Es – ıntensity of radiation to the unit area (kcal / m2.day);

Fk – total net collector area in the system (m2). When all these values are determined and substituted in Formula.1, instantaneous efficiency values are found for each period in both systems. The average daily efficiency values of these instantaneous efficiency values are:

o 

 a1   a 2  ...   as sp

(4)

where  as – instantaneous efficiency value for each period (%); s p – number of period of measurement (number).

However, because of the days and the periods in which the negative experiences such as the low radiation intensity and the natural circulation are not observed from the experiments made during MMSE Journal. Open Access www.mmse.xyz

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September, only the measurement values of 6 days between 3 September - 2015 and 10 September 2015 when the regular results were taken into account were taken into consideration. Average yield values of both systems for 6 days were found from formula 5 [4-5];

 ort 

 go1   go2  ...   gos sg

(5)

Table 1. Experiments results. Time

Experiment

Daily efficiency

Average value  go

Days

Dates

For 1st. System

For 2nd. System

1st. Day

03 / 09 / 2015

51,09

71,25

2nd. Day

04 / 09 / 2015

49,14

70,21

3rd. Day

06 / 09 /2015

48,25

68,96

4th. Day

08 / 09 / 2015

52,61

72,02

5th. Day

09 / 09 / 2015

53,42

74,02

6th. Day

10 / 09 / 2015

51,18

72,28

Average efficiency ηort

50,94

71,54

Summary. For both systems, the instantaneous efficiency values (  a ) of the 6 periods during the day are evaluated together with the operating parameters, and the daily average efficiency (  go ) values and average efficiency values (  ort ) of the 6 days in formula 4 [2] are calculated according to table 1. In addition, the curves of the efficiency values of the first system are shown in graph 1, the curves of the second system efficiency values are shown in graph 2 and the average efficiency values of both systems are shown in graph 3. EFFICIENCY VALUES FOR 1st SYSTEM 54

DAILY AVERAGE EFFICIENCY

53.42

DAILY AVERAGE EFFICIENCY

52.61

52 51

51.09 50.94

50.94

51.18 50.94

50 49.14

AVERAGE EFFICIENCY

48.25

48 47 46 45 1st.DAY

2nd.DAY

3rd.DAY DAYS

4th.DAY

5th.DAY

Graph 1. Systematic Efficiency Curves for 1st system. MMSE Journal. Open Access www.mmse.xyz

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6th.DAY

Mechanics, Materials Science & Engineering, December 2016 – ISSN 2412-5954 EFFICIENCY VALUES FOR 2nd SYTEM 75

DAILY AVERAGE EFFICIENCY

74.04

DAILY AVERAGE EFFICIENCY

73 72.52 72.28

72 71.54

71.54

71.25

70.21

AVERAGE EFFICIENY

68.96

68 67 66 1st.DAY

2nd.DAY

3rd.DAY DAYS

4th.DAY

5th.DAY

6th.DAY

Graph 2. Systematic Efficiency Curves for 2nd system.

AVERAGE EFFICIENCY VALUES FOR BOTH SYSTEMS 80

DAILY AVERAGA EFFICIENCY

71.54

FOR 1st.SYSTEM

60 50

50.94

40 FOR 2nd.SYSTEM

30 20 10 0 1st.DAY

2nd.DAY

3rd.DAY DAYS

4th.DAY

5th.DAY

6th.DAY

Graph 3. Mean Efficiency of Both System. From the values in table. 1, it can be seen from the curves in graph 1, graph 2 and graph 3 that the closed system with moving and follow-up system (following the sun with Photo- controlled Unit) and pumped circulation system, named as 2nd system, It is more efficient than a closed system with naturel circulation. We can say if it is so, "The system efficiency is high in the system because photo-control follows the continuous solar rays with photocell control in the quality system of the quality, the collector keeps the sunray perpendicular to 90° angle, and the circulation can be continuously circulated during the period.

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References [1] M.M.O, “Basis of sanitary installation project” Machine Engineers Association, Edition number 122, 1987, İst [2] Sukhatmane Sp, “Solar Energy Principles of Thermal Collection and Storage”, Mc Gramer Hill 1984, New Delhi. [3] Atagündüz G. “Principles of Solar Energy Application”, 1989, İzmir, Turkey [4] Öztürk A., Kiliç A., “Solar Energy Applications”, Kipaş Yayncılık, 1983, İstanbul,Turkey [5] Kreider J.F., Keith F., “Solar Energy Handbook”, Mc. Gaw Hill Book, 1981 [6] Nguyen The Bao (2016). Numerical Modelling of Basin Type Solar Stills. Mechanics, Materials Science & Engineering, Vol. 4. doi:10.13140/RG.2.1.4601.9449 [7] Howell Y., Becerny JA "Güneş Enerjisi ile Mühendis Kılavuzu", Güneş Energi Hizmetleri (1989) [8] F. Rinaldi, M. Binotti, A. Giostri, G. Manzolini. Comparison of Linear and Point Focus Collectors in Solar Power Plants, Proceedings of the SolarPACES 2013 International Conference, Volume 49, 2014, Pages 1491-1500, doi:10.1016/j.egypro.2014.03.158 Cite the paper Kenan Karacavuş (2016). Various Comparison of Additional Conditions of Different Designed Thermal Solar Technology Systems with the Same Collector Field. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.13.44.508

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I I I . M a c h i n e B u i l d i n g M M S E J o u r n a l V o l . 7

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Conceptual Model of “Lapwing” Amphibious Aircraft19 Iftikhar B. Abbasov1, V’iacheslav V. Orekhov1 1 – Southern Federal University, Nekrasovskyi lane, 44, Taganrog, Russia DOI 10.13140/RG.2.2.12856.14081

Keywords: conceptual model, amphibious aircraft, bionics, 3D model, method of polygonal extrude, shading and rendering.

ABSTRACT. The paper is dedicated to computational modelling of conceptually new amphibious aircraft. Based on the analysis of bionical forms of operational medium there provided are the visual and graphical solutions of the developed model. Sketch drawings considering the requirements of ergonomics are provided, sketch of amphibious aircraft 3D model is created. Based on sketch projects the stage-by-stage 3D modelling of amphibious aircraft structural parts was performed. Modelling has been provided by methods of polygonal extrude. Materials shading and rendering provided at sub-object level. There provided are the scenes of rendering of shaded 3D model of amphibious aircraft.

Introduction. Today hydroaviation is actively used in different fields, starting from fire-fighting and effective-rescue operations up to passenger traffic. The issues of applying modern technologies of modelling for aircraft designing are challenging. The most important stage is the development of preliminary concept of transportation means. Let us review some of the modern literary sources in this field. The article [15] is dedicated to conceptual designing of aircraft, where aerodynamic properties of bird wings are considered. The works [14], [18] study the issues of designing economical passenger aircraft. The article [7] is dedicated to conceptual designing of passenger aircraft of “flying wing” type. There provided and analysed are the different variants of aerodynamic configurations. The work [8] contains the peculiarities of conceptual designing of new generation of supersonic aircraft with original arrangement of landing gear and fuel tank. Article [9] describes the peculiarities of implementing modern program tools for the purposes of designing. There described are the possibilities of new program for aircraft structure development. The issues of conceptual designing initial stage are described in detail in book [13]. There provided is the methodological base of idea generation stages, determination of initial requirements for future structure. The book [23] contains the peculiarities of preliminary and conceptual designing of aircraft. Modern systems of automated designing are described in detail. This work is dedicated to three-dimensional computer-aided modelling of new concept of amphibious aircraft. It is supposed that the developed model will be in the middle segment of hydroaviation market. In the result of amphibious aircraft market review we can remark the following aircraft of low passenger capacity up to 25 persons: Be-103 produced by Beriev Aircraft Company [21], flying amphibious boat Airmaster Avalon-680 produced in the USA, amphibious aircraft Do-24 produced by German company Dornier Seastar [20]. For the developed model the crew will consist of 2 persons, the passenger compartment can contain up to 24 passengers.

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It is necessary to note, that the issues of computer-aided modelling of aircraft were studied by the authors in the works [3-4]. The work [3] provides conceptual visual and graphical solutions of new aircraft based on bionical forms analysis. Concept development. In every field of our life, everything in our environment is the product of human thought. The manufacturing of these subjects and objects starts from concept development, creation of prototype of future item [11], [12]. If earlier rather large expenses and materials were required for this purpose, then today in the era of computer-aided technologies this task is simplified, there is no limit for the designersâ&#x20AC;&#x2122; ideas and imagination. The process of conceptual development and modelling of transportation means takes several stages. At the first stage the sketch was created, the general view of future model is drawn: compositional solution; proportion of component parts relatively each other; main style solutions [17], [10]. Based on the analysis of natural shapes rendering the concept of future prototype is selected. In the course of concept development a method of designing based on bionical forms was used. Mammals, fish and birds can provide the designer with interesting visual solutions. At that aircraft fuselage, and mainly flying boat one, shall meet the requirements of aero- and hydrodynamics at the same time. That is why the designers have the task of searching for a compromise. In the course of creative search of aircraft outlines, some visual and graphical solutions were found, the base of which became natural biological forms living in this environment (Fig.1-4).

Fig. 1. Blue whale and sketch of amphibious aircraft fuselage.

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Fig. 2. Finback whale and sketch of amphibious aircraft fuselage.

Fig. 3. Mackerel and sketch of amphibious aircraft fuselage.

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Fig. 4. “Flying fish” in natural living conditions and sketch of amphibious aircraft fuselage. Based on the analysis of natural forms rendering of off-shore strips the bird lapwing (northern lapwing) has been selected. Northern lapwing (vanellus vanellus - in Latin) is a small bird of dotterel family, it lives in water ponds, has good flying properties, during mating season the males attract the females by air games (Fig.5) [22]. Black-and-white colour of its coat will be used for threedimensional model shading in future. Fig.6 provides preliminary design, sketches of the future item forms.

Fig. 5. Lapwing bird.

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Fig. 6. Preliminary sketch. Then the model is drawn in detail with reference to medium dimensions, in which the item is planned for operation, biometric parameters of a man considering the requirements of ergonomics (Fig.7, 8) [19], [2].

Fig. 7. Left board view of prototype.

Fig. 8. Prototype reference to anthropometric and ergonomic requirements. The base of future hydro-aircraft “Lapwing” concept is water-borne wing capable of glissading on three points (step, left and right rear edges of centre wing). Such scheme is very advantageous for stable movement on the water at taking-off and landing regimes and increase of seaworthiness. Low location of the wing relatively the boat creates increase of elevating force due to ground effect at taking-off and landing, allows simplifying and lightening the structure of aircraft (Fig.9). MMSE Journal. Open Access www.mmse.xyz

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Fig. 9. Front view and top view of amphibious aircraft prototype. The dimensions of prototype body shall consider the requirements of future interior and tasks on cargo containers arrangement. Wing span is 18.5 m, aircraft length is 16.9 m, and height is 4.87 m. Fuselage structure can be done from aluminium alloys with the application of composite materials. In the top part of fuselage there are power elements on the base of solar batteries for partial power supply to aircraft on board network. Aircraft wing has all-metal structure, it has trapezoidal shape with root extensions; it consists of centre wing and two removable panels. On the wing end there are winglets and tips that are designed for increasing effective wing span and lifting force. For the provision of resistance to flooding the wing is separated by water-proof partitions to sections. Vertical tail fins are single-fin, cantilever. In the top part of the fin there is controllable stabilizing fin. Landing gear is three-leg type, the diameter of rear leg tires is larger than the front one. Power unit consists of two turbojet engines located on the pylons close to fuselage tail part. For cargo-carrying variant, the increase of fuselage length by 1 m is provided with the help of insert. It aims to locate cargo door with dimension 1700Ń&#x2026;1700 mm along the right board. The crew consists of 2 persons (as for business class variant one steward is added). The passenger compartment can contain up to 26 passengers, in cargo-carrying variant 4 LD2 containers are provided.

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Fig.10 provides shaded sketch of three-dimensional model of amphibious aircraft. The aircraft is designed for use at short-distance lines in different regions of the world, in regions with large number of rivers, lakes, shallow water ponds that are hard-to-reach for other types of transport. It can be used for transportation of passengers, cargos, fire-fighting supervision, patrolling, ecological control of water areas, provision of emergency medical care, rendering emergency-rescue works, rest and tourism.

Fig. 10. Shaded sketch of three-dimensional model of amphibious aircraft. 3D modelling of amphibious aircraft “Lapwing” Modelling of amphibious aircraft structure shall be done with the help of graphic system of threedimensional modelling – 3ds Max. The graphic system 3ds Max allows working with drawings made in other graphic packages, thus extending the possibilities of the designer [1]. Three-dimensional model of amphibious aircraft can be created by different methods, one of which is the method of polygonal extrude. For this method, the modelling starts from creating three perpendicular planes with aircraft projections located on them. For fuselage modelling created using the polygon based on Plane primitive element with the number of segments at Х and Y axes equal to 1. Later this primitive element shall be transferred into Editable Poly object. According to fuselage projection the object surface is created by sequential duplication of one of polygon planes (Fig.11). At that body half is created for construction convenience with consideration of model longitudinal symmetry.

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Fig. 11. Sequential extrude of fuselage polygons. In the course of planes extruding it is necessary to maintain constant number of polygons along the whole fuselage in order to prevent problems with geometry and further modification of model. Then the aircraft body is created by method of sequential extrusion of group of polygons followed by projects adjustment (Fig.12).

Fig. 12. Model control in front view. The received result is the base for fuselage, the other structural parts of the aircraft are extruded by similar method: tail fins, wing, engine pylon, engine body, lifting propeller (Fig.13, 14, 15) [24], [16]. The wing has complicated profile, because it plays the lifting role for the aircraft in glissading mode and works as the screen increasing the lifting force in the moment of taking-off from water surface. At the next stage the model geometry is modified. Fuselage modification supposes modelling of transparency and side windows. The wing together with steering control and horizontal stabilizer is also designed in detail.

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Fig. 13. Fuselage body blank.

Fig. 14. Creation of tail fins.

Fig. 15. Engine body with carrying pylon. Initially all model component parts are faceted. The capabilities of 3ds Max graphic system allow smoothing faceted objects by different methods. One of the variants is the application of smoothing method NURMS (Non Uniform Rational Mesh Smooth). When surfaces are smoothed the second mirror-like longitudinal half of the aircraft is constructed (Fig.16).

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Fig. 16. Assembly of aircraft body half. Shading and rendering of 3D model of “Lapwing” amphibious aircraft The next step of designing is shading and rendering of constructed model. The process of materials rendering to fuselage separate parts is done at the level of polygons. After all performed operations we can obtain finished model for further rendering with the help of realistic models of lighting (Fig.17). Integrated V-Ray module is used for scene rendering. Fig.18 a, b, c, shows final rendering scene of shaded model of “Lapwing” amphibious aircraft.

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Fig. 17. Assembled three-dimensional model with rendered materials. As a result, we can note that the developed three-dimensional conceptual model of amphibious aircraft is performed from creative idea to photorealistic rendering.

Fig.18, a

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Fig.18, b

Fig.18, c. Rendering of “Lapwing” amphibious aircraft conceptual model. References [1] Abbasov I.B. Basics of three-dimensional modeling in the graphics system 3 ds Max 2009: Textbook. - Moscow: DMK Press, 2010. – 176p. [2] Abbasov I.B. Computational modeling in industrial design. - Moscow: DMK Press, 2013. –92p. [3] Abbasov I.B. Conceptual model of aircraft “Chiroptera” //American Journal of Mechanical Engineering. 2014, V.2, № 2, pp. 47-49. doi:10.12691/ajme-2-2-3 [4] Abbasov I.B., Orekhov V.V. Amphibious. Computational modeling. – Saarbrucken, Germany.: – LAP Lambert Academic Publishing, 2012. 69p. MMSE Journal. Open Access www.mmse.xyz

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[5] Abbasov I.B., Orekhov V.V. Computational modeling of multipurpose amphibious aircraft Be-200 //Advances in Engineering Software. 2014. V.69, №3, pp. 12-17, doi:10.1016/j.advengsoft.2013.12.008 [6] Bolsunovsky A.L., Sonin O.V., et all. Flying wing – problems and decision. Aircraft Design. 2001. V.4, №4. pp. 193-219. doi:10.1016/S1369-8869(01)00005-2 [7] Gavel H., Berry P., Axelsson A. Conceptual design of a new generation JAS 39 gripen aircraft. Collection of Technical Papers - 44th AIAA Aerospace Sciences Meeting. Reno. USA; 9 - 12 January 2006; Volume 1, 2006, Pages 395-406. [8] Haimes R., Drela M. On the construction of aircraft conceptual geometry for high-fidelity analysis and design. 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 2012, Article numberAIAA 2012-0683. USA; 9 - 12 January 2012 [9] Happian –Smith J. An Introduction to Modern Vehicle Design. Elsevier Limited, 2002, – 600p. [10] Howe D. Aircraft Conceptual Design Synthesis. – London: Professional Engineering Pub. Ltd, 2000. – 474p. [11] Jenkinson L.R., Marchman J.F. Aircraft design projects. – Oxford.: Butterworth-Heinemann. – 2003. 371p. [12] Kroll E., Condoor S.S., Jansson D.G. Innovative Conceptual Design: Theory and application of parameter analysis. Cambridge University Press. 2001. 227p. [13] Liebeck R. H. Design of the Blended Wing Body Subsonic Transport //Journal of Aircraft. Vol. 41, No. 1, 2004. pp. 97-104, doi: 10.2514/1.9084 [14] McMasters J.H. and Cummings R.M. Airplane Design - Past, Present and Future. Journal of Aircraft. 2002. V.39, №1, pp. 10-17, doi: 10.2514/2.2919 [15] Raymer D.P. Living in the Future; The Education and Adventures of an Advanced Aircraft Designer, Design Dimension Press, Los Angeles, 2009. 360p. [16] Runge V.F., Manusevich Y.P. Ergonomics in environmental design. - Moscow: Architecture-C, 2005. –328p. [17] Saeed T.I., Graham W.R., Hall C.A. Boundary-layer suction system design for laminar-flyingwing aircraft // Journal of Aircraft, 2011. 48 (4), pp. 1368-1379. doi:10.2514/1.C031283 [18] Vasin S.A., Talaschuk A.U., et al. Design and modeling of industrial products. - Moscow: Mashinostroenie, 2004. – 692p. [19] Website / Internet resource. - Mode of access www/URL: http://airwar.ru (date access 20.07.2016) [20] Website / Internet resource. - Mode of access www/URL: www.beriev.com, (date access 20.07.2016). [21] Website /Internet resource. Mode of access https://en.wikipedia.org/wiki/Northern_lapwing (date access 19.05.2016).

www/URL:

[22] Willem A. J. Anemaat. Conceptual Airplane Design Systems, Vehicle Design, Air Vehicle Design, Published Online: 2010. doi:10.1002/9780470686652.eae394 [23] Yeger S.M., Matvienko A.M., Shatalov I.A. Basics of aircraft: Textbook. - M: Mashinostroenie, 2003. 720p. Cite the paper Iftikhar B. Abbasov, V’iacheslav V. Orekhov (2016). Conceptual Model of “Lapwing” Amphibious Aircraft. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.12856.14081 MMSE Journal. Open Access www.mmse.xyz

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IX. Economics & Management M M S E J o u r n a l V o l . 7

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Cost Reduction of Taxi Enterprises at the Expense of Automobile Fleet Optimization20 Novytskyi А.V. 1, Melnikova Yu. I. 1 1 – Department of Transport Management, National Mining University, Dnipropetrovsk, Ukraine DOI 10.13140/RG.2.2.24945.89447

Keywords: taxi service, queuing system, probability of service denial, cost

ABSTRACT. Results of taxi service operation using techniques of queuing system theory have been demonstrated. It has been shown that probability of service denial is the key quality criterion of transport services for taxi services. It is expedient to use total expenditures of queuing system as target function to estimate the efficiency of taxi service. It has been determined that application of queuing theory techniques makes it possible to identify optimum value of the number of operating motor vehicles for specific environment. The value is optimum according to minimum-cost criterion.

Introduction. Cost saving to provide services under the conditions of competitive indicators of quality is one of the most important problems for any transport enterprise. The problem becomes topical in the context of excessive supply. On the one hand, customer acquisition involves improvement of quality indicators which results in extra costs; on the other hand, economic situation requires cost cutting. Taxi enterprises should operate under those conditions. Currently more than 200,000 motor vehicles of various ownership forms operate in the market (data by the Trade Union of taxi drivers of Ukraine). That is an obvious excess of supply. Except that the figure experiences constant expansion due to private car owners engaged in private cabbing to repay loans. In this context, increase in the number of taxi supply is followed by quality degradation. That depends chiefly on poor skills of staff of taxi enterprises resulting in protraction of waiting period and travel time, nonoptimal delivery routes, and high-cost transportation. Analysis of operation of taxi enterprises in Ukrainian cities shows that the majority of organizational decisions are made relying upon the experience of prior periods. Even if economic and mathematical substantiation is performed, it is based upon simplified techniques using averaged values of influencing parameters. The authors have analysed six enterprises in Dnipropetrovsk region. Four of the six enterprises keep records of the number of orders according to oral information by drivers. No enterprise accumulates and analyses information concerning the period of bringing the order to effect, the number of unexecuted orders etc. Moreover, in many cases the number of motor vehicles operating during a shift depends on the availability of serviceable motor vehicles. As a result, there is no necessary information to develop transportation scheme of transport services. The number of service denials is one of the most important qualitative indicators in the process of taxi service management. To attract clients, transport operators put up considerable capital. According to experts’ research, acquisition of a new client costs a company six times more than retention of available one. If however a client leaves unsatisfied, her/his return will cost twenty-five times more [1]. Practically the number of service denials or their possibility is controlled by the number of operating motor vehicles: the more motor vehicles operate during certain period, the higher is the probability to execute order and the less is probability of denial. In the context of favourable economic situation, cost escalation is covered with extra income from executed orders. However, in the context © 2016 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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of purchasing power erosion and increase in expenditures connected with maintenance of road transport vehicles such a solution not always results in expected outcomes. Currently techniques of queuing theory are often used to solve a problem concerning substantiation of transport service parameters. The techniques are more advantageous to compare with traditional modelling methods as they consider random nature of inflow of orders and time to service them [2]. This very fact transforms queuing theory into powerful tool to model various processes including a process of transport service. Use of queuing theory techniques makes it possible to determine probability parameters of inflows of orders, operating parameters, and qualitative indicators concerning service of orders by taxi enterprise. Objective. Identification of rules to change expenditures of taxi enterprise in the context of varying parameters of inflows of orders and services to substantiate optimum number of car park. Data for the analysis. Taxi service «Elit taxi» operating in the town of Novomoskovsk (Dnipropetrovsk region) and neighbouring districts has been analysed. The enterprise renders services within 24 hours operating by means of three 8-hour shifts. The accepted practice covers service denial if vacant motor vehicles are not available. Hence, it is possible to consider the enterprise as multichannel queuing system with denials. Automobile park consists of 27 units. According to data by finance department of the enterprise, specific expenditures connected with motor vehicle movement are 136 UAH/(motor vehicles∙hour), expenditures connected with unproductive time of motor vehicle are 41 136 UAH/(motor vehicles∙hour), and expenditures connected with service denials are 176 UAH/(motor vehicles∙hour). Average number of inflowing orders is taken to be equal to: shift 1 – 32.33 orders per hour, shift 2 – 20.11 orders per hour, shift 3 – 11.15 orders per hour. The enterprise normalizes average time to execute order as follows: shift 1 – 0.7 of hour (intensity of service flow is μ1б = 1.42 orders per hour), shift 2 – 0.47 of hour (μ2б = 2.12 orders per hour), and shift 3 – μ3б = 0.34 of hour (2.96 orders per hour). Stage one of the research involved accumulation of information and its analysis concerning the number of orders and average service time (Fig.1). Results of data processing according to technique [2] have helped determine that values of intensity of flow of orders taken at the enterprise are valid; values of service flow intensity differ greatly. Thus, for shift 1 actual average time to execute order is 0.64 of hour, for shift 2 it is 0.54 of hour, and for shift 3 it is 0.41 of hour. Thus, relying upon comparison of experimental values and critical values of Pearson criterion with α = 0.05 significance level it has been determined that the both flows are described by means of Poisson distribution law with following intensities: – For flow of orders: λ1ф = 32.33 orders per hour, λ2ф = 20.11 orders per hour, λ3ф = 11.15 orders per hour; – For service flow: μ1ф = 1.56 orders per hour, μ2ф = 1.85 orders per hour, μ3ф = 2.44 orders per hour. Comparison of information obtained at the enterprise with experimental data has shown that gaps are as follows: 9% for shift 1; 15% for shift 2; and 19% for shift 3 (Fig.1).

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0,70

0,64

Базовый вариант Basic scenario Design scenario

0,54

0,40

Проектный вариант

0,47

0,30

0,34

0,20

0,41

0,10 0,00

Shift 2 ІІ смена

Shift 1 І смена

Shift 3 ІІІ смена

Fig. 1. Results of data processing. It is evident, that use of averaged data introduces significant errors into determination of flow parameters preventing from adequate evaluation of queuing system. Stage two of the research involved determination of basic parameters of queuing system for basic scenario and design scenario to organize service of orders. Key indices of multichannel queuing systems with denials are [3]: – The number of service channels, i.e. total number of motor vehicles operating during a shift; – Probability of service denial, i.e. probability that order will not be completed and will leave queuing system. Besides substation of optimum number of motor vehicle operating during every shift using criterion of minimal total expenditures of queuing system is one of the research tasks. General costs of queuing system with denials are determined by formula [4]:

CСМО  Спр n св  Сдв n з  Сотк pотк  , where С пр – is specific cost connected with unproductive time of motor vehicle, UAH/(motor vehicles∙hour);

Сдв – is specific cost connected with motor vehicle movement, UAH/(motor vehicles∙hour);

Сотк – is specific cost connected with service denial, UAH/(motor vehicles∙hour); n св , n з – is average number of vacant and motor vehicles under service respectively;

pотк – is probability of service denial. Thus, target function is expressed as

С

пр n св



 Сдв n з  Сотк pотк   min .

Basic scenario used data obtained at the enterprise under study. On the ground of cost saving every shift involves minimum quantity of operating motor vehicles to achieve predetermined load intensity. According to information by the enterprise, shift 1 involves 23 motor vehicles; shift 2 involves 10 motor MMSE Journal. Open Access www.mmse.xyz

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vehicles, and shift 3 involves 4 motor vehicles. Table 1 demonstrates calculation results of key indices of queuing system operation. Table 1. Calculation results concerning queuing system operation (basic scenario). Index The number of operating motor vehicles, units Probability of service denial “Currency lost /income” Expenditures, connected with motor vehicle movement, UAH per hour Expenditures, connected with unproductive time of motor vehicle, UAH per hour Expenditures, connected with service denial, UAH per hour Queuing system expenditures, UAH per hour

Shift 1 23 0.143 0.167

Shift 2 10 0.235 0.307

Shift 3 4 0.212 0.269

2745

986

402

145

113

902 3792

832 1931

414 859

Analysis of the results demonstrates poor efficiency of queuing system operation in terms of basic scenario of transport service management. During every shift the enterprise uses minimum possible number of motor vehicles being geared to load intensity and trying to cut expenditures connected with movement of motor vehicles. That very time, possibility of service denial is 23.5%, and “currency lost /income” index is 0.307 to be invalid under the conditions of competitive market. Following calculations were performed with the help of identical technique. However, the calculations were required to determine optimum number of operating motor vehicles providing a condition for minimum aggregate expenditure. To do that, basic parameters of multichannel queuing system were calculated. The calculations involved denials in the context of various numbers of operating motor vehicles. Taking into account the fact that actual values of order service flow intensity differ greatly from those taken before, in terms of design scenario, load intensity of the system will be as follows:  фI  20.69 orders per hour for shift 1;  фII  10.86 orders per hour for shift 2; and  фIII  4.55 orders per hour for shift 3. Table 2 demonstrates an example of calculation results. Table 2. Calculation results of queuing system operation indices (design scenario, shift 2). Index Probability of service denial Average number of busy channels Expenditures, connected with movement, UAH per hour Expenditures, connected with unproductive time, UAH per hour Expenditures, connected with denial, UAH per hour Total expenditures of queuing system, UAH per hour

The number of motor vehicles 11 12 13 14 15 16 17 0.2002 0.1534 0.1136 0.0810 0.0554 0.0362 0.023 8.69 9.20 9.63 9.98 10.26 10.47 10.62 1181

1251

1309

1357

1395

1424

1444

115

138

165

194

227

262

709

543

402

287

196

128

1985

1908

1850

1809

1786

1779

1786

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As analysis of the results has shown in terms of increase of the number of operating motor vehicles, possibility of service denials decrease according to exponential law; average number of motor vehicles engaged in order servicing also increases nonlinearly resulting in proportional growth of expenses connected with movement of motor vehicles and their unproductive time. Dependence graph Ссмо (n) has its minimum when n = 16 (Ссмо = 1779 UAH per hour). It has been determined analogously that in the context of concerned conditions, optimum number of motor vehicles operating during shift 3 is 9 automobiles and for shift 1 the number is 27 automobiles. That is, minimum expenses will involve increase in 4 motor vehicles (shift 1) and 5 motor vehicles (shifts 2 and 3) (Table 3). Table 3. Comparison of efficiency indices of queuing system for basic scenario and design one.

Intensity of influent flow of orders Average service time Intensity of order servicing Intensity of queuing system load The number of motor vehicles Probability of service denial Expenditures, connected with movement Expenditures, connected with unproductive time Expenditures, connected with probability of service denial Total expenditures of queuing system, UAH per hour Changes in queuing system expenditures, UAH per hour

Design scenario

Shift 3

Basic scenario

Design scenario

Shift 2

Basic scenario

Index

Design scenario

Basic scenario

Shift 1

32.33 32.33 20.11 20.11 11.10 11.10 0.70 0.64 0.47 0.54 0.34 0.41 1.42 1.56 2.12 1.85 2.96 2.44 22.72 20.69 9.48 10.86 3.75 4.55 23 27 10 16 4 9 0.143 0.034 0.235 0.036 0.212 0.025 2745 2817 986 1424 402 603 145

288

113

227

187

902

216

832

128

414

3793

3321

1931

1779

859

840

-472

-152

-19

Increase in the number of operating motor vehicles is favourable for service quality as probability in service denial decreases (Fig. 2) to be particularly relevant for taxi enterprises. Meanwhile it should be noted that in terms of the number of motor vehicles increase, deviation of shiftable value of denial probability from daily average one is 14.3 %, while it is 21.2% for basic scenario. Minor spread of denial probability makes it possible to control quality of passenger service.

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Possibility of service denial

Вероятность отказа в обслуживании

0,250

0,200

0,150 0,235 0,212

0,100 0,143 0,050 0,036

0,034

0,025

0,000 23

Количество автомобилей Amount of motor vehicles

Fig. 2. Probability of service denial in the context of different number of operating motor vehicles. Analysis of changes in queuing system has shown that increase in the number of operating motor vehicles results in escalation of costs connected with movement (up to 50%) and unproductive time (up to 100%). That very time expenses connected with service denial decrease proportionally to increase in service denial probability (by 80%); as a result it compensates cost escalation for movement and unproductive time. It should also be noted that shift 1 demonstrates the greatest reduction of general costs when demand is the most intensive (Fig. 3).

4000

Затраты, грн/час

Expenditures, UAH per hour

3500 3000 2500 2000 1500 1000 500 0 23

Количество автомобилей Motor vehicles amount

Motor vehicles operational costs автомобиля Затраты, связанные с движением Expenditures for unproductive Затраты, связанные с отказом вtime обслуживании

Expenditures connected with service denial Затраты, связанные с простоем автомобиля

Fig. 3. Changes in queuing system expenses. Summary. Results of order servicing modelling process by taxi enterprise with the help of queuing system have helped determine the following: 1) To provide high-level passenger service and effective use of motor vehicles it is required to perform constant (automated if possible) on-line collecting and processing of parameters of inflow of orders and service. Along with collecting and analysing information concerning the number of transportation

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orders, constant control over the order execution time is required. Otherwise, considerable deviations of the obtained parameters from optimum values are possible; 2) Substantiated choice of rational parameters of technological scheme of taxi transportation involves queuing system theory as it fives ability to consider random nature of inflowing orders and service time; 3) Reduction of total expenses of taxi enterprise is possible owing to attraction of extra motor vehicles to serve orders. It allows reducing costs connected with transportation denials at the expense of increase in service possibility; 4) Effect resulting from the use of queuing system theory is the most evident in terms of sharp shiftable variations in inflow order intensity and service as well as in terms of loads on a system close to maximum ones. References [1] Kleinrock L. (1979). Queueing theory: translation from English [Teoriia massovogo obsluzhivaniia]. Moscow, “Mashinostroeniie”, 432 pp. [2] Wentzel E. S. (1991). Theory of random processes and its engineering applications [Teoriia sluchaynykh protsessov i eio inzhenernyie prilozheniia]. Moscow, “Vysshaia shkola”. 384 pp. [3] Koroliuk V. (1985). Reference book on the theory of probability and mathematical statistics [Spravochnik po teorii veroiatnostei i matematicheskoi statistike]. Moscow, “Nauka”. 640 pp. [4] Khinchin A. Mathematical methods of queuing theory [Matematicheskie metody teorii massovogo obsluzhivaniia]. Moscow, “Nauka”. 248 pp. [5] Ruibin Bai, Jiawei Li, Jason A. D. Atkin, Graham Kendall. A novel approach to independent taxi scheduling problem based on stable matching, Journal of the Operational Research Society, (2014) 65: 1501. doi:10.1057/jors.2013.96 Cite the paper Novytskyi А.V., Melnikova Yu. I. (2016). Cost Reduction of Taxi Enterprises at the Expense of Automobile Fleet Optimization. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.24945.89447

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Factor Analysis of Passenger Cars Using as a Taxi21 Deriugin O.V.1, Novikova О.О.1, Cheberyachko S.І1 1 –National Mining University, Dnipropetrovsk, Ukraine DOI 10.13140/RG.2.2.31977.90721

Keywords: taxi, tariff, velocity, comfort, transportation safety

ABSTRACT. A procedure to select passenger cars has been proposed. The procedure helps substantiate choice of effective transportation means in accordance with taxi class to meet consumption requirements of those taking part in transportation process from the viewpoint of comfort, safety, and minimum expenditures in the context of such transportation type.

Introduction. Taxi transportations are the integral segment of urban passenger transportations. Over the recent years, the segment has demonstrated increase in demand. The fact promotes to rash emergence of a number of motor transport enterprises with various property categories in the market of transport services. Total satisfaction of consumer demands providing the fastest arrival during short period of time in terms of adequate comfort and safety as well as reasonable tariff is topical task for such transportations. Statement of the analysis task. In the total volume of urban passenger transportation, a share of taxi services is up to 10% of the whole traffic flow [1]. According to data by All-Ukrainian Association of Transportation Organizations (AATO), 130-140 thousand drivers provide regular taxi services in Ukraine. Roughly speaking, it is almost every 50 th car owner [2]. Annual returns of taxi driver are almost UAH 120,000 in Kyiv, almost UAH 80,000 in multi-million-strong cities, and almost UAH 56,000 in regional centers. Altogether, annual returns of Ukrainian taxi market are UAH 1.5 - 2 bln [3]. Analysis of research sources has shown that following problems are burning ones for taxi services: inadequate legal acts specifying demands concerning taxi services; inadequate legal acts specifying use of corresponding type of motor vehicles to provide taxi services; inadequate legal acts specifying demands concerning driver proficiency [3, 4]. The above helps conclude that regulation of corresponding norms aimed at improvement of quality indices concerning transportation management, motor vehicles, and proficiency of drivers engaged in the type of passenger transportations are quite important. Objective of the analysis and its task. The performed analytical studies pursued an objective to determine a procedure of making managerial decision concerning choice of motor vehicle, which will meet the requirements of consumers. Following problems should be solved for pursuing the objective: - Determination of the most important indices of passenger cars taking into consideration their priority to improve quality as well as comfort and safety of taxi services;

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- Determination of passenger car for taxi services having the best indices in terms of consumer demands of those taking part in transportation process. Results of the research. Determination of effective passenger car to be used as a taxi should involve the analysis of a number of factors. Moreover, solution of the problem should take into consideration basic requirements of the main participants of transportation process, namely a driver and a passenger. Marketing research was carried out with the help of questionnaire. In the context of passengers it covered various population segments with different income levels, social statuses, and ages. In the context of drivers it covered their places of employment including relevant taxi type driving. Current laws do not govern standards concerning certain passenger car and its use as a taxi. Thus, the process is supposed in terms of available types of passenger cars. For example, following passenger cars of “C” class (where minimum perimeter is 11002mm) can be considered as taxis: Renault Logan, Daewoo Lanos, Citroen Berlingo, Chevrolet Aveo, Geely CK, Kia Ceed, Volkswagen Polo, and VAZ 2111. In terms of “Business class” following passenger cars of “D” class (where minimum perimeter is 12006mm) can be considered as taxis: Chevrolet Lacceti, Hyundai Elantra, Toyota Corolla, Peugeot 308, Skoda Octavia, and Renault Fluence. “Elite class” of taxis involves following passenger cars of “E”class where minimum perimeter is 12664mm: Volkswagen Passat, Toyota Camry, Nissan Teana, Mazda 6, Skoda Super B, and Ford Mondeo. Diversity of the listed taxi classes has a number of negative factors. Deficiency of unified standards to provide adequate comfort and safety of passenger; various transportation tariffs; availability of illegalized drivers in the market of transportation services are among them. The market research carried out by the Department staff has helped determine following advantages of consumer demands: economic (tariff), operating (velocity), ergonomic (comfort), and safe (safety). Modern passenger car is characterized by a variety of quality indices. Thus, it is expedient to unite them into above groups determined by consumers (Fig. 1). That makes it possible to select the most efficient passenger cars for corresponding operational environment or to create appropriate comfortable and safe conditions for those taking part in transportation process as well as to replace road transport vehicles of enterprise effecting such type of transportation. The determined indices for every car class helped calculations of weighing coefficient. For this purpose, a matrix to compare groups according to corresponding quality indices has been developed depending upon consumer demands of those taking part in transportation process (Table 1). The data adequacy was evaluated relying on consistency of results of different experts. To do that, consistency index was determined [5]. Calculations of weighting coefficient according to the indices have shown that the consistency index is 0.05; it is less than critical value 0.1.

Fig. 1. Indices of advantages of effective passenger car selection for taxi services.

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Profile method is the optimum approach to solve the problem. Its principle is to unite set of indices without weighing into integral quality index. Ease of use and possibility to integrate a great variety of indices are advantages of the method. Then, different characteristics of passenger car can be grouped on the assumption that they are equivalent in one group. Analysis of group properties should be performed using weighing approach. That will help structure them basing upon effect on components of requirements of those taking part in taxi services. The algorithm is described appropriately in [5]. The method was applied to assess quality of fifteen models of passenger cars to determine the most effective taxi for certain class. Table 1. Matrix of pairwise advantages of group of quality indices for taxis. Criteria

Tariff

Tariff Velocity Safety Comfort

1 1/2 1/4 1/4

Velocity Comfort Tariff Safety

3/3 2/3 1 3/5

Comfort Velocity Safety Tariff

1 3/2 5/3 3/5

Velocity

Safety

Comfort

Component assessment

Weighing coefficient

4/1 3/1 1/1 1

0.06 0.03 0.05 0.05

0.5 0.3 0.1 0.1

3/2 1 3/2 1/1

0.08 0.06 0.08 0.05

0.3 0.2 0.3 0.2

3/3 1/2 1 3/5

0.84 0.28 0.41 0.13

0.4 0.2 0.3 0.1

“Economy-class” 2/1 4/1 1 3/1 1/3 1 1/3 1/1 “Business-class” 1 3/2 2/3 1/1 3/3 5/3 2/3 1 “Elite-class” 3/5 5/1 1 5/3 2/1 1 2/3 1/5

Calculations were performed basing upon the data from the sites of companies dealing with certain car makers. The calculations were carried out with the help of Microsoft Office – MS Excel 2010 software. The software was also used to calculate complex quality index according to the assumed four groups of properties determining the efficiency of passenger car use during transportation. Tables 2-4 demonstrate calculation results for integral quality coefficient in terms of the selected cars. Table 2. Summary table of the determined advantages of “Economy-class” taxis. Priority Index

Weighing Coefficient

Tariff 0.5 Velocity 0.3 Safety 0.1 Comfort 0.1 Integral index Rating position

Renault Logan (1.6 i) 0.057 0.211 0.068 0.073 0.800 1

Daewoo Lanos (1.5 i) 0.033 0.215 0.061 0.072 0.798 2

Geely CK (1.5 i) 0.053 0.215 0.068 0.070 0.785 4

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Chevrolet Aveo (1.6 i) 0.049 0.219 0.046 0.067 0.786 3

VAZ 2111 (1.6 I) 0.042 0.205 0.047 0.065 0.774 5

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Table 3. Summary table of the determined advantages of “Business-class” taxis. Priority Index

Weighing Coefficient

Velocity 0.3 Comfort 0.2 Tariff 0.3 Safety 0.2 Integral index Rating position

Skoda Oktavia (1.8 i) 0.221 0.165 0.044 0.193 0.888 1

Renault Fluence (1.6 i) 0.195 0.153 0.030 0.193 0.870 3

Hyundai Elantra (1.8 i) 0.205 0.136 0.038 0.108 0.835 4

Chevrolet Lacceti (1.8 i) 0.202 0.153 0.005 0.122 0.833 5

Toyota Corolla (1.8 i) 0.178 0.169 0.032 0.193 0.870 2

Analysis of the calculations shows that in terms of “Economy class” and according to integral quality index value, passenger car Renault Logan (1.6 i) ranks first. Passenger car Daewoo Lanos (1.5 i) ranks second, and Chevrolet Aveo (1.6 i) ranks third. In terms of passenger “Business-class” taxis, Skoda Oktavia (1.8 i) is the best one while Toyota Corolla (1.8 i) and Renault Fluence (1.6 i) rank second and third respectively. In terms of “Elite class”, passenger car Toyota Camry (2.4 i) ranks first as it is characterized by maximum level of comfort, safety, and velocity features as well as minimum economic indices of operating expenses in comparison with the listed passenger cars. Table 4. Summary table of the determined advantages of “Elite-class” taxis Priority index Comfort Velocity Safety Tariff

Weighing coefficient

0.4 0.3 0.2 0.1 Integral coefficient Ranking position

Toyota Camry (2.4 i) 0.342 0.215 0.193 0.006 0.932 1

Nissan Teana (2.5 i) 0.333 0.214 0.193 0.007 0.930 3

Mazda 6 (2.5 i) 0.316 0.219 0.193 0.014 0.928 4

Skoda Super b (2.0 i) 0.328 0.208 0.193 0.017 0.930 2

Ford Mondeo (2.5 i) 0.285 0.201 0.121 0.005 0.884 5

Thus, the selection has helped determine the belonging of passenger cars to certain classes, which relatively correspond to consumer demands of transportation process. It should be noted that the determined integral quality indices of passenger cars differ slightly. The objective of the research is to demonstrate advantages of one passenger car over another one irrespective of the differences in their components. Such problem solving makes it possible to substantiate selection of effective passenger car according to criteria of consumer demands of those taking part in transportation process. Summary. The proposed indices of consumer properties of passenger cars help substantiate choice of effective passenger car belonging to certain taxi class to meet consumer demands of those taking part in transportation process and to improve quality of transport services, comfort, and safety. The above also involves minimum expenses in the process of the type transportation. References [1] Fatkhutdinov R.A. (2000), “Konkurentosposobnost’: ekonomika, strategiya, upravlenie” [Competitiveness: business, strategy, management.]. Fatkhutdinov, R.A. // М.:INFRA-М, 2000. – 312 pp.

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[2] Petukhov D.V. (2013) “Pidsumki diyalnosti Departamentu avtomobil’nogo transportu Ministerstva infrastruktury Ukrainy” [Outcomes of activities by the Department of Road Transport of the Ministry of Infrastructure of Ukraine [Text]]. Petukhov, D.V. // “Pereviznyk UA”, ## 1-2. – pp. 4-6. [3] Geiets V.M. (2006) “Innovatsiyni perspectyvy Ukrainy” [Innovative challenges of Ukraine [Text]: Monograph]. Geiets, V.M., Seminozhenko, V.P. // Kh. :“Konstanta”, 2006. – 272 pp. [4] Shyriaeva C. V. (2012) “Zarubizhnyy dosvid podatkovogo stimulyuvannya dla zabezpechennya tekhnologichnogo onovlennya pidpryemstv pasazhyrs’kogo avtomobil’nogo transportu” [World practice of tax stimulation to provide technologic renovation of motor transport enterprises engaged in public conveyance [Text]]. Shyriaeva, C. V., Tolchanova, Z. О, Valiullina, Z.V. // Project management, system analysis, and logistics: academic periodical. – К.: NTU. – 2012. – Publication 10. – pp. 302-307. [5] Deryugin О.V. (2015) “Obgruntuvannya vyboru vantazhnogo avtomobilya za kriteriyem minimizatcyy psykhofiziologichnogo navantazhennya na vodiya” [Substantiation of load-carrying vehicle selection in the context of criterion of minimization of psychophysiological stress of a driver]. Deryugin, О.V., Cheberyachko, S.І. // Eastern European journal of advanced technologies. – 2015. – #3/3 (75). – pp. 15 – 22. [6] Novytskyi А.V., Melnikova Yu. I. (2016) Cost Reduction of Taxi Enterprises at the Expense of Automobile Fleet Optimization, Mechanics, Materials Science & Engineering Journal, Vol. 7, Magnolithe GmbH, DOI 10.13140/RG.2.2.24945.89447 Cite the paper Deriugin O.V., Novikova О.О., Cheberyachko S.І. (2016). Factor Analysis of Passenger Cars Using as a Taxi. Mechanics, Materials Science & Engineering, Vol 7. doi:10.13140/RG.2.2.31977.90721

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Mathematical Models Concerning Location of Vehicular Gas-Filling Stations within Cities 22 Kuznetsov A.P.1,a 1 – Department of Transport Management, National Mining University, Dnipro, Ukraine a – taran_70@mail.ru DOI 10.2412/mmse.52.18.599

Keywords: optimality criterion, location, NGV-RCS, distribution of vehicle flows, modelling, vehicle flow.

ABSTRACT. The optimal criterion concerning NGV-RCSs locations in the cities and the mathematical model of vehicle flow distribution on the road network of cities were analysed. It has been determined that optimization of NGV-RCS locations is a multi-criterion problem having no definite solution. The criterion for solving the problem can be the number of vehicle flows within street and road network which requires solving the problem of forecast;, in turn, the forecasting problem consists of two subproblems – formation of vehicle flows and optimization of vehicle flow distribution within street and road network. The problems are of NP type; moreover, there are no algorithms making it possible to obtain accurate solutions.

Introduction. All known concepts of transport and road system of the world cities involve the improvement of ecological and sanitary and epidemiological conditions at the expense of solving both ecological and energy problems. Implementations of the measures are complicated due to scientific difficulties connected with uncertainty of effect by components of transport systems; among other things that concerns the effect of location of NGV-filling compressor stations (NGV-RCSs) on the efficiency of transport systems and extraordinary labour intensity in the process of the parameters determination in the context of available street and road networks. Thus, solving the problem of the improvement of efficiency of transport systems of cities at the expense of decrease in environmental pollution and reduction in the above fuel consumption reduction in terms of commercial success of projects concerning modernization of transport systems of cities is important practical task. The problem can be solved providing that important problem connected with formation of automobile transport infrastructure in cities is solved. Statement of the problem. Both theory and practice of automobile transport infrastructure formation in cities pays much attention to determination of rational quantity and location of car services, gasoline stations, and NGV-filling compressor stations (NGV-RCSs). In this context, opinions of researchers as for parameters concerning estimation of alternatives and ways to solve the problem vary. The problem concerning optimization of development decisions and transport infrastructure location within territory of a city was analysed intensely both in Ukraine and abroad. In the context of automobile transport, the following may be listed as principal directions in the field: the development of street and road network and components of transport infrastructure (all types of filling stations, car services, garages etc.).

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Analysis of the research and publications. Studies belonging to the latter tendency may be divided into two large groups. One part of them concerns the optimization of the capacity of components of transport infrastructure; another one concerns their optimum location. Both tendencies involve all the aspects of transport infrastructure organization. However, their main disadvantage is the fact that while focusing on current situation and state of transport system they do not involve prospects of its development and possibilities of the problem comprehensive solution. Thus, papers [1, 2] propose mathematical models and approaches based upon queuing theory for one car service or gasoline station. In this context, such optimization is aimed at minimization of cumulative expenditures resulting from idle time of equipment and idle time of transport in terms of isolated component of transport infrastructure. Such an approach cannot be applied to optimize transport system on the whole. Solution of the problems of optimum location of transport infrastructure components proposes models based upon the assumption concerning uniform distribution of transport means over region territory [3, 4, 5]. Despite the fact that the models take into consideration rather wide range of factors, the assumption diminishes greatly the accuracy of forecast models as it does not correspond to real conditions. The fact is taken into account by many researches [6, 7, 8]. In [3, 10, 11, 9, 12] papers, authors, recognizing the necessity to consider both temporary and spatial irregularity of transport flows, propose various forecast models to distribute transport flows within street and road network – entropy models [3, 9] and kinematic ones [10, 11, 12]. However, the models describe a process of traffic without taking into consideration the traffic process goal, i.e. without taking into account the requirements or tasks of a driver. That is why the proposed models are characterized by large errors; as a result, they could not find their practical use. Solving the problem. The paper considers substantiation of optimality criterion to locate NGV-RCSs in cities and mathematical model to distribute traffic flows within street and road network of cities. Selection of location areas for NGV-RCSs involves time consuming multicriteria problem to optimize their location. Solution of the problem should involve: first, provision of maximum attractiveness of NGV-RCSs for potential clients; second, provision of minimum additional environmental load on a city resulting from distance to gas stations; third, minimization of negative effect of NGV-RCSs availability on urban matrix; fourth, provision of maximum efficiency of the NGV-RCS performance. The two former requirements come into conflict with the two latter ones as they need as many NGVRCSs as possible to be located within the city area while the third requirement is to minimize their quantity, and the last one needs partial decision making. In this context, it is required to take into consideration criteria factors of NGV-RCSs location relative to available objects of municipal infrastructure – garages, industrial enterprises, traffic centers, points where passenger traffic flows are formed and those where they are merged, car services, and gas stations. In the context of the problem all factors as well as criteria ratios may be united into the four large groups: ecological, environmental, technical, and technological. Efficiency criterion to develop a project for NGV-RCSs construction as well as value of one or another location area for NGV-RCSs is specific efficiency for marketing of 1 cubic meter of methane being calculated as follows

Е

С  Sм  Н , Sм

where С – is prime cost of 1 cubic meter of methane, UAH/cubic meter; Sм – is production cost of 1 cubic meter of methane, UAH/cubic meter;

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(1)

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Н – is tax amount (value added tax, profit tax, land tax) in terms of 1 cubic meter of methane, UAH/cubic meter; Production cost for filling with 1 cubic meter of methane is calculated by the formula S м  Sеn  Sеkspl  З  А  Sв

(2)

where Sеn – are expenses connected with electric power consumption, UAH/cubic meter; Sеkspl –are expenses connected with day-to-day operation of equipment, UAH/cubic meter; З – are wages of operating personnel, UAH/cubic meter; А – is amortization of fixed assets, UAH/cubic meter; Sв – is input NGV-RCS price, UAH/cubic meter. Determination of specific values of components of production cost and assessment of the designs are possible when suppliers of the equipment for NGV-RCS are regulated. As for the question two (that is mathematical model to distribute automobile traffic flows within street and road network being analyzed in the paper) the description of the problem concerning distribution of automobile traffic flows in the context of cities is as follows. There is unoriented G(N, P) network with a set of N, n = |N| nodes and a set of P, p = |P| arcs where integer matrix A = ||aij|| n×n of single traffic flows is specified. Flows aij are subject to single transfer from i sources into j, (i,j = 1…n) in certain transportation blocks of internodal connections. The connections addressed to various acceptors should be transferred within the network in general transportation blocks on a periodic predetermined base. Following values are known: block capacity w >> aij set with the help of the number of flow units being housed in it and timeframe of the flows departure. It is required to minimize a functional

F



i , jS

i 1

fij (uij , dij )   fi ( xi , qi )  i (ui )

(3)

Under following limitations: tij  Tij , for all i,j  S;

(4)

xi  hi , i = 1…n,

(5)

Where n

xi   ( xij  x ji )

(6)

j 1

n  1, qi    ij ; i  1..n;  ij   j 1 0,

if uij  0; if uij  0;

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(7)

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ui   (uij  u ji );

i  1...n,

(8)

j 1

S – is a set of ordered pairs of flow indices determined on Cartesian product nxn;

 xij  uij    – is a flow of transportation blocks from i to j (first all xij are equal to aij); w dij – is distance between nodes i and j; fij, fi, φi – are certain linear as well as non-convex expenditure functions to transfer flows and process them processing in general case; tij, Tij – are estimated time and predetermined time to transfer single flows from i to j; hi – is capacity of ith node. The formulated problem belongs to a class of combinatorial optimization problems being NPcomplete. Thus, to solve it approximation method based upon a scheme of sequential analysis of variants and a series of heuristic algorithms are used. Development of the heuristic algorithms is substantiated by the fact that it is rather difficult to determine fij, fi, φi functions for real communication networks though the functions characterize expenditures connected with flow processing and transferring adequately. However, the problem definition dismisses a possibility for a driver to select traffic route freely, which deforms real traffic operations within street and road network. Thus, the problem should be completed in terms of distribution of traffic flows within real street and road network. A process of the problem solving assumes that any diver selecting traffic route acts in such a way to provide maximum traffic efficiency under the current conditions. That is why it is required to solve a problem concerning optimum distribution of automobile traffics within street and road network being as follows. It is necessary to minimize the functional l

F   f k ((

x ), d   

k 1

, qk i , jS

ij , k

)    (  ( yij,k  yij,k )),  1

(9)

 1 k 1 i . jS

under the limitations

aij ,   0,  a ,  ij

y  y     1 k 1

ij , k

1 k 1

ji , k

if i   ; if i   , j   ;

(10)

if j   ;

  1..n, i, j  S , n

( y  y  )   a   a   2b ;   1...n ,    1 k 1 i , jS

ij , k

j 1

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(11)

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 x

i , jS

ij , k

 W k for all  ,   qk , k  1...l ,

(12)

o k (  ( yij,k  y  ji , k ))  t  t ,   k , k  1...l ,

(13)

 1 i , jS

tij  Tij , i, j  S ,

(14)

yij,k 

(15)



, xij , k

 .

Nomenclature for expressions (9)  (15): {mk}, k = 1..l –is a set of routs of vehicles or communication channels; each of them consists of sequence of nodes and topological arcs of GМ network uniting starting node and final node of route or communication channel; GM(N, PM) – is a route network where N is a set of the network nodes, PM is a set of its oriented route arcs (route arc is available between any i and j nodes of GM network if at least one route of vehicle connects them with {mk}); A = ||aij|| n×n – is a matrix of flows of transportation communications; B = ||bi||, i = 1..n – is a vector of capacities of nodes as for transit flows processing;

yij, k – is a flow in p  P arc obtained from mk route ( yij,k determine arc flows within route network GM);

xij, k – is a flow in topological arc p  P within mk route; qk – is ordered set of arcs consisting of P making mk route; νk – is ordered set of nodes consisting of N within mk route;

 : yij,k  xij,k  , p  PM , p  P, i, j  S , k  1...l , where  – is certain operator reflecting a flow in route arc per corresponding subset of topological arcs; fk – is piecewise and convex function determining dependence of expenditures on the number of transportation blocks transferred along mk route and the route distance dk;

  –is nonlinear function of expenses connected with processing of transportation blocks within β node; Wk – is the capacity of mk route; to – is the time required to transfer one block of;

tk – is limitation of vehicle waiting period within mk route α node; tij, Tij – is calculated and predetermined time to transfer blocks of vehicles from і to j. MMSE Journal. Open Access www.mmse.xyz

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Conditions (10) provide flow continuity and (11) – (14) are node capacity limitations, route traffic capacities, time for recommutation of transit blocks of vehicles within all the nodes of each route. The formulated problem belongs to the class of discrete multiflow problems with nonlinear and nonconvex functional. The problems of the type are NP-complete and to solve it accurate polynomially limited in terms of labour intensity algorithms are unknown. In this connection the paper proposes following heuristic algorithm. In the context of the model of street and road network (Fig.1) expert method is applied to determine main (flow-forming and flow-merging) nodes subjecting to obligatory analysis (they are represented as forms with solid contour line). They are sure to include peripheral crossroads along main roads where city ingresses/egresses are located. For the determination total number of such nodes is assumed as one node per 40-50 thousand residents. Within the points, visual technique is applied during rush hours to determine intensity of traffic flow, its components, and traffic directions. After observation data processing total traffic flows entering each node are capacities of nodes in terms of arrival and total traffic flows leaving each node are capacities of nodes in terms of departure. To predict the values of traffic flows within the areas of street and road network being out of observation, gravitational model is used. The model is based upon following hypothesis [13] bij  k  HOi  HPj  f (Cij ) ,

(1)

where bij – are ideal communications between districts; HOi – is the number of vehicles leaving the i district; HPj – is the number of vehicles arriving to j district; f(Cij) – is a certain function of total expenditures by passengers to move from district i to district j; k – is a certain constant. Ratio (16) should be carried out together with following limitations n

b j 1

b i 1

 HOi ,

(17)

 HPj

(18)

where п – is the number of districts. Standard gravitational model can be expressed mathematically as follows [13]

hij 

HOi  HPj  k j  d ij n

 ( HP  k j 1

 d ij )

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(19)

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where hij – are communications between areas i and j districts; HOi – is the capacity of i area in terms of departure; HPj – is the capacity of j area in terms of arrival; kj – is the coefficient leveling attraction of travels into j district; dij – is the attraction function between i and j districts; п – is the number of districts; i – is the number of district where travels originate.

4 23

11 22

16 10

14 17

20 25

19 8 7

9 9

– the node of street and road network within which traffic flows are inspected;

24  the node of street and road network within which there is no traffic flow inspection Fig.1. Physical model of street and road network. Iteration technique is used to calculate correspondence matrix. After each iteration, leveling attraction coefficient is calculated by the formula

k jk 

HPjk n

h j 1

(20)

To calculate interchange travels between the areas, each iteration equation of gravitational model with the use of levelled attraction coefficients obtained at the stage of previous iteration. Thus, the model equation becomes as follows MMSE Journal. Open Access www.mmse.xyz

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hijk 

HOi  HPjk  k jk  dij n

 HP

j 1

(21)

 k jk  dij

where hijk – is correspondence between i and j districts in terms of iteration k. Calculations are performed until following condition is met n

h i 1

 HPj .

(22)

Then the obtained correspondences are “conducted” through street and road network according to the shortest routes which lays of line cross in transit way those points where observations have not taken place. In this context, total value of input transit traffic flows is that very target vehicle density making it possible to forecast operation intensity of NGV-RCSs. Summary. The research performed made it possible to determine following regularities: 1. A problem concerning optimization of NGV-RCSs location is a multicriteria one having no singlevalued solution. 2. Intensity of vehicle flows within street and road network can be taken as the integral criterion to solve the problem; that involves solving a problem of the parameter forecasting. 3. The problem concerning vehicle flows intensity forecasting within road and street network consists of two subproblems – formation of vehicle flows and optimization of vehicle flows distribution within road and street network. The both problems are NP-complete and there are no algorithms to find accurate solutions for them. 4. To forecast vehicle flows, heuristic algorithm was proposed. The algorithm is based upon gravitational model providing calculation with such accurateness meeting the requirements in the process of practical problem solving. 5. To initialize output data in the process of the algorithm implementation, field studies are required within street and road city network with the use of basic observation stations. References [1] Govorushchenko N. Ya. System technique to design transport machines / N. Ya. Govorushchenko, А. N. Turenko. – Kharkov, KhNASU, 2004. – 206 pp. [2] Semionov V. V. Mathematical methods for transport flows modeling // Non-linear world. – 2005. – #6. – Pp. 48–52. [3] Lobanov Е.М. Problems of imitation modeling of transport flows movement within street and road city networks and highway system / Е.М. Lobanov // Theoretical and practical problems of automobile and road system development in Russia. – Moscow: MTUSI , 2006. – Pp. 4–7. [4] Shvetsov V.I. Mathematical modeling of transport flows / V.I. Shvetsov // Automation and telemechanics. – 2003. – #11. – Pp. 41–48. [5] Smirnov N.N. Mathematical modeling of transport flows / N. N. Smirnov, А. B. Kiseliov, V. F. Nikitin. – Moscow, MSU, 1999. – Pp. 39–47. [6] Chowdhury D. Statistical physics of vehicular traffic and some related systems / Chowdhury D., Santen L., Schadschneider A. // Physical Reports. – 2000. – Vol. 329. – P. 199–329. MMSE Journal. Open Access www.mmse.xyz

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[7] Cremer M. A fast simulation model for traffic flow on the basis of Boolean operations / Cremer M., Ludwig J. // Mathematical Computing Simulation. – 1986. – Vol. 28. – P. 297–303. [8] Binder P.M. Stochastic model of car routing / Binder P.M., Paczuski M., Barma M. // Physical Review. – 1997. – Vol. 49. – P. 1174. [9] Daganzo C.F. Remarks on Traffic Flow Modelling and its Applications / Daganzo C.F. // Berkeley: Department of Civil and Environmental Engineering University of California. – 2001. – 489 p. [10] Nagel K. Still flowing: Approaches to traffic flow and traffic jam modeling / Nagel K., Wagner R., Woesler R.: Grow Hill, 2003. – 317 p. [11] Holland J.F. Adaptation in natural and artificial systems. An introductory analysis with application in biology, control and artificial intelligence / Holland J.F. – London: Bradford book edition, 1994. – 211 p. [12] Kolesov V.I. Dynamic characteristics of uniform transport flow / V. I. Kolesov, S. P. Kolesnikov, G. V. Kolesov // Transport problems of West-Siberian gas and oil producing complex: Interuniversity collection of scientific papers. – Tyumen, Vector Buk, 2002. – Pp. 130–136. [13] Spirin I.V Management and control of passenger vehicle transportation. / I.V.Spirin. – Moscow, Akademia, 2014. – 400 pp. Cite the paper Kuznetsov A.P. (2016). Factor Analysis of Passenger Cars Using as a Taxi. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.52.18.599

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IX. Philosophy of Research and Education M M S E J o u r n a l V o l . 7

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On Communicative Competences as a Satisfactory Solution for Masters in Engineering23 K.A. Ziborov1, T.A. Pismenkova1, S.A. Fedoriachenko1, I.V. Verner1 1 – National Mining University, Dnipropetrovsk, Ukraine DOI 10.2412/mmse.25.82.979

Keywords: education, Master program, remote access to knowledge base, communicative competences.

ABSTRACT. The paper provides the analytical observe of the Ukrainian educational process and its problems, occurred while integrating into European educational environment. Several challenges, which has been illustrated in the paper shoe, that a new approach for Masters trainee is necessary. The first one in the remote access to scientific databases and educational services and the second is the necessity to teach the Maters communication technologies. The second challenge is a great gap in today’s education in Ukraine amongst the majority of educational fields.

Introduction. Ukraine's integration into European and world educational area sets a new task for domestic institution, which will allow their graduates being competitive in the international labour market. The transition to a two-tier system of training (Bachelor, Master) sets a number of challenges to the universities to develop not only the appropriate legal guarantees to ensure employment, but also the need to introduce the educational process, trainee, first of all for Masters. For example, disciplines, which allowing students successfully integrate into the modern labor market. The problem of demand for masters in the domestic labor market is now becoming increasingly important. This problem is caused by a lack of understanding by employers of a qualification that can be expected from graduates with Master's degrees. As others, National Mining University tends to take into account employers' interest. There is also the participation of domestic companies and institutions in organizing and conducting practices, as well as the formation of the target subjects of Master's theses, according to the latest objectives of employers' organizations. Working closely with representatives of potential employers both in the preparation and employability of graduates, as well as the implementation of continuous feedback was the basis for the successful solution of numbers of important tasks. The main of them is the quality of training of graduates and the demand of the labor market. To assess the quality of training at the University of fundamentally important point necessary to have feedback from employers and graduates. One of the main criteria for the quality of education at the university and an indicator of professional formation of students are respective competences. The survey of graduates and employers led to the conclusion that now among the key competencies employers and graduates isolated along with the specialist skills of engineering profile, the ability to build a psychologically comfortable relationship with different people regardless of their social or ethnic background.

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The purpose of the article – to substantiate the necessity and opportunity to improve the quality of training of masters of technical specialties, through the acquisition of communication skills with the use of modern technical means. Employers are increasingly using new forms of communication with the applicant – remote, through social networks, etc. The trends of the modern world are forced to take another look at the degree of importance of the information flow in both its traditional and new computer form. New developments require from the applicant in addition to the ability to present themselves, the ability to use information technology to the full range of possibilities. Often the employer's requirements include the skills in development and presentation of the project (fig. 1), and for this you must have the ability not only to use information technology, but also the ability to convey information in a way that positively affect the employer's decision.

Fig. 1. Presentation of the project by means of electronic communication. When remote communicating is a primary function of providing information - informing, no longer crucial. The problem of choice shifts to the aesthetic categories, feelings, emotions [1]. The structure of communicative competences includes a certain set of knowledge and skills to ensure the effective flow of communication process. Communicative competence determines the level of training of the interaction with others, which requires the individual successfully operating in a given society. Analysis of the literature shows that communicative competence – is a generalized communicative properties of the person, which includes the development of communicative abilities formed skills and interpersonal skills, knowledge of the basic rules and its laws. According to researchers, communicative competence should be divided into levels. The first of them – strategic – is a set of orientations, expressing attitude towards dialogue: as an end or as a means; focus on the dialogue or monologue, to intimate personal or functional role relationships. At the tactical level of communicative competence – the knowledge of the rules of organization of communication. Finally, on the technical – techniques that allow to implement the planned strategic line. Under the communicative competence is understood as a system of knowledge about themselves and others; skills, skills in communication, behavior strategies in social situations, allowing to build interpersonal communication in accordance with the purposes and conditions of cooperation. Today man is facing an hourly basis with the various information streams. In many cases, it seems that the facts speak for themselves, and that they almost do not need a graphical aid for the faithful interpretation and understanding. However, this is one of the most common misconceptions. The facts as presented bad for perception, automatically entail the wrong conclusions. If we are generally aware MMSE Journal. Open Access www.mmse.xyz

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that a lot depends on how the information is presented, the graphic component would demand a greater extent. The lack of images and accuracy of information transmission clarity leads to misunderstanding and misinterpretation of information. It is appropriately selected from a variety of existing options (fig. 2), a graphical representation of information helps to achieve this goal.

Fig. 2. Options graphical display. The goal of visual communication usually is to maintain a text message, and not an independent effect. The design has the opportunity to express the aesthetics of the author, his character and ability to convey an idea. A visual representation of ideas and images reproduced in the design project. The design is in demand in all sectors. For example, the Joint European Project TEMPUSMULTICEP JEP 24006-2003 for the implementation of the approved concept formed the group of developers and designers. The task group of designers was to develop a multimedia textbook "Engineering Pedagogic", the choice of the software environment and the necessary software components [2]. The demand for new skills, including design, professional activities of each region, provoking a constant correlation with time. This position allows selecting on the basis of computer technology to spread, new in essence, the form of design, are no longer associated with the mandatory features of the traditional design - with industrial production, the instrumental function of the product. Among the names of the young spheres (which necessarily associate themselves with the design) featured options such as computer design, information design, design software interfaces, media design, interactive design, the design of the electronic media, and so on. The most preferred are the last option. This e-media design changes our understanding of the usual in terms of processes and product design [1]. The design of the electronic media and the design process, and the product does not dependent on the instrumental function of the object, the material as a carrier of information, real-world designs, the physical laws of nature and even space and time. This modelling tool posts, images, and so on. Their broadcasting, receiving, reproducing material remain. The functional space culture design not only has a definite place in the spectrum of material phenomena between the poles of "practical start" and "state-of-art", but also forms a spectrum of forms of activity between conversion and communication [4]. Information technology in the design is one of the specific areas in which the creativity becomes a special professional competence of a qualified specialist. The sphere of information technologies in the design is an area in which the two main professional competence can be identified. The first from the sphere of natural scientific field, and another â&#x20AC;&#x201C; a humanitarian nature. Formation of professional thinking of students â&#x20AC;&#x201C; is the development of creative approach. High school training should form specialist with necessary creativity: an opportunity to see and formulate the MMSE Journal. Open Access www.mmse.xyz

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problem; the ability to hypothesize, to find or invent a way to test it; the ability to collect data, analyse it, suggest a methodology of their processing; ability to draw conclusions and see the practical application of the results; the ability to see the problem as a whole, all aspects and stages of its decision, and in the collective work – to determine the measure of personal involvement in solving the problem. Obviously, for the preparation of the expert in charge of the labor market, it must take place on the training curricula and programs focused on the practical needs of the real economy. The trends of the modern world are forced to take a different view on the degree of importance of the information flow in both conventional and new computer form. To this end, the Department of the machinery design fundamentals developed and implemented in the curricula of masters of engineering specialties the discipline «Communication Design» [1, 3]. Discipline "Communication Design" aims to provide masters engineering disciplines specific knowledge and advice on the procedure and practice of the transfer of technical information (fig. 3.).

Fig. 3. Technical information in graphical form. Communication Design is a significant part of the functional area of design where objects are designed, intended mainly for the transmission of messages. Communicative correlate well with media design, both in practical terms and in the ontological, where from it has historically been considered a separate sphere, alternative classical object-spatial environment, electronic design environment. We have found that ideally corresponds to the transformation of the instrumental function of objects, while communication - communicative. Accordingly, the ultimate goal of communication design is not the creation of the product, goods, and the creation of some "community" – the environment in which the creator and the consumer, the seller and the buyer, addresser and the addressee find each other and "speak" the same language on the "general" theme. This function is on the one hand a practical and other on another – mainly art. Depending on this information is transmitted spectrum by utilitarian and objective knowledge to subjective attitude, expressing someone else's aesthetic position, evaluation, reflection. MMSE Journal. Open Access www.mmse.xyz

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Closest to the objectivity of the area is practical communication design information, aimed at the organization and presentation of data and to transform them, in the value and meaningful information. This chain of N. Shedrof is provided on the following scheme of information process (fig. 4) [4].

Fig. 4. Driving information process An important role in the design plays a communicative advertising. Often, advertising design is in the middle. On the one hand, advertising informs, on the other – often carries an artistic image of the product and company. Currently, communicative design is mainly focused on the objects of the graphical plan and electronic media according to the authors [4]. However, you can disagree. Communication design today is "engineering" planning processes in complex organizational structures. It brings in components such as visual design, advertising, illustration, font culture, printing processes, data objects in an urban environment, animation, performance (theatrical performance), branding, copywriting (texts compilation), TV and WEB-design, Internet, the psychology of personality and perception of information. Summary. Now the situation has qualitatively changed, from university graduates appear fundamentally new challenges: along with the form supplied the information necessary to efficiently and effectively handle the available information. The quality of the playback information directly determines the level of the final communications products. Therefore, an important part of the learning process is not only technical, but also methodological training, mastery of psychological methods of investigation of various phenomena of social life, including in the field of the psychology of art, the development of visual culture and visual perception skills, art therapy with visual painting. Discipline "Communicative design" generates in students competencies to effectively design a variety of communication forms a system of knowledge about modern principles of design in communication design, communication design of the chain because of its connection with the marketing, sociology, psychology; generates skills and competencies with the research method of training as an effective means of enhancing creative abilities and formation skills. References [1] V.V. Protsіv, K.A. Zіborov, T.S. Pismenkova, І.V. Verner. (UKR) Communicative design - Step to for employment realization, Contemporary Innovation Technique of the Engineering Personnel Training for the Mining and Transport Industry 2016 MMSE Journal. Open Access www.mmse.xyz

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[2] V.M. Prihodko. L.G. Petrova. Yu.P. Shkitsky. E.I. Makarenko. European program TEMPUS as a factor of innovative development of higher education system in Russia and Ukraine, Conference proceedings on Intern. innovation. development and innovation. cooperation: state, problems and prospects, Materials conference "Problems and perspectives of innovation development of economy", 2006b S. 270-277. [3] S. Felonenko, KA Zіborov, TS Pismenkova. On Students’ Self‐Learning Practice While Studying Knowledge‐Based Courses, Contemporary Innovation Technique of the Engineering Personnel Training for the Mining and Transport Industry 2016 [4] AA Poleuhin The development of communication design, Proceedings of the Russian State Pedagogical University. AI Herzen. 2009. № 15. [5] Biocca, F. (1993). Communication technology matrix. Chapel Hill: Center for Research in Journalism and Mass Communication, University of North Carolina at Chapel Hill. [6] Biocca, F. (1992). Communication within virtual reality: Creating a space for research. Journal of Communication 4, 5-22. Cite the paper K.A. Ziborov, T.A. Pismenkova, S.A. Fedoriachenko, I.V. Verner (2016). On Communicative Competences as a Satisfactory Solution for Masters in Engineering. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.25.82.979

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The Use of Online Quizlet.com Resource Tools to Support Native English Speaking Students of Engineering and Medical Departments in Accelerated RFL Teaching and Learning24 Kh.E. Ismailova1,a, K. Gleason2,b, E.A. Provotorova1,c, P.G. Matukhin1,d 1 – People’s Friendship University of Russia, Moscow, Russia 2 – American Center, Moscow, Russia a – holisa1967@mail.ru b – KGleason@amc.ru c – provelar@yandex.ru d – m-pg@mail.ru DOI 10.2412/mmse.05.805.901

Keywords: Russian as a foreign language, English teaching, learning, tests, BYOD, Quizlet.com, internet, 3D printer.

ABSTRACT. The paper presents a description of the methodology and some results of the application of tools of the language learning support portal Quizlet.com to improve the effectiveness of the accelerated development of the basic communicative skills in Russian as a foreign language (RFL) for the group of the English-speaking students who arrived to study in Russia engineering, medicine and other areas. The application of the development is the basics of Russian teaching and learning in the classroom as well as in the mode of self-education and out-of-classroom events. Special attention is paid to the use of cloud-based tools to organize and conduct extracurricular activities. Particularly in the promising subject connected with the use of 3D printers for the solution of engineering problems of prosthetics of the lost bodies of animals and birds on the example of the Toucan key restoration. Analysis of the results of the use of flash cards, tests, and group games showed the promise of using the sets of Quizlet.com tools for accelerated assimilation of the native English speaking students in the area of General and special RFL vocabulary, as well as students showed that in a short time they can get and develop their basic skills of listening, reading and writing in Russian communication when Quizlet tools being used in different modes.

Introduction. Because of the development of world integration processes in economy, culture and education the concept of multilingualism of students and future professionals becomes more important and relevant. With the desire of the peoples of the planet to master one or several foreign languages, to use them for communication and mutual understanding, is manifested increasingly. Russian language as a language of international communication, studying in different countries of the world. To study Russian language in Russian speaking environment, foreigners come to Russia. One of the training centers, where Russian as a foreign language (RFL) is taught to foreign citizens with a basic level, is the Faculty of Russian language and General educational disciplines of the Peoples Friendship University of Russia (RLGED, PFUR). Along with textbooks in the traditional paper mode, the faculty teachers develop and apply modern innovative means to support RFL teaching and learning. More electronic educational products, teachers are designed for use in the classroom and at home. The faculty can provide training in computer classes. All computers are plugged-in to the Internet. The widespread of mobile devices and Internet technologies allows us to complement the set of software and hardware to help foreign

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students in the Russian language learning. It also opens new perspectives in the establishment and practical application of new information educational and pedagogical technologies The present paper discusses some elements of information technology aimed to support the online study of RFL. They were used by us to improve the efficiency and reduce the time of passage of the basic level language training in the group of native English-speaking students. These students first arrived in Russia to prepare to enroll the university in medical, engineering and other areas where study and work are strongly associated with the use of up-to-date computer technologies. Teacher designed information products specifically for students in this group. The set is based on tools of the Quizlet.com portal. New instruments can be used in a variety of modes – classroom-based, independent and targeted extracurricular activities. Guides are used in stationary language computer labs, mobile computer classrooms and BYOD-technology mode (from the English “Bring Your Own Device”). The last assumes the use of students own mobile devices with Internet access for Russian learning. To develop information products all the features of the portal Quizlet.com were used. Primarily it is sets of electronic flash cards. They are the main component of the study of Russian words, terms and their definitions with English translations. Cards equipped with embedded systems, dubbing and visual support on the basis of the Quizlet internal image library. We provided also the use of the online group language learning games system Quizlet.live on various categories and sections of the RFL course in the classroom and during extracurricular activities – self-study, excursions, etc. This paper presents a description of the special form of the students work aimed at supporting the learning of the Russian language of specialty. It's the preparation, organization and conduct of the visit the student festival at the American Center at the U.S. Embassy in Moscow by a group of foreign English-speaking students. The event is dedicated to exploring advanced computer technologies in the application of 3D printers in medicine and medical engineering. Purposes. The goal is the investigation of possibilities of the development of the IT elements to support processes of formation and increasing of the native English-speaking students elementary Russian language and information technology communicative competence on the basis of online language training environment Quizlet.com tools. Problems. The objectives of our investigation consisted of identifying and finding solutions to complex problems: 1. Analysis of the capacity of the resource Quizlet.com terms of use of its tools for solving problems of forming native English-speaking students’ basic language, information technology, education and household communicative competences matching the assessments of the elementary course of RFL. 2. The formation of students’ basic oral communication skills in educational and professional sphere in Russian as a foreign language elementary level. 3. The formation of basic communicative competence in accordance with the requirements of the standards and programs of the RFL elementary level standard. 4. The development of educational IT-communicative competence of future student and specialist in the application of cloud technologies in learning and self-education. 5. Development of elements of innovative Russian teaching technologies based on online Quizlet.com tools using stationary and mobile Internet access. Method. The necessity of finding new effective techniques to increase the effectiveness of language training, primarily by providing students opportunities for intensification of self-sufficiency of the work on the study of the Russian language, due to several circumstances: • Time study of the elementary course of RFL significantly reduced. • The study of grammar an elementary-level RFL are given 72 hours. MMSE Journal. Open Access www.mmse.xyz

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• RFL is perceived by foreign students through the prism of their native language, namely English. • English language we consider to be a mediator for students of South Africa in their elementary Russian studies. Elementary Russian language level — is the level of initial skills in the acquisition of individual language knowledge and speech communication. The student copes with standardized phrases simple conversation, uses only learnt material, its speech consists of isolated words or phrases and is clear to native speakers accustomed to communicating with foreigners. At the hearing the student understand short learned phrases, requires frequent repetition and a slow pace. He recites familiar words and phrases, understands the general content of the text if there is visual support and background knowledge. Can write learned words and phrases to fill in the forms. When learning any foreign language, it is important in the beginning of the course to study vocabulary well. It is the vocabulary by interacting in the speech grammar and phonetics, is a leading means of verbal communication in oral and written forms. Vocabulary is inextricably linked to the grammatical system of the language, one cannot exist without the other, and the lexicon is having a huge impact on grammar. Learning vocabulary is not just learning new words. It’s also mastering the phonetic, grammar, semantic and associative relationships existing between them at all. It is known that the study of the Russian language among representatives of different audiences arise different challenges. Comparison of the structures of the native and Russian languages facilitates the process of learning Russian language. Rational use of the native language of students, on the one hand, facilitates the efficient transfer of knowledge and skills from the sphere of the mother tongue in Russian language learning. On the other side, it helps to overcome specific difficulties arising from the discrepancy between native and studied languages. In our case, the fact that the native language of students is English significantly influenced the choice of software environment to support teaching and learning. The Quizlet.com website is an online service that aimed to assist students to quickly memorize a large number of new foreign words. Including special terms. The idea of service is simple. The teacher creates and places in a virtual class sets of new words with translation (the Quizlet environment supports a large number of languages). The group then begins to train. You can add images, enable automatic pronunciation. This establishes visual contact with the word, but also auditory. The portal Quizlet.com has an interface in English, eliminating the additional costs of teaching time to study its control. Students, for whom English language is native, are easy to conduct themselves in this learning environment. At the same time all the tools from this resource allow the use of Russian language for the compliance with the exercises and listening support. The creators of the portal Quizlet laid its design flexibility. Anyone can • find and use ready-made sets of cards; • create his/her own sets with the required lexicon. For training and self-training we developed a number of special sets of pairs of words in English and Russian language. An example of one of the sets is shown in the figure below. That is the 1 st set for Lesson 1.

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Fig. 1. Pairs of Russian and English words in the Quizlet set. The main tools of the portal include the following instruments.  View cards

Fig. 2. Flashcard sides.  The "LEARN" mode (type what you hear).

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Fig. 3. LEARN unit.  The "SPELLER" mode has two options: to type a word and hear the meaning, and write. The second method of training is the most effective. The student in turn is invited to match 7 words from the set in the native language. He needs to write the translation. All the words from the set are to be written correctly two times. Thus, if a student makes a mistake, then the word will meet him again in the next aisle. And so on while he will not study write token without errors. If a student can't remember the translation, he can click on the support button "Don't know". Translation appears in the box, and then disappears. After that, the student will still have to write the word, but as learned in this time it will not be marked.

Fig. 4. SPELLER dialog.

After the next pass it can be available a short statistics of the results of the training session. The student will be able to view how many times the word was written correctly, and the number of remaining, have never met, words. For transfers we can add images for better perception. The "Test" mode automatically generates a set of 3 types of questions: • closed question – write the translation of the word, • Question of the "Quiz", type • "YES – NO" type question. For each type a set of 4 items is being formed. The game "Match" (Let it all disappear!). The student should, using the mouse to move the card with the word and to combine it with another card, containing the translation. With the right combination a pair of cards disappears. The computer records the time of this exercise and ranks the players MMSE Journal. Open Access www.mmse.xyz

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according to this parameter. Thus, it is possible to organize intramural and extramural competition at the time. The game "Gravity" has the goal to save the Earth from falling asteroids. The student must enter the correct translation of the word before the asteroid will fall to the ground. When you dial a certain number of points level of the game increases and increases the speed of falling asteroids. Thus, practicing the accuracy of the translation and grow-up the skills of speed on the computer typewriting. Learning environment Quizlet.com contains a very effective mean of group communication in the process of the words learning. That is a built-in online QuizletLive game. As shown, the use of this tool provides high-speed learning of proper word choices. The methodology of RFL teaching we used assumes that the student since the first class begins to "speak" in Russian. He does not teach individual words – he talks in sentences, since the patterns are blocks, proposals, initially primitive but increasingly difficult. And on the basis of the proposal every student explores the basic meanings of the bowls and verbs that govern these cases. Grammar is to be absorbed not as a result of learning the case endings, and in the process that the student understands the value of cases of nouns using the same models. The introduction sequence of the case values is determined by the frequency of their use. Extracurricular classes. The main form of learning at the preparatory faculty is the classroom. However, to achieve complete results when learning trials are not enough classroom teaching, where students hear Russian spoken only from the lips of the teacher. As a complement, we used the opportunities of extracurricular activities. Development of relevant activities on the subject of "3D printer" was largely focused on independent work of students with the materials placed by the teacher in advance on the website Quizlet.com. This allowed us to avoid the cost of the topic classroom learning time. It was also prepared, organized and conducted a visit to one of the activities of the student science festival at the American Center Moscow at the U.S. Embassy in Moscow. The theme of the event was the acquaintance with the device, principle of operation and application of 3D printers as a promising direction of the use of computer technologies in engineering, health care and other fields. The work was carried out in a number of several stages. 1. The choice of theme and venue of classes. From the online newsletter of the American Center (American Center Moscow, AMC) we had received the information on holding a festival of students and special events – demonstrations of new models of 3D printers. The AMC management agreed to conduct special classes for groups of students from South Africa being studied the RFL in PFUR on this topic. The choice of AMC as the venue of the classes was due in particular to the fact that all center staff members are either native English speakers or professionally own it. Thus, language barriers of the organizers and the participants were reduced. 2. The choice of software and hardware. At its disposal the AMC has a sufficient number of portable Apple computers with access to the Internet via Wi-Fi that has led to the connection of all participants to the profile of the teacher’s virtual class at the Quizlet.com portal. At the same time, as the number of participants exceeded initially planned, some students used their own mobile devices. Thus, to provide the access for participants to the materials of the classes was not a problem. 3. The investigation of the RFL teacher of all the opportunities and possibilities provided by the Quizlet.com portal language teaching tools and technologies. 4. Preparation of the manuals involves the typewriting of the short adapted text in Russian on the «3D printers and their applications in engineering and medical assistance» topic. Since the group was attended by students of both directions, we choose some papers described the 3D printer use to solve the problem of lost organs or parts of birds and animals artificial design. The basic article was devoted to the use of 3D printer to reconstruct the beak of a toucan. MMSE Journal. Open Access www.mmse.xyz

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5. Preparation of pretext and after-text exercises included formation of a set of simple test questions to execute them in the classroom and independently. Those assignments were included in the text file as well as in a special kit of educational tasks placed in the teacher’s virtual class at the Quizlet.com portal. 6. Preparation of additional materials. During the event it was planned a viewing of the film on the history of the creation of the first models of 3D printer as well as some clips from the YouTube.com service devoted to the "Save the Toucan" theme. 7. Lecturers training, preparations of the 3D printer work demo and testing of the classes equipment. 8. Preparation of special terms sets for classes and advanced classroom training aimed on the student’s acquaintance with the subject, basic professional lexicon in Russian and technologies of the learning in the Quizlet.com language learning environment. 9. The foreign students’ instruction on the movement route using various vehicles and orientation in the city of Moscow with the support of the Yandex.com portal services. 10. Pre-inform students about the rules of visiting the AMC. 11. The arrival of the venue, the onboard control. 12. Watching the movie, listening to a lecture, familiarity with the work of 3D printer listening to more messages and view more videos. 13. The test on the «3D printer» topic. 14. Group Quizlet.live play. 15. The end of the event, a photo session, the band's return to the hotel. 16. Summing up the event in the classroom, topics discussion, and test results announce. To prepare the extracurricular event, students were suggested to perform a number of preparatory exercises, to read and study the text on 3D printers specially designed for this lesson. The text is placed in advance on the cloud, Microsoft One Drive. It is open for access via desktop computers and mobile devices with mobile Internet for all participants. All additional materials prepared by the teacher in the form of Quizlet simulators and group games were placed on the Quizlet.com portal teacher’s profile. This form of out-of-class preparation for the session greatly expands the horizons of students, maintains they have the skills studied in the classroom on lexicon and grammar, and also leads the foreign students to have the prerequisites for the application of new information technologies in education. Before reading the text, students must perform preliminary tasks. Those aimed to help foreign students to understand the Russian text better. TOPIC: "CASES OF WORDS "3D PRINTER" AND "PROGRAMME"" PRETECTIVE JOB 1) Learn the new words Русский

English

Русский

English

3D принтер

3D printer

Модель

model

чертёж

drawing

Пластик

plastic

оператор

operator

Гипс

gypsum

нагреватель

heater

Стекло

glass

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прут

rod

Металл

metal

двигатель

engine

Деталь

detail

USB

Нить

thread

встроенная память

built-in memory

Ток

current

Форма

form

Деталь

detail

2) Read the new verbs and sentences with them. Try to understand the meaning of new verbs. In case of difficulty, consult the dictionary. 1. To do, to do what?

2. To build, to build what?

3.To draw, to draw what ? 4.To study, to study what?

5. To generate, to generate what? 6. Stick together, stick together with what? 7 To be powered, to be powered by what? 8. Stores, what does computer memory store?

9.To build, to build what?

model. 3D printer makes models from plastic, plaster, glass and metal - detail. The printer builds the item exactly according to the drawing drawing. The operator draws a drawing on the computer. - work. To become an operator, you need to study the work of 3D printer - heat. The heater generates heat. – with model. To stick molten thread together with a model exactly at the specified location. – by current. It is powered by an electric current data. The printer memory stores data about the shape of the details transferred from a computer. model. The 3D printer can build models of different shapes and sizes.

1.Делать – сделать что? 2.Строить построить что?

- модели. 3D принтер делает модели из пластика, гипса, стекла и металла - деталь. Принтер строит деталь точно по чертежу

- - чертёж. Оператор рисует чертеж на компьютере. 4.Изучать – - работу. изучить что? Чтобы стать оператором, нужно изучить работу 3D принтера 5. Выделять – - тепло. выделить что? Нагреватель выделяет тепло. 6. Склеиваться – – с моделью. склеиться с чем? Расплавленная нить склеивается с моделью в точно заданном месте. 7. Питаться – –током. питается чем? Он питается электрическим током 3.Рисовать нарисовать что?

8. Хранятся храниться что?

9.Строить – построить что?-

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- – данные. В памяти принтера хранятся данные о форме детали, переданные компьютером - модели. На 3D принтере можно строить модели разных форм и размеров.

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10. To meet, to meet what?

- with a 3D printer . To become better acquainted with 3D printing and his work, you need to read the description.

10. Знакомиться – познакомиться с чем?

- с 3D принтером. Чтобы лучше познакомиться с 3D принтером и его работой, нужно прочитать его описание.

3) Explain from which words are formed these words Printing, molten, electrical, computer, integrated. 4) Make a phrase: model (plastic), drawing (computer), be (operator), head (heating), form (detail) Read the text 3D PRINTER

3D ПРИНТЕР

The 3D printer produces models made of plastic, plaster, glass and metal. The printer builds the item exactly according to the drawing. The operator draws a drawing on the computer. To become an operator, one needs to study the work of a 3D printer.

3D принтер изготавливает модели из пластика, гипса, стекла и металла. Принтер строит деталь точно по чертежу. Оператор рисует чертеж на компьютере. Чтобы стать оператором, нужно изучить работу 3D принтера. У 3D принтера Maker Bot есть печатающая головка с нагревателем. В головку подается пластиковый прут. Нагреватель выделяет тепло. Под действием тепла головка плавит прут и формирует тонкую нить из пластмассы.

The 3D printer Maker Bot is equipped with the typing head with a heater. The head supplies plastic rod. The heater generates heat. Under the heat of the head the rod melts and forms the thin filament of plastic. Работой 3D принтера управляет программа. The work on a 3D printer is controlled by a Программа устанавливает головку в нужное program. The program sets the head at the место. Головка подает нить к модели и right position. The head delivers the thread to сплавляет нить с поверхностью детали. the model and fuses the thread with the Расплавленная нить склеивается с моделью в detail. The melted filament is glued to the точно заданном месте. model in the exactly specified location. Головка приводится в движение электрическим The head is driven by an electric motor. The engine is in the frame of the printer. It is powered by an electric current. The engine is controlled by the computer program. The program starts and stops the motor. It changes the direction of current flow and varies the printer head moving.

двигателем. Двигатель находится на рамке принтера. Он питается электрическим током. Двигатель работает под управлением компьютерной программы. Программа включает и выключает двигатель. Она меняет направление тока и задает перемещение головки принтера.

The program is in the computer. Commands from the computer are transmitted to the 3D printer via USB. The printer has built-in memory. It stores data about the detail shape transferred from the computer.

Программа находится в компьютере. Команды от компьютера передаются 3D принтеру по USB. У принтера есть встроенная память. В ней хранятся данные о форме детали, переданные компьютером.

The 3D printer can build models of different На 3D принтере можно строить модели разных shapes and sizes. Shapes can be round, форм и размеров. Формы могут быть круглые, MMSE Journal. Open Access www.mmse.xyz

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square, triangular, and any other. To become better acquainted with 3D printing and its work, one needs to read the description. On the Internet you can find a film about the 3D printer Maker Bot, its design and control.

квадратные, треугольные и любые другие. Чтобы лучше познакомиться с 3D принтером и его работой, нужно прочитать его описание. В сети Интернет можно найти фильм о 3D принтере Maker Bot, его устройстве и управлении.

AFTER TEXT JOB. 1. Answer the questions. – 1) What does a 3D printer make the model from? 2) What does the 3D printer use to build the item? 3) Where does the operator plot the drawing? 4) What does the Maker Bot 3D printer have?

5) What does the heater release? 6) What controls the operation of the 3D printer? 7) Which models can be built on a 3D printer?

A. cardboard B. plastic C. stone A. drawing B. paint C. photography A. on the computer. B. on the table. C. on paper A. printing head with heater. B writing head with heater. C. drawing a head with heater. A. heat. B. cold. C. air. A. program. B. operator. C. engineer. A. linear. B. two-dimensional. C. three-dimensional

2. Tell in another words.

1) Из чего делает модели 3D принтер? 2) Как принтер строит деталь? 3) Где оператор рисует чертеж? 4) что есть у 3D принтера Maker Bot?

5) Что выделяет нагреватель? 6) Что управляет работой 3D принтера? 7) Какие модели можно строить на 3D принтере?

А. из картона Б. из пластика В. из камня А. по чертежу Б. по рисунку В. по фотографии А. на компьютере. Б. на столе В. на бумаге А. печатающая головка с нагревателем. Б. пишущая головка с нагревателем В. рисующая головка с нагревателем А. тепло Б. холод В. воздух А. программа Б. оператор В. инженер А. линейные Б. двумерные В. трехмерные

2.Скажите по – другому.

1. To become an operator, everyone needs to 1. Чтобы стать оператором, нужно изучить study the work of a 3D printer. работу 3D принтера. 2. The head delivers the thread to the model 2. Головка подает нить к модели и сплавляет and fuses the thread with the surface. нить с поверхностью детали. 3. The engine is powered by an electric 3. Двигатель питается электрическим током. current.

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Quizlet TEST QUESTIONS TO the TEXT "3D PRINTER" ON THE SUBJECT OF "CASES OF WORDS "3D PRINTER" AND "PROGRAMME"" Choose the correct cases for the sentences below. 3D (printer – И.п., что?) makes models from plastic, plaster, glass and metal.; 3D (printer – Р. п., у чего?) Maker Bot has a typing head with a heater. ; Commands from a computer are transmitted in 3D (printer – Д. п., чему?) by USB. ; To become an operator, you need to study the work of a 3D (printer – В. п., чего?); To become better acquainted with 3D (printer – Т. п., с чем?) and its work, you need to read the description. ; On the Internet you can find the film on 3D (printer – П. п., о чём?) Maker Bot device and control research institute. ; What is it? It is program – I. p. What's this?; The computer has no program R. p. No what?; Data is sent to the program – D. p. To what?; The command is entered into the program – V.p. In what? ; Printer is controlled by the Program – T.p. By what? ; Film about the Program of 3D – P.p.) about what? ;

Вопрос в форме заготовки предложения

Правильный ответ Correct answer 3D (принтер – И.п., что?) делает 3D принтер. модели из пластика, гипса, стекла и металла.; У 3D (принтер – Р. п., у чего?) у 3D принтера Maker Bot есть печатающая головка с нагревателем. ; Команды от компьютера 3D принтеру. передаются 3D (принтер – Д. п., чему?) по USB. ; Чтобы стать оператором, нужно 3D принтера. изучить работу 3D (принтер – В. п., чего?). ; Чтобы лучше познакомиться с 3D с 3D принтером. (принтер – Т. п., с чем?) и его работой, нужно прочитать его описание. ; В сети Интернет можно найти о 3D принтере. фильм о 3D (принтер – П. п., о чём?) Maker Bot, его устройстве и управлении. ; Что это? (Программа – И. п.) Это Это программа. что? ; У компьютера нет (Программа -– Нет программы. Р. п.) Нет чего? ; Данные передаются (Программа - Программе. – Д. п.) Чему? ; Команда введена (Программа – В. В программу. п.) Куда? ; Принтер управляется (Программа Программой. – Т. п.) Чем? ; Фильм о 3D (Программа – П. п. ) О программе О чем? ;

Simulator : https://quizlet.com/_2ektpg Results. Our analysis of the possibility of using the Quizlet.com portal tools in organizing and conducting classroom and extracurricular classes led us to an important conclusion. The implementation of the learning environments into the language learning practice allows us to include in the process a wide variety of the students own systems of the mobile Internet access. By this way we allow students to push the space-time framework of the educational communication for all participants of the educational process. Studying the features of the Quizlet.com portal we found that the program is adjustable to be used for the decision of a number of tasks of forming of the basic competencies of English-speaking students at the elementary level of RFL. It is a productive tool to study Russian words with specific meaning. MMSE Journal. Open Access www.mmse.xyz

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It is particularly important that both the apparatus of sight and hearing contributes to a more rapid and so on in relation to the assimilation of the values of the new words. The translation, combined with the images demonstration and the ability to listen to the sound of the Russian word corresponding object is the most economical and effective method of interiorization of the values of the studied lexicon. The above-described Quizlet.com environment integrated tools provide opportunities to enhance the learning process through their use in the classroom trials in the computer lab. The leading role is played by visualization of the words, concepts, terminology through the use of the image library of the portal. Demonstration of the written form of the words on flash cards and its English equivalent is accompanied by a picture showing the corresponding object. Often it is necessary to examine words which are quite difficult to understand for foreigners, because the data objects or phenomena do not exist in their language picture of the world. Quizlet.com resource tools provide the opportunity for a more complete understanding of this kind of image or concept. The visibility and enabled listening promote emotionally-estimated relations to the learning material. So those increase the student motivation and interest in knowledge and in the Russian learning process. The set of the Quizlet.com tools facilitates the process of the vocabulary learning of the basic course in RFL. Also confirmed is the effectiveness of using Quizlet.com tools for independent work of students in the process of preparing and conducting extracurricular classes in special computer topics. Summary. The findings of classroom as well as extracurricular studies and their analysis showed that the use of the Quizlet.com portal training support tools to improve the effectiveness of accelerated learning of English-speaking students in the basics of RFL provides wide opportunities for more productive formation and the development of the basic skills of verbal communication for all participants of the learning process. Including listening, speaking, reading and writing. The use of this online resource of the Internet opens up means for the formation of the complex of Russianlanguage competence of foreign citizens held at the faculty of Russian language and general educational disciplines, (Peoples ' Friendship University of Russia) pre-preparation for studying at a Russian university. It opens new dimensions for class work and self-education of students, helps direct intellectual abilities of students in the development of RFL. Application in addition to classroom work extracurricular forms, as well as focus them on advanced information and computer technology in engineering and its use in medicine, such as 3D printers and programming, increases motivation and interest of students in learning the Russian language, and special sections related to new fields of knowledge, develops creative abilities of students. References [1] P. G. Matukhin, S. L. Elsgolts, E. V.Pevnitskaya, O. A. Gracheva & E. A. Provotorova (2016). Multimedia Tutorial In Physics For Foreign Students Of the Engineering Faculty Preparatory Department. Mechanics, Materials Science & Engineering, Vol. 2. doi:10.13140/RG.2.1.2067.3045 [2] Ismailova Kh. E, Matukhin P. G. Word online as a tool to support BYOD-technology extracurricular formation and development of elementary skills in Russian speech of foreign students. M.: Pen .2016. – pp. 193 – 198. In proc. of the II International scientific-practical seminar «A foreign audience teaching of General educational disciplines in the Russian language». RLCI of MSU named after M. V. Lomonosov, 3 March 2016 – 302 S. [3] Apkina L. V., Matukhin P. G., Provotorova, E. A., Titova, E. P. Elements of the distance support of study and monitoring of the course "Anatomy" for foreign students, based on the integration of simulators ОneDrive/Excel-online in LMS MOODLE// II international scientific-practical seminar "Teaching of General subjects in the Russian language in a foreign audience" IRLC MSU M. V. Lomonosov, 03 Mar 2016 [4] Ismailova Kh.E., Matukhin P. G., Preparation of text items of BYOD technologies in WORDONLINE to support extracurricular formation and development of elementary skills in Russian MMSE Journal. Open Access www.mmse.xyz

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speech of foreign students. Vestnik RUDN. Series Informatization of education, No. 2, 2016, pp. 3442. [5] Gracheva O.A., Matukhin P.G. Development of elements of remote monitoring and self-control of the foreign students basic language of physics mastering based on the OneDrive cloud resource and the lms MOODLE in the mobile mode. // II international scientific-practical seminar "Teaching of General subjects in the Russian language in a foreign audience" IRLC MSU M. V. Lomonosov, 03 Mar 2016 [6] Ismailova Kh.E.., Matukhin P. G. Preparation of test items of BYOD technologies in the MOODLE type environment for the effective formation and development of elementary skills in Russian speech of foreign students in extracurricular activities.,/ Proc. of scientific-practical conference (may 13-14, 2016), dedicated to the 25th anniversary of the state independence of the Republic of Tajikistan. Topical issues of functioning and teaching of Russian language in the Republic of Tajikistan. ISBN 978-99975-909-0-9. 304 S. Publishing house: Tajikistan: Dushanbe. Tajik state Institute of languages named after Sotim Ulugzade. 2016. – pp. 90 – 102. [7] Callanova, M., (2014). Retrieved from http://www.amigas.cz/callanova-metoda-vyukyjazyku.html . on September 08, 2014. [8] Hubackova and Ruzickova, 2011, Experience in foreign language teaching with ICT support In Procedia Computer Sciences by Elsevier Ltd., 3 (2011), pp. 243–247 C ISSN: 1877-0509. Retrieved Februar 08, 2011 from http://www.sciencedirect.com/science/article/pii/S1877050910004163 [9] Wintergerst et al., The construct validity of one learning styles instrument, System, 29 (3) (2001), pp. 385–403 [10] Robert C. Kleinsasser, Language teachers: Research and studies in language(s) education, teaching, and learning in Teaching and Teacher Education, 1985–2012, Teaching and Teacher Education Vol. 29, 2013, pp. 86-96, http://dx.doi.org/10.1016/j.tate.2012.08.011 Cite the paper Kh.E. Ismailova, K. Gleason, E.A. Provotorova, P.G. Matukhin (2016). The Use of Online Quizlet.com Resource Tools to Support Native English Speaking Students of Engineering and Medical Departments in Accelerated RFL Teaching and Learning. Mechanics, Materials Science & Engineering, Vol 7. doi:10.2412/mmse.05.805.901

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