MMSE Journal Vol.2 2016

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

MMSE Journal. Open Access www.mmse.xyz 1

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

Sankt Lorenzen 36, 8715, Sankt Lorenzen, Austria

Mechanics, Materials Science & Engineering Journal

January 2016 MMSE Journal. Open Access www.mmse.xyz 2

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

Mechanics, Materials Sciences & Engineering Journal, Austria, Sankt Lorenzen, 2015

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.

MMSE Journal is dedicated to knowledge-based products and services for the academic, scientific, professional, research and student communities worldwide.

Open Access model of the publications promotes research by allowing unrestricted availability of high quality articles.

All authors bear the personal responsibility for the material they published in the Journal.

The Journal Policy declares the acceptance of the scientific papers worldwide, if they passed the peer-review procedure.

Mechanics, Materials Science & Engineering Journal by Magnolithe GmbH is licensed under a Creative Commons Attribution 4.0 International License.Based on a work at www.mmse.xyz.

Editor-in-Chief Mr. Peter Zisser

ISSN 2412-5954 e-ISSN xxxx-xxxx

Design

and

layout:

Mechanics,

Materials

Science & Engineering Journal, www.mmse.xyz Technical support: hotmail@mmse.xyz ©2016, Magnolithe GmbH © Copyright, by the authors MMSE Journal. Open Access www.mmse.xyz 3

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

CONTENT

I. MATERIALS SCIENCE ................................................................................................ 5 THE CARBON-FLUORINE ADDITIVES FOR WELDING FLUXES ......................................... 5 INFLUENCE VOLTAGE PULSE ELECTRICAL DISCHARGE IN THE WATER AT THE ENDURANCE FATIGUE OF CARBON STEEL ................................................................... 15 ALUMINUM COMPOSITES WITH SMALL NANOPARTICLES ADDITIONS: CORROSION RESISTANCE.................................................................................................................. 25 II. MECHANICAL ENGINEERING & PHYSICS ............................................................. 31 PERFORMANCE OPTIMIZATION OF A GAS TURBINE POWER PLANT BASED ON ENERGY AND EXERGY ANALYSIS

.............................................................................................. 31

CERTAIN SOLUTIONS OF SHOCK-WAVES IN NON-IDEAL GASES .................................. 44 ANALYTICAL MODELING OF TRANSIENT PROCESS IN TERMS OF ONE-DIMENSIONAL PROBLEM OF DYNAMICS WITH KINEMATIC ACTION .................................................... 57 ON INFLUENCE OF DESIGN PARAMETERS OF MINING RAIL TRANSPORT ON SAFETY INDICATORS ................................................................................................................. 62 VIII. Information Technologies .............................................................................. 70 THE ASSESSMENT OF THE STABILITY OF THE ELECTRONICS INDUSTRY FACILITY IN THE MAN-MADE EMERGENCIES WITH THE USE OF INFORMATION TECHNOLOGY .............. 70 X. Philosophy of Research and Education .............................................................. 78 TEACHING REITLINGER CYCLES TO IMPROVE STUDENTS’ KNOWLEDGE AND COMPREHENSION OF THERMODYNAMICS .................................................................... 78 MULTIMEDIA TUTORIAL IN PHYSICS FOR FOREIGN STUDENTS OF THE ENGINEERING FACULTY PREPARATORY DEPARTMENT ....................................................................... 84 PETRUS PEREGRINUS OF MARICOURT AND THE MEDIEVAL MAGNETISM ..................... 90 DEPLETION GILDING: AN ANCIENT METHOD FOR SURFACE ENRICHMENT OF GOLD ALLOYS .................................................................................. 98 MMSE Journal. Open Access www.mmse.xyz 4

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

I. Materials Science

The Carbon-Fluorine Additives For Welding Fluxes R.Е. Kryukov1, O.А. Kozyreva1,a, N.А. Kozyrev1,b 1 – Federal State Budgetary Educational Institution of Higher Professional Education «Siberian State Industrial University», Research and Development Center «Welding Processes and Technologies», 654007, Russia, Novokuznetsk, 42, Kirov str. a – kozireva-oa@yandex.ru b – kozyrev_na@mtsp.sibsiu.ru

Keywords: welding, flux, metal, slag, gas-forming compounds.

ABSTRACT. Is carried out the thermodynamic estimation of the probability of the flow of the processes of the removal of hydrogen from the weld with the welding in the fluorine-bearing flux in the standard states in the range of temperatures 1700 – 2200 K. In this case, as the standard states for the substances – of reagents they were selected: Na3AlF6L, SiO2L, SiF4g, NaAlO2s, Na2SiO3l, CaF2l, CaSiO3l, H2g, SiF2g, HFg, O2g, SiFg, Hg. As a result the calculations of standard energy of Gibbs and equilibrium constants of reactions it is determined, that from the reactions of the direct interaction of ftoragentov of slag with hydrogen and oxygen of the metal most probable appears the reaction with the cryolite. In the mechanism of more complex interaction with the participation in the reaction, besides ftoragentov, silica of slag and by the possible formation of the intermediate product of SiF 4g more probable is the process with fluorite.

Calculations showed the expediency of using the connection Na3AlF6 together with fluorite for the removal of hydrogen with the submerged welding. The carried out calculations became the basis of the development of the compositions of the new flux- additives, protected by patents RF.

Introduction. The issue of new fluxes and their additives development has been attracting much attention currently, as well as research into their influence on welding and technological characteristics of a weld and on the concentration of oxygen and non-metallic impurities in a weld [1-5].

Submerged arc welding is attended by intensive mass transfer of liquid molten metal and slag, forming from welding flux. Reactions of oxidation and deoxidation of manganese, ferrum, and silicon, i.d. exchange processes involving oxygen are typical for this process. The most grades of domestically produced fluxes, which are applied for welding low-alloyed steels are oxidizing ones and ground on silicon-manganese oxidation-reduction processes. Here, the products of these reactions are oxide compounds of silicon, manganese, ferrum, aluminum etc., which often can’t surface and assimilate to slag, forming from welding flux, the level of impurity of weld metal by non-metallic admixtures increases consequently; as the result, the complex of physical and mechanical characteristics deteriorates. Apparently, restoratives, which form gaseous products of reactions, are advisable to apply in order to avoid impurity of weld metal. It is carbon that can be a restorative of this kind, and forms gaseous compounds CO2 and CO when reacting with oxidizers.

MMSE Journal. Open Access www.mmse.xyz 5

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

Materials and methods of research. Shielding is usually provided through pushing atmospheric gases aside from weld zone by forming gases CO2 (CO); that helps to reduce or even exclude the probability of molten metal saturation with oxygen, nitrogen or hydrogen from atmosphere. Gasforming compounds of carbonates like CaCO3, MgCO3, FeCO3, MnCO3 and their derivatives are usually used for this purpose. Gas shielding is possible due to CO2 as high-temperature decomposition of carbonates takes place according to the following reactions and temperatures [6]: CaCO3 → CaO + CO2 (900-1200 ºC),

(1)

MgCO3 → MgO + CO2 (>650 ºC),

(2)

FeCO3 → FeO + CO2 (280-490 ºC),

(3)

MnCO3 → MnO + CO2 (330-500 ºC)

(4)

According to stoichiometric calculations the results of decomposition are as follows: 1 kg CaCO3 – 0.224 m3 CO2, 1 kg MgCO3 – 0.267 m3, 1 kg FeCO3 – 0.192 m3, 1 kg MnCO3 – 0.194 m3.

Without taking into account the costs of carbonates decomposition, MgCO3 and CaCO3 are the most optimal components, which help to get most CO2 when decomposing 1 kg of material, succeeded

by MnCO3 и FeCO3.

Furthermore, when decomposing CaCO3 and MgCO3 basic oxides CaO and MgO are formed and improve basicity of welding flux, and that of a forming slag, respectively, whereas, when MnCO 3 and FeCO3 decomposing oxides FeO and MnO are formed, which raise the degree of oxidation in slag systems and oxygen concentration in a weld. The latter causes all negative consequences – increasing level of impurity by non-metallic oxide components in a weld and deterioration of mechanical properties.

Having followed all mentioned pre-conditions we have developed a flux – ANK additive, protected it by a patent of the Russian Federation and applied in production process at Open Joint Stock Company “Novokuznetsk Plant of Reservoir Metalware named after N.E. Kryukov” [7]. For its manufacturing ferrosilicon FS75 (GOST 1415-78), marble М92- М97 (GOST 4416-73 (92-97% СаСО3)), and liquid glass (GOST 13078-81) were used. Production technology was as follows.

Marble and ferrosilicon were grinded to less than 1 mm fraction. Grinded marble and silicon were mixed in 50 to 50% mass proportion. It was dried at temperature 100-200 0С for 10 - 20 minutes, succeeded by grinding and size grading to 2.5 mm. 3-5% of additive was introduced into fluxes.

Before a flux with an additive is used its 40 – 60 minutes annealing in the furnace is recommended at temperature 250-350 0С.

This additive is used for roll welding of tanks. The technology involves assembling, welding, controlling and rolling plates of tanks walls, all the processes are performed on special roll facilities with upper and down rolling. Two-side submerged arc welding of butt joints of wall plates is applied in the process, first on the upper tier, then on the lower one, after the plate is rolled. An additive helped to avoid pore formation and improve quality of welds.

However, shielding gases CO and CO2 can form due to carbon, added to the flux, according to the reactions:

(C) + [O2] = {CO2}, MMSE Journal. Open Access www.mmse.xyz 6

(6)

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

(C) + ½[O2] = {CO}

(7)

Here 1.863 m3 CO2 and 1.864 m3 CO release per each kg of carbon (in normal conditions).

The second important issue is that of weld metal dehydrogenization. As a rule, it is carried out by introducing fluorine-containing additives (fluorite or cryolite), hydrogen combines with fluorine and is further removed as a compound HF. The following chemical transformations can be considered as probable reactions of removal:

1/2 (CaF2)+ [H]+ 1/2 [O] = 1/2(CaO) + HFg, 1/6(Na3AlF6)+ [H]+ 1/2 [O] = 1/6NaAlO2 s+ HFg + 1/6(Na2O),

(8) (9)

As well as reactions:

2(CaF2) + 3(SiO2) = 2CaSiO3 s + SiF4g,

(10)

2/3(Na3AlF6) + 5/3(SiO2) = SiF4g + 2/3NaAlO2 s + 2/3 (Na2SiO3),

(11)

succeeded by reactions of dehydrogenization with SiF4:

1/2 SiF4g + [H] = 1/2SiF2 g+ HFg

(12)

1/4 SiF4g + [H]+ 1/2 [O] = 1/4 (SiО2) + HFg

(13)

1/3 SiF4g + [H] = 1/3SiFg + HFg

(14)

1/2 SiF4g + [H] = 1/2 SiF2g + HFg

(15)

Thermodynamical characteristics in standard conditions [∆rН°(Т), ∆rS°(Т), ∆rG°(Т)] needed to assess reaction probability were calculated by well-known methods [8] in the temperature range of welding processes 1700 – 2200 К [9] in terms of thermodynamic properties of reagents [[Н°(Т)Н°(298,15 K)], S°(Т), ∆fH°(298,15 K)] [10,11]. Here, chemical states Na3AlF6l, SiO2l, SiF4g, NaAlO2 s,Na2SiO3l, CaF2l , CaSiO3 s, H2г, SiF2g, HFg, О2g, SiFg, Hg were selected as standard ones for substances – reagents in the range 1700 – 2200 К according to fact aggregate states of phases in the system under consideration.

The results of calculations are provided in the Table 1.

Table 1 demonstrates that reaction (9) is thermodynamically the most probable (cryolite dehydrogenization), the second one is reaction (8) (fluorite dehydrogenization), followed by reactions (10, 11), where silicon tetrafluoride is formed as an intermediate product of further reactions (12) - (15); the latter result in formation of gaseous compound HF. Here, reaction (13) is thermodynamically the most probable (SiF4 combines with hydrogen and oxygen). The stoichiometric reactions (15), (12), (14) are the least probable ones.

MMSE Journal. Open Access www.mmse.xyz 7

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

Table 1. Standard Gibbs energy of reactions (8) – (15) and reaction equilibrium constants according to temperature ∆rG°(Т), kJ К(Т)

Reaction 1700К 8

9

10

11

12

13

14

15

1800К

1900К

2000К

2100К

2200К

-16,22

-18,61

-20,93

-23,17

-25,36

-27,47

3,2

3,5

3,8

4,0

4,3

4,5

-32,32

-33,82

-35,20

-36,46

-37,62

-38,68

9,8

9,6

9,3

9,0

8,6

8,3

41,80

35,98

30,62

25,71

21,22

17,18

0,05

0,09

0,14

0,21

0,30

0,39

82,41

76,11

70,40

65,22

60,56

56,38

0,003

0,006

0,012

0,020

0,031

0,046

86,62

78,13

69,68

61,27

52,90

44,57

0,002

0,005

0,012

0,025

0,048

0,087

-90,16

-89,83

-89,51

-89,21

-88,91

-88,63

589,5

404,5

289,1

213,8

162,8

127,2

113,04

104,93

96,86

88,82

80,80

72,82

0,0003

0,0009

0,0022

0,0048

0,0098

0,0187

-38,07

-40,60

-43,08

-45,49

-47,84

-50,14

14,78

15,08

15,29

15,42

15,49

15,51

Therefore, Na3AlF6 is the most reasonable to use for dehydrogenization when submerged arc welding as if compared with fluorite.

Having taken into account the aforementioned preconditions, we have developed a technology of submerged arc welding with carbonaceous additives. As the basis of carbon and fluorine containing additive we took metallurgical production wastes. It was dust with the following chemical composition (mass %): Al2O3 = 21 – 46.23; F = 18 – 27; Na2O = 8 – 15; К2O = 0.4 – 6; CaO = 0.7 – 2.3; SiO2 = 0.5 – 2.48; Fe2O3 = 2.1 – 3.27; C = 12.5 – 30.2; MnO = 0.07 – 0.9; MgO = 0.06 – 0.9; S = 0.09 – 0.19; P = 0.1 – 0.18. Mineralogical makeup of dust was determined according to the data of X-ray structural analysis made by difractometer DRON-2 in the mode: Fe – K α radiation, voltage 26 kV, electrical current 30 mA. The research into the dust of electrostatic precipitators revealed that the material consisted of bidimensionally ordered carbon (d0O2=3.47Å, Lc=45.8Å), X-ray amorphous substance, cryolite, corundum, hyolithe, and various admixtures. Diffraction patterns of roasted at 700°С material demonstrate no indication of graphite, that is caused by nearly complete burning out of carboncontaining mass in this temperature range, as well as significant curve flattering on the diffraction pattern, and decrease in X-ray amorphous substance. The reason of the latter is probably chemical MMSE Journal. Open Access www.mmse.xyz 8

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

composition of X-ray amorphous substance, which carbon compounds are main components of. At 700°С the change in indication intensity of mineralizing components (cryolite, corundum, X-ray amorphous substance, fluorite, hematite and various admixtures) was recorded.

From the theoretical point of view the additive makes possible: 1) dehydrogenization by fluorinecontaining compounds (like Na3AlF6,), decomposing at the temperatures of welding processes and isolating fluorine, which combines with dissolved in steel hydrogen and forms gaseous HF; 2) intensive carbon “boiling” due to forming CO and CO2, when fluoric carbon CFx (1 ≥x>0) combines with dissolved in steel oxygen, here, as carbon is in a bound state steel carbonization is hardly possible; 3) improvement of arc stability due to potassium and sodium, facilitating ionization in arc column.

To make an additive to flux carbon and fluorine containing substance was mixed with liquid glass, then this mixture was dried, cooled down and grinded. Afterwards this additive was mixed with flux in a special mixer according to a definite, strictly determined proportion. АN-348А, АN-60, АN-67 fluxes were taken as basic ones and their mixtures with flux-additives.

The experiments were carried out on 200  500 mm 09Mn2Si steel samples 16 mm in thickness.

Fay welding of butt joints was made on two sides, as when welding wall plates of tanks on roll facility. Sv-08Mn wire 5 mm in diameter was used as a filler metal.

Submerged arc welding of samples was made in similar modes. The samples were cut of welded plates and subject to the following tests: X-ray spectral analysis of weld metal chemical composition, metallographic tests of welds; total concentration of oxygen in welds, mechanical properties, strength of joint welds and impact strength of welds were determined at temperatures 20°С and -40°С. Concentration of carbon, sulphur, phosphorus was determined in chemical composition of weld metal by chemical methods in terms of GOST 12344-2003, GOST 123452001, and GOST 12347-77, respectively. Concentration of alloying elements in weld metal; that of calcium oxide, silicon, manganese, aluminum, magnesium, ferrum, potassium, sodium and fluorinecompounds in fluxes with additives and slag, obtained after welding was determined by SHIMADZU roentgen-fluorescent spectrometer XRF-1800.

The experiments demonstrated that maximum 6% carbon and fluorine containing additive provided carbon concentration in weld similar to its concentration in original metal (Figure 1), whereas concentration of oxygen, hydrogen and nitrogen dropped (Figures 2, 3, 4).

Fig. 1. Influence of carbon and fluorine containing additive on carbon concentration in a weld MMSE Journal. Open Access www.mmse.xyz 9

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

Metallographic research into polished sections of joint welds was carried out by optical microscope OLYMPUS GX-51 in bright field and zooming ×100, ×500. The microstructure of metal was found out by etching in 4 % HNO3 solution in ethanol. The structure of base metal in all samples consists of ferrite grains and lamellar pearlite (4-5 µm). In base – to – added metal zone a fine-grain structure occurs (1-2 µm), which was formed as the result of re-crystallizing when heating in course of welding. In the microstructure of a weld there are ferrite grains stretched towards heat rejection because of heating and speeded up cooling down. Structures of welds didn’t differ much irrespectively of used fluxes. The level of impurity by non-metallic substances decreased in samples, which were welded with fluxing agents, containing carbon and fluorine additives; it was caused by reduction of total oxygen concentration.

Fig. 2. The change in oxygen in dependence on carbon and fluoride containing additive concentration

Fig. 3. The change in hydrogen in dependence on carbon and fluorine containing additive

The research into mechanical properties (yield point, strength, modulus of elongation, impact strength at temperatures below zero) carried out on cut according to GOST 6996-66 samples, demonstrated that the level of properties went beyond the values required in GOST 31385-2008 and MMSE Journal. Open Access www.mmse.xyz 10

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

increased as the concentration of carbon and fluorine containing additive rose. Increasing impact strength KCV and KCU at temperatures -20°С and -40°С, respectively (Figures 5, 6) is worth mentioning. Flux-additives, which were developed, have been protected by the Russian Federation patents [12, 13].

Fig. 4. The change in nitrogen in dependence on carbon and fluorine containing additive

Fig. 5. The change in impact strength KCV at temperature -20°С in dependence on carbon and fluorine containing additive.

Summary. 1. On the ground of made calculations and carried out experiments we can conclude that carbon containing additives to welding fluxes are possible and promising ones in order to improve welding and technological characteristics of welded metalware.

2. The probability of dehydrogenization of a weld in fluorine containing submerged arc welding has been assessed thermodynamically in the temperature range 1700 – 2200 К. Here, Na3AlF6l, SiO2l, SiF4g, NaAlO2s, Na2SiO3l, CaF2l, CaSiO3 s, H2г, SiF2g, HFg, О2g, SiFg, Hg. were selected as standard states for substances - reagents. In terms of calculation of standard Gibbs energy reactions it has been found out that the reaction of gaseous hydrogen fluorine direct formation by cryolite is thermodynamically the most probable one, the second probable is the group of reactions resulting in MMSE Journal. Open Access www.mmse.xyz 11

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

formation of silicon tetrafluoride as an intermediate product for further HF formation. In this group the most thermodynamically probable reaction is that of SiF4 with hydrogen and oxygen. In terms of calculations Na3AlF6 is more reasonable to use for dehydrogenization when submerged arc welding in comparison to fluorite.

Fig. 6. The change in impact strength KCV at temperature -40°С in dependence on carbon and fluorine containing additive 3. Introduction of developed carbon and fluorine containing additive into fluxes АN-348А, АN-60 and АN-67 reduces gas content of a weld, the level of impurity by oxide non-metallic substances, and improves required mechanical properties and impact strength (at temperatures below zero, especially).

References [1] Study of the relationship between the composition of a fused flux and its structure and properties/ Amado Cruz Crespoa, Rafael Quintana Puchola, Lorenzo Perdomo Gonzáleza, Carlos R. Gómez Péreza, Gilma Castellanosa, Eduardo Díaz Cedréa & Tamara Ortíza / Welding International.

– 2009. - Volume 23. - №2. - p. 120-131 [2] Using a new general-purpose ceramic flux SFM-101 in welding of beams/ Yu. S. Volobueva, O. S. Volobueva, A. G. Parkhomenko, E. I. Dobrozhelac & O. S. Klimenchuk // Welding International.– 2012.- Volume 26. - №8. - p. 649-653 [3] Special features of agglomerated (ceramic) fluxes in welding / V. V. Golovko & N. N. Potapov // Welding International. – 2011.- Volume 25. - №11. - p. 889 - 893.

[4] The influence of the air occluded in the deposition layer of flux during automatic welding: a technological aspect to consider in the quality of the bead / Rafael Quintana Puchola, Jeily Rodríguez Blancoa, Lorenzo Perdomo Gonzaleza, Gilma Castellanos Hernándeza & Carlos Rene Gómez Péreza // Welding International. – 2009.- Volume 23. - №2. - p. 132-140.

[5] Obtaining a submerged arc welding flux of the MnO–SiO2–CaO–Al2O3 – CaF2 system by fusion / A.C. Crespoa, R.Q. Puchola, L.P. Goncaleza, L.G. Sanchezb, C.R. Gomez Pereza, E.D.

MMSE Journal. Open Access www.mmse.xyz 12

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

Cedrea, T.O. Mendeza & J.A. Pozola//Welding International.– 2007.- Volume 21. - №7. - p. 502511.

[6] Reaction of non-organic substances / R.А. Lidin, V.А. Molochko, L.L. Andreeva – М.: Drofa, 2007. – 637 p.

[7] Manufacture of vertical bulk –oil storage tanks for northern climates using special welding materials/ Kryukov N.E., Koval'skii I.N., Kozyrev N.A., Igushev V.F., Kryukov R.E.// Steel in Translation. -2012. - Т. 42. -№ 2.-P. 118-120.

[8] Thermodynamical properties of substances: Reference book. V.1. Issue 1 / Edited by V.P. Glushko, L.V. Gurvich et al. M.: Nauka, 1978. pp. 22.

[9] Welding materials for arc welding: СReference book in 2 volumes. V. 1. Shielding gases and welding fluxes: Konishchev B.P., Kurlanov S.А., Potapov N.N. et al. / Edited by Potapov N.N. М.: Machinebuilding, 1989 – pp. 104.

[10] John L. Haas, Jr., Gilpin R. Robinson, Jr., and Bruse S. Hemingway // J. Phys. Chem. Ref. Data. – 1981. – Vol. 10. – № 3. – P. 575 – 669.

[11] NIST-JANAF Thermochemical Tables 1985. Version 1.0 [Electronic resource] : data compiled and evaluated by M.W. Chase, Jr., C.A. Davies, J.R. Dawney, Jr., D.J. Frurip, R.A. Mc Donald, and A.N. Syvernd. – Available at: http://kinetics.nist.gov/janaf.

[12] Patent 2467853 RF, МPК 8 V23 К35/362 Ceramic flux-additive / Kryukov N.Е., Kovalsky I.N., Kozyrev N.А., Igushev V.F., Krykov R.Е.; Open Joint Stock Company ОАО «Novokuznetsk Plant of Reservoir Metalware» named after N.E. Kryukov.- № 201112341602/02(034654), Application 08.06.2011.

[13] Patent 2484936 PF, МPК 8 V23 К35/362 Ceramic flux-additive / Kozyrev N.А., Igushev V.F., Kryukov R.Е., Goldun S.V.; FSBEI HPE “Siberian State Industrial University”.№2012104939/02(007484), Application 13.02.2012.

MMSE Journal. Open Access www.mmse.xyz 13

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

Influence Voltage Pulse Electrical Discharge In The Water at the Endurance Fatigue Of Carbon Steel I.A. Vakulenko1, a, A.G. Lisnyak2, b 1 – Department of Materials Technology, Dnepropetrovsk National University of Railway Transport named after Academician V. Lazarian. Street. Lazarian, 2, Dnepropetrovsk, Ukraine, 49010, Tel. 38 (056) 373 15 56, ORCID 00000002-7353-1916 2 – Department "The technology of mining machinery" Dnepropetrovsk National Mining University, pr. Karl Marx, 19, Dnepropetrovsk, Ukraine, 49027, Tel. 38 (0562) 46 99 81, ORCID 0000-0001-6701-5504 a – dnuzt_texmat@ukr.net b – aleklisn@gmail.com

Keywords: hardness, distribution, impuls pressures, electric digit, limited endurance

ABSTRACT. Effect of pulses of electrical discharge in the water at the magnitude of the limited endurance under cyclic loading thermally hardened carbon steel was investigated. Observed increase stamina during cyclic loading a corresponding increase in the number of accumulated dislocations on the fracture surface. Using the equation of CofinoManson has revealed a decrease of strain loading cycle after treatment discharges. For field-cycle fatigue as a result of processing the voltage pulses carbon steel structure improvement, followed by growth of limited endurance decrease per cycle of deformation. With increasing amplitude of the voltage loop gain stamina effect on metal processing voltage pulses is reduced. The results can be used to extend the life of parts that are subject to cyclic loading.

Introduction. In the process of cyclic loading of carbon steel, the extent, to which the cycle amplitude exceeds fatigue limit, affects the character of structural change considerably [2]. For this reason, the rate of increase in the number of crystalline defects, and evenness of their distribution in the metallic matrix are the determinants of the conditions of the fatigue damage sites formation in metals and alloys [14]. Considering that, dislocations are basic carrier units of plastic deformation [3], the possibility of purposeful control over the process of their growth and redistribution under the fatigue loading can be considered a promising direction of development of the measures on improvement of the finite life. The information on the use of electric pulse effects [6, 10] in the carbon steel after a certain degree of plastic deformation can serve as example. As a result, there was such a change in the internal structure of a metallic material, which was required to achieve a desired set of properties.

Status of the problem. At the certain stage of the development of metal materials processing technology, in the production of complex shapes, especially of plate stock of considerable size, they detected certain difficulties in the implementation of the technical solutions. One of the ways to solve this problem was the proposal to use the shock wave resulted by an electric discharge in liquid [4].

Based on numerous studies [4‒8], it was found that this technology allows not only the manufacturing of products by the formation of a complex deformed state but also managing a range of properties. Based on this, we can confidently assume that the value of the energy of pulse loading, its momentum distribution [7, 13] may significantly change the result to be achieved.

Considering the existence of a certain threshold dependence of the impulse of voltage being formed, MMSE Journal. Open Access www.mmse.xyz 14

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

it is possible to obtain the result of different quality, ranging from the reinforcing effect to the metal weakening [4, 11, 12]. In most cases, the effect of hydraulic shock caused by the electric discharge in liquid for many metallic materials has reinforcing nature [4, 5], which is supposed to be followed by the change in the number of accumulated dislocations. Thus, if the effect has reinforcing nature, the increase in the dislocation density may be expected. Considering that the result depends on a large number of individual factors, the cumulative effect often leads to qualitatively opposite results. For example, the rise of the stress wave amplitude increases the number of dislocations [4].

On the other hand, the pulse length largely determines the conditions for the movement of the dislocation structures. Most of the known experimental data concerns the study of the influence of the electric discharge shock waves in liquid on the properties of metallic materials under static loading [5]. Based on this, we can confidently assume that the assessment of the impact of this effect on the behavior of the metal under the fatigue is quite an important issue.

Purpose. Assessment of the impact of voltage impulses of the electric discharge in liquid on the behavior pattern of carbon steel under fatigue loading.

Methodology. The carbon steel of the railway wheel pair axle with 0.45% carbon content was the material under research. The content of other chemical elements corresponded to the grade composition. The samples for alternating bending test under symmetric loading cycle were metal sheets of 1 mm thick, 15 mm wide and 180 mm length. The samples were subjected to martensite quenching and tempering at 300°C, for 1h. The analysis of the fracture surfaces was performed using a scanning electron microscope and fractography techniques; the dislocation density was evaluated by X-ray methods [1].

Metal fatigue testing was performed under alternating bending under symmetric loading cycle by means of the ten-station test machine “Saturn-10”. Electrical discharge impulse action on the samples of steel in water was performed by the “Iskra-23”, with the amplitude of the voltage to a maximum of 2 GPa. The total number of pulses was about 10 4 , at the frequency of 2-3 Gts. Results. Selection of the structural state of steel after martensite quenching and subsequent tempering at 300°C was driven by the possibility of achieving, under the high density of dislocations, enhanced values of fatigue resistance of a metal under cyclic loading. From the analysis of the internal structure of the metal, it follows that after quenching and tempering at 300°C, there the stages occur in the process of dispersed carbide particles liberation at the dislocations, both in the middle and at the boundaries of martensite laths. Besides, as follows from the results of studies [9], the development of dislocation recombination processes resulting in a decrease in their total amount should always result in the lowering of their mobility. Therefore, we can confidently assume that most of the dislocations that have appeared in the metal as a result of mentioned thermal treatment are immobile to different extents.

The analysis of the shock stress treatment effect on the fatigue behavior of a metal was carried out in a particular sequence. Fatigue curve was build first, for the samples that had undergone the thermal treatment (Fig. 1, curve 1), by which the finite life of the metal was determined. Further, the newly prepared samples were loaded, under the corresponding amplitudes of the cycle to the level of 0.6‒0.7 of the value of the finite life. Then they were subjected to the shock stress. Further, the cyclic loading continued until the final destruction of the samples. Finite life value is the total number of cycles including the number of cycles before the shock stress treatment and after it, up to the final destruction of the sample (Fig. 1, curve 2).

The analysis of fatigue curves shows the expected difference in the evolution of the fine crystalline structure of the metal depending on the treatment applied. Indeed, for the similar amplitudes of loading there is a clear increase in the fatigue resistance of the metal that has been subjected to the shock wave impulse.

MMSE Journal. Open Access www.mmse.xyz 15

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

a,

Ряд2; 0,2; 120 Ряд1; 0,2; 110 Ряд2; 0,25; 100

2

Ряд1; 0,25; 93 Ряд2; 0,35; 90 Ряд1;10,35; 75

Ряд2; 0,7; 80

Ряд1; 0,7; 60

N i  10 6 cycle.

Fig. 1. The diagrams of cyclic loading steel 45 after tempering and annealing at 300  C (♦) and after treatment of SS (■).(Stress straik).

To explain the observed increase in the finite life of the metal, the dislocation density was estimated by the interference (110) and (211) on the fracture surfaces of the samples.

Regardless of the treatment (before and after the shock stress), the decrease in the amplitude of the cycle is followed by the accumulation of the amount of dislocations in the volume of metal under plane-strain loading. The absolute values of  (hkl) are of great interest. Thus, during cyclic loading at high amplitude the absolute values of the dislocation density at the fracture surface of the samples are almost the same. It can be explained by the fact that under high cyclic overstress the formation of elementary shifts within the structural element of steel causes significant plastic deformations localization, simultaneously with the rapid transition of the metal to the plane-strain condition.

Further, during the subsequent decrease of  a the increase in the accumulated number of dislocations occurs, with the rate of increase  211 that is significantly higher than the corresponding value 110 (Fig. 2, a).

The nature of the changes of  211 and 110 (Fig. 2, a) corresponds to the known experimental data for metal loading under unidirectional static and cyclic loading [2].

By treatment of the metal that had been subjected to the preliminary cyclic loading (up to 0.6-0.7 of the value of the finite life with certain  a ) by shock wave impulses, we have received the qualitative differences in the nature of the change of the dislocation density on the investigated interference (Fig. 2, b). The received level of absolute values:  211 is less than 110 , and their change rate with the decrease of  a appeared quite unexpected.

In order to explain the nature of the observed effect of the shock stress on the finite life under cyclic loading, we analyzed the fracture surface of the samples.

MMSE Journal. Open Access www.mmse.xyz 16

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

 ( hkl),  1010 см 2

a , а)

 ( hkl),  1010 см 2

Ряд1; 80; 21

Ряд2; 80; 14

Ряд1; 90; 15 Ряд1; 120; 13 Ряд2; 90; 11

Ряд1; 100; 10 Ряд2;

Ряд2; 120; 10

a , b) Fig.2. The change of dislocations density, estimated on interferences (110) - ♦ and (211) - ■ depending on amplitude of cyclic loading and preliminary treatment: without SS (a) and after SS (b).

The general analysis of fracture pattern in the samples after 256  10 3 cycles with the amplitude of 950 MPa (Fig. 3) shows that the surface of fracture was formed by a mixed mechanism. It is indicated by the presence of chips inside grains (Fig. 3, A) and formation of the faceted surfaces of intergranular fracture (Fig. 3, B) at the fracture surface.

The mechanism of formation of the chips inside grains is associated with the high overload along the cycle. The first phase of structural changes caused by the emergence of elementary shifts within MMSE Journal. Open Access www.mmse.xyz 17

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

the individual grains due to the movement of the unevenly distributed dislocations. Randomly oriented shifts lead to the rapid partition of the grain into pieces, the boundaries of which are the series of microcavities. The fatigue microcracks appear and extend along the specified boundaries due to the local low resistance of the metal [15]. In the case of discrepancy of surfaces of the simultaneously growing microcracks, in the places where they meet, a step or another boundary appears that separates the other fragments (light lines in Fig. 3).

Fig.3. Fractographic investigation of the sample after the 260x. ďƒ— 10 3 cycles at an amplitude of 950 MPa.

Formation of the facets of intergranular fracture has a different mechanism. Instead of the chip within the grain, due to the reduction of the cyclic overload in individual grains, the microcavities appear near the angle boundaries, which reduces the bond between individual grains in the metal.

Moreover, the movement of dislocations near the large angular boundaries for several crystallographic systems results in a series of vacancies. Under the influence of cyclically varying loads in the metal, the areas accumulating the vacancies near the grain boundaries turn into volumes with high concentrations of microcavities, along which the fatigue crack grows. The more detailed analysis shows additional features, which indicate the participation of other failure mechanisms in the formation of the fracture. In fact, there are dimples ( F ) on the fracture surface. These elements of the structure of the fracture surface explain the emergence of a significant number of microcracks ( E ), which grow mostly at the ferrite grain boundaries. Based on this, it can be assumed that the sample loading conditions with an amplitude of 950 MPa correspond to low-cycle fatigue, with the finite life of 256 thousand of cycles.

The reduction of the amplitude to 750 MPa is followed by the expected prolongation of finite life (up to 350 thousand of cycles). The analysis of the fracture surface (Fig. 4) testifies to the mixed mechanism of fracture just as under higher amplitude of loading. While under 950 MPa, the fracture

MMSE Journal. Open Access www.mmse.xyz 18

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

surface is formed mainly due to the chips inside grains and formation of the faceted surfaces of intergranular fracture, under 750 MPa the chips inside grains do not appear (Fig. 4, в, A label).

Fig.4. Fractographic investigation of the sample after 370 x10 3 cycle at an amplitude of 750 MPa.

The formation of the separation areas with the crests, which look like the light lines (Fig. 4, A label), and the intergranular fracture facets (B label) with a significant dispersion should be considered the dominating mechanism of the fracture surface formation. The sign that confirms the fatigue resistance improvement is the fewer number of decompositions and microcracks. At the same time, the number of pits of different sizes and shapes increased; this indicates an increase in the number of microcavities in the plane of the growing crack. Moreover, on the surface of the fracture, the occurrence of the sites with an equidistant arrangement of lines can be observed. The lines have external characteristics similar to fatigue striations (C label). Based on the analysis of the fracture it can be assumed that under the loading amplitude of 750 MPa the behavior of the sample corresponds to the conditions of low-cycle fatigue with the signs explaining the increase in the number of cycles to failure.

After the shock stress processing of the samples, the fracture surfaces have a slightly different structure (Fig. 5).

According to the external characteristics, the elements of the fracture surface (Fig. 5) has been formed by the mixed mechanism with almost the same range of particle dimensions as compared to the sample that has not undergone the shock stress (Fig. 3). The fracture pattern analysis (Fig. 5) shows the absence of the signs indicating the chip formation within the grains, which was observed in Fig. 3. At the same time, a considerable part of the fracture surface is occupied by the facets of intergranular fracture (Fig. 5, A label). There is approximately the same number of micro-cracks as in the sample that has not undergone the shock stress (Fig. 3), which are located along the grain boundaries (Fig. 5, B label), decompositions (C), separation areas with the crests (D) and dimples (F).

MMSE Journal. Open Access www.mmse.xyz 19

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

Fig. 5. The fracture surface of the sample with an amplitude 1000 MPa, after the total number of 260 x10 3 cycle with UN interim treatment.

As for the presence of the fatigue striations as in the case of the sample shown in Fig. 3, it is quite difficult to determine uniquely, although there are similar sections (E). By means of the comparative analysis of the fracture surfaces and the obtained level of finite life, it is quite difficult to determine the influence of shock stress for the high-stress low-cycle region. On the other hand, it is known that in proportion to the degree of cyclical overload the influence of the static component on the development of fatigue phenomena increases. The static component that determines the effect of the deformation and precipitation hardening treatment on the structural changes, in fact, can mask the effect of the shock stress treatment. The confirmation of the above explanations may be received under the lower degree of the cyclic overload.

Fig. 6 presents the fracture pattern of the sample that survived 370 thousand cycles at an amplitude of 900 MPa, which has undergone the intermediate shock stress processing. In comparison to the sample with the same number of cycles to failure but without shock stress treatment (Fig. 4), the degree of dispersion of the fracture elements that has undergone the shock stress is higher. Firstly, the facets formed on the fracture surface have a more equiaxial shape (Fig. 6, a, A label). Compared to the fracture surface of the sample shown in Fig. 4, there are large areas with very small dimples (Fig. 6, b, B label); their formation mechanism is based on the coagulation of microcavities [2]. At the same time, there is a certain number of facets with crests of separation (C) and equidistant arrangement of the metal decomposition (D), with a low number of the facets of intergranular fracture (E). In the case of reduction of the test results to the equal cycle amplitude, the finite life of the metal after the shock stress treatment increases by about 30 %.

Summary. The voltage impulse treatment of metal produced by the electric discharge in water contributes to the increase of finite life of the carbon steel under cyclic loading. With the rise of the cycle amplitude, the gain in fatigue resistance resulted by the shock stress declines.

MMSE Journal. Open Access www.mmse.xyz 20

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

Đ°)

b) Fig. 6. The fracture surface of the sample with an amplitude of 900 MPa, after the total number of 370 x103 cycle with UN interim treatment.

References [1] Gine A. Rentgenografiya kristallov [Roentgenography of crystals]. Moscow, Gosudarstvennoye izdatelstvo fiziko-matematicheskoy literatury Publ., 1961, 604 p.

MMSE Journal. Open Access www.mmse.xyz 21

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

[2] Nott Dzh.F. Osnovy mekhaniki razrusheniya [Fundamentals of fracture mechanics]. Moscow, MetallurgiyaPubl., 1978. 256 p.

[3] Yefremenko V.G., Murashkin A.V., Ivanchenko Ye.P. Sovershenstvovaniye sostava i termicheskoy obrabotki staley dlya nozhey kholodnoy rezki listovogo prokata [Improvement of composition and heat treatment of steels for knives for cold cutting of sheet metal]. Stal – Steel, 2007, no. 1, pp. 75-77.

[4] Meyers M.A., Murr L.B. Udarnyye volny i yavleniya vysokoskorostnoy deformatsii metallov [Shock waves and phenomena of high-rate deformation of metals]. Moscow, Metallurgiya Publ., 1984. 510 p.

[5] Chachin V.N. Elektrogidravlicheskaya obrabotka mashinostroitelnykh materialov [Electrohydraulic processing of engineering materials]. Minsk, Nauka i tekhnika Publ., 1978. 184 p. [In Russian] [6] Yao K-F., Wang J., Zheng M. A research on electroplastic effects in wire-drawing process of an austenitic stainless steel. Scripta Materialia, 2001, vol. 45, issue 15, pp. 533-539. doi: 10.1016/s1359-6462(01)01054-5.

[7] Ait Aissa K., Achour A., Camus J. Comparison of the structural properties and residual stress of AIN films deposited by dc magnetron sputtering and high power impulse magnetron sputtering at different working pressures. Thin Solid Films, 2014, vol. 550, pp. 264-267. doi: 10.1016/j.tsf.2013.11.073.

[8] Conrad H. Effects of electric current on solid state phase transformations in metals. Materials Science and Engineering : A, 2000, vol. 287, issue 2, pp. 227-237. doi: 10.1016/s09215093(00)00780-2.

[9] Dhadeshia H.K.D.H. Bainite in Steels. Cabridge, The University Press Publ., 2001. 454 p.

[10] Vakulenko I.A., Nadezdin Yu.L., Sokirko V.A. Electric pulse treatment of welded joint of aluminum alloy.Nauka ta prohres transportu. Visnyk Dnipropetrovskoho natsionalnoho universytetu zaliznychnoho transportu– Science and Transport Progress. Bulletin of Dnipropetrovsk National University of Railway Transport,2013, no. 4 (46), pp. 73-82. doi:10.15802/stp2013/16584.

[11] Tang G., Zhang J., Zheng M. Experimental study of electroplastic effect on stainless steel wire 304L.Materials Science and Engineering : A, 2000, vol. 281, issue 1-2, pp. 263-267. doi: 10.1016/s0921-5093(99)00708-x [12] Morgan W.L., Rosocha L.A. Surface electrical discharges and plasma formation on electrolyte solutions. Physics of Low-Temperature Plasmas, 2012, vol. 398, pp. 255-261. doi: 10.1016/j.chemphys.2011.06.037.

[13] Razavian S.M., Rezai B., Irannajad M. Numerical simulation of high voltage electric pulse comminution of phosphate ore. Intern. Journal of Mining Sci. and Tech., 2015, vol. 25, issue 3, pp.

473-478. doi:10. 1016/j.ijmst.2015.03.023.

[14] Vakulenko I.A., Proydak S.V. The Influence Mechanism of Ferrite Graine Size on Strength Stress at the Fatigue of Low-Carbon Steel. Nauka ta prohres transportu. Visnyk Dnipropetrovskoho natsionalnoho universytetu zaliznychnoho transportu – Science and Transport Progress. Bulletin of Dnipropetrovsk National University of Railway Transport, 2014, no. 1 (49), pp. 97-104. doi: 10.15802/stp2014/22668 [In Russian].

MMSE Journal. Open Access www.mmse.xyz 22

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

Aluminum Composites With Small Nanoparticles Additions: Corrosion Resistance L.E. Agureev1a, V.I. Kostikov2, Zh.V. Eremeeva2, A.A. Barmin3, S.V.Savushkina4, B.S. Ivanov5 1 – Researcher, Department of Nanotechnology, Keldysh Research Center, Russia 2 – Doctor of Science, Associate Professor, Moscow State University of Steel and Alloys, Russia 3 – Ph.D., Leading Researcher, Department of Nanotechnology, Keldysh Research Center, Russia 4 – Ph. D., Senior Researcher, Department of Nanotechnology, Keldysh Research Center, Russia 5 – Engineer, Department of Nanotechnology, Keldysh Research Center, Russia a – trynano@gmail.com

Keywords: nanometric particles, aluminum composites, PM method, corrosion resistance. corrosion rate

ABSTRACT. Research of corrosion resistance of the aluminum powder composites containing microadditives (0.01 – 0.15% is executed about.) zirconium oxide nanoparticles. Extreme dependence of speed of corrosion of aluminum composites in 10-% solutions of sulfuric and nitric acid from the maintenance of nanoadditives is shown. It has been shown the dynamics of mass loss of aluminum composites with nanoparticles of ZrO 2 during corrosion tests in acids solutions. The lowest corrosion rate of 3.36 mm/a of nitric acid was observed in the sample containing ZrO2 0.01 vol.% nanoparticles. For the case of sulfuric acid with the best result of 2.21 mm/a showed the material with 0.05 vol.% nanoadditive.

Introduction. Nanotechnologies allow to create the strong and lightweight materials steady against various aggressive influences. Influence of nanoparticles on structure of material is caused by high superficial energy. There is a huge number of the works devoted to creation of composite materials, both with metal, and with a ceramic matrix, the nanoparticles strengthened by various concentration [1-7]. The light and strong materials, like aluminum alloys, for creation of various bearing designs of spacecraft have high value For astronautics [8-11]. In many works, the researchers conducted the development of aluminum composites containing nanoparticles of different nature in concentrations of more than 5 vol.%. It is rarely possible to find work devoted to low concentrations of nanoadditives in aluminum [12-18]. This work is dedicated to the creation of aluminum composites with small amounts (0.01-0.15 %vol.) of nano-oxide ZrO2 by powder metallurgy techniques.

Attention to small concentrations of the nanoparticles was based on the following provisions: – high surface energy of nanoparticles; – ease of uniform distribution of small amounts of nanoparticles and their disaggregation within the matrix; – high impact of nanoparticles on the structure and properties of interfacial layers (matrix-MFSnanoparticle).

The theory of irreversible processes and catastrophe theory say that small changes of operating parameters can jump the most important characteristics of the system [19,20]. Nanoparticles possessing high superficial energy, brings it in material and to interphase layer, influencing MMSE Journal. Open Access www.mmse.xyz 23

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

functional characteristics of composite in one direction or another. In this regard, a researcher separate issue is the determination of threshold effects of nanoparticles on the material and the search for the optimal technology of its receipt, depending on performance requirements.

The objective of the work was creation of aluminum composites, hardened with small additions of metal oxide nanoparticles like ZrO2, and determination of its corrosion resistance in acids solutions.

According to ideas of a number of famous scientists on the structure and properties of an interphase layer in solids nanoparticles having a high surface energy and making changes to structure of a matrix, even at very small concentration at the level of 0.001-0,. about. % can cardinally change characteristics of material [21-24]. In tab. 1 influence of nanoparticles on properties of materials is briefly explained.

1. Experimental procedure. The charge used: as a matrix - aluminum powder with mean diameter of 4 μm (ASD-4, "SUAL", Russia), as reinforcer - nanopowder of zirconia (dav = 50 nm, Ssp = 32 m2/g), Keldysh Research Center, Russia). The technology of preparation of composites consisted in the following. At the beginning aluminum powder was sieved through a sieve with a cell of 14 microns, then mixed with alcohol in a ratio of 1:4. Then, placed in an ultrasonic bath while stirring the mixture by rotary stirrer. Nanoparticles dispersed in ultrasound, after which the dispersion was added to the stirred alumina powder in alcohol. Quantity of nanoadditives varied from 0.01 to 1.5 vol.% Mixing lasted for 20-40 min. Drying of suspensions took place on air at a temperature of 60 ° C within 24 hours. The resulting blend compressed into a cylindrical mold with a pressure of 400 MPa. Next, sintering was performed in forevacuum at 640 ° C during 120-180 minutes.

The corrosion resistance was measured as follows. The total exposure time of samples was 15 hours. Samples were weighed prior to the experiment and during the measurements on scales up to 4-th sign. Samples were immersed in 10% solution acid (nitric acid or sulfuric acid). The difference in mass (primary - to experiment and obtained by checkweighing) was determined by mass loss of samples and plotted on it. At each check weighing and date recorded.

By results of tests of samples of aluminum composites for corrosion resistance values of speed of corrosion (γ) on a formula were calculated [25]:



x  365  24 , mm/a,  1000

where x1 – mass loss rate, g/(m2∙h); ρ – density of material, g/cm3.

2. Results and discussions. The results are shown in Fig. 1-4. Particularly interesting is the results on corrosion resistance in a solution of nitric acid. The lowest rate of mass loss of 3.36 mm/a was observed in the sample containing nanoparticles of ZrO2 0.01 vol.% . For the case of sulfuric acid with the best result of 2.21 mm/a showed the material with 0.05 vol.% of the nano-additive.

The worst level of resistance in H2SO4 showed a sample with 0.15 vol.% of nanoparticles. Perhaps this is due to the number and size of the brought defects (cavities) by mixing aluminum powder with nano-additives . Nevertheless, it should be noted that all of the samples in comparison with pure aluminum sintered showed considerably greater resistance to corrosion in both acid solutions.

While first (pure aluminum) at all dissolved in nitric acid after 15 hours and in sulfuric through 10.

MMSE Journal. Open Access www.mmse.xyz 24

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

Fig. 1. The dependence of the aluminum composites corrosion rate of the content nanoparticles ZrO2 (test in a 10-% nitric acid solution).

Fig. 2. Composites mass loss over time in a solution of nitric acid.

Summary. Samples of aluminum composites with ZrO2 nanoparticles were examined for corrosion resistance in 10-% solutions of nitric acid and sulfuric acid. The lowest corrosion rate of 3.36 mm/a of nitric acid was observed in the sample containing ZrO2 0.01 vol.% nanoparticles. For the case of sulfuric acid with the best result of 2.21 mm/a showed the material with 0.05 vol.% nano-additive.

Acknowledgements. Authors thank collectives NITU "MISIS" and Keldysh Research Center for the help in development of aluminum composites.

MMSE Journal. Open Access www.mmse.xyz 25

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

Fig. 3. The dependence of the aluminum composites corrosion rate of the content nanoparticles ZrO2 (test in a 10-% sulfuric acid solution)

Fig. 4. Composites mass loss over time in a solution of sulfuric acid.

References [1] Berestenko V.I., Torbov V.I., Torbova O.D. Poluchenie ul'tradispersnyh poroshkov dioksida cirkonija v plazme SVCh razrjada. Tezisy dokladov IV Vsesojuznogo simpoziuma po plazmohimii, g. Dnepropetrovsk, 1984 g., s. 59-60. - Berestenko V.I., Torbay V.I., Torbova O.D. Getting ultrafine powders of zirconia in microwave plasma discharge. Abstracts of IV All-Union Symposium on Plasma Chemistry, Dnepropetrovsk, 1984, p. 59-60. [In Russian] [2] Kevorkijan, V.M. Aluminum composites for automotive applications: a global perspective / VJVL Kevorkijan // JOM; -19991- â„–11.- P. 54- 58.

MMSE Journal. Open Access www.mmse.xyz 26

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

[3] Tang, F. The microstructure-processing-property relationships in an A1 matrix composite system reinforced by Al-Cu-Fe alloy particles / Thesis D.Ph. -Iowa State University. - Ames, Iowa.

- 2004.

[4] Kang Y.C., Chan S.L.-I. Tensile properties of nanometric Al2O3 particulate-reinforced aluminum matrix composites // Materials chemistry and physics, 85, 2004. P. 438-443.

[5] Ma Z.Y., Tjong S.C., Li Y.L. et al. High temperature creep behavior of nanometric Si3N4 particulate reinforced aluminium composite .// Materials Science and Engineering, A225, 1997. -P. 125-134.

[6] Mazahery A., Osfadshabani M. Investigation on mechanical properties of nano-Al2O3reinforced aluminum matrix composites .// Journal of Composite Materials, 45 (24), 2011. -P. 25792586.

[7] Roduner Je. Razmernye jeffekty v nanomaterialah. –M.: Tehnosfera, 2010. -252 s.- E. Roduner size effects in nanomaterials. -M .: Technosphere, 2010. -252 p. [In Russian] [8] Kostikov V.I., Varenkov A.N. Sverhvysokotemperaturnye kompozicionnye materialy. –M.: Intermet Inzhiniring, 2003. -560 s. - Kostikov V.I., Varenko A.N. Ultra high temperature composites. -M .: Intermet Engineering, 2003. -560 p. [In Russian] [9] Tehnologija proizvodstva izdelij i integral'nyh konstrukcij iz kompozicionnyh materialov v mashinostroenii./ Nauchnye redaktory A.G.Bratuhin, V.S.Bogoljubov, O.S.Sirotkin. –M.: Gotika, 2003. -516 s.- The production technology and integrated manufacturing of composite structures in mechanical engineering. / Scientific Editors A.G.Bratuhin, V.S.Bogolyubov, O.S.Sirotkin. -M .: Gothic, 2003. -516 p. [In Russian] [10] Pilotiruemaja jekspedicija na Mars./ Pod red. A.S.Koroteeva. –M.: Rossijskaja akademija kosmonavtiki imeni K.Je.Ciolkovskogo, 2006. -320 s. - Manned expedition to Mars. / Ed. A.S.Koroteeva. -M .: Russian Academy of Cosmonautics Tsiolkovsky, 2006. -320 p. [In Russian] [11] Alifanov O.M., Andreev A.N., Gushhin V.N. i dr. Ballisticheskie rakety i rakety-nositeli. –M.: Drofa, 2004. -512 s. - Alifanov OM, Andreev AN, VN Gushchin and others. Ballistic missiles and launchers. -M .: Bustard, 2004. -512 p. [In Russian] [12] Kalashnikov, I.E. Razvitie metodov armirovanija i modificirovanija struktury aljumomatrichnyh kompozicionnyh materialov [Tekst]: avtoref. dis. na soisk. uchjon. step. dokt.tehn.nauk (05.16.06)/ Kalashnikov Igor' Evgen'evich; IMET RAN. –Moskva, 2011. -26 s. Kalashnikov IE Development of methods of reinforcement and modification of the structure of aluminum-matrix composite materials [Text]: Author. Dis. on soisk. Kazan. step. dokt.tehn.nauk (05.16.06) / Kalashnikov Tamm; IMET RAS. -Moscow, 2011. -26 p. [In Russian] [13] Kurganova, Ju.A. Razrabotka i primenenie dispersno uprochnjonnyh aljumomatrichnyh kompozicionnyh materialov v mashinostroenii [Tekst]: avtoref. dis. na soisk. uchjon. step. dokt.tehn.nauk (05.16.06)/ Kurganova Julija Anatol'evna; IMET RAN. –Moskva, 2008. -26 s.Kurganova, Y. Development and application of dispersion hardened aluminum-matrix composite materials in engineering [Text]: Author. Dis. on soisk. Kazan. step. dokt.tehn.nauk (05.16.06) / Kurganova Juliya; IMET RAS. -Moscow, 2008. -26 p. [In Russian] [14] Grigorovich V.K., Sheftel' E.N. Dispersionnoe uprochnenie tugoplavkih metallov. –M.: Nauka, 1980. -302 s.- Grigorovich V.K., Sheftel E.N. Precipitation hardening refractory metals. -M .: Nauka, 1980. -302 p. [In Russian]

MMSE Journal. Open Access www.mmse.xyz 27

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

[15] Sliney N.E. Kompozicionnye materialy dlja podshipnikov i uplotnitelej gazovyh turbin // Sovremennoe mashinostroenie, 1991, №3, s. 175-201. - Sliney N.E. Composite materials for bearings and seals of gas turbines // Modern Machinery, 1991, №3, p. 175-201. [In Russian] [16] Sliding, wear response of an Al - Cu alloy the influence of SiC particle reinforcement and test parameters / Prasad B.K., Jha A.K., Modi O.P., Das S., Dasgupta R., Yegneswaran A.N. // J.Mater.

Sci. Lett.- 1998.-17, № 13, p. 1121-1123.

[17] Hosking F.M., Portillo F., Wunderlin R., Mehrabian R. Composites of aluminum alloys; fabrication and wear behaviour // J.Mater.Sci. -1982.- 17, №2. P.477-498.

[18] Rohatgi P. Cast aluminum - matrix composites for automotive applications // JOM. -1991. - 43, №4.- P.10-16.

[19] Prigozhin I., Nikolis G. Samoorganizacija v neravnovesnyh sistemah: Ot dissipativnyh struktur k uporjadochennosti cherez fluktuacii. –M.: Mir, 1979. -512 s.- Prigogine I., Nicolis G. Selforganization in nonequilibrium systems: From dissipative structures for ordering through fluctuations. -M .: Mir, 1979. -512 p. [In Russian] [20] Arnol'd V.I. Teorija katastrof. Teorija katastrof. «Sovremennye problemy matematiki.

Fundamental'nye napravlenija. T. 5(Itogi nauki i tehniki VINITI AN SSSR». –M., 1988, s. 5-218. Arnold V.I. Catastrophe Theory. Catastrophe Theory. "Contemporary Mathematics. Fundamental Directions. T. 5 (Results of Science and Technology VINITI. "-M., 1988, pp. 5-218. [In Russian] [21] Obrazcov I.F., Lur'e S.A., Belov P.A. i dr. Osnovy teorii mezhfaznogo sloja. Mehanika kompozicionnyh materialov i konstrukcij, 2004, t. 10, №3, s. 596-612.- Samples IF, Lurie SA, Belov PA et al. Basic theory of the interfacial layer. Mechanics of Composite Materials and Structures, 2004, v. 10, №3, p. 596-612. [In Russian] [22] Tajra S., Otani R. Teorija vysokotemperaturnoj prochnosti materialov. –M.: Metallurgija, 1986. -280 s.- Taira S., R. Otani theory of high-strength materials. -M .: Metallurgy, 1986. -280 p.

[In Russian] [23] Chuvil'deev V.N. Neravnovesnye granicy zjoren v metallah. Teorija i prilozhenija. –M.: FIZMATLIT, 2004. -304 s.- Chuvildeev VN Non-equilibrium grain boundaries in metals. Theory and Applications. -M .: FIZMATLIT, 2004. -304 p. [In Russian] [24] Ohji T., Jeong Y.-K., Choa Y.-H., Niihara K. Strengtheing and toughening mechanisms of ceramic nanocomposites .// Journal of American Ceramic Society. - 1998. - №81. - P. 1453-1460.

[25] Handbook of Corrosion Data / Ed. by B.D.Craig, D.S.Anderson. – Ohio: ASM International, 998 p.

MMSE Journal. Open Access www.mmse.xyz 28

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

II. Mechanical Engineering & Physics Performance Optimization of a Gas Turbine Power Plant Based on Energy and Exergy Analysis Ghamami M.1, a, Fayazi Barjin A.1, Behbahani S.1 1 – Department of Mechanical Engineering, Isfahan University Technology, Isfahan, Iran a – Mghamazi@ut.ac.ir

Keywords: Gas turbine, Exergy, Multi-objective, optimization, Fireflies algorithm, thermoflow.

ABSTRACT. The purpose of this study is energetic and exergetic analysis of combined cycle power plant, study of the variables that affect the efficiency and performance and provide a solution to improve the efficiency and performance of the gas turbine. Therefore, after modeling gas cycle, the impact of environmental conditions and performance of gas turbine cycle will be checked, eventually we achieve two objective optimization of gas cycle that optimized by firefly algorithm in six cold months of the year. The objective functions are exergy efficiency and cost of the gas cycle maintenance, fuel cost and destroyed exergy cost. The proposed optimized result show increase in net output power of the gas cycle, energy and exergy efficiency and decrease in air pollution amount.

Introduction. Gas turbine is one of the power generating machines that have been widely used in various industries such as power plants, refineries and oil and gas industries. Since a high percentage of the power requirements of the country, is provided in the gas power plants and due to the fact that fossil fuels are the energy requirements of these power plants, thus the performance improvement of these power plants is very important. From about 70 years before gas turbines have been used to generate electricity, in the last twenty years the production of these type of turbines has increased by twenty times. Thermodynamic Simulator of gas cycle and combined cycle, is a useful tool to predict the behavior of each components of the cycle, by which the basic parameters of the processes in the cycle can be obtained. Exergy analysis is a good way to evaluate the quality of the energy with the aid of laws of conservation of mass and the first law of thermodynamics, and is on the basis of the second law of thermodynamics. The tool is used for design, analysis and optimization of thermal systems. The main objective of exergy analysis, finding solutions to eliminate or reduce thermodynamic defects in the processes. We can reduced exergy destruction by identifying the irreversibility factors and situation. Many studies have been done in this field, research done in this field can be mentioned the following: Siddiqui et al. [1] In their article they simulated a 100 MW gas cycle of one of the power plants in Iran is hot and dry regions ,by thermoflow software ,and investigated the effect of steam injection into the combustion chamber based on the exergy concept in order to improving gas turbine cycle.

Sadeghi et al. [2] they studied and simulated the effects of light and heavy fuel on operational parameters of the gas turbine and combined cycle in Kazeroon power plant.

Kim and Hwang [3] examined the performance of a gas turbine with recovery in half-load situation, by considering and comparing different mechanisms to control the turbine. Salary et al. [4] have studied exergy analysis of 112 MW Power Plant in Ahvaz Zergan. They optimized the cycle by MMSE Journal. Open Access www.mmse.xyz 29

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

increasing the turbine inlet temperature in terms of energy and exergy. Abdul Khaliq [5], used exergy method to analyze gas turbine cycle with inlet air cooling and has shown that most exergy destruction occurs in the combustion chamber, he also showed that by use of cooling the compressor inlet air, energy efficiency and the cycle Exergy will be increased. Ehyaei et al. [6] at the same time studied exergic, economic and enviromental analysis affected by Fog cooling system in the gas cycle of Rajayee power plant. Sanaye and Jafari [7] work in optimizing field, they have examined effect of inlet air cooling in gas turbine cycle by absorption refrigeration. The twoobjective optimization of the system is done by the genetic algorithm. kaviri et al. [8] have done thermodynamic modeling and two-objective optimization of a combined cycle power plant. Ahmadi [9] study on thermodynamic analysis of a gas cycle power plant and obtained best design parameters by using multi-objective optimization.

In this study, energetic and exergetic analysis of gas turbine power plants have done and solutions to improve efficiency and performance of gas turbine are suggested. Factors affecting the efficiency of power plants have been studied and finally variables to improve the efficiency of power plants have been selected.

Exergy (or ability to perform work). The maximum work that a system may do during a reversible process from initial state to reach a dead end is called exergy. Exergy of a system in a given state depends on environmental conditions and system properties, and for a control volume, it’s equal to or reversible work with a dead end. Exergy has potential, physical and chemical components. For the steady flow devices, kinetic and potential exergy can be assumed to be zero.

The sum of physical and chemical exergy, is called thermal exergy [10].

ex  ex Ph  ex Ch

(1)

Physical exergy is defined by Equation 2.

ex Ph  (h  ho ) To (s  so )

(2)

Chemical exergy of mixtures is obtained from equation (3) [11]. ̅​̅​̅

∑

̅​̅​̅

(̅

)∑

̅​̅​̅​̅

( ),

(3) (4)

Exergy analysis by using of the first and second laws of thermodynamics on the components of a system, makes it possible to identify the place and production of irreversibility and unfavorable thermodynamic process of the system, In this way, in addition to evaluate the different components of thermodynamic cycle, approaches to increase efficiency and output are identified [13].

Efficiency of Thermodynamic Second Law (Exergic efficiency). The first law efficiency is defined by an ideal isentropic process that never happens in practice. It makes no mention of the best case, and isn't sufficient to measure the actual system performance alone. To assess the deviation from the best possible processes, second law efficiency is defined. The second law efficiency determines how much work ability or potential used in a process [11]. In fact, it determines how much of exergy given to the system, by a process is achieved and how much of it is wasted in the form of irreversibility. The second law efficiency is defined the ratio of useful exergy MMSE Journal. Open Access www.mmse.xyz 30

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

to exergy input and output intensity of irreversibility is defined as (5) the difference between output exergy and input exergy [13]. ̇

̇

(5) ̇

(6)

Thermodynamic Modeling of gas cycle and power plant. Thermodynamic modeling of gas cycle power plant have been done by using thermodynamic relations. Plant that studied in this paper, included 4 gas unit manufactured by Mitsubishi Japan MW-701D models with nominal capacity of each is 128.5 MW and in total 514 megawatts. By installation of 4 retriever boilers and two steam turbo generator that each has nominal capacity of 100 MW, power plant Transformed to combined cycle power plant. In order to simulate the combined cycle power plant, we set the data related to environmental conditions (Table 1).

Table 1. Environmental condition in power plant Environmental condition

Value

Temperature

31 centigrade

Pressure

0.8964 bar

Relative humidity

RH=29%

Above sea level

1022 meter

Thermoflow software is one of the most powerful software in design and analysis of power plant cycles, which is capable to model various stages of the power plant, including thermodynamic analysis, engineering design and simulating equipment. Combined cycle block consists of two gas turbines, two recovery boilers and a steam turbine. By choosing Siemens W701 D engine which is available in the software engines, combined cycle block is simulated in normal loads and in software. Table 2 shows the software output.

Table 2. Power plant output in normal times (90%) Type of gaseous fuel cycle

Natural gas

Gas oil

Net power output of the plant (kW)

526576

520844

Plant heat rate (kJ/kWh)

7894

7948

Plant thermal efficiency (%)

45.6

45.3

In order to verify the results of the software simulation, the values obtained from the simulation and actual data are compared in Table 3.

Figure 3 shows the flow of incoming and outgoing energy to one block in combined cycle of power plant, also, it shows where the input fuel energy is intended in terms of heat value of fuel. Input energy consists of latent and sensible energy of air and chemical energy of fuel. Most thermal losses is related to the condenser, because discharges the heat taken from the cooling water to the environment. After condenser most heat losses is related to the exhaust flue gas that is at about 118 Celsius degrees, which enters too much heat into the environment without using them.

MMSE Journal. Open Access www.mmse.xyz 31

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

Fig. 1. Operating parameters plant in case of 90% load

Fig. 2. Performance and placement components of HRSG plant in case of 90% load In tables 3, net output power is expressed in kilowatts (kW) scale and heat rate is expressed in kJ / kWh scale. The rate is expressed on a scale of kilograms per second (kg/s). By comparing the study results provided by the simulation and power plant results it can be seen that there is a good adaption between the results. In six cold months (October to the end of April), due to a dramatic reduction in household electricity consumption compared with six warm months of the years, the demand for electricity from power plants in the country declined. The main priority in the six cold months, is increase in exergy efficiency of gas cycle and reduce the annual cost.

MMSE Journal. Open Access www.mmse.xyz 32

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

Fig. 3. Diagram of Energy flow (input and output plant power) Table 3. Data comparing of power plant in case of 90% load Parameter

Software simulation

Power plant

Net power output

532250

526576

Heat Rate

7883

7894

-0.14

Thermal efficiency (%)

45.67

45.6

+0.15

Fuel flow

6.361

6.35

+0.11

Air flow

339.1

338

0.11

The compressor pressure ratio

12.27

12.2

0.57

Turbine pressure ratio

11.29

11.2

0.8

Turbine inlet gas temperature (K)

1387.9

1385

0.21

Error )%( +1.08

With the increase in air temperature, the gas turbine and the compressor's power reduces, due to the more steep decline of power in gas turbine compared with the compressor, the net output power of the gas cycle is reduced. With the increase in air temperature, mass flow of gas turbine exhaust gases reduces, less steam is produced in the recovery boiler and there will be a total loss in power of steam turbine. By reducing the power of steam-gas cycle, the net output of power plant appear with declined more sharply. For one degree Celsius rise in ambient air temperature, pure output power of the gas cycle, steam turbine and power plant will averagely reduce 0.63 and 0.27 and 0.53, respectively. Comparison between output powers with respect to temperature is shown in Figure 4.

MMSE Journal. Open Access www.mmse.xyz 33

Mass flow rate of air entering the compressor [kg/s]

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

365 360 355 350 345 340 335 330 325 320 315 5

8,5

12

15,5

19

22,5

26

29,5

33

36,5

40

Environment temperature [C]

Fig. 4. Special compressor pressure ratio and can shift with ambient temperature Optimization. After reviewing the parameters affecting the performance of plants, defining optimization problem based on target functions and parameters can be done. Optimization problem in finding answers or solutions on a set of possible options aimed at improving the standard or standards of the issue. Multi-objective optimization problem arise from the decision-making methods in the real world that one decision maker faces a set of contradictory and conflicting objectives and criteria. In these types of issues, unlike the single-objective optimization problems and because of the multi-purpose (often conflicting), rather than just a solution optimized set of questions arises.

In the multi-objective optimization, after the introduction of design variables and determine the objective functions, optimal points are determined and the impact of design on objective functions are provided. Many factors affect the performance of gas turbine, therefore, gas turbine cycle has many ways to improve the performance of the industry. Each of these methods has different effects on output power, efficiency and specific consumption of fuel. The selection of a particular method according to plant type, climatic conditions, work area, how it affects the performance of the project cycle, and measures will be considered. Some of the most important factors affecting the operation of the gas turbine are: • Pressure ratio • Compressor inlet temperature • Compressor efficiency • The compressor intake • Turbine inlet temperature • Turbine efficiency • Output power of turbine • Fuel air ratio • Mass flow rate As can be seen in Figure 5, with increasing ambient air temperature, compressor pressure ratio reduces. As well as the temperature increases, air density decreases, resulting in a greater volume of air should be particularly dense, and the special power of compressor will increase.

MMSE Journal. Open Access www.mmse.xyz 34

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

Special power

Compressor pressure ratio

13,2

380 375 370 365 360 355 350 345 340 335 330

13 12,8 12,6 12,4 12,2 12 11,8 11,6 11,4 5

8,5

Special power compressors [kW / kg / s]

Pressure ratio

12 15,5 19 22,5 26 29,5 33 36,5 40 Environment temperature [C]

Fig. 5. Change in net output power cycle gas and steam turbine power plants with ambient temperature For one degree Celsius increase in temperature, compressor pressure ratio and special averaged power increases 0.24 percent and 0.25 percent respectively. Gas turbine is power generation system at constant volume. By increasing the ambient air temperature and constant air pressure in a fixed volume, density and mass flow rate of air flow is reduced, resulting in reduced compressor inlet mass. Figure 6 shows the compressor inlet air mass flow changes to show the changes in ambient temperature. For one degree Celsius rise in temperature, compressor inlet air flow is reduced by an average of 0.24 per cent.

TET

1119

550

1118

548

1117

546 544

1116

542

1115

540

1114

538

1113

536

1112

534

1111

532

1110

530 5

8,5

12

15,5

19

22,5

26

29,5

33

36,5

40

Exhaust turbine gas temperature [C]

Turbine inlet gas temperature [C]

TIT

Environment temperature [C]

Fig. 6. Chart compressor inlet air mass flow changes with temperature With the increase in air temperature, gas turbine inlet gas temperature increases due to the reduced amount of fuel and increase in air to fuel ratio. With increasing temperature due to increased temperature of the exhaust gases from the gas turbine inlet air temperature for cooling turbine blades increases. For one degree Celsius rise in temperature ambient air, intake and exhaust gas MMSE Journal. Open Access www.mmse.xyz 35

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

temperature of the turbine by an average of 0.4 degrees Celsius, respectively 0.17 ° C decrease and increase. Figure 7 shows the change in gas turbine inlet and outlet gas temperature than the ambient temperature shows.

GT GrossPower

ST Gross Power 111 108 105 102 99 96 93 90 87 84 81 78 75

Net power output (Plant) MW

310 300 290 280 270 260 250 240 5

8,5

12

15,5

19

22,5

26

29,5

33

36,5

Net power output (GT-ST) MW

Plant Net Power

40

Environment temperature [C]

Fig. 7. Gas turbine exhaust gas temperature changes graph input and ambient temperature Differences between the energy and exergy system can be expressed as follows [12].

1. Energy just relates to the system condition and the mass flow but exergy in addition to those conditions is dependent on environmental conditions.

2. The amount of energy in the dead system may also have an amount, but the exergy in a dead system is always zero.

3. Energy for all the processes are subject to the law of survival, and is stated in the form of the first law of thermodynamics but exergy is subject to survival only in reversible processes. In irreversible processes, always exergy a destroyed. Exergy, applies a combination of the first and second laws of thermodynamics to the review process.

4. Energy is only a quantitative measure for evaluating processes but exergy is both quantitative and qualitative measure.

5. Energy can be calculated with respect to each case assumptions but exergy basis mode is determined by environmental conditions.

After reading the parameters and variables on power plant performance optimization, optimization process takes place. Because of the simultaneous search of multiple points, no need for an explicit mathematical relationship between objective functions, the need for direct measurement and mathematical calculations needed to optimize the methods of analysis and generalization of random search algorithms, optimization of problem is done by random search algorithms.

The objective function. To compare the achieved considerable optimization problems we need to have a selection criterion. Such a measure, which plan is optimized and is a function of design variables, standard function, is called advantage function or objective function. In this study, the objective functions, exergy efficiency and costs related to gas cycle, and the optimal points represent the highest efficiency and lowest costs. Relation 6 and 7 show the first and second objective function, respectively.

MMSE Journal. Open Access www.mmse.xyz 36

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

OF1:Max OF2: Min ̇ ̇ ̇

(7)

̇

̇ ( ̇

̇ ̇

̇

(8)

)

(9)

̇

(10)

Net Output power of the gas cycle can be obtained as above.

Decision variables. Thermodynamic modeling inputs are decision variables and numbers represent degrees of freedom of the system. Decision variables change during the optimization process, but the parameters are fixed, but some parameters, are dependent parameters which is determined on the amount of basis of the decision variables. The variables which are specified in Table 4, are selected as the decision variables. In order to stay in the recovery boiler circuit, the gas turbine load is considered higher than 55%. Using thermoflow and EES software and range change in environmental conditions, according to the decision of the six variables in Table 1 and also taking into account the load percentage of the gas turbine in the range of 55 to 100% has been obtained.

Firefly algorithm. Firefly optimization algorithm or FA for short is inspired of the natural behavior of fireflies which live together in large collections, and was introduced for the first time in late 2008

by Xin-She Yang [14], this multi-agent algorithms can be a solution of hard optimization problem and it is a very efficient algorithm for solving combinatorial optimization problems.

In summary, the performance of the algorithm is that the number of artificial fireflies (initial population) are randomly distributed in the range and then emits light of a firefly which intensity is proportional to the amount of optimality point Firefly is that it is located. The light intensity of each firefly regularly intensity compared to other fireflies and fireflies brighter too faint to be absorbed.

At the same time the brightest fireflies also aims to increase the chances of finding the optimal solution is the global accidentally move. In this algorithm, exchange information with each other through the light emission occurs. The composition of this combined action makes the overall trend towards a more efficient is fireflies.

Table 4. Optimization variables and their ranges Variable interval

Variable

Compressor pressure ratio Isentropic efficiency turbine Isentropic efficiency compressor Compressor inlet mass flow rate (kg/s)

̇

The output of the gas turbine combustion pressure (bar) Gas turbine inlet temperature (K)

( )

Optimization Results. Given the equations required optimization objective functions according to the decision made and the six variables in MATLAB fireflies algorithm code was used to optimize MMSE Journal. Open Access www.mmse.xyz 37

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

(Millions of dollars) costs

the objective function. The primary population for the first generation is considered 200. In the multi-objective optimization instead of an optimal point, we have an optimal solution that is optimized to the famous pareto point and the set of these points are called pareto front. Figure 8 shows the pareto front of the optimization objective functions, including optimal points. As can be seen by increasing the efficiency of the gas cycle exergy, it also increases annual costs.

6,8 6,6 6,4 6,2 6 5,8 5,6 5,4 5,2 5 4,8 4,6 4,4 4,2 4

C

B A

0,26

0,27

0,28

0,29

0,3

0,31

0,32

0,33

0,34

0,35

Exergy efficiency (%)

Fig. 8. Pareto Front of the first objective functions (cost) for six months Selection the desired optimization of energy systems based on multi-objective optimization decision-making ideas happen after the search. Each individual decision-maker may be due to considerations in mind, their own scenario is to select the optimal point. Pareto front of the optimization objective function shows that the costs for the six months is considered. The results, show minimal costs during the year should be paid for a certain exergy efficiency, and most exergy efficiency that can be achieved for a certain fee during the year. Figure 9 shows the net profit for the six months according to exergy efficiency. Net profit, the difference between the proceeds from the sale of electricity and the cost of the cycle ( CTot ) is obtained. The price of electricity purchased from power plants 0.15 Dollar/kWh is considered [13]. Pareto front of net profit of the previous stage results are plotted in Figure 9.

In Figure 10, the net profit in the six months according to exergy efficiency has been showed in gas cycle power plant. The price of electricity purchased from power plants is intended 0.3 Dollar/kWh. Table 5 Three optimal point A, B and C compared with each other. Given the priority of each objective function optimal point can be selected.

In table 5, net output power and destroyed exergy are in megawatts scale (MW) and amounted net profit is expressed in millions of dollars scale for both 0.15 and 0.3 dollar per Kilowatt hours (dollar/kWh) of generated electricity.

Summary. The main goal of this study was to evaluate and improve the performance of gas cycle power plant in different environmental conditions. The analysis results show that the greatest destruction exergy of gas cycle power plant is happening in the combustion chamber. That reason is high temperature difference between the temperature of the flame and fluid. Much of this destruction exergy is inevitable that cannot be reduced, so exergy efficiency of power plants has been studied and other ways use to reduce the exergy destruction.

MMSE Journal. Open Access www.mmse.xyz 38

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

(Millions of dollars) net profit

1,2

B

1 0,8

C

0,6 0,4

A

0,2 0 0,26

0,27

0,28

0,29

0,3

0,31

0,32

0,33

0,34

0,35

Exergy efficiency (%)

Fig. 9. The change in net profit with electricity prices 0.15 Dollar/kWh

(Millions of dollars) net profit

10

C

9

B

8 7

A

6 5 4 3 0,26

0,27

0,28

0,29

0,3

0,31

0,32

0,33

0,34

0,35

Exergy efficiency (%)

Fig. 10. The change in net profit with electricity prices 0.3 Dollar/kWh Table 5. Comparison of the optimum Point A

Point B

Point C

Exergy efficiency (%)

26.7

31.3

34.5

Efficiency (%)

27.5

32.5

34.9

Net output power

68

90.7

114

Price Six months (millions of dollars)

4.3

4.9

6.4

Exergy destroyed

104

120

141

Net profit price of electricity: 0.3

0.05

0.9

0.9

Net profit price of electricity: 0.15

4.4

6.7

8.3

MMSE Journal. Open Access www.mmse.xyz 39

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

Firefly algorithm has been optimization algorithm in gas cycle power plant. Objective functions are exergy efficiency and cost, cost include the gas cycle maintenance costs, fuel cost and the cost of exergy demolition, highest efficiency exergy and lowest cost are requirements. The results show that by increasing the efficiency of the gas cycle exergy, its cost also increased. Lower temperature reduces emissions and steam quality in the recovery boiler and steam turbine power output is reduced as a result. To remedy this problem, the use of gas turbine exhaust duct burner is recommended. In this case, the temperature of the exhaust gas from the turbine should exceed the temperature of HRSG design.

The study achievements can be cite to use of meta-heuristic algorithm in large search space, nonlinear variables and objective functions such as firefly algorithm. Because that limited studies have been done for examine ability and capabilities of this algorithms, this study is an opportunity to investigate the algorithm and its ability. Multi-objective optimization process has its own challenges and advantages. In the multi-objective optimization not only efficiency but also exergy cycle costs, including the cost of repair and maintenance, the cost of fuel and the cost of destruction exergy have been studied. Time-consuming optimization process is very important. Less computational time and iteration means less computational cost, by using of the optimal response of optimization algorithm, the net power output of the gas cycle power plants by as much as 11.15 and 8.08 percent, energy efficiency and exergy cycle gas 3.64 and 3.61 respectively percent and air emissions, 0.77 percent decrease. This study also examines changes in environmental conditions and levels of load on the gas cycle power plant, Technical and economic assessment, energy and exergy analysis using the first and second law of thermodynamics can be mentioned. As well as alternative ways to reduce destruction exergy and increase exergy efficiency are reviewed.

Thermoflow Software can calculate the pollutions of the turbine gas output. It is suggested that the impact of changing load levels and the effect of cooling system of air entering to compressor will be investigated in order to predict exhaust pollutions of gas turbines.

Reference [1] Siddiqi H, Bayati Gh,Tvakoli A, Fotoohi D, "simulated cycle 100 MW gas and steam injection into the combustion chamber 'exergetic analysis and energetic", conferences energy efficiency, conferences Institute of Technology, Tehran, (2010).

[2] Sadeghi H, Haghighi khoshkhor V, Tanasan M, Moosavian M, "Simulation of the thermodynamic effects of non-gaseous fuels on the performance and efficiency of combined cycle power plant", the twenty-seventh International Conference on Electric Power Research Institute, Inc. Tavanir, Tehran, (2012).

[3] Kim T, Hwang S.H, “Part load performance analysis of recuperated gas turbines considering engine configuration and operation strategy”, J.of.Energy, 31, pp. 260-277, (2006), doi: 10.1016/j.energy.2005.01.014 [4] Salari M, Hashemi Sh, Zayer noori M, "Exergy and Exergy Economic Analysis Zargan Gas Power Plant in Ahvaz", the first International Conference on Energy Planning and Management, Institute for Research in Energy Planning and Management, Faculty of Tehran University,(2006).

[5] Khaliq A. and Dincer I, “Energetic and exergetic performance analyses of a combined heat and powerplant with absorption inlet cooling and evaporative aftercooling”, J.of.Energy, 36, pp. 26622670, (2011). doi:10.1016/j.energy.2011.02.007 [6] Ehyaei M. and Mozafari A. and Alibiglou M, “Exergy, economic & environmental (3E) analysis of inlet fogging for gas turbinepower plant”, J.of. Energy, 36, pp. 6851-6861, (2011), doi:10.1016/j.energy.2011.10.011

MMSE Journal. Open Access www.mmse.xyz 40

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

[7] Sanaye S, Jafari s, "Optimizing the objective cycle gas turbine inlet air cooling by absorption chiller", Second International Conference of chiller and cooling tower, energy Ham Andyshan Kimia, Tehran, (2011).

[8] Kaviri A. and Jaafar M. and Lazim th, “Modeling and multi-objective exergy based optimization of a combined cycle power plant using a genetic algorithm”, J.of.Energy Conversion and Management, 58, pp. 94-103, (2012), doi:10.1016/j.enconman.2012.01.002 [9] Ahmadi P. and Dincer I, “Thermodynamic and exergoenvironmental analyses, and multiobjective optimization of a gas turbine power plant”, J.of.Applied Thermal Engineering, 31, pp.

2529-2540, (2011), doi:10.1016/j.applthermaleng.2011.04.018 [10] Cengel Y. and Boles M, “Thermodynamics an Engineering Approach”, Vol. 5, McGraw-Hill, (2005).

[11] Bejan A. and Tsatsaronis G. and Moran M, “Thermal Design and Optimization”, Vol. 1, Wiley-Interscience, (1995).

[12] Shapiro H. and Munson B. and Moran D, “Introduction to Thermal Systems Engineering: Thermodynamics, Fluid Mechanics, and Heat Transfer”, Vol. 1, Wiley, (2002).

[13] Power Research Institute, Deputy optimize energy consumption, and productivity studies office productivity sources of energy organization of Iran (SABA), the archives information plant.

[14] Yang, X-S., “Nature-Inspired Metaheuristic Algorithm”, Luniver Press, (2008).

MMSE Journal. Open Access www.mmse.xyz 41

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

Certain Solutions Of Shock-Waves In Non-Ideal Gases Kanti Pandey1, a & Kiran Singh1 1 – Department of Mathematics & Astronomy, Lucknow University, Lucknow, 226007, India a – pandey_kanti@yahoo.co.in

Keywords: Shock waves, Non-ideal medium, AMS Classification

ABSTRACT. In present paper non similar solutions for plane, cylindrical and spherical unsteady flows of non-ideal gas behind shock wave of arbitrary strength initiated by the instantaneous release of finite energy and propagating in a nonideal gas is investigated. Asymptotic analysis is applied to obtain a solution up to second order. Solution for numerical calculation Runga-Kutta method of fourth order is applied and is concluded that for non-ideal case there is a decrease in velocity, pressure and density for 0th and II-nd order in comparison to ideal gas but a increasing tendency in velocity, pressure and density for Ist order in comparison to ideal gas. The energy of explosion J0 for ideal gas is greater in comparison to non-ideal gas for plane, cylindrical and spherical waves.

1. Introduction. The assumption that the medium is an ideal gas is no more valid when the flow takes place in extreme conditions. Anisimov & Spiner [1] studied a problem of point explosion in low density non ideal gas by taking the equation of state in a simplified form which describes the behaviour of medium satisfactorily. Robert’s & Wu [2] studied the gas that obeys a simplified Vander Waal’s equation of state.

Vishwakarma et al. [3] have investigated the one dimensional unsteady self-similar flow behind a strong shock, driven out by a cylindrical or spherical piston in a medium which is assumed to be non-ideal and which obey the simplified Vander-Waal’s equation of state as considered by Robert’s & Wu [2]. However, they have assumed that the piston is moving with time according to law given

by Steiner & Hirschler [4]. Madhumita & Sharma [5] have considered the model equation for a low density gas, which describes the behavior of the medium satisfactorily for implosion problems where the temperature for implosion problems were the temperature attained by the gas motion in the strong shock limit is very high. Pandey & Pathak [6] have discussed growth and decay of sonic waves in non-ideal gases. In present paper using asymptotic expansion an attempt is made to obtain non-self similar solution of shock-waves in non-ideal gas. For numerical calculation Runge Kutta method is applied .In preparation of graphs Origin 7.5 is used.

2. Basic Equations The basic equations describing a cylindrically symmetric (α= 1) or a spherically symmetric (α = 2) motion of a non-ideal gas can be written as:  (u  ) u    0, t r r

(2.1)

u u 1 p u  0 t r  r ,

(2.2)

(r  E ) {r  u ( E  p)}  0 t r ,

(2.3)

MMSE Journal. Open Access www.mmse.xyz 42

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

where ρ is the gas density, u is the fluid velocity, p is the pressure and

E  e 

u2 2

,

(2.4)

is the total energy density with e being the internal energy density, the independent variables are the space co-ordinate r and time t: The equation of state characterizing the non-ideal medium is taken to be of the form

p

 RT , (1  b  )

where b is the internal volume of the gas molecules which is known in terms of the molecular interaction potential in high temperature gases, it is a constant with b ρ << 1. The gas constant R and the temperature T are assumed to obey the thermodynamic relations R  C p  CV and e  CV T , R is the specific heat at constant volume and γ is the ratio of specific heats. Thus (  1) in view of these thermodynamic relations, the equation of state can be written as

where CV 

p

 e(  1) .

(1  b  )

(2.5)

Expression for E, in view of equation (2.5) assumes the form p(1  b  )  u 2 .

E  (  1) 2

Using above value of E in equation (2.3), we have p p p  u  u  u      0. t r (1  b  )  r r 

(2.6)

Here α=0,1,2 corresponds to planar, cylindrical and spherical geometries respectively. The assumption of the instantaneous release of constant energy E0 at time t = 0 yields the energy balance equation:

 u2 1 p(1  b  ) p0 (1  b 0 )   E0  K    {  } r dr , 2 (  1)  0  0 S

MMSE Journal. Open Access www.mmse.xyz 43

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

where Kα= 2, 2π, 4 π for α= 0, 1, 2 and S represents the shock radius which is assumed to be zero at t = 0.

  S  1 r dr  . Thus energy balance 0 0 (  1) S

From Lagrangian equation of continuity we have equation transform into:

 S  u 2 p(1  b  )    K S  1 p0 (1  b 0 ) E0  K     .   r dr    (  1)  (  1)(  1) 0 2 

(2.7)

The conservation relations across the shock for the present problem can be written as:

0U  1 (U  u1 ) , p0  0U 2  p1  1 (U  u1 )2 ,

p0 (1  b 0 ) U 2 p1 p1 (1  b 1 ) (U  u1 ) 2      , 0 0 (  1) 2 1 1 (  1) 2 p0

(2.8) (2.9) (2.10)

where subscripts 1 and 0 refer to values immediately behind and ahead of the shock respectively and represents the shock velocity.

U

dS , dt

In following section we introduce the dimension less variables.

3. Transformation of Fundamental Equations in Non-Dimensional Form To transform fundamental equations, we consider principal of similarity & introduces new variables x and y in place of r and t as defined by Sakurai7 x

2 0

U2

r S

(3.1)

 y,

(3.2)

u=Uf(x ,y ),

(3.3)

0U 2 p (1  b 0 ) g ( x, y ) , 

(3.4)

  0 h( x, y) , where

MMSE Journal. Open Access www.mmse.xyz 44

(3.5)

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

 02 

 p0 0 (1  b 0 )

, r  Sx  dr  Sdx .

(3.6)

Thus  1  ,  r S x

(3.7)

D U      ( f  x)   y  , Dt S  x y 

(3.8)

where  dy      S  dS   y   

(3.9)

and λ is a function of y alone.

Substituting equations (3.1) to (3.8) in to fundamental equations (2.1), (2.2), (2.6), (2.7) and boundary conditions (2.8, 2.9, 2.10), equations (2.1), (2.2), (2.6) become

( f  x)

h h  f  f y  h   x y x  x

 , 

(1  b 0 ) g  f f  f  h  ( f  x)   y  ,  x y 2   x   g  ( f  x )

g g  g  f  f  y     x y (1  b 0 h)  x x  .

(3.10)

(3.11)

(3.12)

Equation (2.7) now become  1

S  y 0   S 

 hf 2 g (1  b 0 h)(1  b 0 )   (1  b 0 )2 y    , x dx  2  (  1)  (  1)(  1)  0 1

(3.13)

where 1

 E0  1 S0   .

2   K  0  0   Equations (2.8), (2.9), (2.10) now become as MMSE Journal. Open Access www.mmse.xyz 45

(3.14)

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

h(1, y) 

 1 ,   1  2b 0  2 y(1  b 0 )

(3.15)

h(1, y )  1 , h(1, y)

(3.16)

f (1, y ) 

g (1, y ) 

 (1  b 0 ) y   f (1, y )  .  (1  b 0 )   



(3.17)

Differentiating equation (3.11) with respect to y and using expression,

 hf 2 g (1  b 0 h)(1  b 0 )   x dx  J , 0  2   (  1)  1

(3.18)

 defined in equation (3.9) is given by (1  b 0 ) 2 y (  1) . dJ  J  y dy

 J (  1)  

(3.19)

4. Construction of Solution in Power series of y. While the shock waves are strong, the velocity U is large and y can be considered as small there, so that the quantities f; g; h can be expanded in rapidly convergent series of powers of y in following manner:

f  f (0)  yf (1)  y 2 f (2)  ...........

(4.1)

g  g (0)  yg (1)  y 2 g (2)  ...........

(4.2)

h  h(0)  yh(1)  y 2 h(2)  ..........

(4.3)

where f (i ) , g (i ) , h(i ) , (i = 0,1, 2,………) are all functions of x only . Inserting equations (4.1, 4.2, 4.3) in the expression (3.18), we have

J  J 0 1  y1  y  2  ..... , where

MMSE Journal. Open Access www.mmse.xyz 46

(4.4)

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

 h(0) f ( 0) (1  b 0 ) g (0) (1  b 0 )b 0 h(0) g (0)     x dx , (4.5) J0       2  (   1)  (   1) 0  (1) (0) (1) (1) (0) (1) (0) g (1  b 0 ) b 0 h g (1  b 0 ) b 0 h g (1  b 0 )   h f      x dx (4.6) 2  (  1)  (  1)  (  1)  2

1

1



0



1 J 0    h(0) f (0) f (1) 1

 2 J0   [ 0

(1  b 0 ) (2) 2 2 1 2h(0) f (0) f (2)  h(0) f (1)  2 f (0) f (1) h(1)  f (0) h(2)  g  b 0 h(0) g (2)  b 0 g (1) h (1)  b 0 g (0) h (2) ]x dx 2  (  1)









(4.7)

Using equation (4.4),the equation (3.13)becomes  1

S  y 0   S 

    (1  b 0 )2 2  J 0 1   1   y   2 y  ... ,  (  1)(  1) J 0    

(4.8)

Or in view of (3.1)  1

  0   S0  U   S      2

2 4      0  (1  b 0 )2  0   J 0 1   1     ..... .  2   (  1)(  1) J 0   U  U    

(4.9)

  Equation (4.9) is in form of power series in  0  , which gives a relation between propagation U  velocity U and the position of shock front S. If J 0 and  i are known  can be expanded in following form 2

    (1  b 0 ) 2 2   (  1) 1  y  1    2 2 y  .... .  J 0 (  1)(  1)    

(4.10)

If we use, for simplicity , the expressions

(1  b 0 )2 1   ,  J 0 (  1)(  1) 1

(4.11)

2 2  2 .

(4.12)

Equation(4.10)can be written as

  (  1)(1  1 y  2 y 2  .....) .

MMSE Journal. Open Access www.mmse.xyz 47

(4.13)

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

Now, substituting equations (4.1, 4.2. 4.3) and (4.13) in equation (3.10, 3.11, 3.12) and Comparing the Coefficients of the same powers of y on both sides of (3.10), ( 3.11), (3.12) we get the following system in equations: For zero-th power of y (Ist Approximation)

 f  h    x 

(f

 f  h    x 

(0)

(0)

(f

(0)

 f    x 

 g   ( f (0)  x)    x 

(0)

 g (0) 

 g   x)     x 

(0)

(0)

(0)

(0)

(1  b 0 )



 h   x)    x 

(0)



(  1) (0) (0) f h , 2

(4.14)

f (0) h(0) ,

(4.15)



 x



(0)

(1  b 0 h(0) )  (  1)b 0 g (0) h(0)  (  1) g (0) 

x

f (0) g (0) , (4.16)

For the first power of y (IInd Approximation)  (  1)  f (0)  (0) (1)  (  1) (0)  f   g  (1  b 0 )  f  ( f (0)  x)h(0)          h f   f  ( f (0)  x)    x  x  2  x 2         x    (1)

h

(0)

 f     x 

(1)

(1)

(f

(0)

 h   x)    x 

 g   g  (  1)1 g (0)    ( f (0)  x)  f (1)    x   x  (1)

 f  h(0) f (0)    x 

 f   h(0) f (1)    x 

(2)

(1)



 (  1) (0) (0) ,  h(1)  f h 1 2 

(4.17)

 h (0)  h(0)  (1)  f (0)  f (0)        (  1)  h(1) , (4.18)  f     x  x  x   x  

(1)

(0)

( 0)

(1) (0) (0)    g (0) f (1)  f (0) g (1)  g  (0)  f  (1)  f      ( f (0)  x)b 0 h(1)  (  1)b 0 g (0) h(1)   g     g    x x (1  b 0 h )   x   x   x  

2  f   h(0) f (2)    x 

1

(0)

 f   h(0) x    x 

(0)

2(  1) f (2) h(0)  1 (  1) f (1) h(0)  (  1) f (1) h(1) 

(2)

 f   h(1) f (0)    x 

(1)

 f   h(1) f (1)    x 

(0)

 f   h(2) f (0)    x 

(0)

(  1) (0) (2) (  1) (1) (1) (  1) (2) (0) (1  b 0 )  g  h f  h f  h f    2 2 2   x 

 f   h( 2) x    x 

(0)

 f   h (1) x    x 

(1)



(4.19)

(2)

For the second power of y (IIIrd Approximation)

h

(0)

f

(0)

 f     x 

 f  h(2) x    x 

(2)

 f  (0) 2 (2)  f    h f    x   x  (1)

h

(0)

f

(1)

(0)

 f   h x   x 

(2)

(0)

(0)

 2(  1) f (2) h(0)  1 (  1) f (1) h(0)  (  1) f (1) h(1) 

(1  b 0 )  g  (  1) (0) (2)  f h    2   x 

 h  f (0)    x 

(2)

 f  h(1)    x 

(1)

 h   f (1)    x 

(1)

 f   h(2)    x 



(0)

 f     x 

(1)

h f (1)

(1)

 f     x 

(0)



(  1) (2) (0) (  1) (1) (1) f h  f h 2 2

, (4.20)

(2)

 h   f (2)    x 

(0)

h f (1)

h f (0)

x

(2)

(0)



 h   x   x 

h f (1)

2

(1)

(2)



 f   2(  1)h(2)  (  1)1h(1)  h(0)    x 

h

(2)

f

(0)

x

MMSE Journal. Open Access www.mmse.xyz 48

(2)

, (4.21)

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

 g  b 0 f (0) h(2)    x   g   x2    x 

(2)

1 (  1) g

(0)

 g   g   b 0 f (0) h(1)    b 0 f (1) h(1)    x    x  (1)

(0)

 g   b 0 xh(2)    x 

(0)

 g   f (0)    x 

(2)

 b 0 (  1)h(2)  b 0 (  1)h(1) g (1)  b 0 (  1)1h(1) g (0)  b 0 (  1)h(1) g (1)  2(  1) g (2) (4.22) (1)

  g

(0)

 f     x 

(2)

 f   f    g     g (2)    x   x  (1)

(0)

(1)

In similar manner substituting equations (4.1, 4.2, 4.3) into equations (3.15, 3.16, 3.17), we have

f (0) (1) 

f (1) (1) 

f

2(1  b 0 ) ,  1

2(1  b 0 ) ,  1

(2)

g (0) (1) 

g (1) (1) 

2 ,  1

1  ,  1

h (0) (1) 

h (1) (1) 

 1   1  2b0

2(  1)(1  b 0 ) , (  1  2b 0 )2

4(  1)(1  b 0 ) 2 (1)  0, g (1)  0 , h (1)  , (  1  2b 0 )3 (2)

,

(2)

(4.23) (4.24)

(4.25)

If we take b=0, equations (4.14 – 4.16) with condition (4.23) coincides with the results obtained by Sakurai [7].

Fig. 1. Variation of velocity for zeroth order solution (plane wave) MMSE Journal. Open Access www.mmse.xyz 49

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

Fig. 2. Variation of velocity for zeroth order solution (cylindrical case)

Fig. 3. Variation of velocity for zeroth order (Spherical case)

MMSE Journal. Open Access www.mmse.xyz 50

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

Fig. 4. Variation of pressure for zeroth order solution (plane case)

Fig. 5. Variation of pressure for zeroth order solution (cylindrical case)

MMSE Journal. Open Access www.mmse.xyz 51

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

Fig. 6. Variation of pressure for zeroth order (spherical case)

Fig. 7. Variation of density for zeroth order

MMSE Journal. Open Access www.mmse.xyz 52

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

Fig. 8. Variation of velocity for the first order solution

Fig. 9. Variation of pressure for the first order solution

MMSE Journal. Open Access www.mmse.xyz 53

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

Fig. 10. Variation of density for the first order solution

Fig. 11. Variation of velocity for the second order solution 5. Result and Conclusion 1. For constant solutions, velocity, pressure and density varies linearly and for non-ideal case there is a decrease in comparison to ideal gas.

MMSE Journal. Open Access www.mmse.xyz 54

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

Fig. 12. Variation of pressure for the second order solution

Fig. 13. Variation of density for the second order solution 2. For first order solution velocity, pressure density all varies linearly, but as value of m (= bĎ 0) increases they are increasing in comparison to ideal gas.

3. For second order solution variation of velocity is linear. In plane case it is same for ideal as well as non-ideal case but as m increases there is a slight decrease for cylindrical and spherical case.

MMSE Journal. Open Access www.mmse.xyz 55

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

4. The energy of explosion J0 for ideal gas is greater in comparison to non ideal gas for plane, cylindrical and spherical wave.

Fig. 14. Variation of energy of explosion References [1] S. I. Anisimov and O. M. Spiner, Motion of an almost ideal gas in the presence of a strong point explosion, J. Applied Maths, Vol.36(No.5) (1972), pp.883-887.

[2] P. H. Robert and C.C. Wu, Shock wave propagation in a sonolu-minescing gas bubble, The American physical Society, Vol. 70 (No. 22) (1933), pp.3424-3427.

[3] J. P. Vishwakarma, Self-similar solution of a shock propagation in a non ideal gas. Int. J. of Applied Mech and Engineering, Vol. 12 (No.3) (2007), pp.813-829.

[4] H. Steiner and T. Hirschler, A self similar solution of a shock propagation in a dusty gas, Eur. J. Mech. B/Fluids, Vol. 21 (No.3) (2002), pp.371-380.

[5] Madhumita and Sharma, Imploding cylindrical and spherical shock waves in a non-ideal medium, Journ. of Hyperbolic dif. eq., Vol. 1(No.3) (2004), pp.521-530.

[6] K. Pandey and P. P. Pathak, Growth and Decay of sonic waves in non-ideal gases (Communicated for publication).

[7] A. Sakurai, On the propagation and structure of the Blast wave I, Journal of the Physical Society of Japan, Vol. 8 (No.5) (1953), pp.662-669.

MMSE Journal. Open Access www.mmse.xyz 56

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

Analytical Modeling of Transient Process In Terms of One-Dimensional Problem of Dynamics With Kinematic Action V.Kravets1a, K.Bas1, T.Kravets2 & L. Tokar1 1 – State Higher Educational Institution “National Mining University”, Dnipropetrovsk, Ukraine 2 – Dnipropetrovsk National University of Railway Transport, Dnipropetrovsk, Ukraine

a – prof.w.kravets@gmail.com

Keywords: material system, kinematics action, mathematical model, analytical solution, characteristic equation, dynamic design

ABSTRACT. One-dimensional dynamic design of a component characterized by inertia coefficient, elastic coefficient, and coefficient of energy dispersion. The component is affected by external action in the form of time-independent initial kinematic disturbances and varying ones. Mathematical model of component dynamics as well as a new form of analytical representation of transient in terms of one-dimensional problem of kinematic effect is provided. Dynamic design of a component is being carried out according to a theory of modal control.

Introduction. Analytical modeling is the essential stage of technical system dynamic design followed by computational and full-scale experiment [0, 0]. Analytical modeling of dynamic systems is based upon traditional mathematical methods of solutions of differential equation systems [0], theory of modal control [0], root-locus technique [0], and root-locus method [0].

Free motion dynamics of one-dimensional mechanical system experiences analytical study in a work by Kravets [0]; forced motion dynamics in terms of external dynamic effect was considered in a work by Kravets [0]. The paper models forced motion dynamics in terms of external kinematic effect.

Formulation of the problem. Fig.1 demonstrates dynamic scheme of one-dimensional mechanical system.

Fig. 1. Dynamic scheme of kinematic effect problem Here М and m are interacting masses, с is coefficient of elasticity, µ is damping coefficient.

It is assumed that M>>m. m mass is finite and specified. ( ) motion of m mass cannot effect a(t) motion of М mass. Notion of М mass is supposed as specified function of ( ) time. For example: ( ) = V0t where V0 is М mass velocity.

MMSE Journal. Open Access www.mmse.xyz 57

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

It is required to develop ( ) analytical solution modeling stable transient and determining steady motion of m mass depending upon such running design parameters of mechanical system as µ and c.

Mathematical model. Continuous dynamic model with single degree of freedom is described with the help of following matrix differential equation: ‖ ̇​̇ ‖ where

̇( ) ;

‖

‖ ‖ ‖

( ) ‖ ( )

‖

(1)

( ).

For mechanical system under consideration, the equation coefficients are determined as follows:

=-

,

=-

= 1,

,

(2)

=0.

Power function for kinematic effect is identified in the form of: ( )

̇( )

( )

(3)

f2(t) = 0 .

Analytical solution. Following normalized form for analytical solution x(t) determining motion of mass m is as follows:

( )=

̇

| ̇

|

∑

|+

( )

∑

|

( )

(

)

(

∑

)

(

)

(

)

( )

∑

( )

(4)

.

Here analytical solution is represented in the form of dependence on the roots of characteristic equation: ; specified initial disturbances ̇ ; specified external power effect within the initial time period f(0) and current one f(t).

Analytical modeling. If external kinematic effect is specified as: ̇( ) that both function and its derivatives are: f(t) =

V0 +

̇ (t) =

V0t , f(0) =

V0 , ̇ (0) = ̈ (t) = 0 , ( ).

V0 ,

( )

then considering (5)

V0 ,

Hence: ∑

( ( )

)

;∑

( ( )

)

;

MMSE Journal. Open Access www.mmse.xyz 58

(6)

Mechanics, Materials Science & Engineering, January 2016 – ISSN 2412-5954 ( ( )

∑

)

(

( ( )

); ∑

)

(

).

Substituting the results into general formula and performing simple transformations we obtain laconic analytical representation of transient:

( )=

In case of complex roots of characteristic equation: following function: ( ) =

(V0 – ̇ ) + V0t .

+

[|

̇

1,2

(7)

= α ±iβ transient is modeled by means of

]–

|

t .

(8)

According to the given different forms of transient records, following particular cases of root distribution are being modeled: 1.

2.

3.

, = , =±iβ ,

= 0; = 0.

In the context of particular case one, transient is modeled as:

( )

( ̇ - V0) + (V0 - ̇ + λx0) + V0t.

In the context of particular case two assuming that:

1→ 2

or

(9)

→0, i.е. ∆ →0 and considering

(10)

We obtain following transient: ( ) = eλt[( ̇ Assuming that β→0 , i.е.

1= 2=α

)

]

(11)

and considering that:

(12)

We obtain transient in its equivalent record: MMSE Journal. Open Access www.mmse.xyz 59

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

( ) =

[|

̇

]+

|

t.

(13)

In the context of case three transient is described with the help of following time function: ( )=[|

̇

]

|

t.

(14)

Analytical design. Dynamic design of mechanical systems is to select running design parameters depending upon required transient quality: aperiodic transient or vibration one; degree of stability; oscillation frequency and amplitude; control time etc. Transient performance depends on distribution of characteristic equation roots within complex plane. Adequate distribution of characteristic equation roots is achieved by selection of running parameters of mechanical system.

For linear dynamic systems analytical selection is possible.

Characteristic equation of one-dimensional dynamic system is:

а11  

а12

а21

а22  

0

(15)

Roots of characteristic equations depend on coefficients of differential equations as follows:

=

+

=|

,

|.

(16)

For the involved mechanical system running parameters are directly determined by the formulas: (

)

(17)

In terms of complex roots we obtain: (

c

)

(18)

where α is degree of stability; and β is factor of natural frequency.

In the context of particular case one we determine: c=0, i.е. elastic element is not available in the mechanical system.

In the context of particular case two we determine: MMSE Journal. Open Access www.mmse.xyz 60

(19)

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

(20) or (21) In the context of particular case three we determine: µ = 0, с = mβ2,

(22)

i.е. damping component is not available in the mechanical system.

Summary. New record of analytical solutions of linear differential equations in harmonic form is proposed. The form is applied for analytical modeling and design of one-dimensional dynamic system in terms of kinematic effect. Qualitatively different forms of transients within onedimensional mechanical system as well adequate running design parameters of elastic and damping elements have been obtained.

References [1] Khachaturov, A.A. 1976. Dynamics of a road-railcar-driver system (in Russian). – Moscow: Mechanical Engineering, 535 P. [2] Hubka, W. 1987. Theory of technical systems (translation from German language).– Moscow: Mir, 208 P. [3] Smirnov, V.I. 1974. A course of higher mathematics (in Russian).– Moscow: Nauka V.2, 656 P. [4] Kuzovkov, N.T. 1976. Modal control and monitoring facilities (in Russian). – Moscow: Mechanical Engineering, P. 184.

[5] Udermann, E.Т. 1972. Root-locus method in the theory of automatic systems (in Russian). – Moscow: Nauka, 448 P. [6] Kravets, V.V. 1978. Dynamics of solid bodies system in the context of complex control (in Russian). – Kyiv: Applied Mechanics, Issue 7, P. 125-128.

[7] Kravets, V.V.., Bas К.М., Kravets, Vl.V. 2012. Dynamic design of the simplest vehicle component (in Russian). – Sevastopol: Messenger of SebNTU, Issue 135, P. 188-191.

[8] Kravets, V.V.., Bas К.М., Kravets, Vl.V., Burov, V.S. 2014. Analytical method of the simplest vehicle component dynamic design in terms of external effect (in Russian). – Sevastopol: Scientific Messenger of the First Ukrainian Marine Institute, Issue 1, P. 79-82.

MMSE Journal. Open Access www.mmse.xyz 61

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

On Influence Of Design Parameters Of Mining Rail Transport On Safety Indicators Ziborov Kirill1, Protsiv Volodimir2a, Fedoriachenko Serhii3b, Verner Illya4 1 – Associated professor, Head of the Machinery Design Fundamentals Department, National Mining University, Ukraine.

2 – Professor, Head of the Mining Engineering Department, National Mining University, Ukraine.

3 – Associated professor, Machinery Design Fundamentals Department, National Mining University, Ukraine.

4 – Head of the Computational Engineering Laboratory, Machinery Design Fundamentals Department, National Mining University, Ukraine. a – protsiv@ukr.net b – serg.fedoryachenko@gmail.com

Keywords: tractive effort, safety, mining locomotive, rolling stock, hard rock, mathematical simulation, principal scheme

ABSTRACT. The influence of design parameters of mining rail transport on safety indicators is defined in the paper.

The mining locomotive ЭШК-10 is studied. Substantiated, that during constant locomotive speed V, variation of the tangential component Qx occurs when the increment speed of the boundary layers of friction pair materials δV leads to energy loss in the contact area. This provokes unstable state of the electromechanical system. To increase stability and safety, reduce the load on the bogie, as well as on the rail track, additional movability of the kinematic connection of its links can be used. Basing on the thrust forces equations subject to adhesion and permissible power for definite conditions, we can determine the values of engine voltage Uc as a function of the locomotive speed.

Introduction. The large tonnage hard rock mines, either coal or copper etc., use underground rail.

South and Central America, Canada, China, South Africa, Ukraine these are may be the biggest regions using mining rail transport [0]. Almost each region has its own suppliers of mining locomotives and rolling stock. There is a tendency, that mining rolling stock suppliers focusing on the locomotive rebuilds and refurbishment of old locomotives and rolling stock [0]. However, the economical conditions of the mining regions are different and the development of a new locomotive has its own strategy from region to region.

The Ukrainian locomotive ЭШК-10, that has been developed by the team of scientists from National Mining University, has a lot of specific features, which allows using this loco worldwide from mine to mine.

This happens due to comprehensive mathematical models and usage of sophisticated 3D simulation.

Research results. During the rock mass and coal transportation by the mining rail transport along the mining shafts, the rail’s functions are not only carrying static loads, but to transmit the dynamical stress and bogie mass to the rail track structure as well. The interaction area between wheel and rail facilitates transmitting braking and tractive forces. In order to increase the productivity of the mining rolling stock, an adhesion weight of the modern mining locomotives increases either and now achieves 10-28 tons. This mass allows hauling heavier mining tub with significantly increased static loads on the rail track on the steeper slopes. Due to the fact, that existing mining rail tracks have been designed for much lower locomotives’ weight, increased axial loading on the rail track elements rocketed up to 1,5-2,5 times and for mining tub 7 times more.

MMSE Journal. Open Access www.mmse.xyz 62

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

However, increased adhesive weight did not solve the problem insufficient friction properties of rolling stock that caused unreasonable energy loss, reduction of its exploitation characteristics.

Exploitation indexes of railway transport show, that to overcome friction up to 30 % of all consuming energy is necessary, and loss of material of friction pair amounts 15 % of producing metal [0].

Each of mining drifts has its own climate environment, rail track profile and plan, bending radii, track incline, admissible haulage speed and braking distance etc. All these factors dependence on both economic and exploitation indexes, and on transport system reliability in general. Thus, study of the rail, wheel and their interaction surface as a standalone system elements, wheel-rail interaction control, allow optimizing their work during difficult motion regime.

Modern design methods [0], which base on the scientific simulation and research approaches, facilitate definition of the location and character of arising dynamical loading and prevent their growth during forming within the mining vehicle chassis.

This prevents the following dynamical load transfer on the bolster structure. Thus, the structure selection and selection of mining machines parameters, which bases on the detailed analysis of running processes, might be an essential part of energy-mechanical system and its scheme development during development [0].

The purpose of the paper is to define the influence of design parameters of mining rolling stock on the rational tractive regimes with high exploitation indexes and low energy loss.

As it is known, the frictional surfaces move across the interaction area with tangential velocities V1 and V2. The bodies have the components of angular rotation velocity relatively to the base tangent to the surface. Different relations of the wheel set line speed V1 and speed of rotational motion V2 is characterized by the sliding velocity V .

After each wheel’s turn on the interaction area resilient and plastic deformations arise. As a result, the friction elements wheel-rail start negotiate through the finite size area. Taking into account existing rail track imperfections and imperfections of contact area, let assume nominal and real contact areas. All force interactions of frictional pair wheel-rail are carrying within the real contact area. Therefore, the tangent reaction Qxy is formed with elementary forces Q xyi , which act on each i-th point of the real contact area (fig. 1). Thus, during analytical research we need to proceed from the elementary contacting area of the interacting bodies.

The wheel, moving along the rail, can be either in free (Qxy= 0), tractive (Qxy> 0) or braking (Qxy< 0) regimes (fig. 2, b).

Fig. 1. Real contact areas of interacting bodies These forces are directed opposite to the sliding velocity of i-th point Vi in the contact area (fig.

2) in dependence on motion regime. The total force, in the case when  doesn’t independent on MMSE Journal. Open Access www.mmse.xyz 63

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

Vi

direction, acts in the direction opposite to the wheel’s slipping velocity, and their scalar

product

QxyV defines the power of dissipative forces in the contact area.

Thus: k

Qxy    Qzi cos  i

(1)

i 1

where k – amount of the contact points in the slipping area;

 – coefficient of friction limit.

During mining locomotive motion along the mining drifts, the wheel contacts rolls both on the inner and outer rails, which have different curvature and gage width. This fact induces the lateral displacement of the contact area though its width. The worn wheel tread profile represents the total envelope profile of all rails that are contacting with tread [0]. The tread areas, which contact with rails most often, expose to intensive sliding, high contact stress and significant wear in comparison to other tread areas. Mine drifts with big amount of straight track segments lead to wear concentration on the rolling area at the center of the wheel tread. In this case the wear of the flange is minimal. Otherwise, motion on the curvilinear rail track segments (most often case for coalmines) causes significant flange wear.

a)

b)

Fig. 2. The calculation scheme of forces and velocities. а) tractive regime (Qxy> 0); b) braking regime (Qxy< 0) As a result, of frictional interaction of the wheel and rail, a clearance between contact surfaces forms.

Uncontrollable growth of the clearances provokes additional dynamical forces, acting on the bogie and track, that reduce the exploitation characteristics of the machine.

However, there is possible to revise the machine design and additional kinematical movability either to reduce the duration of nonstationary motion regime. This is essential for mining conditions, which is marked by lots of unfavorable factors [4]. To provide the smooth wear of coupled kinematical members a coupling with local movability can be applied [4].

MMSE Journal. Open Access www.mmse.xyz 64

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

For example, locomotive of the module scheme, that includes a few sections. It allows for development of the vehicle with different trailing weight, energy supply system and necessary exploitation indexes. The distinguish feature of such locomotives is kinematical coupling between bogie and tractive section (Fig. 3).

Such connection provides necessary relative movability and transmits vertical loading from frame to bogie, horizontal lateral forces – centrifugal force, reaction of overrunning rail, which has geometrical imperfections in all surfaces. Movability around the vertical axis is necessary for tractive bogie turn and in order to avoid odd couplings, because the pin does not carry the chassis weight; around lateral axis – for correct weight distribution between locomotive axles and reduction influence on the rail track; longitudinal movability is absent because the tractive effort transmits in this direction.

a)

b)

Fig. 3. Pin joint locomotive (a); Locomotive joint (b) In order to define relations between kinematical and dynamical characteristics of mine rollingstock we need to provide the analysis of rail and wheel interaction, and to evaluate locomotives tractive and safety properties.

The obtained data allows for assessment of the safety index, which is used to describe by safety coefficient [0]:

SF 

tg     Q z 1    tg   Q y

  1  

(2)

where  – angle of wheel flange;

 – friction coefficient; Q z – normal rail reaction under ongoing wheel, N; Q y – guiding force on the ongoing wheel, N.

Local and regular rail imperfections lead to additional growth of guiding force Q y that can cause the derailment at some certain critical value (Fig. 4, 5, b). Reduction of guiding force can improve stability and predict derailment (Fig. 4, 5, a).

MMSE Journal. Open Access www.mmse.xyz 65

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

The most complex motion regime is driving through curvilinear rail track with wheel flange climbing by both rear and front axles. This induces the rotation of tractive bogie in relation to mass center (Fig. 4, 5). Simultaneously, the middle section rotates around pin joint. At axial displacement of the wheels, a reaction force arises at the point of flange contact, which acts flatwise to motion direction. A sudden growth of these forces appears while wheel misalignment. To reduce reactive forces an additional local movability of kinematical pair coupling is necessary.

a)

b)

Fig. 4. The forces on the wheel flange while straight motion (a) and along bend rail segment (b)

Đ°)

b)

Fig. 5. The creep forces between rail and wheel during straight motion (a) and in the bend rail segment (b) The usage of mathematical simulation facilitates the designing and dynamical interconnection of mine rolling stock. The study of mining vehicle dynamics is provided via developed system of differential equations.

Thus, we have obtained several relations of dynamic forces and safety factor (SF) indexes (Fig. 7).

As mentioned above, the characteristics of contact surfaces, and the pressing force define friction properties at the contact point. When the position of the wheel set in the rail track cannot be achieved through the friction forces, there is a two-point contact appears and lateral forces on the MMSE Journal. Open Access www.mmse.xyz 66

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

flange, which protects the wheel set from derailment (Fig. 4 а, b). At the same time, an additional resistance force arises. However, the forces on the flange are connected with frictional components, which may lead to force reduction in the contact area. Thereby it facilitates the wheel climbing on the rail, especially on curved track sections of small radius.

Fig. 6. General scheme of tractive bogie rotation in relation to mass center during wheel climbing (1- tractive bogie; 2 – middle section; 3 – pin joint) To enhance the stability and safety, reduce load on the vehicle’s chassis and the track and to reduce motion resistance become possible while the usage of a new kinematical design where the kinematical pairs will have an additional local movability. Thus, it will reduce the number of redundant links with shortage of the unnecessary weight. To determine the appropriate value of mobility, providing the necessary performance, we can use modern means of computer simulation interoperability of mine transport and track.

Fig.7. Safety factor relation to track curvature subject to structural scheme. V=4 m/s - - - sectional pin-joint locomotive; –– conventional locomotive Taking into account the denoted above approach of wheel and rail interaction evaluation, the motor torque, reduced to the wheel set with rigid connection between the wheels, as a function of absolute motion velocity M дв 

V N

and relative velocity of the boundary layers

 Q xyi R .

i 1

Vi

of the frictional pair wheel-rail, defines as

The value Qxyi for each wheel calculates according to [4]. Each point of the grip

characteristics is corresponded by its distinguish energy state of interaction process of the pair wheel-rail.

Thus, alteration of the grip accompanies by a change of the state. At a constant locomotive speed V alteration of the tangent component Qxy takes place during increase of the boundary layer displacement of frictional pair material

Vi , which leads to energy loss in the contact area and unstable state of the MMSE Journal. Open Access www.mmse.xyz 67

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

eletromechanical system. Such combination of adverse factors can evoke skidding (during tractive regime) or blocking wheels (during braking).

The critical velocity can be determined by equating the limit values for traction grip and power to each other. The maximum permissible torque, at which there will be no grip disruption, can be defined from the expression of M дв. after substitution the relative velocity V [4]. Using the relation between torque and angular velocity of tractive motor, we can determine the voltage U C as a function of the speed V for these conditions and formulate requirements for tractive motor (braking) control algorithm.

However, the operator of the loco can lose the driving control in hard mining environment. As a result the wheels can be slipping or skidding, which will significantly increase the braking distance (especially on the 50 ‰ slopes). As a result, the necessity of automated control ABS (anti-block system) system appeared.

The main purpose of the ABS is to predict the wheel blocking and skidding adjusting tractive and braking characteristics of the locomotive [7]. The ABS must connect to different systems: electromechanical power-train and braking hydraulic systems. The principal electrical-hydraulic ABS system has been developed subject to [8] and is depicted on the fig. 8.

Fig. 8. The general electric-hydraulic scheme of automated control system against skidding and wheel blocking of mining pin-joint loco.

Summary. While constant locomotive speed V variation of the tangential component Qx occurs when the increment speed of the boundary layers of friction pair materials δV leads to energy loss in the contact area and the unstable state of the electromechanical system. To increase stability and safety, reduce the load on the vehicle and chassis, as well as on the rail track, additional movability of the kinematic connection of its members can be used. Basing on the thrust forces equations subject to adhesion and permissible power for definite conditions we can determine the values of engine voltage Uc as a function of the locomotive speed. To improve tractive and braking MMSE Journal. Open Access www.mmse.xyz 68

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

characteristics of mining pin-joint locomotive a special ABS system has been developed and described in the paper.

References [1] Moore P. (2012), Mine locomotion, International Mining, Vol. 3, pp. 88-96.

[2] Isaev I.P., Lujhnov Ju., (1985), Problems of locomotive’s traction grip, Mashinostroenije, 238 P. [3] Ziborov K.A., Protsiv V.V., Fedoriachenko S.A. (2013), Application of computer simulation while designing mechanical systems of mining rolling stock, Scientific Bulletin of NMU, №6, pp.

55-59.

[4] Ziborov K.A., Fedoriachenko S.A. (2014), The frictional work in pair wheel-rail in case of different structural scheme of mining rolling stock, Progressive technologies of coal, coalbed methane and ores mining, Netherlands, pp. 517 - 521., doi: 10.1201/b17547-87 [5] Ziborov K.A. (2014), Characteristics of Friction Pair "Wheel—Rail" of Mining Locomotive with Kinematical and Power Imperfections, mining Equipment and Electromechanics, №3 (100), pp.26-32.

[6] Garg V.K., Dukkipaty R.V. (1988), Dynamics of rail transport, New-York, 391 P. [7] Protsiv V.V., Gonchar O.Ye. (2010), Проців В. В. On the usage of automated system, prevented wheel blocking and skidding of mining pin-joint locomotive, Mining electro-mechanics and automatics, Vol. 84, pp. 116 – 125.

[8] Protsiv V.V. Indicators of arising skid during braking with limited frictional force on the wheel, Scientific bulletin of NMU, Vol. 5, pp.106 – 112.

MMSE Journal. Open Access www.mmse.xyz 69

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

VIII. Information Technologies The Assessment of the Stability Of the Electronics Industry Facility In the ManMade Emergencies With the Use Of Information Technology Hancharyk A.V.1 and Kizimenko V.V.1 1 – Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus

Keywords: evaluation method, system sustainability, electronic industry object, hazard prediction, mathematical model, risk.

ABSTRACT. The object of study is the enterprise (object) of the electronics industry. By industrial object means engineering-technical complex, which includes buildings, structures, power systems, equipment, automated systems, equipment, tools, etc. By the stability of the industrial object we mean ability to produce specified types of products in required quantities in a case of variety of emergency situations, as well as the willingness to self-repairing in if the object proves in the affected area of weak or medium damages. For the stable operation of the facility, in addition to the stability of the object, the security of workers and employees must be ensured, as well as individual and collective protection equipment have to be provided. One of the important indicators for assessing the sustainability of industrial facilities in emergencies is an evaluation of the probability of occurrence of internal and external emergencies and their impact on the operability of the industrial facility. The estimation of probability of occurrence internal and external emergency situation is characterized by a measure of the risk. By the risk means a value, which includes both the probability of accidents and damage from them [1]. The development of criteria for evaluating the stability of the object in the man-made disaster is often identified with the risk. The stability of the facility's operation in the man-made disaster is estimated by the highest acceptable risk. There are the following methods for determining the risk: statistical, model, expert and sociological. Currently, the software «SKEVIA» has been developed, which allows estimating the damage caused by man-made emergencies for a particular industrial facility. Scientific novelty lies in the development of new criteria for sustainable operation of the enterprises of electronic industry. The practical significance lies in the implementation of software «SKEVIA» at the enterprises of electronic industry of Belarus.

Introduction: In this paper, we will consider the work of the facilities of electronic industry in emergency situations. To ensure stable operation of the facility in emergency situations it becomes necessary to increase the level and effectiveness of preventive measures to reduce the scale and impact of disasters. Until recently, the highest priority in solving the problems of protection of the population and territories from emergency situations was paid to eliminate the consequences of accidents, i.e. rapid response to emergencies. However, as time has shown, it is economically feasible to direct limited resources to reduce probability of occurrence of emergencies and to ensure human security, rather than to pay huge costs for covering damage caused by emergencies.

Carrying out activities to identify hazards and the monitoring the probabilities of disaster on the potentially dangerous facilities will prevent the growth and magnitude of the consequences of natural and man-made disasters. The implementation of the complex preventive measures will reduce the cost of the emergency response by 10-15 times in comparison with the avoided damage, and in some cases - to completely avoid them. [2] A rapid change of the conditions of emergency situations significantly complicates quick reaction and the development of adequate measures to eliminate their consequences. Therefore urgent task is MMSE Journal. Open Access www.mmse.xyz 70

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

a minimization the amount of raw data and the development of a rapid method of predicting not only the areas of contamination and damages with a minimum number of parameters, but also assessment of the risks, which can lead to complete loss of the stability of the facility in the situation of man-made disaster [3].

In order to reduce and optimize the processing time to predict the impact of sources of emergency on the production staff and processes, and for development of measures to prevent man-made disaster (and in case of emergency - in order to minimize the damage) is needed to create a software product for operational use by the head of safety department of the facility.

Analysis of recent publications and researches in this area. A great contribution to the development and introduction of methods of assessment of emergency situations have made Akimov V.A., Bariev E.R., Belov P.G., Vetoshkin A.G., Ermin V.G., Mikhnyuk T.F., Kozlachkov V.I., Kukin G.Sh., Safronov A.G., Frolov A.B., Shadsky I.P. and others.

As it was previously mentioned, the criteria for assessing the sustainability of the enterprise are associated with the risk indicator. Currently, there are following methods for determining the risk [1]: – Statistical: based on the statistical analysis of data on accidents; – Model: model of the impact of harmful factors on the production staff, the process and the environment of the facility is built. Such models can describe as a normal mode of operation of the enterprise, as well as damage from an accident on it; – Expert: the risk of accidents, the connection between them and the consequences are determined not by calculation, but by the results of the survey of experienced experts; – Sociological: the danger level is determined by the results of sociological surveys of various large groups of people, which work on the facility.

The probabilities of events, calculated on the basis of information accumulated over a certain period of time in the past can be extrapolated to the future using the law of distribution of random variables in time.

The random variable ζi, which distribution function corresponds to the probability of occurrence of z-th accident scenario, has a compound distribution, calculated by the formula (1): ζi=ξi+γi+ηi,

(1)

where ξi – random variable distributed according to an exponential law and is responsible for the probability of failure due to technical problems; γi – random variable which is responsible for the accident as a result of natural disasters; ηi – random variable is responsible for accidents involving the "human factor".

Distribution of the last two variables is established empirically.

Known methods for evaluating the sustainability of enterprises in emergency situations can be divided into some main approaches.

By the first approach the assessment is made using as a criterion the generalized criteria which includes certain indicators. The difficulty and complexity of the application of these methods of assessment lies in the fact that the number of indicators and their significance of these methods are significantly different for different authors, in addition, given values of parameters are not supported by the regulatory documents.

MMSE Journal. Open Access www.mmse.xyz 71

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

The second approach is to identify the most vulnerable links in the system, and evaluation of stability for these links, which will be the assessment of the stability of the whole system.

The third approach is to identify and develop integral evaluation criterion the stability of the facility. Moreover, this approach can be divided into two groups. The first group includes methods of evaluation using the generalized criterion on the basis of partial indicators. The second group involves the development or the search for a universal integral criterion, which will replace partial ones.

Analysis of information sources has showed that the most promising methods of evaluating and predicting the sustainability of facilities in a man-made disaster are methods which use criteria Multiple-discriminant analysis based on the use of multifactor criteria.

It should be noted that there are several problems in application of known methods in practice, and the main of them is the mismatch in the specificity of the functioning and development of certain industries and their facilities.

Forecasting technological disaster is based on an assessment of the technical state of the object, its equipment and the assessment of the human factor and the environment. The result of the prediction of any man-made disaster is the determination of the risk of its occurrence, which depends on many factors. Let us consider accounting these factors on the example of an estimation of industrial structures and technological equipment, the accident on which usually can led to the disaster. [4].

The essence of the research The following main features were used in research: – The technogenic hazard is considered to be the main hazard; – All hazards are probabilistic by the inherently; – All sources of technogenic hazards, leading to emergencies, are divided into three classes by the nature of occurrence: 1) the human factor; 2) Technical (technological) factor; 3) factor of the environment; – Risk is a measure of hazard. It simultaneously takes into account the possibility of a disaster and an estimate of the risk; – The stability of control system is interpreted as ability to to perform specified functions, not only in normal conditions but also in emergency situations.

The risk of death in the industry is estimated at 10-6 or less per person per year [5]. Thus, during the process of design the operation of technical devices the risk at the level 10-6 per person per year can be accepted valid when the following requirements for risk analysis are provided: the problem of the risk was analysed; i.e. probability of occurrence of adverse events and the probability of it escalating into a emergency was estimated; all factors affecting emergency were considered, etc.

– Analysis carried out before making a decision and confirmed by the available data in a certain time interval; – Analysis and conclusion about the risk, obtained on the basis of the available data do not change after the occurrence of an adverse event; – Analysis and the results of control all the time show that the threat cannot be reduced at the cost of acquitted costs.

As a result of research the algorithm for estimating the stability of the industrial facility in the emergency was considered. (see Fig.1). [3] Estimation of the stability of the object is provided consistently in relation to the effects of each striking factor that may have a significant damaging effect on one or another element. The sustainability of object's element is characterized by the practical value of a factor, when the MMSE Journal. Open Access www.mmse.xyz 72

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

element is not broken and does not fail. However, in order to be able to predict the stability of the facility in the man-made disaster, it is required to calculate the risk of damaging factor and compare it to an acceptable risk.

In this paper we focus on the development of the block "Assessment of probability of occurrence internal and external emergencies and their impact on the working process of the facility."

A special software product «SKEVIA» has been developed (the developers are Alena Hancharyk and Viacheslav Kizimenko) in order to reduce and optimize processing time for the prediction of effect of emergency sources on production personnel and technological process. «SKEVIA» has a very simple and convenient user interface.[2]

Estimation of the stability of the object

Estimation of the probability of internal and external disaster and its impact on the performance of the enterprise объекта

Estimation of protection of facility's personnel

Estimation of the control system stability

Estimation of the physical stability of the buildings, and other systems

Estimation of the stability of the logistics and industrial links

Estimation of the readiness object to the restoration of impaired production Fig. 1. Algorithm for estimating the sustainability of the industrial facility in emergency situations

MMSE Journal. Open Access www.mmse.xyz 73

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

«SKEVIA» is designed for predicting possible consequences of man-made emergencies on the basis of a single industrial enterprise for one personal work place; it does not presuppose work via the Internet or LAN. This condition is required due to the protection of confidential information of the industrial enterprise. For the image of the program, see Fig. 2.

Fig. 2. The image of «SKEVIA» The application deals with two possible ways of emergency development. The first way of emergency development is the explosion of a tank with propane at the railway station near the object (see Fig.3).

Fig. 3. Damage area MMSE Journal. Open Access www.mmse.xyz 74

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

Damage areas are displayed as concentric circles where the centre is in the explosion point. They show the geographic position of the points that are affected by various values of manometric pressure (heavy damage – 0,4 kg/sm2 = 39,24 kPa – within a radius of 306 m, average damage – 0,3 kg/sm2 = 29,43 kPa, light damage – 0,2 kg/sm2 = 169,6 kPa). Calculation results are shown in Fig. 3-4.

Fig. 4. Zones of gas-air mixture explosion base The second way is the emission of the chemically hazardous substance (ammonia) at the processing industry object that is situated nearby (see Fig.5).

Fig. 5. Zones of chemical contamination

MMSE Journal. Open Access www.mmse.xyz 75

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

It is possible to estimate death toll after exposure to poisonous substances. After entering the number of the staff of the enterprise, the total number of victims as well as the number of people with minor and moderate injury and the number of the dead is calculated. Graphic construction is made on the cartographic basis loaded by the user. For user convenience it is possible to press any two points of the map and see the distance in meters below the map. All the objects the location of which is considered in the program as well as the distance between them are displayed on the map after clicking “Objects”. Saving of the maps that contain the data of calculations is done by clicking “Save” that creates a temporary file with the extension .bmp in the work directory of the PC. The program is undemanding towards the processor resources, it is easy to use as it does not require special skills apart from Windows interface basic work skills.

Thus, we have developed the system that significantly facilitates the work of an expert who deals with safety of industrial enterprise personnel. Output graphic information allows to imagine the scale of consequences after man-made catastrophes and to take rapid measures that are necessary for people’s safety.

Currently, with the development of information technologies software «SKEVIA» is being upgraded, which will provide more detailed development of the block algorithm, the stability of the industrial facility in an emergency (Fig. 1) "The evaluation of the probability of internal and external emergencies and their impact on the working process of the facility".

The following risks of man-made disaster will be analyzed: 1. The risk of unacceptable physical stability of buildings and structures; 2. The risk of failure of process equipment; 3. The risk of error in the work of administrative and management personnel and engineers; 4. The risk of errors in the work of service personnel; 5. The risk of failure of power supply systems; 6. The risk of unpreparedness of logistics; 7. Risk of influence of negative factors and working environment; 8. The risk of errors in the work of main production staff; 9. The risk of failure in the management systems; 10. The risk of failure in the systems of telecommunications.

All of these risks affect on the occurrence of man-made disaster at the facilities of electronic industry. If the values of three criteria are higher than acceptable risk, the calculation of the rest can be ignored. These criteria are: the limit of resistance to the shock wave, the limit of resistance to light radiation, as well as the limit of stability to the electromagnetic field (EMF). The novelty is a new criterion for the stability limit to EMF. If it exceeds the limit, then the entire electronic apparatus fails, control systems, which consist of electronic devices, will be denied, as well as technologies and equipment, i.e. the risk will exceed the permissible, therefore further payment other risks impractical.

In case the risk values are within an acceptable risk, we calculate the remaining risks. The worst option of these is selected, and its value will be the criterion for assessing the stability of the object of electronic industry.

Currently, the program units to the software «SKEVIA» are developed, taking into account all described risks, but there are practical difficulties in debugging these additions, as the majority of facilities of electronic industry in Belarus today are not able to conduct testing and debugging this changes.

MMSE Journal. Open Access www.mmse.xyz 76

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

References [1] Kolodkina, V.M. (2001) Quantitative risk assessment of chemical accidents / V.M. Kolodkin, Murin A.V., Petrov A.K., Gorsky V.G. / Izhevsk: Publishing House "Udmurtia University", 2001 228 p. ISBN 5-7029-0260-2 [2] Levkevich, V.E. (2004) Environmental risk - patterns of development, forecasting and monitoring. Minsk.

[3] Dorozhko, S.V. (2008) Protecting the population and facilities in an emergency. Radiation safety: manual. Part 1. Emergency situations and their prevention/ Dorozhko S.V., Rolewicz I.V., Poustovit V.T. / 2nd ed. - Minsk, 2008. - 284 p.

[4] Dorozhko, S.V. (2008) Protecting the population and facilities in an emergency. Radiation safety: manual. In 3 hours. Part 2. The system of survival of the population and territories protection in emergencies / Dorozhko S.V., Poustovit V.T., Morzak G.I., Murashko V.F. /2nd ed., - Minsk, 2008. - 400 p.

[5] Medvedev, V.T. (2002) Environmental Engineering / Ed. by V.T. Medvedev. M., 2002.

MMSE Journal. Open Access www.mmse.xyz 77

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

X. Philosophy of Research and Education Teaching Reitlinger Cycles To Improve Students’ Knowledge And Comprehension Of Thermodynamics Amelia Carolina Sparavigna1 1 – Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy

Keywords: Thermodynamics, Thermodynamic cycles, Regenerative cycles, Thermal efficiency.

ABSTRACT. The second law of thermodynamics puts a limit on the thermal efficiency of heat engines. This limit value is the efficiency of the ideal reversible engine represented by the Carnot cycle. During the lectures on physics, the emphasis on this cycle is generally so strong that students could be induced to consider the Carnot cycle as the only cycle having the best thermal efficiency. In fact, an entire class of cycles exists possessing the same maximum efficiency: this class is that of the regenerative Reitlinger cycles. Here we propose to teach also these cycles to the engineering students of physics classes, to improve their knowledge and comprehension of thermodynamics.

Introduction: Generally, the Carnot cycle is the only thermodynamic cycle that, during the lectures on physics, is discussed as having the maximum possible thermal efficiency. This happens because Carnot cycle is directly connected to the second law of thermodynamics, which puts a limit on the thermal efficiency of heat engines. This limit value is the efficiency of the ideal reversible engine cycle represented by the Carnot cycle. Sometimes, an approach considering only Carnot engines with emphasis on their efficiency, could yield the following result: it is unknown that an entire class of cycles exists, having a thermal efficiency which is the same of that of Carnot cycle. This is the class of the regenerative Reitlinger cycles. Of course, since a large part of engineering students will be required as engineers to deal with relatively simple thermodynamic problems, a discussion of Reitlinger cycles could appear as unnecessary. However, it is unquestionable that a proper knowledge of the fundamentals of thermodynamics is necessary for engineers as well as for scientists in general. For this reason, in the following discussion, we will propose some notes suitable for teaching these cycles to students of physics classes, to improve their knowledge and comprehension of thermodynamics.

Reitlinger cycles. The Reitlinger cycles consist of two isothermal and two polytropic processes of the same kind [1,2], so that the heat which is absorbed during a polytropic, is exactly the same that it is rejected on the other polytropic process. Therefore, if we have a perfect regeneration of heat, by means of which the heat rejected during the polytropic is transferred to a thermal storage (the regenerator) and then transferred back to the working fluid, the thermal efficiency of the Reitlinger cycle equals that of the Carnot cycle (in fact, it is a Reitlinger cycle too).

Of all the Reitlinger cycles, the Carnot cycle is unique in requiring the least regeneration, namely, none at all because its polytropics are adiabatics [1]. Let us note that the mechanical work of the Carnot cycle is not the best we can obtain between extremal states. We can easily evidence this fact from the diagram in Figure 1, which is comparing Carnot and Stirling cycles, having the same temperature and volume extremes [1]. In the Figure 2, we can see how, in general, a Reitlinger MMSE Journal. Open Access www.mmse.xyz 78

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

cycle can be different from a Carnot cycle, in a p-V diagram. Working between the same isothermals, with the same thermal efficiency, a regenerative Reitlinger cycle can give more work or less work, depending on the polytropic process the cycle is performing between the same extremal states.

Fig. 1. The figure (adapted from Ref.1) shows a Carnot cycle inscribed in a Stirling cycle in a p-V diagram. The optimum constant buffer pressure is also shown. The work of the Stirling cycle ABCD is greater than the work of Carnot cycle AB’CD’ Let us note that the ideal Stirling cycle is also a Reitlinger cycle, having as polytropics two isochoric segments. It is the most popular example of a cycle having the same thermodynamic efficiency of the Carnot cycle; however, to attain this result, the Stirling cycle makes quite heavy demands on the process of regeneration [3].

Fig. 2. The figure shows how a Reitlinger cycle can be different from a Carnot cycle, in a p-V diagram. Working between the same isothermals, with the same thermal efficiency, a regenerative Reitlinger cycle AB’’CD’’ can give more work or less work, depending on the polytropic process the cycle is performing between the same extremal states As observed in [6], there are ten elementary power cycles which follow from the combinations of five typical thermodynamic changes of state. In the Figure 3, we can see them and the names of their inventors (for other cycles, see [7]). In [6], Carnot, Ericsson and Stirling cycles are distinguished from the Reitlinger cycles, which have the most general form in idealized cycles MMSE Journal. Open Access www.mmse.xyz 79

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

[4,5], because they have a specific importance in thermodynamics. In these cycles we have, besides the two isothermal processes, the two polytropic regenerative processes realized by adiabatics, isochoric and isobaric processes, respectively.

Fig. 3. The elementary thermodynamic cycles (figure adapted from [6]) Thermal Efficiency: For any thermodynamic cycle, reversible or irreversible, after one cycle, the working fluid is again in its initial state and thus the change of its internal energy is zero. In this manner, the first principle of thermodynamics tells us that the mechanical work produced by the cycle is the difference of input heat energy Qin minus the energy dissipated in waste heat Qout. Heat engines transform thermal energy into mechanical energy or work, W, so that W = Qin − Qout. We can calculate the thermal efficiency of the cycle as the dimensionless performance measure of the use of thermal energy. The thermal efficiency of a heat engine is the percentage of heat energy which is transformed into work, so that: 

W Qin

(1)

For a Carnot engine, it is η = 1−TC/TH, where TH,TC are the temperatures of the furnace and of the cold sink, respectively. Let us discuss the thermal efficiency of the Stirling cycle. Using a p-V diagram, the cycle appears as in the Figure 4. In the same figure, the Ericsson cycle and Reitlinger cycle are also shown.

Fig. 4. Stirling, Ericsson and Reitlinger cycles in p-V diagrams.

MMSE Journal. Open Access www.mmse.xyz 80

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

The work can be easily calculated as: V W  nRT1  T2  ln B VA

(2)

In (2), n is the number of moles and R the universal gas constant. Heat is gained by the thermodynamic system from the reversible isochoric transformation from D to A and during the isothermal path AB. During isochoric process, heat gained is: Qisoc  nCV T1  T2  . CV is the molar specific heat for an isochoric process. During isothermal process, the heat gained is Qisot  nRT1 ln (VB / V A ) .

Let us note that, during the isochoric process, the fluid is obtaining heat from an infinite number of thermal reservoirs [8]. This same amount of heat is lost during the isochoric cooling process, with a thermal exchange with the same reservoirs. Then, for each of the infinite thermal reservoirs that we meet during the isochoric reversible process, it happens what we see in the Figure 5. In this figure, we have two thermal machines that must have the same efficiency, to satisfy the second principle of thermodynamics. Let us suppose the efficiency of the right machine larger than that of the left one.

Let us consider the same work W produced by the two machines, and operate the machine on the left in reversed manner. It is easy to see that, if we consider the net result of these two machines operating together, we have that some heat is transferred from the low temperature reservoir to the high temperature reservoir, violating the Clausius statement of the second principle of thermodynamics. We have the same result if we consider the efficiency of the left machine larger than that of the right one, and operate this last machine in reversed manner.

Fig. 5. The two reversible cycles in the figure have the same efficiency. If it were not so, we should violate the second principle of thermodynamics. Let us suppose the efficiency of the right machine larger than that of the left one. Let us consider the same work W produced by the two machines, and operate the machine on the left in reversed manner. It is easy to see that the net result of these two machines operating together is that of transferring some heat from the low temperature reservoir to the high temperature reservoir, violating the Clausius statement of the second principle of thermodynamics. We have the same result, supposing the efficiency of the left machine larger than that of the right machine Calculating efficiency of working fluid with regeneration: If we consider a regenerative Stirling cycle from an engineering perspective, we have in it the regenerator which is storing the heat.

Therefore the abovementioned thermal reservoirs are not involved. Consequently, considering the system made of working fluid and regenerator, the thermal efficiency is:

MMSE Journal. Open Access www.mmse.xyz 81

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

V nRT1  T2  ln B VA T W    1 2 V Q T1 nRT1 ln B VA

(3)

In (3), Q is the heat the system receives during the high temperature isothermal process, because the heat received from the regenerator is that lost by the fluid during cooling isochoric process. This efficiency is equal to that of a Carnot cycle which is working between the same two isothermal processes. We can repeat the calculation for the Ericsson cycle. The work is: V V W  nC P (T1  T2 )  nRT1 ln B  nC P (T1  T2 )  nRT2 ln D VA VC V nRT2 p D V p  nRT1 ln B  nRT2 ln  nRT1 ln B  nRT2 ln A VA pC nRT2 VA pB

(4)

V nRT1V B V V  nRT1 ln B  nRT2 ln  nRT1 ln B  nRT2 ln B VA V A nRT1 VA VA

In (4), Cp is the molar specific heat at constant pressure. It is clear that the heat lost and gained during the two isobaric processes is the same. Therefore, the thermal efficiency, in the case of a perfect regeneration, is given by:



W  Q

nRT1  T2  ln V nRT1 ln B VA

VB VA

 1

T2 T1

(5)

In (5), Q is the heat the system receives during the high temperature isothermal process. Let us conclude with a Reitling cycle, where polytropics are given by equations pV   const and TV  1  const . The molar specific heat of such polytropic process is Cα. Let us note that from polytropic equation we have (see Figure 4): T1V A 1  T2V D 1 T1V B 1  T2VC 1

(6)

Therefore, we have: V A 1

V V V  1  D  A  D V B 1 VC 1 V B VC

(7)

Then: V V W  nC (T1  T2 )  nRT1 ln B  nC (T1  T2 )  nRT2 ln D VA VC V V  nRT1 ln B  nRT2 ln B VA VA

MMSE Journal. Open Access www.mmse.xyz 82

(8)

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

Again, we find a thermal efficiency of the system (fluid and regenerator), which is equal to that of the Carnot engine. Therefore, since the polytropic index Îą can have any value, we have an infinite number of thermodynamic cycles that have the same value of thermal efficiency, equal to that of the Carnot cycle when operating between the same two isothermal processes. Let us stress that these cycles incorporate a regenerative heat transfer process, in place of adiabatic compression and expansion of the Carnot cycle [5], or, if preferred, an infinite number of mono-thermal processes, not influencing the efficiency of the cycle. Moreover, during lectures, it is better to remark that the fact of possessing the same thermal efficiency does not mean that the same work is obtained from different reversible cycles, when they are operating between the same extremal states.

References [1] J.R. Senft, Mechanical Efficiency of Heat Engines, Cambridge University Press, 2007.

[2] I. Kolin, The Evolution of the Heat Engine, Longman, 1972.

[3] J.R. Senft, An Introduction to Stirling Engines, Moriya Press, 1993.

[4] J. Reitlinger, Uber Kreisprozesse zwischen zwei isothermen. Z. Ost. Ing. Arch. Ver. 1876.

[5] G. Walker, Cryocoolers, Part 1: Fundamentals, Plenum Press 1983.

[6] I. Kolin, S. Koscak-Kolin, M. Golub, Geothermal Electricity Production by means of the Low Temperature Difference Stirling Engine, Proceedings World Geothermal Congress 2000, Kyushu Tohoku, Japan, May 28 - June 10, 2000 , 3199-3203.

[7] J.Selwin Rajadurai, Thermodynamics and Thermal Engineering, New Age International, 2003.

[8] P. Mazzoldi, M. Nigro, C. Voci, Fisica, S.E.S. 1991.

MMSE Journal. Open Access www.mmse.xyz 83

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

Multimedia Tutorial In Physics For Foreign Students Of the Engineering Faculty Preparatory Department P. G. Matukhin1a, S. L. Elsgolts1b, E. V.Pevnitskaya1c, O. A. Gracheva1d, E. A. Provotorova1e 1 – People’s Friendship University of Russia a – m-pg@mail.ru b – selsg@live.ru c – pevrudn@rambler.ru d – nafnaf_08@mail.ru e – provelar@yandex.ru

Keywords: engineering education, multimedia tutorial, foreign students, manual, presentation, tests, OneDrive

ABSTRACT. Foreign students study physics and Russian as a foreign language at the preparatory Department. They are to be trained to study different courses. During only one year the teachers of physics and Russian should help students from Asia, Africa and Latin America to get ready to study in the university. To help students in a short time to learn physical terms, to understand physics by ear, to read and write, teachers are developing the online multimedia tutorial. It is placed on the cloud OneDrive. Tutorial includes the main themes in the Mechanics. They are physical processes and phenomena, units, physical quantities, kinematics, laws of mechanics and others. The Power Point presentation slides contain information on the topics. These slides help students learn to read Russian texts on physics.

There are hyperlinks to sound files on slides. Listening to those recordings, students gain the skills of physical texts listening. After each module we placed the test. Students can prepare for it using the simulator. Tests and exercise equipment made in the form of EXCEL spreadsheets. We provide our students the opportunity to view, read and listen, the tutorial files via their own mobile devices. Thus they can study physics in Russian in the classroom, or at home, but in the library, in the Park etc. Also they have access to it when they are not in Russia, and in their native countries. The tutorial presented seems to be considered as the first attempt to develop the online multimedia aimed to assist foreign students to get success in their efforts to study physics in Russian. It helps our students to learn physics in Russian faster and better. Determined are the directions of further development and improvement of the tutorial.

Introduction. The elements and the structure of the online multimedia manual in physics are the basics for the organization of educational communication in natural and engineering sciences with elements of smart and BYOD technologies and webinars at the preparatory Department of the University. Here we observe a number of the main prospects of the MS OneDrive Internet resource as an IT platform to support the complex solution of the tasks of the formation and development of basic competences of foreign students in Russian language of physics as a foreign language, in physics and in modern information technologies for education including mobile access.

Foreign students come to the preparatory faculty of the University to get the Pre-university training to enter at the faculties with increased demands on natural-scientific disciplines. Its goal is to build a solid educational competent scope as the profile of science and in the language sector of the educational and professional communication. Teachers of physics develop advanced smart multimedia learning tools complex in collaboration with colleagues of the Russian language as a foreign language (RFL) department and IT experts. Compressed terms of training and the need to ensure wide access to the complex and it’s components faced developers the necessity to use Internet technologies. It is supposed to use the elements of smart technologies, webinars and mobile access. The vast opportunities of cloud Internet resources, such as MS OneDrive, make them MMSE Journal. Open Access www.mmse.xyz 84

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

adjustable for use as an IT environment for preparation, loading, storage, access and application of interactive tools to support learning in online mode. Simultaneously the problem of the increase of IT competency of all participants of educational communication was solving.

Components Of the Multimedia Tools Complex For Enhanced Training Of Foreign Students In Physics. One of the main items for future engineering-ditch of any specialty is physics. Teachers in physics on the preparatory level at the Russian Language and Basic Education Department dealing with foreign students coming to study at PFUR face a very complex problem. Despite the fact that foreign students already have some basic education in physics, their earlier knowledge needs to be adjusted to Russian educational standards. At the same time they are undergoing intensive training in Russian of science as a foreign language. Thus, the task of training at the preparatory faculty is not only bringing in accelerated mode of level of preparation of students on the subject in compliance with the standards of the Russian Federation on secondary education taking into account, that the level of knowledge of students from different countries varies greatly.

It is also attended by teachers of profile disciplines in the formation of the basic professional educational competences of students in the Russian as a foreign language for scientific and physical purposes and in the sector of application of information technologies in natural science education.

The aim of such an integrated approach is to achieve a level of preparation of students adjusted to enter the University and to study physics, and other engineering disciplines in Russian language as a foreign language of science based on modern means of in-formation technologies successfully along with native Russian students.

One of the ways to achieve these goals is to use modern information technologies in the educational and professional communication [3-5]. In particular, their application creates interactive electronic training manuals, intended for the use not only offline, but also Internet-resources based. This will allow us to include in the program of training a set of smart elements of online communication [6], such as students’ self-training, including the self-test, mobile access, or conducting exercises with elements of webinars.

It is the ambitious idea to develop the project of multimedia manual complex in physics for foreign students, focused on special training on Russian language of physics as a foreign language. The basis for elaboration includes the principle of providing the wide access to and open use of components of the complex in different modes, including offline, on-line system with Internet access and in mo-bile mode. Multifunctional use of the complex presupposes how to work with the audience and for the students’ self-work. It also provides for the classroom and outdoor control of the level of training and learning of students. Mediacomplex includes audited presentation correlated with the adopted textbook [1] and applications for this tutorial [2] and a set of test tools for the preparation and monitoring of the level of training.

Test system consists of the set of the issues in physics (300 questions) and Russian language of physics as a foreign language (200 items), computer simulators, and tests. Elements of the set are performed in the mode of the table processor Excel files [7] and web pages designed under the specialized training tests environment Hot Potatoes [8].

Audited presentation on the course of «Physics» for for-eign students of the preparatory Department forms is the basis of the mediacomplex. It is intended for training on the topics in mechanics. Slides of the presentation are designed to suit the requirements of the existing educational standards and in accordance with the level of education and language training of foreign students. Each slide contains the header, illustrations, definitions, physical formula. Audio records associated with slides allow students to listen fragments of the manual in Russian language. To increase the efficiency of media complex as a mean to support the training process the presentation is equipped with built-in elements of self-control. These mini tests are designed in the form of interactive web pages, which are prepared under the tests constructor HOT POTATOES environment. They contain the question, variants of the answer and the field to point the correct answer. They have a built-in check module and the test result display. Mini tests are embedded in a presentation after each section. They serve MMSE Journal. Open Access www.mmse.xyz 85

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

as training elements for self control in personal studies. Assembly of different HP tests can be used both as training engines as well as means of the periodical and remote control in the online mode, including for self teaching on physics and for webinar studies. This is covered further in [5].

Computer training tools are included in the media complex formed as Excel tables are intended for self control in the process of the presentation study and for preliminary training, as well as for official testing procedures. Training tools are developed not only to be built-in the individual paragraphs, but also for practical topics of the course «Physics» for foreign students. Files of tests simulators are placed on the MS OneDrive network share. Hyperlinks on the test modules are available in its final part of each section of the presentation. They can be used by students themselves outside-taken in person and on the lessons in the computer class.

Using the test generator and the set of questions, everyone can create an unlimited number of control issues. They can include a number of questions for the control of both the audience and extracurricular. Possibilities and information about the IT support of the media complex built-in testing subsystem are presented in the papers [5-8].

Multimedia Manuals On Rlfs In the Physical Education Of Foreign Students. The need of the development of the broad access online media complex to support preparation for the application of foreign students of engineering and scientific areas, chosen their degree mastering in Russian language, was highlighted by the way of understanding of teachers of Russian language, Physics and Informatics of the difficulties faced by foreign students who participate in the core disciplines in parallel with beginning studies of the Russian as a foreign language and a language of the physical science at a basic level.

The problems in the grammar of Russian language are well-known. This is first of all specific syntax and its implementation with flexible word order, distinctive design, character of links between words in a sentence, case-case system of nouns and adjectives.

Modern realities in the language of engineering and natural Sciences compared with common language have their own specific features in terms of grammar, and in terms of vocabulary, which requires for elaboration of special technologies for correct educational content presentation and fastening. Therefore the main task of the media complex in conjunction with the apparatus of builtin tests on Russian language of physics as a foreign language is to create a foreign language students framework on the subject of «Physics». To solve the problem, the developers of media tutorial focused on the implementation of the following linguistic tasks: 1) Development of lexical physical terms compatibility; 2) Development of the case system and verbal forms in a scientific context; 3) Development of syntactic structures and their implementations in scientific language.

Implementation of these tasks was following by the tests of number of types: 1) Tests for approval kind and number of adjectives and nouns; 2) Tests on the use of prepositions, participating together with the endings in the formation of case grammatical values; 3) Tests to determine the cases of nouns in the syntactic context; 4) Tests for the presence of the verbal word form; 5) Run on understanding the functioning of words and word collocations on «Basic concepts in mechanics».

To support the solution of the above described tasks of teaching foreign students on Russian as a foreign language of science media complex includes interactive elements for training and monitoring of the achieved level of mastering the current language-acoustic material. It is

MMSE Journal. Open Access www.mmse.xyz 86

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

completing the mini tests embedded in slides, simulators, tests on the topics of the manual and sets options for mid-term and final testing.

Language mini tests are included in the presentation in parallel with tests in physics. Their presence allows us to combine the specialist training with the language in the mode of unity. This approach through is quite important for teaching of the contingent of foreign students of the preparatory faculty. And it allows provide the synergy effect from combination of two educational directions – study of physics and language training.

EXCEL kits of tests for the preparation, organization and holding of the computer training and testing on scientific language of physics at the level of Russian as a foreign strange similar to those described above sets of test in physics. Base of 200 questions is also the basis of the simulator and test generator. Using these tools, a set of options with a given number of issues, and embedded environments tools verification is to be designed. Sets of test tools on scientific language of physics are de-signed in such a way that they could be posted online. They may be downloaded and used in standalone mode or when placing on Internet services such as MS-OneDrive, apply for webinars and self-control, including mobile access. These tests are extremely important and useful for training in Russian language because foreign students translate grammatical phenomena from their language into Russian language, making countless mistakes. The instructor provides tests which help to reorient the foreign students from grammar realities of their native language to realities of Russian language. So online tests seem to be indispensable for providing foreign students the necessary time to reflect specific grammar of Russian language and give the opportunity of constant training at a convenient mode, including removed access. Therefore, the advantage of the system of allocation and access for the media complex and built-in tests on the Internet resource MS OneDrive is the fact that it can be used as taken in personal and outside of the classroom, self study language training of foreign students.

The means of IT support of training, similar to that described above, and their components may be effectively used in achieving the goal of preparing foreign students for the core disciplines, combined with enhanced language training under such conditions as the maximum availability and functionality. Solution of such tasks faces a number of certain difficulties.

The first and foremost is the problem of IT competence of the developers. Usually they are extremely well-educated experts in their field of knowledge and have extensive experience with a contingent of foreign students in pre-University stage. But they should not always be considered to be professionals in the field of information technologies, although master them at a level above the advanced computer user level. Thus, one of the tasks of the development and application of informational and methodological support of training is the best free choice of software tools and platforms for placement of their products, educational purpose. On the one hand, the instrument used should provide effective solution of these problems; on the other hand, they should not require significant time and effort on their study.

In the course of analysis of modern network resources and software tools, the aim was to choose the most appropriate subject to the following requirements indicated: • Accessibility; • Reliability; • Easy to use; • Functionality; • Compatibility; • Prospects and some others.

Several different platforms including corporate net-work of the University, some of Internet hosting and cloud services were explored. Most appropriate up-to-day tools taking into account the above MMSE Journal. Open Access www.mmse.xyz 87

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

requirements in our opinion is the Internet-resource MS OneDrive, which is a subsystem of the portal service provided by the Microsoft Company [9].

The structure of catalogues for placing the media complex components based on this resource was created, including test simulators and sets of option tests. Methods of organizing the system of storage simplicity, its identity to the standard file system of Windows allowed developers of the tutorial in short terms to configure the main directory and file management operations under the OneDrive environment control. The Built-in component of the MS OFFICE-online package enables them to create and edit the elements of the complex using the collective mode of remote access. The advantage of the OneDrive resource is availability of developing the access control system. It provides the ability to assign different rights to different groups of users. Developers have the highest access level. They have the right to place components of the complex in the directory, edit them and provide access to users. Users have the right to view the available files and copy them to their computer or mobile device.

The OneDrive performs the function of file storage. This store is a reliable transmission element of educational information in computer mediated communication among teachers and students. Active resource options allow us to organize the direct communication and feedback in this process. The training materials and tests move in the for-ward direction from the teacher to the students. In the opposite direction — filled tests and results of their processing come toward a teacher. Thus, the OneDrive tools provide the opportunity to organize interaction without the chronotop restrictions of the communication. Apparatus for short links makes it possible to organize conveniently hypertext links to various components of the complex together in many different ways. For example, the developers of the complex took advantage of this opportunity to insert hyperlinks on tests and simulators directly in the presentation slides, on the pages of the training group in the office of a teacher on the portal of the University etc. Thus, the MS OneDrive been a part of a resolution of the main tasks effectively used as a medium for improving the IT competence of developers in the mode of self-education.

We particularly should note that the usage of this resource is very high, taking into account its dynamic. For example, recently some instruments were significantly developed. In particular, the functions of the embedded spreadsheet tool SURVEY. It allows us to design the on-line tests of all types with automatic collection of the results and their processing in real time. Currently the possibilities to use the programs for the application in the media complex are under investigation.

Summary. Discussed in the paper results on the development of media complex in physics for foreign students of the preparatory Department and organization of accommodation and access to its components based on Internet resource MS OneDrive and experiences of the network elements of the educational system allows to make a conclusion about the effectiveness of, and prospects for the selected configuration of its tools and to identify areas for further development.

References [1] Yefremov A.P., Pevnitskaya E.V., Kutuzov Yu.A. and others. Mechanics. RUDN. 2008.

[2] Gracheva O.A., Elsgolts S.L., Pevnitskaya E.V. Studying Physics in Russian. P.1-3. RUDN. 2011-13.

[3] Rhuzhentseva T.S., Matukhin P.G. Structure and methodical aspects of the use of professionally - oriented electronic English language Manuals//Bulletin of the PFUR. Series: Russian and foreign languages and methods of their teaching. 2004. № 1. P. 136-145.

[4] Titova E.P., Matukhin P.G., Provotorova E.A., Zabolotnaya I.M. Development of a complex of electronic means of distant study of the course «Anatomy» for foreign medical students of preuniversity training period based on the Microsoft SkyDrive cloud technologies // Natural and technical Sciences. 2013. № 5. P. 299-305 MMSE Journal. Open Access www.mmse.xyz 88

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

[5] Gracheva O.A., Elsgolts S.L., Matukhin P.G. Interdisciplinary IT Projects in The Development of Electronic Manuals and Test Systems on Russian as a Foreign Language of Physics// Bulletin of the People Friendship University of Russia. Series: Information Technologies in Education. 2013. № 4. P. 27-39.

[6] Gerasimenko T.L., Grubinin I.V., Gulaja T.M., Zhidkov, O., Romanova S.A. Development of the language competence of students at a non-language University using smart technologies// UMO Bulletin. Series: Economics, Statistics and Informatics. – M: Publishing house: Moscow state University of Economics, Statistics and Informatics, no: 1, 2013 - P: 3-6 [7] Gracheva O.A., Elsgolts S.L., Matukhin P.G., Pevnitskaya E.V., Matyash, G.A. Base of questions, test simulator, generator of tests and set options for the «Mechanics» section of the introductory physics course for foreign students. EXCEL tables// Moscow, Database of OFERNIO INIM RAO, 2013. - 9 P. [8] Gerasimova A.V. Gracheva O.A., Zavadskaya O.A. Kuznetsova YU.V., Matukhin P.G., Pevnitskaya E.V. Tkachenko D.I., Elsgolts S.L., Introduction to the course of Physics. Set of tests on Russian as a foreign language (the language of physics)// Register of algorithms and programs VNTIC. - M: the Certificate of registration of the electronic resource № 50201350724; Appl.

04.07.2013 ; publ. 09.07.2013.

[9] Hill D. News About Microsoft Skydrive, Windows IT Pro/ RE. 2012. № 8. P. 64.

MMSE Journal. Open Access www.mmse.xyz 89

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

Petrus Peregrinus of Maricourt and the Medieval Magnetism Amelia Carolina Sparavigna 1 – Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy

Keywords: History of Science, History of Magnetism.

ABSTRACT. Petrus Peregrinus of Maricourt, a 13th-century French scholar and engineer, wrote what we can consider as the first extant treatise on magnetism of Europe. This treatise is in the form of a letter, probably composed during the siege of Lucera in Italy, in 1269, where Peregrinus worked to fortify the camp and built engines for projecting stones and fireballs into the besieged town. Peregrinus’ letter consists of two parts. The first is discussing the properties of magnets, describing also the methods for determining their north and south poles. The second part of the letter describes some instruments that utilize the properties of magnets, ending with the Peregrinus’ art of making a wheel of perpetual motion. In this paper, we discuss the first part of the letter and the related medieval knowledge of magnetism.

Introduction: Petrus Peregrinus of Maricourt was a 13th-century French scholar and engineer, that conducted and reported several experiments on magnetism. His abilities as an experimenter were well-known in that period and highly praised by one of his contemporaries, the English philosopher and Franciscan friar Roger Bacon. Peregrinus wrote what we can consider as the first extant treatise on magnets of Europe. This treatise is in the form of a letter, and it is entitled “Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, Militem, de Magnete”, “Letter of Peter Peregrinus of Maricourt to Sygerus of Foucaucourt, Soldier, on the Magnet”. In one of the surviving manuscript copies, it is told that the letter was composed during the siege of Lucera in Italy, dated 8 August 1269. Probably, Petrus Peregrinus was in the army of Charles I, duke of Anjou and king of Sicily, who was besieging Lucera in a “crusade” sanctioned by the pope.

Peregrinus’ Letter on the magnet consists of two parts. The first treats the properties of the lodestone (magnetite), providing a description of the polarity of magnets and methods for determining their north and south poles. In the first part, Peregrinus describes also the effects of attraction and repulsion between poles. The second parts of the Letter describes instruments that utilize the properties of magnets, in particular the floating compass, and proposes a new pivoted compass in some detail. The Letter ends with the Peregrinus’ art of making a wheel of perpetual motion.

As we will see in the following discussion, some observations about magnets were existing in the medieval cultural environment. However, Peregrinus was able organizing the whole into a text that formed the basis of the science of magnetism. The Letter is generally considered as one of the great works of medieval experimental research, and, the methods exposed in it as precursors of modern scientific methodology [1]. We can find the Letter in the text entitled “Petrus Peregrinus on the Magnet, A.D. 1269” [2], translated from Latin by Brother Arnold (Joseph Charles Mertens [3]), Principal of La Salle Institute in Troy. The Letter was introduced by a discussion of Brother Potamian (Michael Francis O Reilly [4]), professor of Physics at Manhattan College of New York.

Magnetism in classic antiquity and middle ages: In the classic antiquity and in the medieval period, we can find several descriptions of the attraction which lodestone manifests for iron. In his introduction to Peregrinus’ Letter [2], Brother Potamian writes that Lucretius (99-55 BC) gave a poetical dissertation on the magnet in his “De Rerum Natura”, Book VI. Lucretius recognized MMSE Journal. Open Access www.mmse.xyz 90

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

magnetic repulsion, magnetic induction, and, according to Potamian, “to some extent the magnetic field with its lines of force”. The poet Claudian (365-408 AD) wrote a short idyll on the attractive virtue of the lodestone and its symbolism; Saint Augustine (354-430 AD), in his work “De Civitate Dei”, wrote that a lodestone, held under a silver plate, draws after it a scrap of iron lying on the plate [2,5]. It is also interesting to note that the Augustinian Abbot Alexander of Neckam (11571217) was distinguishing between the properties of the two ends of the lodestone. In his “De Utensilibus”, Neckam provides what is perhaps the earliest reference to the mariner's compass in the Western Europe. In the world, it was a Chinese encyclopedist author, Shen Kuo, who gave the first known account of suspended magnetic compasses, a hundred years earlier, in 1088 AD, in the book entitled “Meng Xi Bi Tan” (Dream Pool Essays) [6].

The Dominican friar and bishop Albertus Magnus (1193-1280), in his treatise “De Mineralibus”, describes several kind of magnets and states some of the properties commonly attributed to them [2]. The minstrel Guyot de Provins, in a satirical poem written about 1208, refers to the directive quality of the lodestone and its use in navigation [2,7]. We find the magnetic compass also in the “Historia Orientalis” (1215-1220) by Cardinal Jacques de Vitry, in the “Tresor des Sciences” (1260) written in Paris by Brunetto Latini, poet and philosopher, in a treatise written by the ‘Enlightened Doctor’ Raymond Lully, and in the famous canzone “Al cor gentil rempaira sempre amore” (Love always has its home in the noble heart), composed by Guido Guinizelli, the poetpriest of Bologna [2]. In Ref.1 we find mentioned other scholars too. Bartholomaeus Anglicus (1220-1250) refers to the magnet in his encyclopedic treatise “De proprietatibus rerum” (On the properties of things). Henry Bate (1246-1317) included a substantial discussion of magnetism in his “Speculum divinorum et quorundam naturalium” (Mirror of divine things and of some natural ones).

Magnets and diamonds: Let us discuss for a while the reference to Guinizelli’s poetry. In his canzone on love, the poet tells “Amore in gentil cor prende rivera per suo consimel loco com’adamas del ferro in la minera,” that is “love has home in a gently noble heart, like, in the same manner, adamas has home in an iron mine.” What is the “adamas”? Some commentators translate it as “diamond”, others, probably more correctly, as “magnet” [8]. In fact, the word “adamas” is the medieval word for both lodestone and diamond. In the Guinizelli’s canzone, when we consider “adamas” as “magnet”, we have a clear example of the medieval similitude between “love” and “magnet” that was common in troubadour lyrics. For instance: “tira com azimans, la bela”, that is, “the fair lady draws me toward her like a magnet”, writes Bernart de Ventadorn [9]. The similitude is reinforced by a phonetic resemblance between the words for “magnet” and “love”. As noted in [8], for medieval poets the true lover (amans) was like a magnet (azimans, adamas).

In the book of William Gilbert (1544-1603), English physicist and natural philosopher, on magnetism [10], we find several names for magnets from different countries. Gilbert writes that in English, the magnet is known as “lodestone” and “adamant stone” (William Shakespeare used “adamant” too, in the Midsummer Night’s Dream: “You draw me, you hard-hearted adamant, but yet you draw not iron; for my heart is true as steel”). Adamant is another form of “adamas”. In various forms (adamas, adamant, aimant, azimans, aymant, yman) and in many languages, we find the original ancient Greek “adamas”, the “unconquered”. Originally, the word was applied by the Greeks to the hardest of the metals with which they were acquainted, that is to say, to hardtempered iron or steel. Due to its meaning, this word was subsequently applied to diamond for the same reason. In the writings of the middle ages, and even in Pliny the Elder, we find some confusion between the two uses of “adamas” to denote the lodestone as well as the diamond [10].

Petrus Peregrinus and the perpetual motion: As told in [2], of the early years of Peregrinus nothing is known. He studied probably at the University of Paris and graduated with the highest scholastic honors. His surname is coming from the village of Maricourt, in Picardy, whereas the appellation Peregrinus, or Pilgrim, is due to the fact that he visited the Holy Land. He was also

MMSE Journal. Open Access www.mmse.xyz 91

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

known as ‘Peter Adsiger’, as we can find in a book of 1787, written by Tiberio Cavallo (17491809), entitled “Treatise on Magnetism” (London) [11].

In 1269, we find Peter Peregrinus in the engineering corps of the French army that was besieging Lucera, in Southern Italy. Peregrinus worked to fortify the camp and lay mines. He also worked to build engines for projecting stones and fireballs into Lucera. It seems that, during such warlike preoccupations, an idea occurred to Peregrinus: the idea was of devising a mechanism able of keeping the astronomical “sphere” of Archimedes in uniform rotation [2].

Of the “spheres” of Archimedes, wrote Cicero, the Roman philosopher and politician, in the first century BC. Cicero wrote of two spherical objects built by Archimedes, that Marcellus, the Roman consul who conquered Syracuse in 212 BC, brought to Rome [12]. One was a solid sphere on which were engraved or painted stars and constellations; the second sphere was much more ingenious and original. It was a planetarium, a mechanical device showing the motions of sun, moon, and planets as viewed from Earth. No physical trace of Archimedes' planetarium survives, but we can have some ideas about it. In 1900, a shipwreck found near the Greek island of Antikythera uncovered an exceptional object. Amidst the cargo of a ship dated from the first century BC, there was a small lump of wood and corroded gears of bronze, which revealed itself as an analog computer designed to predict astronomical positions and eclipses. The device is known as the ‘Antikythera mechanism’ [13,14]. Of course, we cannot attribute this mechanics to Archimedes, but we can imagine he could had built a similar device too, that the consul Marcellus brought to Rome. And in fact, recently, a model of Archimedes’ sphere had been reconstructed by Michael Wright, who was a curator at the Science Museum in London and that spent many years studying the Antikythera mechanism. His globe, made from copper and brass displays the movements of the sun, moon and planets as they travel through the night sky [15].

Peregrinus, attracted by the mechanical problems connected with Archimedes’ planetarium, was gradually led to consider the problem of perpetual motion. The result was that he described, “to his own evident satisfaction,” [2] how a wheel might be driven round forever by the power of magnetic attraction. “Elated over his imaginary success,” Peregrinus wrote to inform a friend at home. To allow his friend comprehending the mechanism of the motor and the functions of its parts, “he proceeds to set forth in a methodical manner all the properties of the lodestone, most of which he himself had discovered.” [2]

Fig. 1. Two drawings from the notebook of Villard de Honnecourt, an artist from Picardy, contemporary of Peter Peregrinus. A drawing is showing how could appear a soldier at the time.

On the right, we can see a wheel of perpetual motion as imagined by Villard de Honnecourt.

MMSE Journal. Open Access www.mmse.xyz 92

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

Peter Peregrinus was not the only person from Picardy that studied the problem of perpetual motion.

Another one was his contemporary Villard de Honnecourt. Villard is known to history only through a surviving notebook of 33 sheets of parchment containing about 250 drawings dating from the 1220s/1240s, which is now in the Bibliothèque Nationale, Paris (MS Fr 19093). The great variety of subjects (religious and secular figures, architectural plans and mechanical devices), makes it difficult to determine his profession. Since the discovery of his notebook, it is general opinion that Villard was an itinerant architect. Among the mechanical devices sketched by Villard, we see the perpetual-motion machine shown in the Figure 1. The problem of perpetual motions was of great appeal during the middle ages. This interest was probably stimulated by the books on mechanics coming from Arabic world, where we can find such wheels. The wheel sketched by Peregrinus is discussed in a very interesting article [16], which is also showing several layouts of it in different manuscripts and also wheels from Arabic manuscripts.

Roger Bacon’s opinion: Peregrinus’ Letter was the first landmark among the studies on magnetism, the next being William Gilbert's De Magnete, in 1600. The Letter was addressed to Sigerus de Foucaucourt, his "amicorum intimus," the dearest of friends. Another friend was Roger Bacon, who held Peregrinus in the very highest esteem, as shows by his following words: "There are but two perfect mathematicians," wrote the English monk, "John of London and Petrus de Maharne-Curia, a Picard" [2]. Bacon thus writes of Peregrinus [2]: "I know of only one person who deserves praise for his work in experimental philosophy, for he does not care for the discourses of men and their wordy warfare, but quietly and diligently pursues the works of wisdom. … he is a master of experiment. … he knows all natural science whether pertaining to medicine and alchemy, or to matters celestial and terrestrial. He has worked diligently in the smelting of ores as also in the working of minerals; he is thoroughly acquainted with all sorts of arms and implements used in military service and in hunting, besides which he is skilled in agriculture and in the measurement of lands. It is impossible to write a useful or correct treatise in experimental philosophy without mentioning this man's name”. Other references and information on Petrus Peregrinus are reported in [17].

Analysis of the Letter: The analysis proposed in [2] shows that, according to the known manuscripts: 1) Peter Peregrinus was the first to assign a definite position to the poles of a lodestone and to provide a method for determining which is north and which south; 2) he proved that unlike poles attract each other, and that similar ones repel; 3) after experiments, he established every fragment of a lodestone, however small, has two poles and then it is a complete magnet; 4) he recognized that a pole of a magnet may neutralize a weaker one of the same name, and even reverse its polarity; 5) he was the first to describe the use of a pivot for a magnetized needle and surround it with a graduated circle, creating, in such a manner, a model for the modern magnetic compass; 6) he determined the position of an object by its magnetic bearing as done in modern compass surveying; and, at the end of the letter, 7) he described his perpetual motion machine, based on the idea of a magnetic motor, a clever and new idea for a thirteenth century engineer [2].

The copies of Peregrinus’ Letter for nearly three centuries, remained unnoticed among the libraries of Europe, until William Gilbert, who makes frequent mention of it, published his “De Magnete” in 1600. After, a Jesuit writer, Niccolò Cabeo, refers to it in his “Philosophia Magnetica”, 1629. And Athanasius Kirches quotes from the Letter, in his “De Arte Magnetica”, 1641. Kircher also constructed a magnetic clock, the mechanism of which is described in his book.

In the first part of the Letter: After an introduction, where Peregrinus writes that he wants to explain to his friend the hidden virtue of the lodestone in a simple style, he poses the “qualifications of the experimenter”. “Whoever wishes to experiment, should be acquainted with the nature of things, and should not be ignorant of the motion of the celestial bodies. He must also be skilful in manipulation in order that, by means of this stone, he may produce these marvelous effects…

Besides, in such occult experimentation, great skill is required, for very frequently without it the

MMSE Journal. Open Access www.mmse.xyz 93

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

desired result cannot be obtained, because there are many things in the domain of reason which demand this manual dexterity” [2].

After the experimenter has found a good lodestone, he can find and distinguish its poles. “I wish to inform you that this stone bears in itself the likeness of the heavens, as I will now clearly demonstrate.” That is, we have in the heavens “two points more important than all others, because on them, as on pivots, the celestial sphere revolves:” these points are the Arctic or north pole and the Antarctic or south pole. The lodestone has two points which are respectively the north pole and the south pole. “If you are very careful, you can discover these two points in a general way. One method for doing so is the following: with an instrument with which crystals and other stones are rounded, let a lodestone be made into a globe and then polished. A needle or an elongated piece of iron is then placed on top of the lodestone and a line is drawn in the direction of the needle or iron, thus dividing the stone into two equal parts. The needle is next placed on another part of the stone and a second median line drawn. If desired, this operation may be performed on many different parts, and undoubtedly all these lines will meet in two points just as all meridian or azimuth circles meet in the two opposite poles of the globe. One of these is the north pole, the other the south pole.”

[2] In fact, Peter Peregrinus is telling that it is possible to create a globe and, on it, finding the poles by drawing on it a set of meridians, which are following the lines of the magnetic field, detected by means of a needle (see Figure 2).

Fig. 2. A spherical magnet with poles and meridians, as illustrated in the “Tractatus, sive Physiologia nova de magnete, magneticisque corporibus & magno magnete tellure” by William Gilbert, published 1633 by Lochmans.

In the Figure 2, the spherical magnet looks like a “terrella”, Latin of "little earth", a small magnetised model representing the Earth. Terrella is usually thought to have been invented by William Gilbert, but based on an idea of Peter Peregrinus.

Peter Peregrinus is describing another method for determining the poles. “Note the place on the above-mentioned spherical lodestone where the point of the needle clings most frequently and most strongly; for this will be one of the poles as discovered by the previous method. In order to determine this point exactly, break off a small piece of the needle or iron so as to obtain a fragment about the length of two fingernails; then put it on the spot which was found to be the pole by the former operation (see Figure 2). If the fragment stands perpendicular to the stone, then that is, unquestionably, the pole sought; if not, then move the iron fragment about until it becomes so; mark this point carefully; on the opposite end another point may be found in a similar manner. If all this has been done rightly, and if the stone is homogeneous throughout and a choice specimen, these two points will be diametrically opposite, like the poles of a sphere” [2].

North and South Poles: After we have found the poles, we have to determine which is north and which south. We can proceed in the following manner, according to Peregrinus. He is proposing to use the celestial pole as a reference. Let us take a wooden vessel, made like a dish, and place in it MMSE Journal. Open Access www.mmse.xyz 94

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

the stone in such a way that the two poles will be equidistant from the edge of the vessel. Then, let us place the dish in another and larger vessel full of water, so that “the stone in the first-mentioned dish may be like a sailor in a boat”. The second vessel should be of considerable size, in order that the lodestone may not be impeded by contact of one vessel against the sides of the other. “When the stone has been thus placed, it will turn the dish round until the north pole lies in the direction of the north pole of the heavens, and the south pole of the stone points to the south pole of the heavens”.

And then “since the north and south parts of the heavens are known, these same points will then be easily recognized in the stone because each part of the lodestone will turn to the corresponding one of the heavens,” Peregrinus explains.

How lodestones attract each other: After we discovered the north and the south pole in the lodestone, we have to mark them both carefully. If we want to see how one lodestone attracts another, then, with two lodestones selected and prepared as previously told, we can proceed as follows. “Place one in its dish that it may float about as a sailor in a skiff, and let its poles which have already been determined be equidistant from the horizon, i.e., from the edge of the vessel.

Taking the other stone in your hand, approach its north pole to the south pole of the lodestone floating in the vessel; the latter will follow the stone in your hand as if longing to cling to it. If, conversely, you bring the south end of the lodestone in your hand toward the north end of the floating lodestone, the same phenomenon will occur; namely, the floating lodestone will follow the one in your hand. Know then that this is the law: the north pole of one lodestone attracts the south pole of another, while the south pole attracts the north. Should you proceed otherwise and bring the north pole of one near the north pole of another, the one you hold in your hand will seem to put the floating one to flight. If the south pole of one is brought near the south pole of another, the same will happen. This is because the north pole of one seeks the south pole of the other, and therefore repels the north pole” [2].

After the discussion of this experiment, Peregrinus continues remarking that it “is well known to all who have made the experiment, that when an elongated piece of iron has touched a lodestone and is then fastened to a light block of wood or to a straw and made float on water, one end will turn to the star which has been called the Sailor's star because it is near the pole; the truth is, however, that it does not point to the star but to the pole itself”. Peregrinus is also telling an important fact, that every fragment of a lodestone has two poles and then it is a complete magnet. “Take a lodestone which you may call AD, in which A is the north pole and D the south; cut this stone into two parts, so that you may have two distinct stones; place the stone having the pole A so that it may float on water and you will observe that A turns towards the north as before; the breaking did not destroy the properties of the parts of the stone, since it is homogeneous; hence it follows that the part of the stone at the point of fracture, which may be marked B, must be a south pole; this broken part of which we are now speaking may be called AB. The other, which contains D, should then be placed so as to float on water, when you will see D point towards the south because it is a south pole; but the other end at the point of fracture, lettered C, will be a north pole; this stone may now be named CD. If we consider the first stone as the active agent, then the second, or CD, will be the passive subject. You will also notice that the ends of the two stones which before their separation were together, after breaking will become one a north pole and the other a south pole. If now these same broken portions are brought near each other, one will attract the other, so that they will again be joined at the points B and C, where the fracture occurred. Thus, by natural instinct, one single stone will be formed as before” [2].

The natural virtue of magnets: In the part of the Letter discussing the natural virtue of magnets, we can find an experimental device, which Peregrinus is proposing for having a magnetic clock. To Peregrinus, “it is clear that the poles of the lodestone derive their virtue from the poles of the heavens. As regards the other parts of the stone, the right conclusion is that they obtain their virtue from the other parts of the heavens. … You may test this in the following manner: A round lodestone on which the poles are marked is placed on two sharp styles as pivots having one pivot under each pole so that the lodestone may easily revolve on these pivots. Having done this, make MMSE Journal. Open Access www.mmse.xyz 95

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

sure that it is equally balanced and that it turns smoothly on the pivots. … Then place the stone with its axis in the meridian, the poles resting on the pivots. Let it be moved after the manner of bracelets (the bracelets are the circles, “armillae”, of armillary spheres) so that the elevation and depression of the poles may equal the elevation and depressions of the poles of the heavens of the place in which you are experimenting. If now the stone be moved according to the motion of the heavens, you will be delighted in having discovered such a wonderful secret; … With such an instrument you will need no timepiece, for by it you can know the ascendant at any hour you please, as well as all other dispositions of the heavens which are sought for by astrologers” [2].

About this experiment, William Gilbert tells in his book [10]: “I omit what Peter Peregrinus constantly affirms, that a terrella suspended above its poles on a meridian moves circularly, making an entire revolution in 24 hours: which, however, it has not happened to ourselves as yet to see …”.

A comment in [10] tells us that, besides Gilbert, Galileo too discussed this experiment in the third of his Dialogues, the book which presents a series of discussions among two philosophers and a layman: Salviati, who presents some of Galileo's views directly, Sagredo and Simplicio, a follower of Ptolemy and Aristotle. About Peregrinus’ experiment, Salviati tells “I will speak to one particular, to which I could have wished, that Gilbert had not lent an ear; I mean that of admitting, that in case a little Sphere of Loadstone might be exactly librated, it would revolve in itself; because there is no reason why it should do so; For if the whole Terrestrial Globe hath a natural faculty of revolving about its own centre in twenty four hours, and that all its parts ought to have the same, I mean, that faculty of turning round together with their whole, about its centre in twenty four hours; they already have the same in effect, whilst that, being upon the Earth, they turn round along with it: And the assigning them a revolution about their particular centres, would be to ascribe unto them a second motion much different from the first; for so they would have two, namely, the revolving in twenty four hours about the centre of their whole; and the turning about their own: now this second is arbitrary, nor is there any reason for the introducing of it” [18].

With the discussion of the pivoted sphere made by Galileo, let us conclude this discussion on the medieval magnetism as we find in the Peregrinus’ Letter. However, let us stress that the attraction the Peregrinus had for pivoted magnets, forced him to imagine new devices. In the second part of the Letter, he discussed three devices: one is an instrument for measuring the azimuth of sun, moon and stars on the horizon, the second a pivoted compass and the third a wheel of perpetual motion.

The use of a pivoted compass to determine the azimuth of the sun is clearly shown by the Figure 3, which is obtained adapting images from [2]. The devices described by the Peregrinus will be the subject of a future paper, on pivoted mechanisms of the Middle Ages.

Fig. 3. The pivoted magnet used for measuring the azimuth of stars.

MMSE Journal. Open Access www.mmse.xyz 96

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

References [1] T.F. Glick, S. Livesey, F. Wallis (2014). Medieval Science, Technology, and Medicine: An Encyclopedia, Routledge.

[2] Peter Peregrinus (1904). The Letter of Petrus Peregrinus on the Magnet, A.D. 1269, Translated

by Brother Arnold, with introductory notice by Brother Potamian, New York, McGraw Publishing Company.

[3] E. Grant (1974). A Source Book in Medieval Science, Volume 1, Harvard University Press.

[4] W.J. Battersby (1953). Brother Potamian: Educator and Scientist, Antic Hay Books.

[5] E. Du Trémolet de Lacheisserie, D. Gignoux, M. Schlenker (2005). Magnetism, Springer Science & Business Media.

[6] T. Breverton (2012). Breverton's Encyclopedia of Inventions: A Compendium of Technological Leaps, Groundbreaking Discoveries and Scientific Breakthroughs that Changed the World, Hachette UK. [7] J. Block Friedman, K. Mossler Figg (2013). Trade, Travel, and Exploration in the Middle Ages: An Encyclopedia, Routledge.

[8] L. Spitzer, A.K. Forcione, H.S. Lindenberger, M. Sutherland (1988). Representative Essays, Stanford University Press.

[9] F. Jensen (1994). Tuscan Poetry of the Duecento: An Anthology, Taylor & Francis.

[10] W. Gilbert (1600). De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure, On the Magnet, edited and with notes by Silvanus P. Thompson. Available on line at: https://ebooks.adelaide.edu.au/g/gilbert/william/on-the-magnet/complete.html [11] G.W.F. Hegel (2004). Philosophy of Nature, Volume 2, Psychology Press.

[12] https://www.math.nyu.edu/~crorres/Archimedes/Sphere/SphereSources.html [13] D. De Solla Price (1975). Gears from the Greeks, The Antikythera Mechanism-A Calendar Computer from ca. 80 B.C., Science History Publications, New York, 1975, [14] D. De Solla Price (1974). Gears from the Greeks, The Antikythera Mechanism-A Calendar Computer from ca. 80 B.C., Transaction of The American Philosophical Society, New Series, Volume 64, Part 7.

[15] J. Marchant (2015). Archimedes’ Legendary Sphere Brought to Life; Recreation of a 2,000year-old Model of the Universe to Appear in Exhibition, Nature 526(19), 01 October 2015.

Available on line at: http://www.nature.com/news/archimedes-legendary-sphere-brought-to-life1.18431 DOI: 10.1038/nature.2015.18431 [16] A. Kleinert (2003). Wie funktionierte das Pepertuum Mobile des Petrus Peregrinus?, International Journal of History & Ethics of Natural Sciences, Technology & Medicine, 11(3):155170. DOI: 10.1007/s00048-003-0168-5 [17] T. Bertelli (1868). Pietro Peregrino di Maric e la sua Epistola de Magnete, Roma, Tipografia della Scienze Matematiche e Fisiche.

[18] Galilæus Galilæus Lyncæus, His System of the World, The Third Dialogue. Available on line at: http://www.chlt.org/sandbox/lhl/Salusbury/page.376.php?

MMSE Journal. Open Access www.mmse.xyz 97

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

Depletion Gilding: An Ancient Method for Surface Enrichment of Gold Alloys Amelia Carolina Sparavigna 1 – Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy

Keywords: Gilding, Depletion Gilding, Gold-Copper Alloys, Tumbaga, Gold-Silver-Copper Alloys, Electrum, Archaeological Artefacts, Gold-Copper nanoparticles, Nanoporous Gold.

ABSTRACT. Ancient objects made of noble metal alloys, that is, gold with copper and/or silver, can show the phenomenon of surface enrichment. This phenomenon is regarding the composition of the surface, which has a percentage of gold higher than that of the bulk. This enrichment is obtained by a depletion of the other elements of the alloy, which are, in some manner, removed. This depletion gilding process was used by pre-Columbian populations for their “tumbaga”, a gold-copper alloy, to give it the luster of gold.

Introduction: A phenomenon often encountered when ancient objects made of noble metal alloys are analyzed is that of their surface enrichment. Let us consider, for instance, a statuette made of an alloy of gold with copper and/or silver; it can occur that its surface has a percentage of gold higher than that of the bulk. This enrichment can be due to an addition of gold on the surface, or to a depletion process during which the less chemically stable elements leach out causing the surface composition to change. In both cases, the local percentage of gold is increased consequently.

Therefore, both processes are gilding processes, the second being known as “depletion gilding”. It happens because a specific depletion process had been applied to the surface of the object or because it had been buried for a rather long time [1] (of course, besides such a slow gilding process, time is causing a long series of damaging and corrosive effects [2]). Masters of the depletion gilding were the pre-Columbian populations of America that used it for their “tumbaga”, an alloy of gold and copper, to give the luster of gold to the objects made of it. In this paper, we will discuss some aspects of tumbaga and depletion gilding.

Gilding: The term “gilding” covers several techniques for applying a gold leaf or a gold powder to solid surfaces, in order to have a thin coating of this metal on objects. Several methods of gilding exist, including hand application, chemical gilding and electroplating. These are additive methods, which act by depositing gold onto the surface of objects usually made of a less precious material.

Among the techniques of gilding, some are quite old. Fire-gilding of metals for instance goes back at least to the 4th century BC, and was known to Pliny the Elder and Vitruvius. Fire-gilding is a process by which an amalgam of gold is applied to metallic surfaces. Objects are set on fire and mercury volatilizes, leaving a film of gold or a gold-rich amalgam on the surface. About the coating with gold leaf, Pliny is also telling the following. “When copper has to be gilded, a coat of quicksilver is laid beneath the gold leaf, which it retains in its place with the greatest tenacity: in cases, however, where the leaf is single, or very thin, the presence of the quicksilver is detected by the paleness of the colour” [3].

As previously told, besides the gilding obtained by the abovementioned techniques, we have also the subtractive process of depletion gilding. In this gilding, some material is removed to increase the purity of the gold. Of course, gold must be already present on the surface of the object. For this reason, this gilding procedure can be applied only to objects composed by gold alloys, usually gold with copper and/or silver. The gilding is performed by removing the metals, which are not gold.

These metals are etched away from the surface by means of the use of some acids or salts, often MMSE Journal. Open Access www.mmse.xyz 98

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

combined with the action of heat. Of course, there is no gold addition, because the object already contains gold.

Depletion gilding: Depletion gilding is based on the property of gold of being resistant to oxidation or corrosion by most chemicals, whereas many other metals, such as copper and silver, are not so.

Therefore an object, cast for instance by an alloy of gold with copper and silver, can be immersed in a suitable acid or packed in a salt, which attacks the copper and silver in the object's surface. The action of acid or salt is transforming these elements to some copper/silver compounds that can be removed from the object's surface by washing or heating, or by using a brick dust [4, 5]. The result is a thin layer of nearly pure gold on the surface of the object. Often it is necessary to repeat this procedure several times, making the resulting surface soft and spongy with a dull appearance. For this reason, most depletion-gilded objects are burnished to make their surfaces more durable and give them a more attractive polished finish.

Depletion gilding was widely used in antiquity. A historical and technical introduction of this gold surface enrichment is given in [6], which discusses how goldsmiths have used the depletion gilding technique for “coloring the gold”. The process requires some skill to execute it properly, but it is technologically simple. Moreover, it is requiring materials that were available to most ancient civilizations, those that were able of making alloys.

For what concerns the color of gold, let us note that pure gold is slightly reddish yellow in color.

Other colors can be produced making alloys with silver, copper, nickel and zinc in various proportions, producing white, yellow, green and red golds [7] (see Appendix for some data). In the case of an alloy of gold and copper, the result is a red or yellow-red color. These alloys were used especially in the pre-Columbian Meso- and South America. Known as “tumbaga”, this material was used widely both for castings and for hammered metal works. A further depletion gilding was giving to these objects the color and luster of pure gold.

Today, gold alloys have many applications in dentistry, jewelry and industrial areas too (let us note that gold is used for corrosion protection of electrically conductive surfaces [8]). For economic reasons then, much effort has been made to lower the gold content in the bulk of such alloys. As a consequence, the surface enrichment of low gold alloys became an interesting subject of researches [9]: in this reference, we find the modern methods for the creation of a gold-enriched surface on a gold alloy by depletion processes. Experiments tell that the additions of sodium chloride to pure water speed up the oxidation of copper to copper chloride, which is dissolved at the metal-solution interface. Additions of sodium sulfide to pure water should also speed up the oxidation of copper to cuprous or cupric sulfide, but these compounds are insoluble in water, and then they are tarnishing the alloy [9]. Let us remember that, in pure water, copper dissolves regardless of being in a gold alloy or as metal [9].

American goldsmiths: However, how did the pre-Columbian populations of Meso- and South America a depletion gilding? This question was the subject of several researches made by archaeologists. In [4], we can find a description of techniques. It is also told that was Gonzalo Fernandez de Oviedo (1478-1557), to give a hint on pre-Columbian depletion gilding, writing that the pre-Columbian goldsmiths knew how to use a certain herb for gilding objects made of debased gold. The alloys used were generally of two types [4]. One type is composed by the tumbaga copper-gold alloys produced with differing gold contents, the other was that of pale greenish-white ternary silver-gold-copper alloys, containing a high proportion of silver, similar to the Mediterranean electrum and widely used in Peru.

For tumbaga, a depletion gilding technique was the following: the object made of tumbaga was rubbed with the juice of a plant and then heated so that it assumed a gold coloration. This process was repeated many times to improve the colour and increase the superficial gold contain. It is believed that the plant was a species of oxalis and that the juice contained oxalic acid [4]. For objects made of alloys of electrum type, they were probably gilded using a cementation process or by using some aqueous pastes [4]. In the first process, the object was placed in a crucible and MMSE Journal. Open Access www.mmse.xyz 99

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

surrounded with a powdered mixture containing alum, common salt and brick dust [4]. The crucible and its contents were heated. The mixture reacted with the surface of the object, forming chlorides of silver, copper and other impurity metals. The chlorides were absorbed by the brick dust [4].

Probably, additional ingredients may have been used too. After cooling, and subsequently washing the object, the brilliance of the surface was increased by burnishing [4]. The second method was that of immersing the object in an aqueous paste or solution of alum, iron sulfate and salt at room temperature. After about ten days [4], the object was washed in a strong salt solution and then heated to convert the spongy, gold-enriched surface to a smooth and compact surface. Both cementation and aqueous methods work equally well on electrum and tumbaga [4].

Phase diagram of gold and copper: Tumbaga is an alloy of gold and copper then. However, we can tell more about these two metals together. A study of the phase diagram of copper and gold shows that they are completely soluble in each other with eutectic type low melting point, occurring at a composition of 80.1% gold at 911 °C. In the Figure 1, the phase diagram is shown, adapted from [10]. Phase diagrams of gold with other elements, such as platinum, silver, nickel and cobalt are given in Ref.11. Let us remember that a naturally occurring alloy of gold and silver exists, the electrum.

Fig. 1. Phase diagram Au/Cu In the Figure 1, it is easy to see the eutectic composition. The word “eutectic” comes from the Greek word “eutektos”, that is, “easily melted”. At the eutectic-composition, an alloy of two or more metals, when heated to its melting point, completely changes from solid to liquid at the same temperature [12]. Thus, the eutectic-composition is characterized by being the first alloycomposition to melt during heating [12], such as the last to freeze during cooling.

The rounded shapes at the bottom of the diagram in Fig.1 show the regions where ordered phases exist. According to [10], these ordered phases are usually harder than the disordered alloy of the same composition, and they may make the process of working and annealing to shape more difficult. Moreover, the quenched alloys between about 85% gold and 50% gold are softer than the alloys that are allowed to cool slowly in air (quenching is the rapid cooling of a work piece). This is the opposite of what happens in alloys such as iron and carbon, where the material is hardened by quenching because of the formation of martensitic phase [10]. For the gold-copper alloys, the softening by quenching process happens because it is suppressing the formation of the ordered phases, which need some time to form. As told in [10], South American populations used water quenching after annealing in order to make their alloys easier to work to shape and to avoid embrittlement.

MMSE Journal. Open Access www.mmse.xyz 100

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

The raft of El Dorado: The alloys of gold with copper or silver were produced by the preColumbian people to create wonderful statues and ornaments. In the Figure 2, it is shown one of such objects. It is the Muisca Raft, obtained in a lost-wax casting by the Muisca culture in a region which currently corresponds to the center of Colombia. A recent study on Muisca metallurgy shows that gold alloys were especially composed for votive metalwork [13], and in fact, the Raft is a votive object. Today, it is exhibited at the Gold Museum in Bogota. The Raft refers to the ceremony of El Dorado, during which Muisca chief, after covering his body with gold powder, dove into the Guatavita Lake. Then, El Dorado was El Hombre Dorado, the Golden Man.

Fig. 2. The Muisca Raft (Courtesy: Wikipedia). It is a representation of the legend of El Dorado.

The cacique at the center of the raft is surrounded by attendants and oarsmen The legends surrounding El Dorado changed over time, so that it became a golden city or a lost kingdom full of gold. Many expeditions were made in the search for El Dorado: among the most famous there was that led by Sir Walter Raleigh [14, 15]. All the expeditions did not find El Dorado but mapped a large part of South America.

After failing in discovering El Dorado and its gold mines, the Spaniard conquistadores that had promised their king a mass of gold in return for investing in the transatlantic voyage, resorted to looting the treasuries of the local chiefs and the grave goods of cemeteries [16]. However, as Shakespeare writes in his play “The Merchant of Venice”, “all that glitters is not gold”: when Spaniard soldiers began to melt down the mass of the glittering ornaments, they discovered that they had not pure gold, but an alloy debased with large amounts of copper. The result was that a large part of beautiful objects, such as those held in the Gold Museum, were plundered by the Spaniards and melted into “tumbaga” bars for transport across the Atlantic. Hernan Cortes and his men for instance improvised a manufacture of such metallic bars [17].

Because all the metals that reached Europe were melted back into their constituent metals in Spain, there is only an example of such a load, a group of over 200 tumbaga bars, discovered in the remains of an unidentified shipwreck (around 1528), off Grand Bahama Island. This shipwreck was found in 1993 [17]. Since we have mentioned Hernan Cortes, the conquistador who caused the fall of Aztec Empire and brought Mexico under the rule of the King of Castile, let us mention an interesting article on the metallurgy of Aztecs [18]. In it, is mentioned the pioneering research work of Dora M.K. de Grinberg and others on the metallurgical skills of the pre-Columbian population [19]. De Grinberg, an Argentinian archeologist working in Mexico, uncovered ample evidence that the ancient American metalworkers were far more skilled than had previously been supposed [18].

Tumbaga: The word “tumbaga” is not native to any language of the area of Meso- or South America. But it is not a Spanish word too. It is coming from Malay and means copper [20]. The MMSE Journal. Open Access www.mmse.xyz 101

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

historical documentation on ancient American gold alloys begins with Columbus, who reported that the word "guanin" was employed to express these alloys. Washington Irving, in his “Life of Columbus”, wrote that in 1503 Columbus was on the Mosquito Coast. “There was no pure gold to be met with here, all their ornaments were of guanine; but the natives assured the Adelantado that in proceeding along the coast, the ships would soon arrive at a country where gold was in abundance” [21]. In the reports of Columbus, it is evident his quest for gold. The same happens for other explorers. In a 1546 communication to his king, Juan Perez de Tolosa reported on a population of the Northwestern Venezuela that, in addition to possessing gold and other precious metals, had ornaments of a copper-gold alloy called “carcuri”. Similar reports appear in the writing of Pedro de Cieza de Leon, who explored the Cuca Valley of Northern Colombia during 1532-1550.

In a book of 1760 [22], written by Antonio de Ulloa (1716-1795), Spanish general and explorer, we find other information about gold: “In the district of Choco are many mines of Lavadero, or wash gold … There are also some, where mercury must be used, the gold being enveloped in other metallic bodies, stones and bitumens. Several of the mines have been abandoned on account of the platina; a substance of such resistance, that, when struck on an anvil of steel, it is not easy to separate … In some of these mines the gold is found mixed with the metal called tumbaga, or copper, and equal to that of the east”. Antonio de Ulloa uses the word “tumbaga” for copper then.

He continues telling that “its most remarkable quality is that it produces no verdigrease (verdigris), nor is corroded by any acids, as common copper is well known to be” [22]. In fact, if we treat tumbaga with an acid, copper is dissolved off the surface. On the surface, it remains a shiny layer of nearly pure gold. As previously discussed, the use of an acid produces a process of depletion gilding, not the verdigris. Note that, in the description made by Antonio de Ulloa, there is also mentioned another material, the platina, that is, the platinum.

Among the first modern reports about tumbaga, there is that by G. Créqui-Montfort and P. Rivet, published in 1919 [23], who described the tumbaga in Colombia. The documentation of a similar pre-Columbian alloy with depletion gilding to produce a golden surface is given in the Ref.24. In a report of 1949, W. Root is comparing the physical properties of tumbaga with those of unalloyed gold and copper. In his review [25], Root tells that tumbaga seems to have originated in Colombia or Venezuela before AD 1000 and spread to Ecuador and Peru. But, in a discussion about gilding [26], Heather Lechtman et al. tell that the depletion gilding was first developed by the Moche culture of Peru, about AD 100-800. Therefore, depletion methods of gilding used in Peru, from this center of origin, spread north into Ecuador, Columbia, Venezuela, Panama till Mexico [26].

In nanotechnologies: Today, tumbaga has an important role in nanotechnology. In fact, the goldcopper alloys are emerging as an important catalyst. In [27], the authors investigated the phase diagrams of various polyhedral nanoparticles, made of gold-copper alloy. In these particles, the researchers revealed a gold enrichment at the surface, like in tumbaga, leading to a kind of coreshell structure, analogous to the surface enrichment of archaeological artifacts. The most stable structures of the nanoparticles were determined to be the dodecahedron, truncated octahedron, and icosahedron with a Cu-rich core/Au-rich surface. In [28], nanorods of AuCu3 had been investigates, in particular to determine the catalytic activity of them, when different surface ligands are used.

Besides nanoparticles, in catalysis, sensing, and other areas, porous gold is used [29-32]. This material is made by dealloying gold alloys [29]. In fact, this relatively new material is like the surface of tumbaga, the spongy gold which is produces by dealloying the surface layer with gilding depletion. For what concerns porous gold, let us conclude with an interesting feature of the layer of gold on tumbaga, discussed by Stuart J. Fleming in Ref.16. Fleming tells that tumbaga has a “selfhealing” property. When corrosion happens, some gold atoms are set free by it. These atoms can migrate and seal the minute channels, which are originated by the corrosive attack. For this reason, objects made of a relatively gold-rich tumbaga can retain for a long time their original luster. This property of self-healing of gold alloys could be interesting for nanotechnologies too, where surfaces have a relevant role, due to the reduced dimensions of involved materials.

MMSE Journal. Open Access www.mmse.xyz 102

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

Appendix on colors of gold-copper alloys: Here a table on the color and chemical composition of some alloys with karat number 18 [7]. Let us remember that 24 kt gold is pure gold. The designations 18 kt, 14 kt, or 10 kt indicate how much pure gold is present in the mix: 18 kt gold (75% gold) has 18 parts gold and 6 parts of another metal(s), 14 kt gold (58.3% gold) has 14 parts gold and 10 parts of another metal(s), and so on for 12 kt and 10 kt gold. 10 kt gold is the minimum karat designation that can still be called gold in the US [7].

Table 1 Color of Gold

Alloy Compositions Containing Copper

Yellow Gold (22 kt)

Gold 91.67%, Silver 5%, Copper 2%, Zinc 1,33%

Red Gold (18 kt)

Gold 75%, Copper 25%

Rose Gold (18 kt)

Gold 75%, Copper 22.25% Silver 2.75%

Pink Gold (18 kt)

Gold 75%, Copper 20%, Silver 5%

Gray-White Gold (18 kt)

Gold 75%, Iron 17%, Copper 8%

Light Green Gold (18 kt)

Gold 75%, Copper 23%, Cadmium 2%

Green Gold (18 kt)

Gold 75%, Silver 20%, Copper 5%

Deep Green Gold (18 kt)

Gold 75%, Silver 15%, Copper 6%, Cadmium 4%

References [1] Hall, E.T. (1961). Surface-Enrichment of Buried Metals, Archaeometry, 4(19):62-66. DOI: 10.1111/j.1475-4754.1961.tb00535.x [2] Scott, D.A. (1983). The Deterioration of Gold Alloys and Some Aspect of Their Conservation, Studies in Conservation, 28:194-203. DOI: 10.2307/1505967 [3] Sparavigna, A.C. (2011). Materials Science in Ancient Rome, arXiv:1107.3831 [physics.popph] [4] Grimwade, M. (1999). The Surface Enrichment of Carat Gold Alloys - Depletion Gilding, 13th Santa Fe Symposium on Jewelry Manufacturing Technology, Albuquerque, N.M., USA, May 1999.

[5] Lewton-Brain, C. (1990). Some Notes on Depletion Gilding, Brain Press Publications.

[6] Lewton-Brain, C. (1990). Depletion Gilding: A Historical and Technical Introduction, Lulu.com.

[7] Vv. Aa. (2009). Gold and Gold Alloys, Total Materia Database. Retrieved 22 Dec 2015, http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=230 [8] Song, J.; Wang, L.: Zibart, A.; Koch, C. (2012). Corrosion Protection of Electrically Conductive Surfaces, Metals, 2:450-477. DOI: 10.3390/met2040450 [9] Hultquist, G. (1985). Surface Enrichment of Low Gold Alloys, Gold Bulletin, 18(2):53-57. DOI: 10.1007/BF03214686 [10] Scott, D.A. (1991). Metallography and Microstructure of Ancient and Historic Metals, Getty Conservation Institute, in association with Archetype Books.

[11] Vv. Aa. (2014). Gold Based Materials. Retrieved 18 December 2015, http://www.electricalcontacts-wiki.com/index.php/Gold_Based_Materials

MMSE Journal. Open Access www.mmse.xyz 103

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

[12] Kay, D. (2012). Eutectics - The Good and the Bad! Retrieved 18 December 2015, http://vacaero.com/information-resources/vacuum-brazing-with-dan-kay/1268-eutectics-the-goodand-the-bad.html [13] Villegas, M.A.U.; Martinón-Torres, M. (2012). Composition, Colour and Context in Muisca Votive Metalwork (Colombia, AD 600-1800). Antiquity, 86(333):772-791. DOI: 10.1017/s0003598x00047918 [14] Aronson, M. (2002). Sir Walter Ralegh and the Quest for El Dorado, Houghton Mifflin Harcourt.

[15] Sellin, P.R. (2011). Treasure, Treason and the Tower: El Dorado and the Murder of Sir Walter Raleigh, Ashgate Publishing Ltd. [16] Fleming, S.J. (1999). Confounding the Conquistadors: Tumbaga's Spurious Luster, Expedition, 41(2):6–7. Available at the site of Expedition Magazine of Penn Museum, http://www.penn.museum/sites/expedition/?p=5746 [17] Garcia-Barneche, A. (2010). The Tumbaga Saga: Treasure of the Conquistadors, Daniel Frank Sedwick LLC. [18] Burton, T. (2008). Did You Know? Lots of "Real" Aztec Gold Was Only Tumbaga. Retrieved 22 December 2015, http://www.mexconnect.com/articles/1238-did-you-know-lots-of-real-aztecgold-was-only-tumbaga [19] M.K. de Grinberg, D.; Pérez-Duarte, I. (1990). Los Se ores del Metal : Minería y Metalurgia en Mesoamérica, Consejo Nacional para la Cultura y las Artes, Dirección General de Publicaciones, Mexico, Pangea.

[20] Blust, R. (1992). Tumbaga in Southeast Asia and South America, Anthropos, Bd.87, H.4./6., pp.443-457.

[21] Bollaert, W. (1860). Antiquarian, Ethnological, and Other Researches in New Granada, Equador, Peru and Chili: With Observations on the Pre-Incarial, Incarial and Other Monuments of Peruvian Nations, Trübner & Company.

[22] De Ulloa, A. (1760). A Voyage to South America, Printed for L. Davis and C. Reymers, Holbourn, Royal Society.

[23] Créqui-Montfort, G.; Rivet, P. (1919). Contribution à l'Etude de l'Archéologie et de la Métallurgie Colombiennes, Journal de la Société des Américanistes de Paris, Nouvelle série, XI(1914-1919):525-591.

[24] Rivet, P. (1923). La Orfévrerie Précolombienne des Antilles, des Guayanes et du Vénézuela dans Ses Rapports avec l'Orfévrerie et la Métallurgie des Autres Régions Américaines, Journal de la Société des Américanistes de Paris, Nouvelle série, XV:183-213.

[25] Root, W. (1949). Metallurgy, in the Handbook of South American Indians, Vol.5, Smithsonian Institute, Washington, Bulletin 143.

[26] Lechtman, H.; Erlij, A.; Barry, Jr., E.J. (1982). New Perspectives on Moche Metallurgy: Techniques of Gilding Copper at Loma Negra, Northern Peru, American Antiquity, 47(1):3-30.

[27] Guisbiers, G.; Mejia-Rosales, S.; Khanal, S.; Ruiz-Zepeda, F.; Whetten, R.L.; José-Yacaman, M. (2014). Gold–Copper Nano-Alloy, “Tumbaga”, in the Era of Nano: Phase Diagram and Segregation, Nano Lett., 14 (11):6718–6726. DOI: 10.1021/nl503584q [28] Jenkins, S.V.; Chen, S.; Chen, J. (2015). Gold–Copper Alloyed Nanorods for Metal-Catalyzed Organic Reactions: Implication of Surface Ligands on Nanoparticle-Based Heterogeneous Catalysis, Tetrahedron Letters, 56(23):3368–3372. DOI: 10.1016/j.tetlet.2015.03.041

MMSE Journal. Open Access www.mmse.xyz 104

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

[29] Shulga, O.V.; Jefferson, K.; Khan, A.R.; D’Souza,V.T.; Liu, J.; Demchenko, A.V.; Stine, K.J. (2007). Preparation and Characterization of Porous Gold and its Application as a Platform for Immobilization of Acetylcholine Esterase, Chem. Mater., 19(16):3902–3911. DOI: 10.1021/cm070238n [30] Kertis, F.; Snyder, J.; Govada, Lata; Khurshid, Sahir; Chayen, N.; Erlebacher, J. (2010).

Structure/Processing Relationships in the Fabrication of Nanoporous Gold, Jom, 62(6): 50-56. DOI: 10.1007/s11837-010-0087-6 [31] Hua Dong; Xiaodong Cao (2009). Nanoporous Gold Thin Film: Fabrication, Structure Evolution, and Electrocatalytic Activity, Journal of Physical Chemistry C, 113(2):603-609. DOI: 10.1021/jp8086607 [32] Renyun Zhang; Håkan Olin (2014). Porous Gold Films - A Short Review on Recent Progress, Materials, 7:3834-3854. DOI: 10.3390/ma7053834

MMSE Journal. Open Access www.mmse.xyz 105

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

Mechanics, Materials Science & Engineering Journal Š

ISSN 2412-5954 Published by Magnolithe GmbH Printed by Magnolithe GmbH

Mechanics, Materials Science & Engineering Journal by Magnolithe GmbH is licensed under a Creative Commons Attribution 4.0 International License.Based on a work at www.mmse.xyz.

MMSE Journal. Open Access www.mmse.xyz 106