Thermal Analysis of Disc Brake | Ijirstv3i12017

IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 12 | May 2017 ISSN (online): 2349-6010

Thermal Analysis of Disc Brake Mr. Sumeet Satope UG Student Department of Automobile Engineering R.M.C.E.T. (Ambav)

Mr. Akshaykumar Bote UG Student Department of Automobile Engineering R.M.C.E.T. (Ambav)

Prof. Swapneel D. Rawool Assistant Professor Department of Automobile Engineering R.M.C.E.T. (Ambav)

Abstract Each single system of automotive along with brake system has come a long way in past years. In two wheeler brake system the material used for disc brake mostly is, alloy martensitic stainless steel and sometimes in high end bikes is carbon – carbon composite and grey cast iron. But when brakes is subjected to structural and wear issues it is important to study analytical calculation in order to obtain temperature, heat flux, heat generated etc. with the help of which optimum material is selected as per the requirement of vehicle system. The steady state thermal analysis of two wheeler disc rotor aimed towards the evaluating the braking performance of two wheeler disc brake under braking condition. In this paper mathematical inputs, and thermal loads of brake rotor, calculations of different parameters required for thermal analysis is done by taking suitable assumptions. The design of brake rotor is done on solid works 15 and analysis is done with the help of ansys 14.5.

Keywords: Analysis, brake, disc, heat, thermal _______________________________________________________________________________________________________ I.

INTRODUCTION

When a vehicle is in motion the only system which assists in stopping or retarding the motion is ‘brake system’. Earlier block of wood wrapped in friction material such as leather, known as mechanical “scuff” brake were used. As the automotive technology ameliorated, they came across drum brakes. The working of drum brake is quiet simple, the effective function is the brake shoe pressure or force is applied against the drum which stops or retard the rotating moment of the drum. The next leap in brake system was the invention of Disc brake. Earlier disc brake where mostly made of cast iron, sandwiched between the stationary parts called as brake pads situated inside the brake calliper. In this paper we are presenting study of temperature distribution of brake rotor while brake is applied In today’s emerging and advanced automotive market demand for efficient braking system is increasing competitively. The retardation of wheel is achieved by applying external force on brake pads. As the automotive brake works on principle of friction and heat dissipation the thermal behaviour of disc is an important parameter in order to improve the brake efficiency. When the bake is applied the artificial friction resistance causing the retardation of brake rotor, during this process, kinetic energy achieved by the moving vehicle is converted into heat generated between rotor and brake pads. Over heat generation during braking process leads to brake fading, brake squealing and crack formation. These faults have large effect on braking performance.

II. FACTORS GOVERNING BRAKING Four basic factors determine the brake power of the system. The first three factors govern the generation of friction: pressure, coefficient of friction, and frictional contact surface. The fourth factor is a result of friction. It is heat or, more precisely, heat dissipation.

Pressure: The amount of friction generated between moving surfaces in contact with each other depends in part on the pressure exerted on the surfaces. In a brake system, pressure applied with the help of hydraulic system.

Coefficient of Friction: The amount of friction generated between the two surfaces is expressed as coefficient of friction. The required COF depend on the vehicle and the other factors are carefully chosen by manufacturers to ensure safe and reliable braking.

Frictional Contact Surface: The third factor is amount of surface area that is in contact. For most part, the vehicle weight ad potential speed determines the size of frictional surface area.

All rights reserved by www.ijirst.org

68

Thermal Analysis of Disc Brake (IJIRST/ Volume 3 / Issue 12/ 012)

Heat Dissipation: This is the most important parameter to be taken into consideration while designing brake system. The excessive heat generated during continuous or hard braking tends to brake fading. As shoe or pad temperature rises, they can generate gas. So in order to eliminate the gas and avoid brake fading the friction material must have high heat dissipation characteristics.

III. MATERIALS OF DISC ROTOR Brake rotor is the most decisive part in automotive system for controlling the vehicle and safety point of view. Selection of brake rotor material is to be done on basis of consistency, friction and wear properties under varying condition of load, velocity, temperature, environment and high durability. There are many parameters to be taken in consideration while selecting materials, of which most important parameters are friction, density and wear rate. The required available material must also be selected with respect to cost.

Martensitic stainless steel: Martensitic stainless steel is a type of steel which has high corrosion resistance and forms hardened crystalline structure after heat treatment. Grade 410 stainless steel is general purpose martensitic stainless steel which contains 11.5 % chromium. Considering its cost, relative ease of manufacture and thermal stability it is widely used in two wheeler disc brakes.

Carbon – Carbon composite: It is mixture of two major elements, carbon fibres and carbon matrix. Carbon - carbon composites brakes have an ability to absorb much energy in a short period of time as compared to other material. It also exhibits light weight, high thermal efficiency and excellent mechanical properties at high temperature. But due to its high cost and method of actuation takes place only at high temperature range above 400 ℃ it is mostly used in aeroplane and sport cars braking system.

Cast iron: Metallic iron containing more than 2% dissolved carbon within its matrix but less than 4.5% is referred to as grey cast iron (12). Cast iron also contains 1-3% silicon, and consequently these alloys should be considered ternary Fe-C-Si alloys.

It provides good wear characteristics, dampen vibration and resist cracking in subsequent use. Hence it is most commonly preferred material for disc rotor of four wheelers.

Aluminium Metal Matrix Composites: Aluminum is the most popular matrix for the metal matrix composites (MMCs). The low density, their capability to be strengthened by precipitation, their good corrosion resistance, high thermal and electrical conductivity, and their high damping capacity, the aluminium alloy are quite attractive. Aluminium matrix composites (AMCs) belongs to the class of light weight high performance aluminium centric material. The reinforcement in AMCs could be in the form of continuous or discontinuous fibers, whisker or particulates, in volume fractions ranging from a few percent to 70%. In the last few years, AMCs have been utilized in high-tech structural and functional applications including aerospace, defence, automotive, and thermal management areas, as well as in sports and recreation [12].

Table – 1 Properties of candidate materials for disc brake. properties Tensile Strength (MPa) Compressive Strength (MPa) Friction Coefficient µ Yield Strength (MPa) GCI 290 1293 0.41 189 Ti-6AI-4V 1156 1070 0.34 951 TMC 878 1300 0.31 744 AMC 1 76 406 0.35 28 AMC 2 85 761 0.44 32

IV. MATERIAL ANALYSIS

Fig. 1: coefficient of friction of different materials.

All rights reserved by www.ijirst.org

69

Thermal Analysis of Disc Brake (IJIRST/ Volume 3 / Issue 12/ 012)

Fig. 2: Competitive mechanical properties of brake disc materials

V. STUDY OF BRAKE MATERIALS The test was carried out on two discs whose base metal was same, the difference in chemical compositions was observed due to the difference in wear rate.

Element % C Mn Si S P Cr

Material 1 0.060 0.730 0.373 0.014 0.034 12.030

Material2 0.030 0.657 0.396 0.013 0.033 11.860

Study of changes in composition of brake disc after wear.

Fig. 3:

VI. DISC BRAKE CALCULATIONS Assumptions 1) 2) 3) 4)

The analysis is done taking the distribution of the braking torque between the front wheel and rear wheel is 65:35 Brake is applied on rear wheel only.

The analysis is based on pure thermal loading. The analysis does not determine the life of the disc brake.

Only ambient air-cooling is taken in to account and no forced convection is taken.

All rights reserved by www.ijirst.org

70

Thermal Analysis of Disc Brake (IJIRST/ Volume 3 / Issue 12/ 012)

5) The kinetic energy of the vehicle is lost through the brake discs i.e. no heat loss between the tyres and the road surface and the deceleration is uniform.

6) The disc brake model used is of homogenous material.

7) The thermal conductivity of the material used for the analysis is uniform throughout.

8) The specific heat of the material used is constant throughout and does not change with the temperature.

9) Heat flux on each front wheel is applied on both side of the disc only.

Calculation for Input Parameters: The rotor model heat flux is calculated for the car moving with a velocity 27.78 m/s (100kmph) and the following is the calculation.  Mass of vehicle (m) - 150kg  Initial velocity(u)- 100 km/h = 27.77 m/s  Final velocity(v)- 0 m/s  Brake rotor dia.-0.230m  Axle weight distribution(γ)- 0.35  Kinetic energy absorbed by disc(f)- 90%  Acceleration due to gravity(g)- 9.81 �2  Coefficient of friction- (¾)0.4  Kinetic energy defined by equation 1

đ?‘š(đ?‘˘âˆ’đ?‘Ł)2

1) Kinetic energy =đ?‘“ đ?›ž 2 2 1 150(27.77 − 0)2 0.9 Ă— Ă— 0.35 Ă— = 9080.56 J 2 2 2 đ?‘˘ 2) Stopping distance(x)= 2đ?œ‡đ?‘”

27.772

3) = 98.26đ?‘š 2Ă—0.4Ă—9081 4) Deceleration time= đ?‘Ł = đ?‘˘ + đ?‘Žđ?‘Ą 5) đ?‘Ą = 4.09đ?‘ đ?‘’đ?‘?. đ??ž.đ??¸.

6) Braking power(đ?‘?đ?‘? )= 7)

9080.56 4.09

đ?‘Ą

= 2220.18đ?‘Š

8) Heat flux(Q)= 2220.18

đ?‘?đ?‘? đ??´

9) = 55504.5 đ?‘Š/đ?‘š2 0.04 Note: the distribution of braking torque for both the wheels is 60:35 hence taking braking efficiency for rear wheel as 35% Hence total heat flux = 0.35 Ă— 55504.5 = 22201.8 đ?‘Š/đ?‘š2 From the above calculations following boundary conditions have been used for steady state thermal analysis of brake disc.

Braking power Heat flux Heat transfer coefficient for stainless steel Heat transfer coefficient for cast iron Ambient temperature

2220.18 đ?‘Š 22201.8 đ?‘Š/đ?‘š2 28584.48 đ?‘Š/đ?‘š2 ℃ 25015.26 đ?‘Š/đ?‘š2 ℃ 15℃

VII. THERMAL PROPERTIES OF CAST IRON AND STAINLESS STEEL Material properties Stainless steel Cast iron

Thermal conductivity (đ?‘¤/đ?‘š. đ?‘˜) 30 46

Density (đ?‘”/đ?‘?đ?‘š3 ) 7.8 7.2

Specific heat (J/kg.k) 460 380

Thermal expansion (đ?œ‡đ?‘š/đ?‘šđ?‘˜) 11 11

Elastic modulus(GPa) 210 110

Coefficient of friction (Âľ) 0.4 0.4

All rights reserved by www.ijirst.org

71

Thermal Analysis of Disc Brake (IJIRST/ Volume 3 / Issue 12/ 012)

VIII. DIMENSIONAL MODELLING OF BRAKE DISC.

Fig. 4: Dimensional model of brake disc

The modelling of brake disc rotor is done with Solidworks 14, above model is imported in Ansys 14.5, thus the steady state thermal analysis is done to obtain max and min temperatures.

IX. FEA ANALYSIS

Fig. 5: Steady state analysis of cast iron brake disc

Fig. 6: Steady state thermal analysis of stainless steel brake disc

All rights reserved by www.ijirst.org

72

Thermal Analysis of Disc Brake (IJIRST/ Volume 3 / Issue 12/ 012)

X. CONCLUSION From our study of various design patterns for different materials we have observed that the maximum temperature rise for cast iron is much less as compared to stainless steel and thus on the basic of thermal analysis, cast iron is the best preferable material for manufacturing disc brake. However cast iron disc brake suffers a drawback of getting corroded when it comes in contact with moisture and hence it cannot be used in two wheeler and thus we prefer stainless steel.

REFERENCES [1] [2] [3]

[4] [5] [6] [7] [8] [9] [10] [11]

[12] [13]

Swapnil R. Abhang, D.P Bhaskar, International journal of engineering trends and technology (IJETT), “Design analysis of disc brake”, Volume 8 Number 4-Feb 2014.

Telang AK*1, Rehman A2, Dixit G3, Das S4, Journal Of Engineering Research and Studies, “Alternate material in automobile brake disc application with emphasis on all composites” JERS/Vol. I/Issue I/July-Sept. 2010/35-46.

Rakesh Jaiswal, Anupam Raj Jha, Anush Karki, Debayan Das, Pawan Jaiswal, Saurav Rajgadia, and and Ankit Basnet, International Journal Of Mechanical Engineering and Technology (IJMET), “Structural and thermal analysis of disc brake using Solidworks and ANSYS”,Volume 7, Issue 1 Jan- Feb 2016, pp.

67-77, Article ID: IJMET_07_01_008.

C. Baron, T. Ingrassia, V. Nigrelli, V. Ricotta, Università degli Studi di Palermo, Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica – 90128 Palermo, Italy “Thermal stress analysis of different full and ventilated disc brake”, 34 (2015) 608-621; DOI: 10.3221/IGF-ESIS.34.67.

Benjamin Paulik, Krauss GmbH Haugweg 24 D-71711 Murr, “Temperature measurement applied in Krauss friction tester and Dynos”, 07.07.2015.

M.A Maleque1, S. Dyuti2 and M.M Rahman (Member, IAENG)3, Proceedings of the World Congress on Engineering , “Material selection method in design of automotive brake disc”, 2010 Vol III WCE 2010, June 30 - July 2, 2010, London, U.K. Aleksander Grkic, Davorin Mikluc, Slavko Muzdeka, Zivan Arsenic, Cedomir Duboka, ,“A model for the estimation of disc brake interface”,.

Mr. Pravin N. Jawarikar, Dr. Subhim N. Khan, Mr. Balaji D. Kshirsagar, International Journal of Innovative Research in Science and Engineering, “Structural optimization, thermal and vibration analysis of two wheeler disc brake rotor”, Vol. No.2, Issue 08, August 2016.

P. S. Ghoshdastidar, second edition (Professor Department of Mechanical Engineering, IIT Kanpur), Oxford University press 2012.

B. H. Maruthi , H.L. Guruprasad, indian joural of science and research, “Transient Thermal and Structural analysis Of Rotor Disc Of Disk Brake”,2014.

Mahmood Hasan Dakhil1, A. K. Rai2, P. Ravinder Reddy3 & Ahmed Abdulhussein Jabbar4, “Design And Structural Analysis Of Disc Brake In Automobiles”, International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN(P): 2249-6890; ISSN(E): 2249-8001 Vol. 4, Issue 1, Feb 2014.

Saifeldein Arabab, Southern Illinois University Carbondale, “Carbon-Carbon Composites”, Presented on 3rd of April, 2015.

V.M.M.Thilak, R.Krishnaraj, Dr.M.Sakthivel, K.Kanthavel, Deepan Marudachalam M.G, R.Palani, “Transient Thermal and Structural Analysis of the Rotor Disc of Disc Brake”, International Journal of Scientific & Engineering Research Volume 2, Issue 8, August-2011.

All rights reserved by www.ijirst.org

73