Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

Thermal Investigation of Disc Fade During Long Braking

Anant W. Nemade1* , Samir A. Telang2 , Arvind L. Chel3

1Lecturer, Dept. of Mechanical Engg. Government Polytechnic, Aurangabad (M.S) India-431005 2Lecturer, Dept. of Automobile Engg. Government Polytechnic, Aurangabad (M.S) India 3Associate Professor, Dept. of Mechanical Engineering, MGM’s Jawaharlal Nehru Engg. College, Aurangabad (Maharashtra) India

*Corresponding Author: [email protected]

Abstract: are used to inhabit the motion of a . During braking kinetic energy of vehicle is converted in to heat energy due to between pads and rotor. There should be sufficient provision for heat dissipation otherwise heat accumulation will result in to rise in temperature. In case of , they are open to atmosphere therefore more convection takes place than in . Vehicle is in motion which forces air on the brake disc resulting in to fast cooling. To increase the surface area brake disc of light motor are made up of two plates with small joining ribs between them called ventilated disc. These types of brake disc braking system are presently used in all most all light motor vehicle and are working satisfactorily for small braking time. But in modern vehicles the speed of the vehicles is increasing as per the modern generations demands, braking to these vehicles from high speed requires more time therefore braking time increases, which results in to more friction and high heat generation sometimes may be above critical temperature. This paper investigates the heat generation in long braking time, its effect on friction pad material and braking performance of vehicle.

Key Words: Disc Brake, Heat, Braking Time

1.0 Introduction that µ goes on decreasing [1]. This is termed as brake fade and vehicle will not stop at expected location. Braking is an active safety provided to every vehicle. Heat generation measurement in braking is a very The braking inhabits the motion of the vehicle with complicated process [2]. During braking vehicle is the help of friction between rotor and friction pads. In also moving with high velocity therefore convection light motor vehicles rotors are made up of cast iron rate is also high. Exact temperature rise for a and friction pads are made up of combination of particular instance is required to be noted in dynamic different metal powder. When friction takes place condition [3]. In this paper experimentation is carried between rotor and friction pads kinetic energy is out on the test rig specially designed for measuring converted in to heat energy. If this heat energy heat generated during braking with constant source of increases beyond the critical temperature then it forced air on ventilated brake disc. With constant affects on the different components of braking system braking pressure every time the effect of temperature such as friction pads, braking fluid, piston of calliper, is investigated on friction pads. calliper, braking disc/rotor etc. friction pads are manufactured from the composition of different powders and are compressed to form a friction liner of 2.0 Theoretical Kinematic Friction required thickness with predefined coefficient of Coefficient friction (µ). The heat generated during braking for a long time results in to weakening of bond in friction Coefficient of friction between brake disc and friction material and will loos the coefficient of friction of pads depends upon too many factors such as oil pads. Andrew Day in its book “Braking” investigated pressure, temperature generated, rotating speed of disc that up to certain extent of rise in temperature and other material compositional factors of disc and coefficient of friction goes on increasing but beyond pads [4].

Volume XII, Issue VIII, August/2020 Page No:1402 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

The friction force generated at contact surfaces of 2.2 Temperature Generated on Disc brake disc and pads can be determined as it depends Surface upon the coefficient of friction and the normal force acting on it [5], [6]. It can be calculated as, Temperature Generated on disc surface can be calculated by using thermal relation [9]. Ff = µFn Heat Generated Q = M x Cp x T J/s Fn Can be known from the oil pressure (P) gauge installed on the experimental setup M is mass of disc in KG, Cp is specific heat capacity J/kg0c , T is time taken to stop the vehicle Fn = P X(piston area) A And heat flux q = Q/A W/m2 Braking torque can be calculated from the equation A is the area of disc = (R2-r2) TB = Ff re And Thermal Gradient K = q/k K/m Where re = effective radius of friction pad.

Above terms in Torque equation can be written as. 3.0 Experimental Work

TB = µPAre For caring out experimentations to investigate brake fade due to heat generation in brake disc an For two pair of friction pads this equation can be experimental setup is designed. This setup enables to written as measure the temperature generated during braking by using rubbing thermostat [10]. The setup is fitted with TB = 2µPAre hydraulic braking system to apply brake, pressure

And from setup the values of P, A, TB, re can be measuring gauge installed in line. is determined. Therefore, coefficient of friction between used to drive the brake assembly with inertia load.

brake disc and friction pads can be determined as Brake disc can easily be installed on setup. To create the realistic situation force air cooling is provided on µ = TB/2PAre brake disc [11]. 2.1 Thermal Stresses Induced in Brake Disc

Disc and friction pad is a compact assembly, due to friction between them heat is generated at contact surfaces this heat induces thermal stresses in disc as there is less chance to expand the material due to continuous rotation of disc as vehicle is in motion. These thermal stresses mostly induced because of the variation of temperature [7] [8].

This can be obtained by equation

σ =

Whereσ is thermal expansion coefficient of brake disc, E is Young’s modulus, is poisons coefficient, is difference between local disc temperature and Fig 1: Experimental setup environmental temperature, depends upon thermal stress with temperature. For experimentation initial temperature of brake disc is considered at room temperature, and then with the help of electric motor brake disc is rotated at a 2540

Volume XII, Issue VIII, August/2020 Page No:1403 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

RPM measured by tachometer. The inertia weight is Table1. Chemical composition of brake pads 42 kg. After rotating the brake disc sufficient time is Sr. No. Composition Weight by % given to stabilize the system. Then brakes were 01 Mg 11.1 applied at regular interval with varying time interval 02 Si 6.3 [12]. Stopping time of disc is noted after each brake. 03 Al 9.8 The braking time is increased after each braking, 04 S 5.6 temperature and brake applied pressure is recorded. 05 Ca 5.2 Thermostat can be set at any position e.g. t1, t2 or t3 06 Fe 7.6 as shown in fig 2. 07 Cu 5.8 08 Zn 13.4 09 Cr 3.5 10 Zr 0.1 11 Sn 9.3 12 C 22.3

Brake disc made of gray cast iron has chemical composition as shown in table No. 2.

Table2. Chemical composition of brake disc

Sr. No. Composition Weight by % 01 C 3.40 02 Si 1.70 03 Mn 0.57 04 P 0.03 Fig 2: Rubbing K type Thermocouple and locations on brake disc 05 S 0.26 Experimental setup is designed for fitting different 06 Fe 93.6

friction pads. In this experimentation two types of friction pads are used [13]. Both the friction pads are During testing some assumptions are made that there manufactured from same material composition, only is no driver’s reaction time, no system response time, they differ in surface pattern which will be in contact no deceleration rise time, no release time, but in actual with brake disc. One is flat with uniform surface practice when brakes are applied these time zones are where as other is having linings on the surface as in existence as shown in fig 4 [15]. shown in figure [14].

Fig 4: Braking time zones

Fig 3: friction pads used for experimentation, flat surface and lining When driver responds to situation and move his foot surface. to pedal the time zone is t0 to t1, next when he applies braking force and reaches to tyre t1 to t2, now time to

Chemical composition of brake pads is as shown in reach peak deceleration is t2 to t3, braking time till the

table No. 1. vehicle stops is t3 to t4, brake release time t4 to t5 Trials were taken on the friction pads of above description. The braking time is varied and noted readings of

Volume XII, Issue VIII, August/2020 Page No:1404 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

temperature generated at the interface of disc and pad. Fig 5: Temperature analysis at different braking time Every time the braking pressure is kept constant at 27 bar with the help of adjustment rod and air flow on the disc is also kept constant. The recorded readings were analysed in the Ansys software for obtaining the results [16].

4.0 Results and Discussion

Using Finite Element thermal analysis method, steady state thermal analysis was performed with some boundary conditions on brake disc pad assembly [17] [18]. The heat flux of 57317.72 W/m2 was applied on the surface of disc where pads are in contact with disc. The film coefficient for convection is taken as 106 W/m2K and coefficient of conductivity taken as 51 W/m K. The brake pressure of 2.70 Mpa is applied on pads. Finite temperature analysis of the disc brake during braking was done by using Ansys 15.0. Figure 5, 6 and 7 shows the temperature distribution between interface of braking disc and friction pads at different braking time [19].

Fig 6: Heat flux in friction pads

Fig 7: Interface temperature analysis of friction pads .

Volume XII, Issue VIII, August/2020 Page No:1405 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

This analysis shows that the temperature rises as the lining friction pad as case-II and conclusion were braking time increases. Temperature rise during drawn that case-II has less temperature rise at braking reduces the strength of compact bonding interface than the plane friction pads [06] [26]. between the particles of friction pad [20]. Also during braking when plane surface type friction pads are used then increases as compared to lining friction pads [16].In this experimentation the speed of the present setup AC motor is constant, for both types of friction pads temperature generated at interface is different and found that lining friction pads generates less temperature than the plane one. Temperature increase in the interface will reduce the coefficient of friction and reduces the performance of braking system [21]. Analysis also shows that heat generation is more at the interface of friction pads and disc area in contacts, leading to non-operation of brake by reducing

coefficient of friction (μ) and subsequently fast wear Fig 9: comparative graph of heat generation in plane and lining of braking pads; termed as brake fade [22]. However, friction pad [26] change in (μ) due to rise in temperature depends upon the frictional material [23] [24]. In present experimentation also it has been observed Figure 8 shows the total deformation at the braking that there is less heat generation than the plane with variation of coefficient of friction. It is observed sample. In manufacturing unit of friction pad, testing that there is no significant variation with the increase procedure carried out from 1000c to 9000c with a of coefficient of friction. difference of 1000c. The speed reduction achieved

from 50 km/hr to 0 km/hr [27].

Table3. Comparison of measured temperature and simulated temperature

Sr. Measured Simulated Difference No. Temperature Temperature 0 in 0C C 0C

01 109 111.56 2.56

At μ=0.26 At μ=0.29 02 224 227.83 3.83

03 342 344.11 2.11

04 434 437.13 3.13

The results obtained with experimentation are compared with the results of simulation and are found to be same with minor difference. For better performance of friction pads manufacturer are At μ=0.35 continuously testing them for thermal wear and Fig 8: Total Deformation during Braking with variation of μ braking performance, in spite of such type of rigorous testing of friction pads when they perform in actual Temperature rise creates deformation in both disc and field, friction pads show reduction in coefficient of pad which forms uneven surface at the contact area and leads to form local wear spots because of high friction by reducing braking efficiency. temperature [25]. Similar study results obtained by Saeed Abu Alyazeed Albatlan in his research where in he mentioned the plane friction pad as case-I and

Volume XII, Issue VIII, August/2020 Page No:1406 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

[13] Eunbi Jeong, Cheol Oh (2017) Evaluating the effectiveness 5.0 Conclusion of active vehicle safety systems , Elsevier, http://dx.doi.org/10.1016/j.aap.2017.01.015 . The paper presents the thermal effect on friction pads [14] P. D. Neis et.al.(2017), Towards a better understanding of the structures existing on the surface of brake pads, using Ansys software. The results obtained during Tribiology International experimentation can be concluded as below. ,dx.doi.org/10.1016/j.triboint.2016.09.033. [15] Qifei Jian et.al.(2017), Numerical and experimental analysis of transient temperature field of ventilated disc 1) Simulated results were validated using brake under the condition of hard braking, Elsevier, experimentation. http://dx.doi.org/10.1016/j.ijthermalsci.2017.08.013. [16] Supachai Lakkam et.al. (2017), A Study of Heat Transfer on Front and Back Vented Brake Disc Affecting Vibration, 2) Temperature rise has significant effect on the Engg. Journal ,at http://www.engj.org/ braking performance of vehicle. DOI:10.4186/ej.2017.21.1.169. [17] Abdulwahab A. Alnaqi et.al. (2018), Reduced scale thermal 3) Temperature rise at the interface between characterization of automotive disc brake, Applied Thermal Engineering , doi: 10.1016/ friction pad and brake disc will reduce the j.applthermaleng.2014.10.001. braking performance of vehicle. [18] İbrahim Mutlu et.al.(2015), The effects of porosity in friction performance of brake pad using waste dust, SciElo,http://dx.doi.org/10.1590/0104-1428.1860. 4) Plane surface of friction pads will generate [19] A. Adamowicz,(2015), Effect of Convective Cooling on more heat than the lining type of friction Temperature and Thermal Stresses in Disk during Repeated Intermittent Braking, ISSN 10683666, Journal of pads. Friction and Wear, 2016, Vol. 37, No. 2, pp. 107–112. DOI: 10.3103/S1068366616020021. 5) The results are found to be acceptable as per [20] M. Timur et.al. (2014), Heat transfer of brake pad used in the autos after friction and examination of thermal tension the available literature reported by the earlier analysis, http://dx.doi.org/10.5755/j01.mech.20.1.6595. researchers in this area. [21] www.ijerd.comAmit Maske et.al. (2016) Design and Analysis of Paeking Brake System of , IJIRSET,ISSN:2319-8753, vol-5,Issue-7. References [22] Belhocine Ali et.al. (2013), Thermomechanical Modelling of Disc Brake Contact Phenomena, FME Transactions (2013) 41, 59-65, 60 ▪ VOL. 41, No 1, 2013. [01] Day A. J.et al, “Investigation of Disc/Pad interface [23] Vlastimil Matějka et.al. (2017), On the running-in of brake temperature in friction braking,” J. wear,Vol-262,PP 205- pads and discs for dyno bench tests, Tribology 513, 2007 International ,DOI: 10.1016/j.triboint.2017.06.008. [02] McPhee A.D, Johnson D.A (2007) Experimental heat [24] Jean Greselle Balotin, jeangb et.al. (2017), Analysis Of The transfer and flow analysis of a vented brake rotor. Int J Influence Of Temperature On The Friction Coefficient Of Thermal Sci 47(4):458–467. Friction Materials, ABCM Symposium Series in [03] Heinz H, (2001), Vehicle and Engine Technology, Second Mechatronics – Vol. 4 - pp.898-906. Edition, Butterworth – Heinemann publications, [25] Xuefei Ji et.al.(2013), Hyperbolic Distribution of All- Nurumberg. Independent Braking Force for Cornering Vehicle, [04] Vytenis Surblys et.al., (2015), Research of the Brake IFAC Japan. Testing Efficiency, Elsevier, procedia engineering 134 [26] Saeed Abu Alyazeed Albatlan,(2013) ,Study Effect of Pads (2016) 452-458. shapes on Temperature Distribution for Disc Brake [05] Nickolay Podaprigora et.al. (2016) Method of Assessing Contact Surface, e-ISSN: 2278-067X, p-ISSN: 2278- the Influence of Operational Factors on Brake System 800X, Efficiency in Investigating Traffic Accidents, Elsevier, [27] X. D. Nong et.al.(2017), Numerical analysis of novel procedia engineering 20 (2017) 516-522. SiC3D/Al alloy co-continuous composites ventilated [06] Saeed Abu Alyazeed Albatlan (2012) Automotive Brake brake disc, Elsevier, International Journal of Heat and Pipes Characteristics and their effects on Brake Mass Transfer 108 ,1374–1382 Performance, Ain Shams Engineering Journal,(2012) 3, [28] H. B. Yan et. al.(2016), Heat transfer enhancement by X- 279-287. type lattice in ventilated brake disc, Elsevier, International [07] Darredy Ramana Reddy (2017) Development of A New Journal of Thermal Sciences 107 ,39-55. Bio-degradable Friction Material for Brake Pads from [29] J.R. Laguna-Camacho et. al.(2015), A study of the wear Palm Kernel Shell, IJMST: 11(1). mechanisms of disk and shoe brake pads, Elsevier, [08] Radhakrishna Maske et. al.(2017) Automatic Brake Failure Engineering Failure Analysis 56 ,348–359. Indicator and Braking System ,IJARIIE,vol-3, ISSN(O)- [30] Yongheng Zhanget.al., (2019), The Convective heat 2395-4396. transfer characteristics on outside surface of vehicle brake [09] Dr. M. Ben Swarup et. al.(2014),FMEA-based Failure disc, Elsevier, Masson SAS, (2017) 366-376. analysis of Brake-by-Wire Automotive safety-Critical [31] L. Wei et.al. (2019) A study of brake contact pairs under System,IJARCCE,ISSN:2278-1021. different friction conditions with respect to characteristics [10] Prathamesh Baing et.al. (2016),Implementation of of brake pad surface, Elsevier, Tribology International Alternative Braking System in Case of Brake Failure 138 (2019) 99-110. Situation,IJRAT,E-ISSN:2321-9637 [32] Alexey Vdovin (2019) A coupled approach for vehicle [11] Farmarz Talathi et.al (2009) Analysis of heat conduction in brake cooling performance simulations, Elsevier, a disk brake system, Springer, DOI 10.1007/s00231-009- International Journal of Thermal Science 132,(2019) 0476-y. 257-266. [12] A M Puncioiu et al (2015) Analysis of heat conduction in a [33] Marcel Mathissen et. al (2018) A novel real-world braking drum brake system of the wheeled armored personnel cycle for studying brake wear particle emissions, Wear, arriers, IOP Conf. Series: Materials Science and https://doi.org/10.1016/j.wear.2018.07.020 Engineering 95 (2015) 012039 doi:10.1088/1757- [34] Elia Marin et. al (2019) Diagnostic spectroscopic tools for 899X/95/1/012039 .

Volume XII, Issue VIII, August/2020 Page No:1407 Journal of Interdisciplinary Cycle Research ISSN NO: 0022-1945

worn brake pad materials: A case study, journal DOI - https://doi.org/10.1016/j.wear.2019.01.126. homepage: www.elsevier.com/locate/wear. [36] Swapnil R. Abhang et. Al(2014) “ Design and Analysis of [35] Peng Zang et.al(2019) Fade behaviour of copper-based Disk Brake “ IJEIT Vol- 8,number-4 Feb-2014 brake pad during cyclic emergency braking at high speed PP 165-167. and overload condition, Elsevier ,

Volume XII, Issue VIII, August/2020 Page No:1408