17 ISSN 1392 - 1207. MECHANIKA. 2014 Volume 20(1): 17-23 Heat transfer of brake pad used in the autos after friction and examination of thermal tension analysis M. Timur*, H. Kuşçu** *Kırklareli University, Voc. Sch. of Tech. Sciences, 39100 Kırklareli, Turkey, E-mail: mustafatimur@kirklareli.edu.tr **Trakya University, Faculty of Engineering and Architecture, 22000 Edirne, Turkey, E-mail: hilmi@trakya.edu.tr http://dx.doi.org/10.5755/j01.mech.20.1.6595 1. Introduction The brakes used in the autos are energy changing tools. They convert the mechanic energy of car into heat energy through friction. The car on the move has kinetic energy. In the braking systems, the kinetic energy of the car is converted into heat energy via the friction of the pads onto disc and this heat emits the atmosphere. If the brakes are given heat more than they can emit to environment, the friction parameter in brake pads declines and the stopping capability of the brakes decreases. After this point, wear is accelerated. The continuous exposure of the brake pads to over temperature leads to the exhaustion of the braking performance of pads. This situation shows itself as de- crease, malfunction, fast pad wear and sound in the per- formance of brakes [1, 2]. Hohmann et al. [3] determined high pressure in the outer radius of pad and pad supporting plate as a result of the analysis they carried out at the end of braking. In their study, Tamari et al. [4] made about the prediction of contact pressure in disk brake pads stated that the contact pressure must be proper in disk brakes so that wear can be proper. Abu Bakar et al. [5], tried to model the pressure distribution between pad and disk in computer environment using different design, dimension and materi- al. They found out that the asymmetric and improper pres- sure distribution cause improper wear and shortening of pad life. They concluded that pad construction is influen- tial on pressure distribution and wear. Abu Bakar et al. [6] made three dimensional analysis of contact pressure distri- bution over disc and pad surfaces using brake and finite element model. The conduction hardness of asymmetrical solid matrix, friction parameter in disk and pad interface constituted the core of the method. They researched model brake disks and contact pressure distribution at different levels. Using a proper model, it was provided to make the predictions of pressure distributions in the interfaces in brake disks. Abu Bakar et al. [7], experimentally found the noise and sound vibration which stem from dynamic ambi- guity because of friction during braking and examined the data using Abaqus packet program. In their study, Valvano and Lee [8] examined thermal attitude under short term and stable state. The maximum temperature of the disk is found in the place where a contact is made with pad and they found that the temperature rose at the time of repeat- ing braking. In his study, Arpat, [9] examined the amount of wear of the pads in drum or disk brake systems occur- ring because of the increase of heat on the surface of fric- tion as a result of frequent braking of light and heavy commercial vehicles. He found out that with the decrease of temperature at the moment of braking, wear in the pad declined. Jacobsson [10], made a conventional disk brake analysis. He reached the conclusion that thermal degrada- tion occurred because of friction depending on the time, and mechanic degradations because of operating forces applied. As a result of the experimental study, it was found that wear appeared in the friction material couple and there was a decrease in the thickness of the disk. Mosleh et al. [11] made analyses about the wear and friction behaviours in the pads which were exposed to braking at different speeds and the tribological characteristics of erosive mate- rials. In the tests experimentally achieved, the characteris- tics of brake material were determined. Depending on the differentiality of the brake material, they determined that the change in the wear rate was dependent on the low and high sliding speeds. Hwang et al. [12] defined the thermo elastic irregularity resulting from the heat which occurred because of friction at the time of braking. They tried to solve the heat and thermal deformation change under a single proper braking and repeating braking through the method of finite elements. They found that the maximum temperature of the disk is found in the place where a con- nection is made with the pad and occurs during repeating braking. Li et al. [13] argued that the occurrence of vibra- tion and noise at the time of braking in the disk brakes result from pressure and heat distribution on the surface of pad. As a consequence of the experimental studies and numerical analyses, it was seen that the temperature distri- bution was not appropriate and there was high pressure in the locations where temperature value was high. They ascertained that temperature was effective in noise and vibration occurring on the surface of pad. In this study, the temperature-stress distribution and change occurring during braking of brake pad material was examined. The thermal and mechanic features of four different pad materials which were mentioned earlier as pad material in literature, the thermal and mechanic behav- iour of the pads were tried to be determined using Solid- Works Simulation Solutions program. In addition, in the study, the impact of wear rate of pad was aimed to be re- vealed. The thermal power forming through the conversion of motional energy into thermal energy during braking was mathematically calculated. Using SolidWorks software program, the pad in the brake system was modelled, and the calculated thermal power was entered in the program and analysis results were obtained [14]. 2. Material and method 2.1. Material In this study it is aimed to determine the effects of thermal and mechanic characteristics of various materials developed as pad material on pad. As a result of literary