Thermal Friction And Wear Mechanism Research Of Large Disc Brake In High Pressure

Disc brake braking process is accompanied with a strong thermal-mechanical-wear coupling phenomenon, the disc in high temperature and fluctuation degree, the pad in wear quickly and uneven state become the main factor of restricting the service life of the disc brake. Therefore, it is of great theoretical significance and practical value to study the thermal friction and wear mechanism of large disk brake in high pressure to improve braking safety. For the friction pair of 24.5 inch gray cast iron disc and resin based composite material pad, using experimental research, theoretical analysis and numerical calculation of combining way to research the thermal friction and wear mechanism at at the 1.2MPa pressure. The main research contents and conclusions are as follows:(1) Through the tension and compression test, thermal parameters test of the disc and the pad in room temperature to 800?, the constitutive model and thermo-mechanical coupled finite element analysis model were established. Using analytical method and CFD technique to determine the heat transfer coefficient between the pad, the disc and the air, combining with temperature field test, variation of temperature field, stress field and contact pressure of the disc and the pad were discussed at the 1.2MPa pressure in emergency braking and repeated braking, proved a strong coupling relationship.(2) Based on the resin matrix composite friction material, the pin-disc friction and wear test was carried out to get the variation of friction coefficient and wear rate as a function of temperature, the reasonable friction and wear model of friction material was established. Friction torque, wear volume, wear depth and contact pressure analysis were performed in the test process, to obtain the conclusion that the wear depth of nodes far away from the center of the disc is greater than those closer to the center. From the range of non-uniform degree of the wear depth(hNU) and non-uniform degree of the contact pressure(piNU),by Orthogonal test range(jR) analysis, it can be concluded that when the non-uniform pressure center is at the center of the lower part of the friction surface, the degrees of non-uniformity of bothhNU andpiNU were the smallest, and the friction and wear properties were the best.(3) By write user subroutine UMESHMOTION, using automatic postprocessing thermo-mechanical coupling calculation results to achieve the themal friction and wear behavior numerical simulation of disc brake, the variation of the wear volume, the wear depth, friction torque, contact pressure and contact area were analysied, and research the effect of temperature on wear depth, contact pressure and contact area. Based on the experiment of inertial platform, the correctness of the simulation of thermal friction and wear was verified, the microstructure of pad after friction and wear was observed using scanning electron microscopy(SEM), and the influnces of temperature on the wear mechanism were studied to achieve the pad's wear form in different period.