The Effect Of Non-uniform Friction Coefficient On The Disk Temperature Field And Stress Field

Brake disc and brake pad are not in uniform contact during braking,and the friction coefficient of each contact point will not be exactly the same.This will affect the temperature field and thermal stress field,thus affecting the temperature distribution of the brake disc and service life.Therefore,it will have practical significance to study the relationship between the distribution of friction coefficient and friction coefficient and the temperature field and stress field on the plate surface.In this paper,friction friction pairs with single friction coefficient and double friction coefficient are designed for two kinds of friction materials.Through numerical simulation and experimental tests,the friction coefficient and surface temperature field,stress field and brake time are studied under various working conditions.Through the simulation calculation,the following conclusions are obtained.(1)The effect of friction coefficient on disk surface temperature is proportional to the braking speed.When the speed are 50 km/h,100 km/h and 160 km/h,the coefficient of friction increases by 0.01 for each brake pressure of 0.4MPa.The maximum temperature on the disk surface increased by 0.28%,0.75%and 1.2%respectively,and the peak time decreased by 3%,3.3%and 3.2%respectively.(2)The effect of friction coefficient on the surface temperature is related to the contact area.Under the condition of brake pressure 0.4MPa and speed 100km/h,in the low-speed area(friction radius 91mm-125mm),the friction coefficient increases by 0.01,the maximum temperature of the disk surface increased by 0.4%;in the high-speed zone.when the speeds are 160km/h and 200km/h respectively and the friction coefficient increased by 0.01,the maximum temperature on the disk surface increased by 0.6%and 0.8%respectively.(3)The maximum stress on the disc surface increases with the increase of the friction coefficient.When the braking speeds are 100km/h,160km/h and 200km/h and brake pressure is 0.7MPa,the friction coefficient increases by 0.01 respectively,the maximum stress on the disc surface increases by 1%,1.5%and 1.2%respectively.(4)The maximum stress of the disk surface increases with the increase of the friction coefficient.When the braking speed are 100km/h,160km/h and 200km/h at a brake pressure of 0.7MPa,the friction coefficient increases by 0.01 and the maximum stress on the disk increases 1%,1.5%and 1.2%respectively.Through the experimental tests,the following conclusions are obtained:(1)The effect of friction coefficient on disk surface temperature is proportional to the braking speed.When the speed are 50kmh,100km/h and 160 km/h,the coefficient of friction increases by 0.01 for each brake pressure of 0.7MPa.The maximum temperature of the disk surface increased by 5.75%,3.59%and 2.69%respectively.(2)The influence of friction coefficient on the surface temperature is related to the contact area.When the braking pressure is 0.7MPa and the speeds are 50km/h,100km/h and 160km/h and the friction coefficient increases by 0.01 respectively.In the low speed area,the maximum temperature of the disk surface increased by 7.2%,3.7%and 2.5%respectively;in the high-speed zone,the maximum temperature on the disk surface increased by 6.24%,1.53%,and 1.38 respectively.By comparing the simulation calculation with the test results,the following conclusions are obtained:(1)The maximum temperature tested is higher than the simulated temperature,and the increase degree decreases with increasing braking speed and pressure.The reason for this difference is that the simulation calculation is based on the uniform contact pressure.Therefore,it is difficult for the calculation result to reflect the influence of uneven contact pressure on the temperature distribution.In the test,the local high pressure on the friction surface causes the frictional heat to concentrate and forms a local high temperature.