The Effect Of Contact Pattern And Contact Area On Temperature Field Of Brake Disc

Disc brake is widely used in high-speed trains because of its stable braking performance and strong thermal carrying capacity.During the braking process,the contact pattern and contact area of the brake disc and pad are changed.The change of contact state can easily lead to local high temperature,increase the thermal stress and change the degree of thermal deformation,there by making the brake disc hot cracks appear,threatening driving safety.Therefore,it is significant to study the influence of contact pattern and contact area on the temperature field and friction properties of the brake disc.In this paper,aiming at four contact patterns and three contact areas of triangular brake pads,the influence of contact area and contact patterns on temperature distribution and friction coefficient of brake disc surface under different working conditions is discussed by combining numerical simulation with friction braking test.(1)The simulation results showed that the contact area and contact pattern have an effect on the temperature field of the brake disc.The contact area is smaller,the peak temperature is higher and the greater the radial temperature difference.Under the condition of braking pressure 0.7MPa and speed 200km/h,the contact area is reduced by 20%,the peak temperature of the contact patterns on both sides is increased by 16%.The mid,mid-outside,and mid-inside contact patterns are increases by about 9.5%.The temperature of the disk surface and its distribution are sensitive to the contact pattern.The heat sources on both sides is dispersed,the temperature distribution on the disksurface is uniform,the peak temperature is low.The mid,mid-outside,and mid-inside contact patterns,the friction zone of the types of contact is located in a long area of the contact arc.The high temperature zone is concentrated in the mid,the peak temperature is 38.3%?41.8%?41.4%higher than the contact pattern on both sides.(2)The simulation results showed that the decrease of the contact area causes the increase of the peak temperature of the disk surface to vary with the braking speed and pressure.The mid,mid-outside,and mid-inside contact patterns,under the condition of braking speed of 80km/h,the contact area is reduced by 20%,and the peak temperature is increased by 9%?14.7%?8.1%and 11.7%.When the speed is increased to 200km/h,the peak temperature increases by 16%?9.9%?9.9%and 9.4%;The effect of increased brake pressure is less.The contact pattern changes,and the braking speed and pressure have different effects on the peak temperature.The braking speed increased from 80km/h to 200km/h.The peak temperatures of the four contact patterns increased by about 0.5 times.(3)The test results showed that the peak temperature of the disk surface is related to the contact area of the friction pair.Under the conditions of brake pressure 0.7MPa and speed 200km/h.Both sides contact pattern,mid contact pattern and mid-outside contact pattern,the contact area is reduced by 20%;and the peak temperature of the disk is increased by 1.3%?9.3%and 17.7%.The friction pair contact pattern also affects the peak temperature.The peak contact temperature of the both sides is the lowest.The peak temperature of the disk surface of the other three contact patterns is 12.7%?11.8%?25.4%higher than that of the both sides.(4)There is a certain deviation between the temperature field of the numerical simulation and the friction braking test.In the mid and mid-outside contact pattern,the test and the simulation have good consistency.Under the low speed condition,the test temperature is higher than the simulated temperature due to the difference of the initial temperature setting,and the temperature of the test is higher than the simulation.At the high speed,the degree of agreement is increased and the peak temperatures are similar.(5)The average friction coefficient is related to the contact pattern and contact area of the friction pair.The smaller the contact area,the lower the average friction coefficient,the contact area is reduced by 20%,and the average friction coefficient is reduced by about 0.01.The average friction coefficient is sensitive to the friction pair contact pattern.The average friction coefficient of the both sides contact pattern is higher.The average friction coefficient of the other three contact patterns is similar and lower about 30%than the both sides contact pattern.At the same time,the average friction coefficient decreases with the increase of the brake pressure and the brake speed.