Simulation And Experimental Study Of Brake Disc Temperature Field Under Non-Uniform Load Under Braking Conditions

In the actual braking process of the train,there is always a random local contact situation between the brake disc and pad,which leads to the problem of uneven contact pressure,and this unevenness affects the temperature of the disc surface and the braking performance.Therefore,it is instructive to explore the influence of the distribution form of contact surface pressure on the brake disc to understand the damage mechanism of the brake disc and to improve the safety and reliability of train braking.In this paper,based on the TM-I inertia scaling test bench,braking tests were conducted at braking speeds of 60 ～ 120 km/h and braking pressures of 1.41 ～ 2.82 k N,and the changes in the temperature distribution patterns of the brake discs were recorded using an infrared thermal imaging camera.Meanwhile,using ADINA software,the contact pressure distribution and temperature distribution patterns were simulated and calculated for five contact pressure distribution patterns,and the results showed that:(1)Pressure inverse "V" distribution,compared with the uniform pressure distribution pattern,the braking speed of 120 km/h,the pressure increased from 1.41 k N to 2.82 k N,the peak temperature increased by 14.9 ～ 15.8%,the temperature difference increased by 0.9 ～17.8%;pressure of 2.82 k N,the speed from 60 km/h to 120 km/h,the peak temperature increased by 11.8 ～ 15.8%,the temperature difference increased by 53.8 ～ 80%.The reason is that the pressure distribution pattern changes the friction power distribution pattern of the contact surface,and the pressure inverse "V" distribution makes the high pressure area and long friction arc area overlap,resulting in a significant increase in peak temperature and temperature difference.(2)Positive "V" pressure distribution,compared with the uniform pressure distribution,the pressure increases from 1.41 k N to 2.82 k N at a braking speed of 120 km/h,the peak temperature decreases by 1.6 ～ 2.6%,and the temperature difference decreases from 40% to16.7%;at a pressure of 2.82 k N,the speed increases from 60 km/h to 120 km/h,the peak temperature decreases from 3.6% to 2.6%,and the temperature difference decreases from 4 ～6℃.The reason is that the high pressure area staggers the long friction arc area,which plays a role in reducing the peak temperature and temperature difference.(3)In the case of two distributions of pressure rising and falling with radial direction,the peak temperature of the disk surface increases in the range of 0.3 ～ 8.3% and the temperature difference increases in the range of 10 ～ 87% compared with the uniform pressure distribution pattern.The reason is that the non-uniform distribution of stress increases the temperature and temperature difference by increasing the concentration of heat.(4)In the test,when the braking speed was 120 km/h,the pressure increased from 1.41 k N to 2.82 k N,the peak temperature increased by 31.6% and the temperature difference increased by 1.2 times;when the pressure was 2.82 k N,the speed increased from 60 km/h to120 km/h,the disc surface temperature increased by 8.37% and the temperature difference increased by nearly 6 times.The high temperature zone appears in the region with the largest contact arc length.(5)The simulated temperature is 11.8 ～ 15.3% higher than the experimental test compared with the simulated test temperature.The reason is that the simulated calculation is based on the premise of full contact area,while there is random local contact between the disk and the gate during the test,and the random fluctuation of the contact area weakens the role of contact arc length and line speed,which reduces the concentration of high temperature area and reduces the peak temperature.