| Disc brake is one of the common train braking methods.It converts the kinetic energy of the train into the heat energy of the friction pair through the friction between the brake disc and the friction block.In the actual braking process,the contact surface between the friction block and the brake disc cannot achieve a complete fit,and local contact occurs,which leads to the local temperature and stress concentration of the brake disc surface,which damages the service life of the brake disc.Therefore,it is meaningful to explore the influence of different contact parts of the friction block on the temperature field and friction performance of the brake disc.This paper uses the finite element software ADINA to simulate the friction pads at four different contact positions,compares the temperature fields of the brake discs of the four friction pads,and analyzes their differences and the reasons for the differences;the four friction pads are the same as the simulation.In the brake test under conditions,the temperature field of the brake disc obtained by the infrared thermal imager was compared with the simulation,and the friction coefficient changes of the four friction blocks were analyzed for analysis.Draw the following conclusions:(1)The peak temperature of the brake disc is closely related to the circumferential contact arc length and linear velocity of the friction block.The circumferential contact arc length of T1 contact is the shortest,and the circumferential contact arc length of T4 contact is the longest,so under the same braking conditions The peak temperature of T1 is the lowest,and the peak temperature of T4 is the highest.However,since the longest circumferential contact arc length of the four friction blocks is the same relative to the position of the brake disc,the linear velocity is also the same,resulting in a small difference in peak temperature.(2)The peak temperature of the simulated and test disc surface is affected by the initial braking speed and the system pressure.The greater the initial braking speed and braking pressure,the higher the peak temperature of the disc surface,and the greater the peak temperature difference caused by the difference in contact arc length.Under the braking condition of 60km/h and 0.5MPa,the simulated peak temperature difference between T1 contact and T4 contact is 20.4°C,and the test peak temperature difference is 15.8°C;at the initial braking speed of 180km/h,the brake pressure is 1MPa Under the working conditions,the simulated peak temperature difference between T1 contact and T4 contact is 42.5°C,and the test peak temperature difference is 51.8°C.(3)The peak temperature of the test is higher than the simulated peak temperature.Under the braking condition of 60km/h and 0.5MPa,the average peak temperature of the four friction block tests is 9.6°C higher than the simulated average peak temperature;under the braking condition of 180km/h,1MPa,the four friction block tests are The average peak temperature is 35.2°C higher than the simulated average peak temperature.This is due to the local adhesion between the friction pairs during the test,causing hot spots.(4)The average friction coefficient of the four kinds of friction blocks all show that it decreases with the increase of the initial braking speed and the brake pressure,and the average friction coefficient of the friction block T1 is higher than that of the friction block T4.This is because The higher the initial dynamic speed,the greater the braking pressure,the longer the contact arc length,and the higher the temperature of the disc surface,which leads to a decrease in the strength of the friction block,which increases the actual contact area between the brake disc and the friction block during the test,resulting in the friction coefficient reduce. |
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