Thermo-mechanical Coupled Simulation And Thermal Fatigue Life For The Disc Brake

Brake is the most important component to ensure the safety of automobile driving. It will be heated during braking by the frictional heat converted from the kinetic energy of the vehicle. The warming of brake will load to decrease of the friction coefficient and thermal stress which can affect the braking performance. The analysis and study on temperature and stress field of the brake is an important method for the performance prediction and optimal design of brake.In this paper, with an example of a ventilated disc brake used for the front wheel of passenger cars, in consideration of physical properties of the disc and pad which varies with the temperature, a three dimensional thermal and stress coupled FEM model including disc and pad was established in ABAQUS. According to the relevant test standards of the brakes, the repeated braking condition was confirmed and the boundary conditions were analyzed and calculated. By using the method of the fully coupled thermal-mechanical analysis for simulation of the first braking time in the repeated braking condition, the distribution and coupling relationship between the temperature and stress field of the disc were obtained in the braking process.In order to improve calculation efficiency of simulation using the method of the fully coupled thermal-mechanical analysis in the repeated braking condition, the cooling process of the brake after the braking was substituted equivalently. The temperature and stress distributions of the disc in the 15 th repeated braking condition were obtained through the simulation. Based on the simulation results, the main failure forms of disc brake and the causes of thermal fatigue were analyzed,the location of the crack caused by thermal stress and direction of extension were also obtained.In the end, thermal fatigue life prediction model of the disc was introduced, and based on the simulation result, the thermal fatigue life of the disc in the 15 th repeated braking condition was forecasted by using the Manson-Coffin equation and the factors which influenced on the thermal fatigue life were analyzed.