Research On Characteristic Of Thermo-Mechanical Coupling And Prediction On Fatigue Life Of Disc Brake

Brake, the core component of automotive brake systems, guarantees vehicle safety. The braking process is a thermal-mechanical coupling process that involves temperature field and stress field, which changes temperature distribution, thermal deformation and contact pressure distribution of the brake disc. Currently, most of the researches on thermal-mechanical coupling are based on finite element method. This paper focuses on the car front ventilated disc brakes, analyzing the characteristics of the thermal-mechanical coupling by combining simulation and experimental method on the basis of the finite element theory, and finally predicts the thermal fatigue life of the brake disc based on the results of the analysis of thermal-mechanical coupling and Mason-Coffin empirical formulas. The research of this paper is divided into the following aspects:Firstly, the foundational theories of this paper were briefly introduced, including contact theory, frictional heating theory, thermal conduction theory and thermo-mechanical coupling theory.Secondly, a ventilated disc brake used in a passenger car was chosen as the research object and the geometric model of the whole disc brake was established by using the CATIA software. The mesh model of the whole disc brake was established by the HyperMesh software. And then the mesh model was transferred to ABAQUS software to establish the transient thermo-mechanical coupling analysis model, and the simulation was carried out in an emergency braking mode with the speed of the initial speed 100km/s in uniform deceleration to 0km/s. And then the characteristics of thermo-mechanical coupling was analyzed, including the characteristic of brake disc temperature rise, radial temperature distribution, circumferential temperature distribution and temperature distribution, brake disc thermal deformation, contact pressure distribution and the influence of characteristic of thermo-mechanical coupled upon the SRO and DTV.Then, the brake was mounted on the brake inertia test bench, and the test was carried out with three steps of running-in, signal debugging and formal experimentation according to the national standard of QC / T564-2008 brake performance requirements and test methods for the braking system of passenger car, and then the results of the bench was compared with the same condition of simulation. It was found that the test results were in good agreement with the temperature rise curve and warping curve, which was proved that the thermal mechanical coupled finite element model was accurate.Finally, the fatigue dangerous position of disc was determined by the basic fatigue theory and the simulation results of three directional stress. The thermal fatigue life of the disc was predicted according to Mason-Coffin empirical formulas. Then the findings of the full paper were summarized systematically and suggestion was made for the future work.