Research On Thermo-mechanical Coupling And Life Prediction Of Disc Brakes

Braking performance affects the efficiency of mining electric locomotives transportation seriously,as well as the efficiency of coal minings.Disc brakes have the characterastics of simple structure,excellent heat dissipation and high braking efficiency,and can be applied to the mining electric locomotives.However,during the braking process,a great amount heat will be generated and a series of problems such as wear and crack will occur and its highest temperature is below 150?.So it is very important to study the variation law of temperature field and stress field and make a good prediction of the fatigue life of disc brakes.In view of the existing problems,this disseration studies the following aspects.The friction thermodynamics of disc brakes was studied.The composition,working condition load,friction mechanism and contact state of electric locomotives disc brake were determined.The coupling mechanism and the coupling process of the engine were analyzed.Based on the heat conduction and coupling theory equation,the initial and boundary conditions of the solution were determined and the method of solving finite element solution was put forward.It laid a theoretical foundation for subsequent test and simulation analysis.Based on the friction test bed,the friction performance parameters were tested and analyzed.Taking the brake pressure and braking speed as the test variables and the friction coefficient as the test target.,the influence of different brake pressure and braking speed on the friction performance of brake discs were studied and the variation law and the mechanism of its effect were analyzed.Combined with the finite element method and experimental test results,the thermal-mechanical coupling numerical analysis of disc brakes was completed.Based on the dynamic change of the friction coefficient and convective heat transfer coefficient,the finite element analysis software ABAQUS was used to solve the temperature field and stress field of the brake disc.The results show that the temperature field and stress field of brake discs show the change of first rises and then decreases and there is a certain deviation compared with the non-coupled.The stress of friction pairs is mainly thermal stress,and the variation law of stress field is very similar to that of temperature field,so the interaction between the temperature field and the stress field is explained.According to the simulation results the fatigue life of brake discs of mining electric locomotives was predicted.The stress distribution of brake discs in the braking process was obtained and the prediction model of the thermal fatigue life of the brake disc and the location of the thermal fatigue damage were determined.The life of the brake disc was predicted based on the Manson-Coffin formula.Finally,the cycle times of the failure of the brake disc was obtained.It verified the good application of disc brakes in mining electric locomotives.