Research On Stress Analysis And Damage Mechanism Of CRH Brake Disc

In recent years,the speed of high-speed trains has been greatly improved.Compared with the past,each component of the train was subjected to more complex loads.If the brake disc which was an important part of the brake system was damaged during the operation,it would brought serious security problems to the train.Therefore,if we could judge the brake disc damage in advance and explored its damage rules,it was of great significance to ensure the safety of the train.Based on the theory of heat transfer,the principle of tribology and the transient dynamics,the finite element simulation is used to analyze the stress field of the train brake disc.The mechanism of the brake disc damage was revealed by the method of mechanical analysis and testing.The main research work is as follows:Firstly,the mechanical analysis of the two states which are high speed running and braking of the brake disc is carried out.In the process of braking,the boundary condition and the equilibrium equation of thermal stress are established with the help of the theory of tribology and thermodynamics;In the running state,combined with the finite element method,the mechanical model of the brake disc is simplified,and the boundary conditions and loading modes of the brake transient dynamics simulation are determined.Secondly,the thermal and structure analysis of the brake disc in the friction braking process is carried out.According to the structural characteristics of the brake disc,a three-dimensional solid model and a finite element model of the brake disc are established.The numerical simulation of the brake disc temperature field is carried out.The thermal stress distribution and stress state of the brake disc in the friction braking process are obtained by using the sequential coupling method to analyze the thermal and structure of the brake disc.The results show that the tooth part of the brake disc is the maximum stress and the tension stress state.Thirdly,the transient dynamic analysis of the brake disc at high speed is carried out.The finite element model of the assembly of the brake disc hub and axle model is established.The stress field of the brake disc under two load conditions of the single rotating inertia force and the compound inertia force is analyzed by the transient dynamics.The results show that the random variation of the vertical inertia load is the cause of the random damage of the brake disc,and the dynamic tensile stress is located at the tooth of the brake disc;The dynamic stress state of the brake disc of different running speed trains is compared,and the checking value of the fatigue damage of the train brake disc with different speed levels is given.Finally,the fatigue damage mechanism of the brake disc was verified by the S-N curve,the residual strength model and the acoustic emission test.Considering the influence of the train speed and mileage on the damage,the fatigue damage law of the brake disc is studied,and the mechanism of the fatigue damage of the brake disc is revealed;The fatigue damage detection test of AE acoustic emission is designed,and the incentive loading scheme is determined according to the finite element simulation analysis;according to Kaiser effect,complete the extraction and analysis of AE parameters.The test data analysis shows that the dynamic stress at high speed would lead to the decrease of the brake disc strength,and the damage of the brake disc is the result of the thermal stress.