Thermo-mechanical Coupling Analysis And Structural Optimization Design Of Vehicle Ventilated Disc Brake

Disc brake,the executive part of the brake system,provides an important guarantee for the driving safety of the vehicle.It involves the coupling effect between temperature field and stress field in the braking process,which has a vital impact on braking performance and may even affects the thermal fatigue life of the brake.Therefore,it is necessary to simulate the thermo-mechanical phenomenon and optimize the structure of the brake,which is significant for designing high-performance brake.The main research contents of this paper are as follows:Firstly,the related theories,relationship and calculation method of thermo-mechanical coupling were introduced in detail.Secondly,a simplified model of a passenger car front wheel ventilated disc brake was established by CATIA software.The geometry model was meshed and given material in the Hypermesh software,and then the mesh model was set up various boundary conditions and submitted calculation in the ABAQUS software.The simulation was applied to the emergency braking model to analyze the brake's thermo-mechanical coupling characteristic,including the characteristics of brake disc temperature rise and stress variation along the circumferential,radial and axial directions.At the same time,the brake bench test was carried out,and the test result curve was compared with the simulation curve,which verified model's accuracy and reliability.However,since the solution time of complete thermo-mechanical coupling method was longer and it was hard to converge;Meanwhile the method of sequential thermo-mechanical coupling method based on fixed heat source can not achieve the rotation of friction heat source of the brake disc and can not accurately simulate the change of temperature and stress.Therefore,a sequential thermo-mechanical method based on rotating heat source was put forward.That is,the ABAQUS user subroutine was called in simulation to achieve the heat source rotation during the braking process.It was found that this method has the advantages of both the first two methods.Then the method was applied to the simulation of heavy load braking condition such as repeated braking condition,which is of great significance to the research and analysis of the brake and the cost saving of the calculation.Considering the cost,time and other issues of the later optimization,the paper obtained the sample data through optimal Latin hypercube experiment on the basis of brake thermomechanical coupling finite element model,and built an approximate model between the design variables and the maximum temperature and stress of the brake disc.Meanwhile,in order to make the prediction model more accurate and lay the foundation for the later optimization,a improved cuckoo search algorithm was proposed to optimize the initial weights and thresholds of BP neural network.The algorithm combines the advantages of particle swarm optimization and cuckoo algorithm,and adaptively improves the two parameters of flights step and elimination probability in the cuckoo search algorithm.Finally,the constraint conditions and the objective function were determined.And based on the approximate model established,a multi-objective optimization method based on genetic algorithm was used to optimize the structural parameters of the brake.And then,the finite element model was rebuilt and the simulation was carried out.The simulation results proved the feasibility of the optimization scheme.