Mechanical Experiment And Simulation Optimization Design Of C/SiC Composite Brake Disc

With the increasing use of automobiles,energy shortage and environmental pollution have become increasingly prominent.In order to achieve energy-saving and emission-reducing of vehicles,automobile lightweight has become a focus of attention.This paper takes the automotive disc brake as the main research content.Due to the disadvantages of conventional cast iron materials such as high density and poor high-temperature braking performance,people turn their attention to new materials.Because of the high temperature resistance,stable friction and low density,C/SiC composite materials have attracted people’s attention.And the experiment and simulation optimization of the braking performance of automobile disc that made of C/SiC composites are studied.The mechanical and thermal properties of self-developed C/SiC composite material are analyzed and the physical properties of the material are got.The strength design value of about 70%of the maximum strength which is measured by acoustic emission equipment is obtained.Making this kind of material into a brake disc then the bench experiment is conducted.The experiment mainly detects the frictional stability of the brake disc,involves the friction coefficient of different pressures,the stability of the friction coefficient under different temperatures and in the dry and wet state.According to the experiment,it is found that the friction coefficient of C/SiC composites do not change significantly under different pressures,and there is no thermal decay at high temperatures.At the same time,the friction coefficient of the C/SiC composites is lower than that of conventional cast iron brake discs under wet conditions.Numerical simulation is performed to analyze the temperature distribution and stress distribution characteristics of brake discs under different braking pressures.lt was found that the maximum temperature of the brake disc appeared in the central part of the brake disc,and gradually decreased from the center to both sides.From the middle to the both sides,the temperature gradient shows increase,decrease then increase.The larger brake pressure makes the higher temperature and temperature gradient.The circumferential temperature distribution is not uniform,and the temperature gradient at the contact location is relatively large.The temperature of the brake lining increases first and then decreases,and the front temperature of brake lining is lower than that of the back.The maximum stress of the brake disc is 34.3MPa,which is far less than the strength design value of the material.The maximum stress occurs at the inner side of the brake disc,and the stress concentration appears at the position of the air duct.In order to optimize the heat dissipation performance,six design variables are identified,including the size of the elliptical openings at the two ends of the brake disc air duct,the thickness of the brake disc,and the design of the air duct radius.Then the amount of heat dissipated is determined to be the optimization goal.Orthogonal test method is used to determine the values of six variables,and 50 sets of models are generated and analyzed using FLUENT to obtain corresponding heat dissipation.The design variables and optimization objectives are used as samples for BP neural network training,and particle swarm optimization is used for extreme value optimization to obtain the optimal model.Through the comparison between the optimized model and the original model,it is found that the air passage,the contact area and airflow flow rate of the optimized model are greater than the original model,the fluid velocity is also higher.After optimization,the steady-state convection heat dissipation of the ventilation channel reached 646W,which played a leading role in the heat dissipation of the brake disc.