Research On Structure Design Of High Power Wheel-mounted Brake Disc Based On Multi-objective Optimization Method

The brake disc of high-speed EMU is a device which undertakes the energy conversion of the EMU during the braking process.In the process of pneumatic emergency braking(UB),most of the kinetic energy of the EMU is dissipated into the environment by heat,so the working condition of brake disc is very adverse.For wheel-mounted brake disc,there are some problems such as large axial deformation of disc and large axial load of bolt,which lead to potential risk such as bolt fracture and so on.Its mechanism involves nonlinear problems such as thermomechanical coupling(TMC)and so on,which is very complex.Taking ZHQ wheel-mounted brake disc as an example,which used in some high-speed EMU.This paper explores the problems of axial deformation of wheelmounted brake disc and TMC of bolt axial load,overcomes some difficulties such as complex nonlinearity,and obtains some research conclusions on theoretical methods and verification examples,which has certain academic value and engineering significance.The main contents of this paper are as follows:(1)The domestic and foreign research results of the thermo-mechanical coupling problem of wheel-mounted brake disc are summarized,the optimization objective are determined,and the technical route is put forward,that is using multi-objective optimization(MOO)method for structural optimization design to improve the above problems.(2)The heat transfer path and deformation rule are explored through experiments,the framework of optimization research is defined,and the MOO model is obtained.(3)The finite element model(FEM)is established and the parametric modeling and analyzing is realized,which is the main method to obtain the research data for the follow-up research.Through the solution and verification of FEM,the constraint conditions of the MOO model are obtained,the concept of "Lever Effect of Cooling Rib" is first proposed.(4)The key dimension parameters that affect the optimization objectives are selected,and the design variables of the MOO model are obtained through the experiments and analysis of single factor significance,double factor interaction and multi factor weighting.(5)The sampling points are obtained by Latin hypercube sample(LHS)method,the surrogate model is fitted by response surface method(RSM),and the surrogate model is evaluated by cross validation(CV)method.The surrogate model is established and the objective function of the MOO model is obtained.(6)NSGA-II is used to solve the MOO model,and the results are verified by finite element analysis(FEA).The optimization scheme of the MOO model is obtained.The research shows that with the sharp improvement of computer performance and algorithm,numerical simulation plays a more and more important role in the analysis of TMC of wheel-mounted brake disc and its combination with MOO method.The constraint conditions,design variables and objective functions of the MOO model are obtained through preceding research,the solving methods(such as intelligent optimization algorithm)and the verifying methods(such as FEA)are used,the structural optimization design can be realized,so as to reduce the axial deformation of the brake disc,reduce the axial load of the bolt and improve the reliability of the bolt.