| During the11 th national Five-Year Plan,the eight vertical and eight horizontal high-speed railway development plan was put forward,which is a symbol of our country entered the era of high-speed rail.With the rapid development of high-speed railway,the performance of high-speed trains have become more and more strict,lightweight and vibration performance of the train are important factors in affecting the train’s comfort,safety and speed.As the main bearing structure of the train,the reasonable design of the structure has been a hot spot and emphasis.The main contents of this paper include the light-weigh design on the EMU body and the optimization of the first-order vertical bending frequency in the equipped vehicle state.In this paper,the FEM of the EMU body is built in the HyperMesh software according to the TB1335-96 and other relevant standards.Then the static strength,stiffness and modal of the FEM are analyzed.The body mass,frequency,stress and displacement sensitivity of the key parts are analyzed for the EMU body based on finite element analysis,in which the thickness of main profile structure,such as the roof,top side sill,side wall and floor etc are considered as the influence factors.The primary variables in the optimization are determined.Based on the static sensitivity analysis results,the lightweight model of the car body is determined with the thickness variables of the roof,top side sill and side wall.The optimization design is carried out in OptiStruct software and the optimization result shows that the total mass of the car body is reduced by 6.64%,which achieves the effective lightweight.Furthermore,the strength,stiffness and modal frequency for the optimal car body reach the design target.In the end of this paper,the initial design variables are selected according to the frequency sensitivity analysis results.Three kinds of methods are used to optimize the EMU body structure by the two ways.In order to improve the first-order vertical bending frequency in the equipped vehicle state.As a result the riding comfort and operation stability of the train are improved.In the first scheme,the model is directly optimized in OptiStruct software,as a result the first order vertical bending frequency of the EMU body increases by 5.5%,and the weight of the EMU body steel structure increases by 1.7%.In the second scheme,the variables are selected again through the analysis DOE,based on the initial variables.Then the sequential optimization method based on surrogate model is used to solve the problem.The model is optimized though MFD and GA in this scheme.The first order vertical bending frequency is increased by 2.4% after MFD optimization,but the weight of the EMU body steel structure increases by only 0.15%.The first order vertical bending frequency increases by 2.4% after GA optimization,and the weight of the EMU body steel structure is increased by only 1.66%.The three methods have achieved the desired purpose. |
