High Speed Vehicle Carbody Structure Parameter Optimization Research Based On Section Thickness Changes

With the continuous development of science and technology in high-speed rail industry,the performance requirements of high-speed trains are also improving,and the structural optimization is attracting more and more attention from researchers.From the selection of structural materials to the specific design of structure distribution,a large number of simulated calculations are needed.How to make full use of the material characteristics to meet the safe operation requirements of the whole life cycle of the train is the most crucial problem.In this paper,CEMU middle vehicle carbody act as the research object,through the torsional and bending stiffness and modal structural strength,calculation of body,body structure characteristic analysis,simulation of vehicle under various operating conditions on the morphology,through the establishment of mathematical model of the vehicle,the carbody structure optimization.The body section plate thickNess act as design variables,the restraint stress,displacement and frequency of torsional and bending stiffness and modal structure strength and body,to achieve the optimization of body structure,reduce vehicle quality,and in ensuring the strength and rigidity of the body to explore to improve the feasibility of quality reduction case.The main contents of this article are as follows:(1)The carbody model is derived from Solid Works software,and the carbody model is simplified,for example,the fillet and chamfer of the structure are removed,and the quality of the equipment suspended below is changed into mass blocks,which evenly distribute the seat and passengers' quality.Using the structure symmetry,the structure of the carbody 1/4 is meshed in the Hypermesh software,and the finite element model is established.(2)According to the relevant requirements of the international railway alliance standard UIC566 and the European standard EN12663:2000,the finite element model of carbody is replaced by ANSYS software for simulation calculation.In order to realize the simulation of the whole life cycle of the safe operation of the train objective,in a variety of loads on the body were calculated,including staffing conditions,lift the car condition,compression condition,tension load etc.Through the finite element calculation resultss of various working conditions,it can be clear whether the strength,stiffness and mode of the model are within the required range,that is,whether the structure of the model meets the design requirements.(3)Using the Isight optimization software to optimize the calculation of the structure,the main idea is to establish the approximate model structure,the mathematical model of finite element model to replace the original characteristics in force and strength,through the optimization of this model and finite element model are optimized.In structural optimization,on the choice of the design variables need to follow the following principle:through structure analysis,the characteristics of the structural components are divided;will the different parts of the different function of the structure and number of packet;by the symmetry structure,will simplify the packet.The design variables are the thickNess of the sections of each component.(4)The multi-objective optimization method is used to optimize the structure of the carbody.The normalization method is used to transform multiple targets into a single target and integrate all the targets with different weight coefficients.The first step is to establish test sample space,using optimal Latin hypercube experimental design;the second step is to establish the approximate model,using Kriging model to ensure the accuracy of the model;the third step is to optimize by selecting algorithm,to achieve a better solution,using combinatorial optimization algorithm.The body quality,strength,stiffness and mode are used as constraints and objective functions to be optimized.CoMPared with several groups of optimization resultss,the optimal solution is obtained by statistical analysis.(5)Through structural optimization resultss,the influence of each component's structure on carbody strength,stiffness and mode are analyzed.By adjusting the thickNess of the structural plate,we can lighten the structure and increase the strength and stiffness of the structure.The optimization resultss are replaced by the finite element model,and coMPared with the original data of the carbody,the torsion,bending stiffness of the carbody and the free vibration frequency of the empty car are analyzed.The optimization scheme is obtained.The research method in this paper provides a reference for the structural analysis of EMU and high-speed train body,and lays a solid foundation for further research of locomotive and rolling stock optimization design.