Research On Optimization Design Of The Couchette EMU Car Body Performance

One of the main contents of railway vehicle design process is to optimize car body performance and achieve light weight.The objective of the car body optimization design is to realize the lightweight of car body,save raw materials,save energy and reduce running cost;Secondly,reduce the wheel and rail force,so improving the running ride comfort,stability and safety.The main research work is as follows:(1)The finite element model of car body is set up.Basing on the finite element method,the car body of the Couchette EMU is taken as an objective,and the finite element model is established that bases on the finite element analysis theory.(2)The car body strength and modal are calculated.According to the European"EN12663-2010" standard,the car body strength of the main cases are calculated and analyzed,the results show that the car body strength are satisfied with the relevant standards.The modal of car body of preparation condition is calculated.(3)The modal sensitivities of car body under preparation condition are calculated.The car body of preparation condition is taken as an objective,the design variables are the thickness of each part of the car body,the number of design variables are 122,the sensitivities of the first four-order modal frequencies with respect to each design variables are calculated by using of the numerical differential method.(4)The optimization design of carbody structure is accomplished.Basing on sensitivity analysis,the promotion of anti-rhombus and anti-bending stiffness of car body of preparation condition is as a goal.The plates thickness of the side wall,underframe and the roof are used as the design variables,and the first two-order modal frequencies of car body and structure weight are each other used as the objective and constraint conditions,the optimization designs of car body are achieved through a variety of optimization design schemes.(5)The improving structure and optimizing design are achieved again.On the basis of the above optimization,the influence of the total thickness of the roof and the underframe and the height of the side wall on the modal frequencies of the car body is studied.The optimum optimization scheme is increasing the total thickness of the roof and the underframe,and so the first two-order mode frequencies are increased.On this basis,the optimization design of the thickness of the car body is studied again,and so the modal frequencies of the car body are further improved,latstly,the optimized carbody strength was verified.(6)The stress sensitivities of end wall is accomplished.Basing on the optimized car body structure,the carbody strength is calculated under compression cases of the end wall,and end wall thickness are as the design variables that are divided into 25 design variables,the sensitivities of the maximum stress with respect to the design variables of the end wall in three load cases are calculated by using of numerical differential method.(7)The optimization design of end wall is accomplished.Basing on sensitivity analysis of end wall,the end wall weight are taken as an objective,the stress of the end wall compression cases and the first two-order modal frequencies of the car body are taken as constrains,the optimization designs of end wall are accomplished.The strength of the optimized carbody structure is analyzed,and results show that the strength meets relative standards.Through the sensitivity analysis and multi-schemes carbody structure optimization design,the first two-modal frequencies are greatly improved under preparation condition,and the carbody strength of each load cases meets the requirement of the relative standards,the light weight of the carbody is realized effectively while improving the dynamic and static characteristics of the car body,the expected optimization design goal is achieved.