Sensitivity Analysis And Optimization Design Of EMU Body

With the improvement of the rail transportation’s speed, the lightweight of the High speed EMU body is a common trend in the designing of railway passenger cars both at home and abroad, the meaning of reducing the weight of the vehicle meaning is reducing the consumption of raw materials and traction power, increasing the operating speed of the train, improving the train’s starting and braking performance, decreasing the dynamic action between wheel and rail, cutting vibration and noise, extending the servicing life of the vehicle and the line, saving shipping costs. Body bearing structure occupies a large proportion of the dead-weight of the passenger car, so the lightening of car-body structure is particularly important in the process of lightweighting the vehicles.Make the TC02car body of the CRH3EMU as the researching object, build Finite element model with Hypermesh software, analyse the strength, stiffness and modal’s sensitivity with MSC.Nastran software. According to the Body natural frequency, strength, stiffness’sensitivity with the boardthick dimensional changes, in the case to ensure the strength, stiffness and dynamic characteristics of the car body meet the requirements of high-speed railway passenger car standards to, complete the lightweight designing of the body.The main contents include:Firstly,according to the Europe "EN12663standard and the need of optimizing the analysis of the body of TC02, carry on the static strength analysis and calculation in five conditions; the stress did not exceed the material’s allowable stress, stiffness is greater than the stiffness of the assessment standards, all of them conforme to the requirements.Secondly, calculate the TC02body’s modal, according to the bodywork modal assessment standards, empty body’s first order vertical bending frequency is not less than14Hz, Readiness state’s first order vertical bending frequency is greater than10Hz, all of them conforme to the requirements.Thirdly, based on the TC02car body’s strength and stiffness and modal analysis, calculate the sensitivity of the position body main stress, static displacement modal frequency of chassis, side wall, roof and side wall’s thickness with differential method.Finally, make roof plate’s thickness as design variables, body structure weight’s minimum as design objectives, the maximum stress of the vehicle body and the chassis maximum displacement of the bound as constraint, lightweight the body with method of feasible directions.The studies have shown that,with the increasing of the modal frequency, modal frequency sensitivity increases, the the EMU vehicle body modal frequency increases with the increasing of the thickness of most of the plate member, the sensitivity of the modal frequencies for the thickness of the base chassis, sidewall spacer plate member is max. Overall, increasing the thickness of the piece, the contribution to the vehicle body stiffness is greater than contribution to the mass; the sensitivity of the stress and displacement of the main body position for the plate thickness of the majority of body is negative, when thickness of the plates increase, the stress and displacement of the main body position will reduce; the sensitivity of the bodywork modal frequency, stress and displacement for the roof plate thickness are all small, so the weight of the roof structure have a greater weight loss of space. Make the roof plate thickness as design variables of the body weight optimized design, so that the body weight is reduced by0.42tons, a weight loss rate of4.3%, achieve the lightweight design of the body effectively.