Research On Optimization Design Of Aluminium Alloy Car Body For Double EMU

The high-speed trains and EMU have become a mainly transport mode,the car body is one of the most important parts of the high-speed train,not only the weight can be reduced and its performance can be improved by optimization,but also the interaction force of between the wheel and rail can be reduced,the ride comfort and safety can be improved,the costs of manufacture and running can also be decreased.The main contents of this paper are as follows.1.The car body of double EMU is used as a research object,its finite element model is established.According to the European standard of "EN12663",the static strengths of car body in main cases are calculated by using of the finite element method;2.Basing on the static strength results,the local structure improvement are accomplished for reducing the local stresses,the serious stress concentration is removed,the car body performance is promoted;3.The first six order modals of car body are calculated for car body of both empty and preparation condition,respectively,the results show that the first order vertical bending frequency is respectively 20.68 Hz and 11.96 Hz for the empty car body and the preparation condition car body,these meet the requirements of greater than 17Hz and 10 Hz regulated by the related standard;4.The plate thicknesses of heavy parts are chose as the design variables,the empty aluminum car body is used as the optimization object.the car body optimization designs are achieved.Firstly,the sum of the first three modal frequencies is chose as optimization objective for increasing modal frequencies and the weight is chose as restriction;secondly,the weight is chose as optimization objective,and the modal frequencies are chose as restriction;the four optimization schemes are accomplished,the optimized plate thicknesses distribution are achieved,then strength and modal of the preparation condition car body are calculated and verified.5.The effect of inner end-wall of car body on performance is analyzed and compared.the strength results show that the local stress on the joint position of between the inner end-wall and floor is very high than the average values,and it is difficult to improve by increasing thicknesses of plates,therefore the strengths and modals are calculated and compared for the having and removing the inner end-wall.The results show that the maximal stress of car body is obviously decreased by removing the inner end-wall,and the performance of the car body is obviously improved.The weight of car body is reduced by 5.5%while the modal frequencies are increased by optimization design,and the strengths and fatigue life are not reduced relatively,the overall performances of car body are promoted,and the expectant design objects are achieved.