The FEA-based Static And Dynamic Characteristics Analysis Of Coach-body Structure

With the development of finite element theory and computer technology, FEA has beenused through the whole productive process, from conceptual design of coach body structure tofinal product forming. The FEA-based simulation analysis can not only shorten thedevelopment period of coaches, but also can reduce development costs. Therefore, FEAmethod has become an important tool for the coach enterprises to develop new models.The paper establishes a FEA model of coach body structure, conducts a simulationanalysis of strength and stiffness under five kinds of typical working conditions, and obtainsthe maximum stress and the maximum displacement as well as the position where it occurswhen the body proceeds under the five conditions mentioned above. Also, in the paper, freeand constrained modal analysis are made on body frame, based on which frequency value andformation figure are acquired. Moreover, simulation analysis on harmonic response of thebody frame structure is made when the engine vibrates in the vertical (Z) and horizontal (Y)direction. Finally, the paper comes to transient response of body frame structure under thedynamic torsion and bending conditions.According to the simulation analysis, the paper comes to the following results. Themaximum stress of the body frame is240.56MPa, and the maximum displacement8.041mm,which are far from exceeding what the material can withstand. The low order naturalfrequency of the coach is between8Hz and30Hz, with first-order torsional natural frequencybeing8.43Hz and the first-order bending natural frequency17.39Hz, the9difference ofwhich can effectively prevent the coupling phenomenon of the first-order bending frequencyand first-order torsional frequency. Besides, based on the harmonic response analysis,32.5Hz,90Hz and110Hz around are the resonant frequency of the body, and therefore the excitationof engine counts a lot for the vehicle sound vibration. Moreover, the results of body frametransient response analysis show that the maximum stress of the body frame is247.7MPa,which is still within the material yield limit, and it also shows that under the torsion condition,maximum displacement changes with time as a parabola, while under bending conditionchanges as vibration wave and gradually decreases. However, under both torsion conditionand bending conditions, in the vertical direction, the wave crest is zero, which means peakacceleration at the moment. Thereby the rationality of the design of the coach is verified andthe results obtained in this paper provide some references for the further optimization analysisof the coach in a direct way.