The Research Of Structural Modal's Effect On The Vehicle Body's Vibration

With the speed of vehicle improving,the light weight vehicle structure of design will be a trend.At the same time people have the higher requirement for ride comfort.So there will be a great challenge for vibration of vehicle.The structural modal is recognized as static index of the vehicle,as well as the dynamic response is recognized as dynamic index.It is necessary to study the relationship between them,to provide a reference for structural design to achieve the best working conditions.In this paper,the structure modal's effect on the vibration of high-speed train is studied by modal contribution.The magnitude of the modal contribution reflects the degree of effect of the modal on the dynamic response.If the dominant modal is identified,the control of the order modal can be clearly achieved to optimize vehicle and control vibration.Firstly,based on the modal analysis theory,the modal analysis of the general multi-degree of freedom system was presented,and the concept of modal contribution factors was derived.The formulas of modal superposition method,static load participation method and modal energy method were derived.The physical meaning,known condition and the advantages of the three methods are compared.Secondly,according to the characteristics of vehicle body's vibration,the car-body was simplified into a beam with three concentrated mass points,for modal analysis.The modal contribution factors via the three methods of the simplified car-body were calculated,and the easiest method was obtained.Then,based on ANSYS simulation software,the substructures model of vehicle was obtained.According to the actual vibration of high-speed train,the model was stimulated by spring excitation and equipment excitation.The response was collected.The modal superposition method was used to calculate the modal contribution of the first 100 order natural modes to the vibration of the vehicle body and the local(floor,side wall and roof).Due to the calculated results,the suggestions for the follow-up car-body design were provided.Finally,the main work of this paper and the conclusion of the study were summarized.The suggestions for the further research on this topic were also proposed.