Fatigue Analysis And Size Optimization Of City D-type Vehicle Body

With the continuous improvement of the demand for lightweight and high-speed development of passenger trains,higher requirements are put forward for the structural strength and reliability of passenger trains.As an important bearing structure of passenger train,the vehicle body bears complex dynamic load when the vehicle is running.As a large welded structure,the vehicle body is prone to fatigue failure when bearing complex alternating load.Therefore,it is necessary to fully evaluate the static strength and fatigue strength of the vehicle body in the design stage,and put forward reasonable optimization suggestions according to the structural strength evaluation results,so as to ensure that the structural strength of the vehicle body in service meets the operation requirements.Firstly,this paper expounds and summarizes the research overview of fatigue and optimization of rail vehicles at home and abroad.Secondly,it introduces and compares the methods and theories of vehicle fatigue and optimization research.Finally,according to the relevant calculation theories and methods,this paper carries out the static strength,fatigue strength analysis and size optimization research on the city D-type vehicle body.The specific research contents are as follows.(1)According to the shape characteristics of the vehicle body plate,Hyper Mesh is used to create the finite element model of the whole vehicle body,and Ansys is used to analyze the static strength,underframe edge beam stiffness and free mode of the vehicle body based on BS EN12663-1-2010 ‘railway application-structural requirements of track vehicle body’.(2)The inertial acceleration condition in BS EN12663-1-2010 standard is applied to the finite element model of the vehicle body as the fatigue strength evaluation condition.The nominal stress method in IIW and the structural stress method in ASME are used to evaluate the fatigue strength of key welds in vehicle body,and the advantages and disadvantages of the two methods are analyzed and compared.The calculation results show that the fatigue strength of the vehicle body evaluated by the structural stress method is more reliable.(3)Based on the static strength analysis of the vehicle body,aiming at the lightweight of the vehicle body,the size of the roof profile is optimized by using the optimization solver Optistruct,so that the weight of the whole vehicle body is reduced to 0.92 tons;Based on the fatigue strength analysis of the vehicle body,aiming at improving the fatigue strength of the key welds at the traction structure of the underframe,the size of the plates of the traction structure of the underframe is optimized,so that the service life of the seven weak welds of the underframe under the fatigue condition of inertial acceleration is increased by more than20 million times.