Performance Simulation And Optimization Design Of Metro Aluminum Head Car Body

The study of metro vehicles is taking an increasing part in the development of modern rail transportation technology.The body of the subway vehicle is the main load-bearing component,and its lightweight and performance optimization design can reduce material costs,reduce track wear and improve economic efficiency.This paper takes the metro aluminum alloy head car body as the research object,and carries out the multi-property(stiffness,strength,modal and fatigue strength)simulation analysis,and verifies and compares with the static strength test,and carries out the topological optimization of the section and lightweight design of the car body based on the results of the performance simulation,and achieves the optimal performance and lightweight goal of the car body through two optimizations,which is important for the performance simulation analysis method and steps of the metro vehicle and the performance optimization of the car body.It has important engineering significance and reference value for the performance analysis method and procedure of the subway vehicle and the performance optimization of the vehicle body.The main research contents are as follows:(1)The finite element model of the vehicle body was established,and eight static strength calculation conditions were obtained based on relevant standards and the stiffness and strength of the vehicle body were evaluated,and the stiffness and strength of the vehicle body met the design requirements,and the static strength analysis was basically consistent with the test results to further verify the accuracy of the finite element model.(2)The modal analysis theory and the modal contribution theory are presented,and the modal contribution evaluation method is analyzed in detail.Carry on the modal analysis of the rigid structure free mode and the ready state of the car body,The first-order vertical bending mode frequency of the rigid structure underframe is 20.18 Hz;the first-order vertical bending mode frequency of the rigid structure underframe is 8.23 Hz in the prepared state.Based on the modal contribution analysis method,the modal effects on the vibration performance of the car body are analyzed,and the modal effects on the transverse and vertical vibration of the car body are obtained.(3)Based on the nominal stress method,the fatigue analysis of the steel and aluminum structures of the vehicle body was carried out based on the steel and aluminum fatigue assessment standards;the fatigue analysis conditions were obtained according to the EN12663 standard and the actual operation of the vehicle body,and the maximum principal stress variation range and the accumulated damage of the steel and aluminum structures at each assessment location were calculated,and the results showed that the damage ratio at each assessment point was less than 1,and the vehicle body met the fatigue strength requirements.(4)According to the actual operation of the vehicle body and the load condition,the topology optimization of the underframe profile and the roof profile is carried out.With the objective of minimizing the weighted flexibility of the profiles,the SIMP variable density method is used to optimize the topology of the underframe and roof profiles respectively,and the optimized rib distribution is used to reconstruct the rib distribution of the whole vehicle.After the optimization,the mass of the vehicle is reduced by 36 kg,and the strength and stiffness of the vehicle meet the requirements;the first-order vertical bending modal frequency of the underframe in the ready state is 9.32 Hz,which is 1.1 Hz higher than the original model.(5)Based on the theory of stiffness contribution analysis,the structures that contribute more to the bending stiffness of the vehicle are the sidewalls and the underframe,and based on the topologically optimized vehicle model,the two parts of the vehicle body,the sidewalls and the underframe,are designed to be lightweight using sub-model and approximate model techniques,and finally optimized using NSGA-II genetic algorithm.The optimized body mass is 7.45 t,which is 5.34% and 5% lighter than the original model and the topologically optimized model,and the body strength meets the requirements.The first-order vertical bending mode frequency of the underframe is 9.55 Hz,which is 1.32 Hz higher than the primitive model.