Performance Simulation Analysis And Optimization Design Of Intermediate Car Body Of Subway Aluminum Alloy

In recent years,with our urbanization process speeding up,the traffic jam problem has become a bottleneck in the development of our major cities.It is urgent to develop public transport and alleviate traffic congestion.As urban rail vehicles with the largest passenger capacity,subway vehicles have been widely used in major cities.Aluminum alloy has been widely used in the structure of urban rail vehicles by virtue of its high strength,good processing performance,strong corrosion resistance and easy extrusion.As the main bearing structure of subway vehicles,the safety performance of the car body is very important,which directly affects the normal operation of the train and the life safety of the passengers.In this paper,a city subway aluminum alloy intermediate car body as the research object,based on the finite element method as the theoretical basis,analysis of the structural characteristics of the car body,the finite element simulation analysis software to establish the car body model,the static strength,stiffness,modal,fatigue strength of the car body analysis,and subsequent optimization.The main research contents are as follows:(1)Combined with the design process of the car body structure,the basic parameters,main materials,interface design and component composition of the car body were introduced in detail,and the finite element simulation model of the aluminum alloy subway intermediate car body was established.Based on the actual production process,the structure of the car body was improved.(2)According to the standard GB/T7928,the maximum vertical displacement of the middle lower flange of the side beam of the car body under vertical overloading condition was6.531 mm,which was less than 1/1000 of the vehicle distance,namely 12.6 mm,and met the requirements of the car body stiffness.Based on the standard TB/T3550.1,the equivalent torsional stiffness under torsional conditions was calculated as6.42×10~8N·m ~2/rad,greater than the recommended minimum value,which met the requirements of car body stiffness.This paper expounded the basic theory of modal analysis,and analyzed the rigid structure mode,reconditioning mode and overloading mode of the aluminum alloy subway intermediate car body,and found out the first order vertical bending vibration frequency and the first order torsional vibration frequency of the car body.The vibration frequency of the first order vertical bending of rigid structure was 20.86 Hz,and the first order torsional vibration frequency of rigid structure was 24.92 Hz.The first-order vertical bending vibration frequency and the first-order torsional vibration frequency of the vehicle body in the condition of reconditioning were 8.46 Hz and 19.83 Hz respectively.(3)Based on the basic theory of finite element method and EN 12663-2010 standard,and combined with the task of checking the strength of the aluminum alloy subway intermediate car body,15 working conditions for the calculation of the static strength of the aluminum alloy intermediate car body were determined.Under the static strength conditions,the static strength of the intermediate car body was analyzed,and finally the safety factor of the static strength of the car body was obtained≥1.15.Therefore,it met the static strength requirement of the car body structure,and completed the relevant strength check of the aluminum alloy intermediate car body,which laid a foundation for the further optimization of the subsequent car body structure.(4)Four fatigue strength calculation conditions were determined based on EN12663-2010 standard.According to BS 7608-2014 and IIW-2015 standard,the standard and process of vehicle body fatigue analysis were introduced in detail.Then,according to the above standards,the cumulative damage ratio of multiple working conditions was calculated to analyze the fatigue strength of vehicle body structure.The nominal stress method was used to evaluate the fatigue strength of the vehicle body under four fatigue working conditions.Finally,the cumulative damage of the selected fatigue weak position was calculated to be less than 1.(5)This paper introduced the basic theory of structure optimization design,and introduced the overview of HyperStudy optimization software and Opti Struct optimization software as well as the optimization process of HyperStudy software,analyzes the stress,displacement,mass and modal sensitivity of each part of the car body,and then carried on the size optimization and modal frequency optimization of the car body.The goal was to minimize the mass of the vehicle,namely lightweight.After two optimizations,the body weight was reduced by 11.37%,and it was verified that the static strength of the body structure after two optimizations met the design requirements.