Topology Optimization Of Front Load-bearing Structure And Crashworthiness Analysis Of Multiple Units

With the continuous development of rail transit industry of China and the continuous improvement of train speed,people have attached great importance to the safety of train operation while using rail vehicles to travel.It has become an important topic to study the passive safety protection technology of the vehicle during the structural design of rail vehicles.In case of a collision accident,the large area plastic deformation of carbody may cause a serious threat to the living space of drivers and passengers.Therefore,improving the front stiffness of carbody is very important to ensure the integrity of main structure of carbody and the safety of drivers and passengers.(1)Carry out topological optimization analysis on the front load-bearing structure of Tc multiple units to improve the stiffness of the front of carbody.Using Opti Struct software,impact the front of Tc carbody with a rigid wall,using volume fraction as a constraint,and minimum strain energy as an optimization goal.Through the optimization results,rearrange the front skeleton structure of carbody.The stiffness performance of the optimized scheme is evaluated from two aspects: the maximum collision force between the front of carbody and the rigid wall,and the maximum deformation of the front of carbody.The results show that the stiffness of the front load-bearing structure of carbody is significantly improved after optimization.(2)Carry out dynamic load-bearing limitation analysis on the optimized Tc carbody.The optimized carbody is loaded at coupler mounting seat,front energy-absorbing structure and anti-creep device three different positions through Pam-Crash software to complete the impact process simulation between the rigid wall and the aluminum alloy carbody.The impact force curve and the stress change rule at different times during the impact process of carbody are analyzed,and the weak stiffness region of carbody is obtained.The dynamic load-bearing limitation of the designated position of carbody is determined through the critical point of stress change.The energy curves of different components in the weak stiffness region are verified with the above load-bearing limitation results.The results show that the energy curve can more accurately analyze the dynamic load-bearing limitation of carbody compared to the stress distribution at different times,and can avoid setting too many output intervals for DSY files during the calculation process,improving calculation efficiency.(3)Analyze the crashworthiness of the multiple units trains before and after optimization.The model of multiple units bogie is equipped with different shock absorbers to more accurately simulate train collision response.The finite element model of the 8-car multiple units trains before and after optimization are constructed,and the simulation analysis of entire vehicle collision and collision with 15 t obstacles are carried out.According to the EN15227 standard,the evaluation is mainly conducted on the maximum average deceleration of trains,wheelset lift,and living space aspects.The results show that the multiple units trains before and after optimization meet the standard requirements,and the maximum average deceleration and wheelset lift of the optimized train are basically consistent with the original train.The collapse amount of living space is significantly reduced,and the crashworthiness of the optimized train is significantly improved.This paper starting from the load-bearing structure of the front of Tc carbody,carry out topology optimization for it,and carry out dynamic load-bearing limitation analysis on the optimized carbody,and carry out collision simulation analysis on the multiple units trains before and after optimization.The results show that,the stiffness of the front load-bearing structure of Tc carbody has been improved after optimization,and the dynamic load-bearing limitation analysis of the carbody can be accurately carried out through the energy curves of different components in the weak stiffness area,and the crashworthiness of the multiple units train has significantly improved after optimization.