| Railway is an important part of China’s transit system,and the passive safety protection technology of railway is always one of the main research topics in vehicle structure design.With the continuous improvement of the train running speed,once the collision accident occurred,it will cause a huge loss of personnel and property,as the end structure of the train,the collision post plays a crucial role in ensuring the safety of locomotives and vehicles.The cross-sections of existing collision posts are almost the single-cell square tube,however,multi-cell configurations have been shown to improve the structural impacting characteristics significantly,therefore,in order to obtain the optimal collision post structure design and improve the vehicle crashworthiness effectively,this study conducted a crashworthiness analysis of a certain type of subway car based on the APTA PR-CS-S-034-99 standard,the main research work was carried out from the following several aspects:(1)The finite element model of the subway head car was constructed and the collision simulation analysis of the train collision column was accomplished by using the explicit dynamics software LS-DYNA,according to the dynamic impact condition in APTA PR-CS-034-99 standard and the oblique impact condition.The collision response parameters of the collision post,such as energy absorption value of the collision post,collision peak crushing force and the invasion size,were used to evaluate the crashworthiness of collision post structure.The analysis shows that the plastic deformation energy absorption of the traditional single-cell square tube collision post is lower than the requirement of APTA PR-CS-034-99 standard when the intrusion size is given,so the crashworthiness of the structure is necessary to optimized.(2)In order to improve the crashworthiness of the collision post,the multi-cell configuration was introduced into the section design of the column.Based on Optistruct software,the minimum strain energy of the structure was taken as the objective function and the element density was taken as the design variable.The topology optimization of the collision post structure under multiple working conditions was carried out,and the effect of loading conditions on the topology optimization results was analyzed.After that,the optimal material density distribution was functionally treated by considering the structural design process principles,and a new multi-cell cross-section configuration was proposed,which provided a feasible scheme for the crashworthiness design of the collision post.(3)In order to further optimize the collision post structure to meet the requirements of crashworthiness and lightweight at the same time,the multi-cell wall thickness of the cross-section was selected as design variables to maximize the energy absorption and minimize the peak crushing force,combining with the polynomial response surface surrogate model and the genetic algorithm,the Pareto frontier solution sets of optimization problem was acquired,and the optimal design for new multi-cell collision post was obtained.Then,the new collision post was applied to train end structure to verify the performance of its crashing performance,the results showed that the impacting energy absorption of the optimized collision post structure meets the requirements of APTA PR-CS-034-99 standard,and its structural performance was significantly improved.In this paper,based on APTA PR-CS-034-99 standard,the crashworthiness of the collision post for subway vehicles was studied,and the collision post structure was designed by combining two methods of topology optimization and multi-objective optimization.The design process makes full use of the characteristics of the two optimization methods,improves the rationality and reliability of the optimization results,provides a feasible method for the design of the train crashworthiness structure,and has certain engineering reference significance. |
