Structural Design And Optimization Of The Guardrail For Train-to-train Collision Test Bench

The train-to-train collision test is a multi-body collision,which has the characteristics of strong nonlinearity and high risk.The train-to-train collision test will cause serious consequences after derailment.It is of great significance to effectively limit the lateral displacement of the test train wheelset and guide the derailment wheelset to reset the pair for the train-to-train collision test.The guardrail installed in parallel on the inner side of the rail can play a significant role in preventing wheel derailment.The guardrail in the train-to-train collision test scenario should have the characteristics of simple and lightweight structure and easy replacement.At present,the guardrail is almost used in projects,and its protect ability is not suitable to the train-to-train collision test scene.There is no uniform design specification for guardrail.Therefore,the structural design and optimization of the guardrail for the train-to-train collision test bench(GR)were carried out in this thesis.This thesis focuses on the protection capability design,structural conceptual design and structural optimization of GR.The main research contents are as follows:(1)Requirements analysis of guardrail protection capability of the train-totrain crash test bench was carried out.In the train-to-train collision test,the protective ability of the guardrail does not need to be infinite,so it is necessary to determine the appropriate protective ability of GR through the protective ability design.Based on the established finite element model of the 8-car high-speed EMU-60 guardrail,the protective capacity design of the guardrail for the crash test bench was carried out,and the full-factor simulation calculation was carried out based on the three factors of collision speed,collision angle and collision protection height.A total of 175 groups of collision conditions was calculated to analyze the mechanical response of the collision between the wheel and the 60-guardrail,and to explore the influence of the contact force with the three factors during the collision process and to obtain the maximum contact force,the analysis of the protection ability was performed.Finally,the protection ability of the GR was determined.The dynamic behavior variations of the test car body and wheelsets provide a reference for the initial configuration design of GR.(2)The conceptual design and optimization method of GR were proposed.The initial configuration of the GR was designed based on the analysis of the protection capability and EN 15227 for the wheel lift requirements in the collision.Due to the high probability of damage to GR in the train-to-train collision test,the installation and replacement frequency is high.Therefore,the removing for strength redundancy of the guard rail and only retaining the designed protection ability have obvious significance.Through the analysis and discussion of the advantages and disadvantages of the existing optimization methods for the optimization of GR,a stepwise optimization idea was proposed,that is,the shape design with topology optimization of supporting post of GR and overall structural space size lightweight optimization were carried out step by step to improve material utilization and achieve optimal space size design.(3)The topology optimization of the shape for supporting post of GR was carried out.The supporting post is a support member for GR,which was designed through topology optimization to obtain the best material distribution form,and finally obtain the best shape of the supporting post.Based on the initial configuration of the GR,in order to explore the topology optimization law of the supporting post alone and the overall topology optimization law after the supporting posts were combined,two optimizing conditions of the supporting post and the combination were designed.Seven sub-conditions loaded at different heights were set in each optimizing condition.The supporting post shape was determined through comparative analysis,and the GR transition configuration structure was established.Finally,the protection capability of the GR transition configuration structure was verified through dynamic impact verification conditions.The design results show that the transition configuration structure of the GR is 41.811% lower than the initial configuration of the GR in mass.(4)The lightweight optimization of the space size of the GR was carried out.In order to explore the optimal configuration of the structure size and arrangement parameters of each part of GR,a lightweight optimization design based on space size was carried out.Based on the design of the protection capability of the GR,the optimization model of the GR was proposed.According to the different positions where the GR was impacted,the supporting post condition and the midpoint condition were proposed,and the design of experimental was carried out respectively to establish a high-precision surrogate model.Parameter analysis was carried out.In order to make the optimal configuration meet two working conditions at the same time,a combined optimization working condition was formed based on the two single conditions,and the optimization goal was light weight.The result shows that the mass per unit length is 43.885%,which is lighter than the initial configuration structure and 3.564% lighter than the transition configuration structure,the maximum lateral contact force is 9.619% which is higher than that of the transition configuration structure,and the maximum plastic deformation is reduced by 9.049%.The maximum stress is reduced by 0.241%,so the GR has higher protection strength and lower mass after the lightweight optimized design.