Research On Crashworthiness Of Five Module 100% Low Floor Vehicle

With the low floor vehicles being put into operation in more and more cities in our country,the safety of the vehicles had received extensive attention.The unique operation mode of low-floor vehicles determined the complexity and diversity of collision accidents.The research on the crashworthiness should be carried out during the design of low-floor vehicles.This paper combined the research results of low-floor vehicle safety protection at home and abroad,using explicit nonlinear dynamics method to study the passive safety protection of low-floor vehicles.This paper introduced the basic theory related to rail vehicle collision simulation,and elaborated the basic control equation of collision,the time step control under the explicit center difference method,the hourglass phenomenon and the nonlinear contact problem,and proposed some methods for adjusting time steps and controlling hourglasses.Thin-walled metal structures were widely used in the manufacture of energy-absorbing elements inside the train end anti-climb device and the coupler buffer device.The plastic deformation caused by the collision was artificially controlled,which could effectively protect the damage of the vehicle body structure and the casualties of the occupants.Based on the research of a large number of thin-walled energy-absorbing structures,this paper used LS-DYNA software to conduct a collision simulation analysis of an aluminum alloy square thin-walled folded tube,and studied the influence of the different parameters of the material on the structure of energy absorption and impact force.A collision simulation of a two-layer nested square aluminum alloy thin-walled pipe model was performed,and analyzed the influence of mesh density on simulation results.The collision resistance of two layers of nested square thin-walled tubes was compared and analyzed.Through pre-distortion treatment,the initial peak load of the structure was effectively reduced.To create a reasonable and effective collision simulation model for rail vehicles was the basis and prerequisite for the research of vehicle passive safety protection.In this paper,the connection relationship between the structure of five-module 100% low-floor vehicle body,bogies,and anti-climb devices was analyzed in depth.Using HyperMesh software,a low-floor vehicle collision simulation model was systematically established based on a simplified and focused modeling principle.The correctness of the material constitutive relation in the collision model was the key to ensure the accuracy and reliability of numerical simulation.In this paper,based on the two-segment material constitutive relation and multi-segment material constitutive relation,the head vehicle finite element model collided with static 15 t deformable obstacle.By comparing and analyzing the results of the collision simulation under the two material constitutive relation models,the effect of different material constitutive relation models on the collision simulation results was studied,and different constitutive models caused differences in the vehicle's living space,average acceleration or deceleration,and other safety indicators during the collision.According to the requirements of EN15227,a five-module 100% low-floor vehicle is subjected to two kinds of crash simulation calculations in the LS-DYNA software,and the energy change,average acceleration,wheelset lift,and living space during the collision are evaluated.And a low-floor train crashing the same static train scene at a speed of 30km/h was proposed to analyze the energy absorption ratio of different materials and different structural regions of the headcar body,to provide a theoretical basis for the energy absorption design of a new low-floor vehicle body structure.