Research And Optimization Design Of Crashworthiness Of Vehicle Side Structure Based In Side Pole Impact

Vehicle side impact is one of the main accident forms causing passenger injury.Side impact has become one of the most important issues in the design of passive safety of vehicle.Side impact test can be divided into side barrier impact test and side pole impact test.Side column impact test is not a mandatory requirement in China,this makes designers consider rarely the crashworthiness of side pole impact in the design stage of vehicle models.However,due to the actual side column collision accident,the column is hard,high collision speed,Small collision contact area,causing more serious damage to the occupants,and puts very high demands on the crashworthiness of the vehicle in side pole impact.Based on this background,this paper studies the side column collision of the research model and improves the safety design method of the existing body side structure.The main research contents and results are as follows:(1)The occupant damage theory,mechanics theory and body stiffness characteristics in side column collision are analyzed,which provides direction and principle for the improved design of the car body against side column crashworthiness.The results show that reasonable design of stiffness of side structure,reducing intrusion speed of side body structure and improving reaction force of the body support structure both can effectively reduce the passenger’s stress and harm in side pole impact.(2)The finite element models of side barrier and side column collisions are established and verify the effectiveness.Compare and analysis the dynamic response,energy absorption and deformation of lateral structural members,intrusion and acceleration of B-pillars,find the damage characteristics of the two types of collisions to the occupants.Studies have shown that side column collisions are more damaging to the body and place higher demands on occupant protection,especially the head and chest.When evaluating the safety performance of the research vehicle,it is recommended to perform two side collision modes at the same time.(3)This paper design the quasi-static three-point bending impact test.The peak force,the SEA and the average force are selected as the evaluation indexes for evaluating the ability of the thin-walled member to resist the lateral impact load.The double-hat beam was finally determined as a simplified structure of the threshold beam.Combining the finite element simulation analysis method and the bending deformation theory,the influences of the material properties,cross-sectional aspect ratio,plate thickness and weld edge height of the thin-walled beam on the bending performance are explored.The research conclusions provide reference guidance for the design of threshold beam in the conceptual design stage.(4)Finally,the multi-objective optimization design of thickness of key structural parts is carried out.Based on the side impact load transfer analysis and energy absorption analysis of a certain type of vehicle,identify key structural parts.On the basis of Latin hypercube test design method and the Kriging approximation model and combined with the NSGA-II optimization algorithm,determine the optimization plan.Optimization results indicate that under the premise of good deformation mode of Bpillar and invasion speed is within the tolerance of the human body and light weight design,peak intrusion of chest is effectively reduced,the optimization objective of improving the crashworthiness of side structure of vehicle is realized.