Research On The Lightweight Design Method Of Automotive Collision Safety Structure Based On Variable Sections And Multiple Materials

Driving safety,energy conservation and environmental protection are three urgent tasks the automotive industry is facing now.The lightweight of automobile is an effective method to accomplish the three tasks,while collision safety performance is the basic guarantee to accomplish the three tasks.Therefore,it has great theoretical significance and engineering application value to study the lightweight design method of automobile combined with collision safety.Aiming at the lightweight design of automotive collision safety structure,a vehicle lightweight design framework of variable section and multiple materials vehicle based on collision safety is constructed.Taking a racing car frame as the research object,the lightweight design of the frame is carried out,and the optimal design scheme of racing car frame with good collision safety performance is obtained.This paper mainly carries out the following research contents:Firstly,the specific optimization methods of vehicle lightweight design and crashworthiness design are analyzed and summarized.According to the design requirements of vehicle collision safety structure,a general lightweight design framework based on vehicle collision safety is constructed.Different optimization mathematical models are built for different collision safety structures,the feasibility and effectiveness of the optimization framework are verified by the optimization design of multi-cavity energy absorption boxes.Secondly,according to the competition rules of the FSEC,the geometric model of the racing car frame is constructed,and the finite element model of this frame is established in the HyperWorks software.The static analysis of the frame under different working conditions is carried out,and ensures that the stiffness and strength of the frame meet the requirements of the competition.Thirdly,according to the collision safety rules of FSEC competition,the evaluation index of car frame collision performance and initial conditions of collision simulation are determined.The finite element simulation of 100% frontal collision of racing frame is calculated based on LS-DYNA and HyperWorks software.The simulation results are analyzed from three aspects: overall deformation of frame,maximum deformation of brake pedal and acceleration of passenger cabin.Finally,the lightweight design of the racing car frame is carried out through the lightweight design framework of variable section and multiple materials based on collision safety.With the collision safety simulation results of the initial design,the initial design is improved from the shape of section and material of the component.On the basis of variable cross-section and multi-material lightweight design of racing car frame,through sampling the thickness parameters of each specification pipe fitting that make up the frame by design of experiment,the response surface models of safety performance parameters are constructed.An optimization mathematical model is established,which takes the thickness of pipe fittings of various specifications as optimization design variables,the minimum frame quality as design objective,the maximum deformation at brake pedal and the peak acceleration of passenger cabin as design constraints.A lightweight optimization scheme for the racing car frame is obtained on the basis of improving the collision safety performance.