BIW Lightweight Research Of A Low-speed Electric Vehicle

BIW is made up of a large number of components connected by welding etc.Facing people’s higher demands on the living environment,the development of pure electric vehicles has become a trend.Debasing the quality of electric vehicles can improve the performance and the cruising mileage of electric vehicles.Debasing the quality of electric vehicles has become the future development trend and important research direction in the auto industry.In this paper,a low-speed electric vehicle is served as the research object.BIW Lightweight Design is using finite element analysis software.The main research contents of this paper are as follows:(1)The dynamic and static performance of BIW is analyzed.Through the analysis of the free modes of BIW,the first six n atural frequencies and mode shapes of BIW are obtained.And through comparing the natural frequency of the vehicle body with the external excitation frequency,the result show that BIW does not resonate.The torsional stiffness and bending stiffness of BIW are calculated.The result show that the values of the torsional stiffness and bending stiffness meet the stiffness requirements of low-speed small electric vehicles.Finally,the strength of BIW is analyzed.(2)Frontal collision of low-speed electric vehicle is analyzed.Using the LS-DYNA solver to carry out the analysis of low-speed electric vehicle frontal collision.Through the energy change curve and the additional quality,the reliability of the frontal collision result of the vehicle is analyzed.In order to ensure frontal collision performance of the whole vehicle after BIW Lightweight Design,the main energy-absorbing components of BIW are selected as safety parts.They won’t participate in BIW lightweight design.(3)The sensitivity of non-safety parts of BIW are analyzed.The thickness of non-safe parts of BIW is selected as the design variable,and the sensitivity of BIW quality,first-order natural frequency,bending stiffness and torsion stiffness are analyzed.The relative sensitivity is obtain ed by the calculated sensitivity dividing the mass sensitivity.The components with high relative sensitivity are selected to improve the performance of BIW,and the components with low relative sensitivity are selected to achieve BIW lightweight design.F inally,26 non-safety parts were obtained for BIW structure lightweight design.(4)BIW Lightweight Design.In order to reduce the optimization time,this paper uses the combination of approximate model and NSGA-II genetic algorithm to carry out lightweight design of BIW.Optimizing the quality and torsional stiffness of BIW to ensure the quality reducing while improving the torsional stiffness.After optimization,the mass of BIW is reduced while the torsional stiffness is improved.The optimization results are checked.The optimized thickness of BIW components are used to the frontal collision analysis.The results show that the lightweight design of the non-safety parts of BIW has little impact on the frontal crash performance of the vehicle.