Multi-objective Optimization Design Research On Body Structure Lightweight Based On Collision Safety

In recent years the domestic car ownership is growing rapidly due to the development of automobile industry.It brings many troubles about environment,energy and safety.These problems have a big effect on the sustainable development of domestic automobile industry.As an effective means on energy saving and emission reduction,automotive lightweight technology has become a crucial research subject in the auto industry progress apparently.The lightweight optimization on car body has now become domestic and foreign various car manufacturers one of the core competition of technology as the most effective way in the automotive lightweight technology.In this paper,by way of car body structure optimization design for certain domestic sedan to carry on the detailed study of lightweight optimization design on the basis of summarizing the automotive lightweight technology at home and abroad.Minimized the quality of the white body to achieve the goal of automobile energy conservation,and emissions reduction in car body bending torsional stiffness and modal performance and collision safety performance under the condition of invariable.The concrete research content is as follows:(1)The structure characteristics of the body in white were analyzed,and the BIW’s finite element model was established by geometric processing unit and the division of finite element mesh and quality inspection and creating analog connections in HyperMesh based on a certain domestic passenger car’s CAD model.(2)The model for static bending torsional rigidity and modal analysis based on the sensitivity of structure parameters were established,and then did the BIW’s stiffness and modal performance analysis.The accuracy of the finite element simulation model was verified when we compared the simulation results and test results which provided by the manufacturer.Using this model to do mixed sensitivity about stiffness and modal,then get to optimization design of safety related parts.And using these parts’ thickness as the design variables for the optimization design of the follow-up work.(3)The joint simulation process about the BIW’s lightweight optimization problem was established by the multi-disciplinary and multi-objective design optimization software called Isight.The design of experiment about the parameters of the sensitivity of related parts’ thickness.With the BIW’s quality and bending and torsion stiffness as the optimization targets,low-order modal performance as constraint,BIW’s lightweight of multi-objective optimization design was carried out and it’s lightweight design scheme was determined through the NSGA-II algorithm.Lightweight optimization on the body in white reduced 17.004 kg,and the reduced rate is 5.7%.(4)The full wide frontal crash simulation on the BIW had been proceeded after optimized.Taking the system kinetic and internal energy variation,the invasion of dash panel and B column and the central channel as index of contrast on BIW’s collision safety performance.Then further verify the static bending and torsional stiffness and low-order natural frequency of the BIW.Compared the experimental simulation results with the data provided by the manufacturer,and verified the feasibility of lightweight optimization scheme.