Lightweight Design Of A Frame Based On Multi-Objective Optimization

Lightweight design of automobile is one of the most important measures to realize the purpose of saving energy,reducing emission,decreasing energy cost and achieving environmental protection.As a main part of the vehicle,frame plays an important role in the whole automobile.The purpose of frame lightweight design is to reduce the weight of the frame and reduce the energy consumption without degrading the performance of the vehicle or increasing the cost of manufacture.In this paper,the frame structure of a special vehicle was taken as the research object.It was found that the weight of the frame exceeded the design requirement and the material was wasted,and the frame needs to be redesigned.Therefore,in the conceptual design phase of the frame,the method of topology optimization design was used.Based on the initial shape and overall layout of the special vehicle,the topology optimization design of the frame was carried out for single and multiple working conditions by using Optistruct software.According to the result of topology optimization,a new frame structure was created and designed by CATIA software to meet the layout of vehicle assembly and actual driving requirements.Then,based on the symmetry of the frame structure,beams on the frame were grouped and the sensitivity of the relative masses of these beams were analyzed,and then the beams that had great impacts on weight reduction were selected.Finally,the size optimization design of these beams was carried out.Compared with the original frame,the weight of the optimized frame was reduced by 119 kg,and the weight loss ratio was 22%.The lightweight effect of the frame structure was obvious.Then,finite element static analysis,modal analysis,transient impact analysis and analysis of collision with trees were carried out for the new frame structure.The calculation results showed that the frame had good performance in many evaluation aspects.Finally,the frame was manufactured,and experimental modal analysis and stiffness tests were performed on the frame structure.Comparing the experimental results with the simulation analysis results,the validity of finite element analysis was verified.The work in this paper has an important application value for lightweight design of the frame,and it provides a reference for the similar design of the related enterprises.