Research On The Conceptual Design Of Body Structure Of Pure Electric Vehicle

Developing pure electric vehicles is an important way to improve the competitiveness of the automotive industry,safeguard energy security and develop low-carbon economy.Currently,the body structure of the traditional internal combustion engine vehicle is still used in pure electric vehicles,while only the power system is replaced.The load of pure electric vehicle body has changed when compared with traditional vehicle,because it is driven by motor and powered by battery,which poses new requirements to the body structure design.And the conceptual design occupies an important position in the development process of the body.Therefore,the conceptual design of pure electric vehicle's body structure is the key issue in the vehicle research and development,and it is the research priority of the automotive industry and academia.The development process of the modern automobile body structure and performance criteria in body concept design stage was analyzed in this paper.The relatively complete concept development process of pure electric car body was proposed.This process is leaded by performance and driven by optimization.The concept form of pure electric car and arrangement of the program were discussed.The quality of component and design space of body structure was determined which laid the foundation for the subsequent topology optimization of body structure.Body structure topology optimization aims at obtaining the most reasonable load path.Based on SIMP theory,static?dynamic and integrated static and dynamic multi-objective optimization model were builded by using compromise programming approach.Topology optimization was used to the body structure and a clear and obvious body structure load path was finally got.The wireframe geometry of car body was established based on the results of topology optimization and a new method of section parameter optimization was proposed.Based on the transfer matrix method,the static and dynamic stiffness chain mathematical model of the white body was constructed which contains characteristic parameters of section.For the problem of body stiffness distribution,the mechanical property of the main section was determined by building a mathematical model of cross-section parameter optimization.Dynamic stiffness and static stiffness of pure electric vehicle body structure were verified to illustrate the feasibility of the design method by using finite element method.The actual cross-sectional shape of the body is a complex structure.There,the main body section matching method based on mechanical properties was studied in order to transfer the rectangular cross-section of stiffness chain model into the actual cross-section which can be used in the detailed design stage.In addition,the reasonableness of matching results was verified by building beam element model.This study provides a body design method leaded by performance and driven by optimization,which has a certain reference value to solve the practical problems of pure electric vehicle development.