Criteria method based on body strength and lightweight design of the structure

In order to improve vehicle fuel economy and lower production costs, car body lightweight design and research have been gradually more and more auto companies in importance as the leading edge structural design issues and hot issues. From this point, lightweight way to become very important, along with the rapid development of computer technology, finite element method was adopted by more and more enterprises to carry out car body lightweight design. Finite element analysis for optimum design lightweight body can greatly reduce product development cycle, saving development costs and improve vehicle performance and driving some reliability. This paper discusses the importance of the research body and lightweight main way lightweight body, followed by the lightweight body of research on domestic and international status have been described, analyzed the development trend of lightweight body structure, is also discussed in this country Lightweight body with foreign research gaps. Then discusses the finite element method in structural analysis of the body, about the theoretical basis of the finite element and finite element commonly used for body design elements have been described, namely: shell element and the spatial beam element. Meanwhile, ANSYS finite element software used to do a brief introduction, cited by ANSYS finite element analysis software to do common ideas. Then the method body strength criterion defines the body's resistance to proposed standards and anti-static and dynamic strength strength criteria, and use rice metal parts of high cycle fatigue life and low cycle fatigue life used to evaluate the anti-body dynamic strength capabilities. Combination of CAD and CAE software, the establishment of a micro-car finite element model, then the finite element model of the definition of material properties and element types selected, the resulting micro-car finite element mesh model. On this basis, the four conditions on the body in the body stress were calculated and analyzed. Integrated four kinds of conditions, found that the stress of sheet metal body part of the surplus is relatively large, the body is very lightweight space. Meanwhile, four more conditions of stress concentration area of sheet metal of the high cycle fatigue life was estimated, in addition to individual cases, the fatigue life can meet the minimum requirements. Finally, the body was lightweight design, select the stress of the larger surplus for the design of sheet metal 30 variables to four working conditions for the state variables within the stress intensity to the volume of the body sheet metal as the objective function is optimized design calculations, optimized to reduce body weight by 5.6% than the original. Then the body of the optimized sheet metal parts for the four conditions of high cycle fatigue life prediction, the estimation of sheet metal parts are to meet the basic requirements of the fatigue life. 

Keywords: Lightweight design; strength; finite element; optimal design