Weight-light Design And Study On Frame Based On Criterion Of Car Body Strength

To improve fuel economy and lower production costs, increasing number of auto companies began to attach great importance to research on the weight-light design of car-body, which turned out to be the frontier and hot issue in the field of structure design. From this point, the ways of weight-light became very important, with the rapid development of computer technology, finite element method was adopted by more and more enterprises to carry out car body weight-light design. Finite element analysis for optimal design of weight-light body can greatly reduce the product development cycle, saving costs and improving vehicle's performance and its reliability.In this paper, the significance of the research on car-body lightening design and it's main methods was firstly discussed. The next part was a review of the studies on weight-light body at home and abroad, which meanwhile gave a analytic study about the development trend of weight-light body structure and the gap in relevant domestic research compared with foreign countries.The third part mainly discussed the application of the finite element method in car-body structural analysis, which covering the theoretical foundation of finite element and the introduction of commonly used Finite Element in car body design, namely, the plates and the space beam element. Meanwhile, the following was a brief discussion on the ANSYS finite element software and a list of common thinking of utilizing ANSYS software to conduct finite element analysis.The fourth part was to define the criterion of body strength, put forward the anti-static strength criteria and anti-dynamic strength criteria, and evaluate the anti-dynamic strength of the car body through high-cycle fatigue life and low cycle fatigue life of sheet metal parts.In the fifth part, combination of CAD and CAE software, a micro-car finite element model was established. The material properties defining and unit type selection for the finite element model finally led to the generation of the micro-car finite element mesh model. On this basis, when calculating and analyzing the car body condition under the four kinds of stress, it finds that surplus stress of body sheet metal parts was much large and car body lightening existed a great potential. In addition, after estimating the high cycle fatigue life of sheet metal on which more stress concentrated under the four kinds of condition, it concluded that most of them could meet the minimum requirements of fatigue life in addition to individual cases.Finally, the light-weight design was conducted to the car body, selecting 30 sheet metal parts with larger stress surplus as design variable, the internal stress strength of the four conditions as the state variable, and the volume of the body sheet metal parts as objective function, a calculating of optimized design was carried out and it turned out that the optimized car body weight reduced by 5.6%compared with the original one. Next, estimating of the high cycle fatigue life of sheet metal of the optimized car body under the four kinds of conditions was conducted and the result was that they all met the basic requirement for the fatigue life.