Optimization Design Method Of BIM Lightweight Based On Response Surface Model

It is clearly witnessed that energy crisis and environmental problem is becomin g increasingly problematic as a result of the rapid development of automobile industry, although it facilitates traveling in our daily life. Therefore, it is urgent to improve the energy efficiency of vehicles as well as the cost-effective utilization of the fuel, and one of the most promising approaches to achieve the goals is through automotive lightweight design. As one of the four major components of automobile, body-in-white(BIW) possesses high potential for weight reduction to realize lightweight of automobiles. In a typical lightweight design of automobile body, the stiffness and modal of BIW are the most basic parameters, as they are highly associated with the safety and comfort as well as the reliability of vehicles. Therefore, it is of great importance to take into account of the effect of lightweight on the stiffness and modal of BIW repeatedly during design.This thesis studied the optimization of the plate thickness and the shape of the main section of some typical parts of BIW through the response surface approximation model technology by focusing on parameters such as body mass, bending and torsion stiffness as well as the first order bending and torsion modal, etc.The main contents are listed as follows:(1)The finite element models of the stiffness and free modal were first established. Based on that, the bending and torsion modal as well as the first-order bending and torsion modal were calculated. Stiffness and modal tests were also performed to verify the accuracy of finite element model by comparing with the results from finite element analysis.(2)Based on the finite element model, the relative sensitivity analyses of some typical parts of white body were carried out, which screen out the necessary components for size optimization. Sample data of design variables and stiffness and modal of BIW were collected by using Latin hypercube sampling(LHS) method so that the response surface model was established. This response surface model can be used for optimization of white body size, since the accuracy of the response surface was proved.(3)Design variables of main section shape change were created by using mesh deformation techniques, and main sections that have significant influence on white body stiffness and modal were screened out by experimental design methods. Higher order response surface model was established by Latin hypercube method and main section shape optimization improved white body stiffness obviously.