轿车白车身隐式全参数化建模与多目标轻量化优化

Implicit Parameterization Modeling and Multi-objective Lightweight Optimization for a Car's Body-in-white

利用SFE-Concept参数化设计软件,建立了某轿车白车身隐式全参数化三维几何模型,在此基础上建立了参数化白车身的有限元模型,计算分析了其低阶固有振动特性和白车身的扭转与弯曲刚度,并通过试验验证了分析结果的有效性。利用相对灵敏度分析方法选出66个白车身零件板厚作为轻量化设计变量,以白车身的总质量、扭转和弯曲刚度为优化目标函数,白车身的1阶弯曲和1阶扭转模态频率为约束条件,利用遗传优化算法对白车身进行了多目标轻量化优化。结果表明,轻量化后的白车身1阶扭转频率和1阶弯曲频率的变化均小于1%,虽然扭转刚度降低了4.5%,弯曲刚度降低了1.8%,但仍满足设计要求。而在不改变用材的情况下,白车身总质量降低了19.4kg,即减轻了6.4%,取得了明显的轻量化效果。

A fully parameterized implicit 3D geometric model and, based on which, a parameterized FE model for the body-in-white （BIW） of a car are successively built with SFE-Concept software, and the low-order natural vibration characteristics and torsional and bending stiffness of the BIW are calculated with their validities verified by tests. A multi-objective lightweight optimization on the BIW is conducted by using genetic optimization algorithm with the thicknesses of 66 BIW panels selected by relative sensibility analysis as lightweight design varia- bles,the total mass and torsional and bending stiffness of the BIW as objective functions and the 1 st order bending and torsional frequencies as constraints. The results indicate that after lightweight optimization the changes in both 1 st order bending and torsional frequencies are within 1% , the stiffness in torsion and bending, though reduce by 4.5% and 1.8% respectively, still meet the design requirements, and the total mass of BIW reduces by 19.4kg, i.e. lightens by 6.4% without changing material, achieving obvious BIW lightweighting results.