The lightweight design of the body-in-white ( BIW) structure of a sedan is conducted with thor-ough considerations of stiffness, strength and frequency constraints. Firstly eighty-two key components are selected with the models for their BIW structure created, in which panels in the same component having same thickness. Then finite element analyses are conducted on car body structure under static bending, twisting and free-mode con-ditions, and an optimization model for BIW structure is set up with minimizing mass as objective, bending and tor-sional stiffness, stress and first three order frequencies as constraints and panel thickness as design variables. Finally sequential linear programming is adopted to perform a nonlinear optimization with a good lightweighting result ob-tained:the mass of BIW reduces by 34. 6kg with a mass reduction rate of 11. 4% achieved.%全面地考虑了刚度、强度与频率约束,对某轿车的白车身结构进行轻量化设计.首先根据工艺要求对白车身结构进行了组件化建模,选取了关键的82个组件,每个组件中的板单元的厚度相同.其次在静态弯扭工况与自由模态工况下对车身结构进行了有限元分析.然后以质量最小为目标,以弯扭刚度、应力和前3阶固有频率为约束条件,板厚为设计变量,建立了白车身结构优化模型.最后采用序列线性规划进行非线性优化,取得了良好的轻量化效果:白车身质量减轻34.6kg,减轻率达11.4%.
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