基于改进图分解法的多材料车身结构优化设计方法

针对概念设计阶段的车身结构轻量化设计,提出了一种可实现车身多材料结构设计的分层迭代优化方法。该优化方法的设计变量中,除常见的板厚、材料外,还包括装配设计中的拓扑连接,以实现“将合适的材料用在合适的部位”的要求。分层迭代优化的第1层以拓扑连接为设计变量,采用图分解和NSGA-II对车身装配拓扑结构进行多目标优化,最大化车身弯扭刚度和1阶固有频率;第2层对板厚和材料进行多目标优化,最小化车身质量和材料成本。最终采用基于模糊集合的评分公式选定综合最优解,实现了考虑成本的车身结构轻量化设计。

Optimization Design Method of Multi-material Car Body Structure Based on Modified Graphic Decomposition

Aiming at the lightweight design of car body structure in concept design phase,a hierarchy iteration optimization scheme is proposed which can realize multi-material structure design of car body.In the optimization scheme,the design variables include the topology connection beside panel thickness and material as usual,for meeting the requirements of‘putting the right material on the right position’.In the first layer of hierarchy iteration optimization,with topology connection as design variable,graphic decomposition and NSGA-II are adopted to conduct multi-objective optimization on the topology structure in car body assembling,maximizing the bending and torsional stiffness and the first-order natural frequency of car body.In the second layer,multi-objective optimization is performed on panel thickness and material,minimizing the mass of car body and material cost.Finally,fuzzy set-based scoring formulae are used to select the comprehensively optimum solution,achieving the light-weight design of car body structure with cost consideration.