考虑动态特性的多工况车身结构拓扑优化研究

Multi-case Topology Optimization of Body Structure Considering Dynamic Characteristic

由于车身结构在汽车行驶过程中主要是保证其静动态承载性能,因此在概念设计阶段考虑其多种承载工况,特别是车身的动态性能要求来确定车身结构的最佳拓扑形式十分重要。结合整车多工况多体动力学分析,运用折衷规划法定义整车实际行驶工况下车身结构静态刚度和动态振动频率最大化的综合目标函数,通过层次分析法确定各工况的最优权重系数,进行车身结构的综合目标优化设计。以方程式赛车的车身结构设计为例,进行综合目标的拓扑优化设计,结果表明该方法进行车身结构的概念设计可行且有效。同时,经对比根据设计经验和基于正交试验定义权重系数的两种方法得出的优化结果,其车身的刚度和前6阶频率均有不同程度的提高,且结构更加合理,同时提高了计算效率。

As the body structure is supposed to guarantee its static and dynamic bearing capacities, so it is very importance to determine the optimal topological body structure to consider a variety of loading case and the requirement of dynamic performance in the conceptual design phase. Combining analysis of multi-body dynamics with multiple loading conditions, a comprehensive objective function maximizing the static stiffness under multi-conditions and dynamic frequency of vibration is defined using the compromise programming approach, and comprehensive objective topology optimization is conducted. Meanwhile, the analytical hierarchy process（AHP） method is applied to obtain the weights of the body stiffness in various load conditions. The instance of the topology optimization results of a formula racing car body structure shows that this method is feasible and effective when it is applied to determine an advanced conceptual body structure. Moreover, the contrastive study is carried out to compare the comprehensive objective optimization approach proposed in this study to those that determine the weight ratio empirically or by orthogonal experiment. The study result shows that the body structure stiffness and the first six frequencies are increased and the structure is more reasonable, while the computational efficiency is improved.