Abstract: The lightweight design of vehicle frame is of great significance to improve vehicle performance. In this paper, the concept design of topology optimization of sports utility vehicle (SUV) frame is carried out using the assembly-free three-dimensional Pareto algorithm. In order to improve the speed of topology optimization in practical engineering applications, the method combines the free assembly finite element method with the topology optimization algorithm based on topological sensitivity, uses the consistent voxel element to divide the grid, uses the compressed conjugate gradient method to accelerate the finite element solution speed, obtains the stress and strain fields, and then obtains the topological sensitivity fields, which can be used to control the topological changes. Firstly, the single objective topology optimization is carried out for the bending and torsional conditions of the frame respectively, to obtain a clear force transmission path and material distribution, and to understand the influence of each part of the frame on the bending stiffness and torsional stiffness. Then, the conceptual structure of the frame is obtained through the multi-condition topology optimization of the bent-torsional combination, which provides a theoretical reference for the subsequent lightweight design. By comparing the proposed method with HyperWorks software, similar topological optimization results are obtained under all working conditions, which proves the effectiveness of the proposed method in obtaining the optimal topology. The computational time of the proposed method is significantly lower than that of HyperWorks, indicating that the proposed method has a significant time advantage in solving large topology optimization problems.

Key words: vehicle frame; topology optimization; topological sensitivity; multi-condition optimization

摘要： 车架轻量化设计对提高整车性能具有重要意义，文章应用免组装三维帕累托（Pareto） 算法对运动型多用途汽车（SUV）车架进行拓扑优化概念设计。为了提高拓扑优化在实际工 程应用中的速度，该方法将免组装有限元法与基于拓扑灵敏度的拓扑优化算法结合，使用一 致的体素单元划分网格，用压缩共轭梯度法加速有限元求解速度，得到应力和应变场，从而 获得拓扑灵敏度场，用来控制结构拓扑变化。先对车架弯曲工况、扭转工况分别进行单目标 拓扑优化，获得了清晰的传力路径和材料分布，了解车架各部位对弯曲刚度和扭转刚度的影 响，然后通过弯扭组合多工况拓扑优化获得车架概念结构，为后续的轻量化设计提供了理论 参考依据。通过该方法和 HyperWorks 软件的对比，各工况下都得到了相近的拓扑优化结果， 证明了此方法在获得最优拓扑方面的有效性；该方法的计算时间相比 HyperWorks 显著降低， 表明此方法在解决大型拓扑优化问题时具有显著时间优势。

关键词: 车架；拓扑优化；拓扑灵敏度；多工况优化