聚类点阵材料的耐撞性跨尺度拓扑优化方法及应用

Lightweight and crashworthiness are significant performance indicators of equipment design in automotive, aerospace and other industries. Topology optimization is an innovative tool for designing lightweight and crashworthiness structures. Only filled with a single solid material on macro-scale, the existing crashworthiness topology optimization methods separate the mechanical relationship between macro and microstructures, which ignore the attribute of clustering distributions of microstructures (different microstructures for different regions in design domain) during the collision process. In this project, taken the structural crashworthiness as the evaluation standard, the cross-scale topology optimization approach and its application with clustering distributions of lattice materials is studied. On macro-scale, the criteria for dividing design domain with clustering energy absorption characteristic is established. On micro-scale, the parameter design variables are introduced to describe the microstructure unit cell patterns. The respective mapping relationships between the design variables and the internal energy density are constructed. Furthermore, the evolution rules for design variables are proposed. Finally, with the proposed method, the optimal design of typical vehicle energy absorption structure is carried out. This project will propose a cross-scale topology optimization model for crashworthiness in.considering the attribute of clustering distributions of lattice materials. This model will reveal the characteristics and advantages of concurrent structures in crashworthiness design and provide a scientific optimization method for lightweight and efficient energy absorbing structure design.

轻量化和耐撞性是汽车、航天航空等行业进行装备设计时均需考虑的重要性能指标。拓扑优化是实现结构轻量化和耐撞性设计的创新性工具。现有耐撞性拓扑优化方法，主要关注由单一实体材料填充的宏观结构设计，割裂了宏观结构与微观胞元间力学性能的联系，无法考虑碰撞过程中，材料型式呈聚类分布（材料型式随区域不同而不同）时对结构能量吸收的贡献。本项目以结构耐撞性为评价标准，开展点阵材料呈聚类分布的跨尺度拓扑优化方法及应用研究。在宏观尺度上探索具有吸能特性的聚类设计域划分标准；在微观尺度上引入参数变量描述微结构拓扑构型变化；构建设计变量与内能密度间映射关系，提出相应的启发式设计变量更新准则。最后，基于提出的优化方法流程，开展典型车用防撞结构优化设计应用研究。本项目将提出点阵材料呈聚类分布的耐撞性跨尺度拓扑优化模型，揭示材料非均匀分布规律，总结一体化结构在耐撞性设计中优势，为轻质高效吸能结构设计提供科学优化方法。

轻量化和耐撞性是汽车、航天航空等行业评价装备性能优劣的重要指标。拓扑优化是实现结构轻量化和耐撞性设计的创新性工具。多孔结构在冲击防护领域有广泛应用，但现有耐撞性拓扑优化方法，主要关注于实体结构设计，尚未开展基于多孔结构的耐撞性拓扑优化方法研究。为实现上述目标，本项目首先开展了多孔结构呈聚类分布的跨尺度拓扑优化模型研究。基于自动元胞机方法，推导了宏、微观应变能表达式，采用K-means算法实现了微观多孔结构在宏观尺度上的聚类分布。实验测试和数值结果均表明，聚类多孔结构较周期性多孔结构的刚度有了较大提升。接着，提出了一种可考虑耐撞性的周期性多孔结构优化设计方法。为了实现多孔结构的周期性，对单元应变能进行了重分配，并通过渐进修改单元应变能目标的方式，实现了在指定体积约束下的最大能量吸收设计。数值算例表明提出的优化策略可有效开展考虑耐撞性的周期性多孔结构设计。此外，在本项目资助下，还分别开展了压扭结构的吸能缓冲和充水薄壳撞击固壁的动态力学行为研究。本项目的研究成果对于高效开展防护结构设计有促进作用，有望在汽车、航空航天领域，为进一步实现高性能轻质防撞结构设计提供技术支持。