圆形子胞驱动的层级柱状结构在轴向载荷下的抗冲击性研究

Impact Resistance Investigation of Hierarchical Columnar Structures Driven by Circular Sub-cells under Sxial Load

为了解决单胞薄壁结构能量吸收效率低的缺陷,进一步改善薄壁结构的防护吸能性能,提出一种基于圆形子胞元的层级柱状结构设计方法,建立方形与圆形层级薄壁柱的几何与数值模型,采用试验研究调查了层级柱状结构的轴向抗冲击性能,发现层级柱状结构吸能性能大大优于相同质量下的单胞薄壁结构;此外,进一步数值调查了层级柱状结构的几何参数(薄壁壁厚t、子胞元直径D)对其吸能特性的影响,发现壁厚t对层级柱的吸能特性有积极作用,且壁厚与子胞元直径的比值t/D对结构的变形模式具有决定性作用。因此,研究也形成了基于壁厚与子胞元直径比值t/D的层级柱状结构设计准则。此外,进一步基于超折叠单元理论对层级柱状结构的平均碰撞力展开了理论预测研究,推导了层级柱状结构在渐进折叠模式下平均碰撞力的理论预测模型,进一步揭示了层级柱状结构的变形与吸能机制与平均碰撞力的内在联系,并且,不同壁厚下方形层级与圆形层级柱状结构的理论预测与数值结果具有较好的一致性,从而验证了层级柱状结构的平均碰撞力理论模型的预测精度。研究结果对具有高吸能效率的轻质薄壁结构的设计具有好的指导意义。

To solve low energy absorption efficiency, and further improve the energy absorption performance of the single walled structure, a design method of hierarchical columnar structures based on circular subcellular elements is proposed, and establishes the geometric and numerical models of square and circular hierarchical thin-walled columns, and investigates the axial impact resistance of hierarchical columnar structures by the experimental test, the energy absorption performance of the hierarchical columnar structures is found to be much better than that of the single walled structure with the same mass. In addition, the influence of the geometric parameters(the wall thickness t and the diameter of subcellular D) on the energy absorption properties of the hierarchical columnar structures is further investigated numerically, and it is found that the wall thickness t has a positive effect on the energy absorption capacity of the hierarchical columnar structures, the ratio t/D of the wall thickness to the diameter of the subcellular determines the deformation mode of the hierarchical columnar structures, therefore, a hierarchical column structure design criterion based on t/D is established. Moreover, a theoretical model of the mean crushing force of the hierarchical column based on the super folding element theory is further developed, and reveals the intrinsic relationship between energy absorption mechanism and the mean crushing force of the hierarchical columnar structures, and theoretical prediction results are good agreement with the numerical results of the square and circular hierarchical columnar structures with different thicknesses, therefore, the prediction accuracy of the theoretical model is validated well. The study is a good guide for the design of lightweight energy absorbing structures with high energy absorption efficiency.