形内自相似层级类蜂窝面外冲击特性研究

为提高传统六边形蜂窝结构的抗冲击特性，基于仿生学原理，考虑层级因子的影响，在六边形蜂窝基础上提出了一种形内自相似层级类蜂窝结构。以比吸能（SEA）、初始峰值力（PCF）、载荷效率（CFE）为冲击特性评价指标，根据简化的超折叠单元理论建立一种理论模型，对类蜂窝结构的冲击特性指标进行预测，在此理论模型基础上，研究了胞元壁厚t、胞壁长度l以及胞元数目n对类蜂窝结构面外冲击平均压缩反力和比吸能的影响。结果表明，在等相对密度条件下，比吸能及载荷效率随着层级的升高而提升，其中，在10 m/s冲击速度作用下，一级蜂窝和二级蜂窝的载荷效率相比于零级蜂窝分别提升21%和40%，比吸能分别提升11%和28%；在等壁厚条件下，随着层级的提升，初始峰值力明显提高，但是比吸能及载荷效率的提升更为显著，在10 m/s冲击速度作用下，一级蜂窝和二级蜂窝的载荷效率相比于零级蜂窝分别提升77%和115%，比吸能分别提升72%和116%。所提理论模型能有效预测类蜂窝结构能量吸收性能参数，可为蜂窝结构冲击动力学研究提供理论参考。

Study on out-of-plane impact performance of self-similar hierarchical quasi-honeycomb

In order to improve the crush resistance of the traditional hexagonal honeycomb structures,based on the principle of bionics and considering the influence of hierarchical factors,a self-similar hierarchical quasi-honeycomb structure was proposed on the basis of the hexagonal honeycomb.With the specific energy absorption(SEA),initial peak crushing force(PCF) and crushing force efficiency(CFE) as the impact characteristics evaluation indicators,a theoretical model was established to predict the impact characteristics of the quasi-honeycomb structure according to the simplified super-folded unit theory.On the basis of this theoretical model,the effects of cell wall thickness t,cell wall length l and cell number n on the mean crushing force(MCF) and SEA of quasi-honeycomb structures under out-of-plane impact load were studied.The results show that under the condition of equal relative density,the SEA and CFE increase with the increase of the hierarchy.Among them,under the impact velocity of 10 m/s,compared with 0th order honeycomb,the CFE of the 1st order honeycomb and the 2nd order honeycomb increase by 21% and 40%,and the SEA increase by 11% and 28%,respectively.Under the condition of same wall thickness,the initial PCF increases obviously with the increasing of the hierarchy,but the improvement of SEA and CFE is more significant than PCF.Under the impact velocity of 10 m/s,compared with the 0th order honeycomb,the CFEs of the 1st order honeycomb and the 2nd order honeycomb increase by 77% and 115%,and the SEAs increase by 72% and 116%,respectively.The theoretical model can effectively predict the energy absorption performance parameters of quasi-honeycomb structures,thereby providing a theoretical reference for the study of honeycomb structure impact dynamics.