新型星-菱形负泊松比蜂窝结构的动态力学特性

Dynamic mechanical properties of novel star-rhombic negative Poisson's ratio honeycomb structure

  • 摘要: 为进一步提高蜂窝结构的抗冲击性能和能量吸收能力,通过周期性阵列传统星形胞元和星-菱形胞元,本文构建了内凹星形蜂窝结构(Reentrant star-shaped honeycomb structures,RSH)和新型的面内增强星-菱形蜂窝结构(Enhanced star-rhombic honeycomb structures,ESH)。通过实验和有限元模拟,系统地研究了ESH在不同加载方向的面内力学响应和吸能特性。与RSH相比,准静态压缩下ESH的负泊松比特性减弱,但吸能能力显著提高。此外,结合微拓扑胞元的变形特征,揭示了低速冲击时ESH-y的应力-应变响应呈现双平台特征的变形机制,并讨论了结构参数αtb对平台应力的影响规律。基于高速冲击下ESH的周期性逐层坍塌变形特征和动量定理,给出了不同加载方向高速平台应力的理论解,理论结果与有限元结果吻合较好。该研究可为创新设计具有更优力学性能的新型负泊松比结构提供参考。

     

    Abstract: In order to further improve the crushing resistance and energy-absorbing capacity of the honeycomb structure, by periodically arraying typical star-shaped and star-rhombic cells, the reentrant star-shaped honeycomb structures (RSH) and the novel in-plane enhanced star-rhombic honeycomb structures (ESH) were constructed in this paper. The in-plane mechanical response and energy absorption characteristics of ESH under different loading directions were systematically investigated through experiments and finite element (FE) simulations. Compared with RSH, the negative Poisson's ratio characteristics of ESH under quasi-static compression are weakened, but the energy-absorbing capacities are significantly improved. In addition, by combining the deformation features of micro-topological cells, the deformation mechanism that the stress-strain response of ESH-y exhibits a double-plateau characteristic at low velocities of crushing is revealed, and the influence of the structural parameters α, t, and b on the plateau stresses is discussed. Based on the periodic layer-by-layer collapse deformation features of ESH under high-velocity crushing and the momentum theorem, the theoretical solutions of the high-velocity plateau stress in different loading directions are obtained, and theoretical results are in good agreement with FE results. This study can provide a reference for the innovative design of novel negative Poisson's ratio structures with better mechanical properties.

     

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