六韧带手性蜂窝结构的动力学响应特性研究

利用显式动力有限元ANSYS/LS-DYNA数值研究了六韧带手性蜂窝结构的面内冲击动力学特性。在保证圆环节点半径不变的前提下，通过改变韧带长度和胞元厚度，首先建立了六韧带手性蜂窝的有限元模型，具体讨论了冲击速度和胞元微结构参数对手性蜂窝材料的面内宏/微观变形行为、密实应变、动态平台应力和比能量吸收能力的影响。研究结果表明，随着冲击速度的增加，六韧带手性蜂窝结构表现为3种宏观变形模态：“> <”型模式、“过渡”模式和“I”型模式。在中、低速冲击载荷下，能够明显观察到拉胀材料在轴向压缩时独特的“颈缩”现象，其主要与韧带绕着圆环中心节点的旋转变形有关。通过引入无量纲“动态敏感因子”，还研究了六韧带手性蜂窝材料的面内动态冲击强化效应。

Investigation on the dynamic response characteristics of hexagonal chiral honeycombs

The in-plane dynamic crushing behaviors of hexachiral honeycombs have been numerically studied by means of explicit dynamic finite element (EDFE) simulations using ANSYS/LS-DYNA. Under the assumption that the circular radii are all the same, the FE models of hexachiral honeycombs are firstly established by the variation of ligament length and cell-wall thickness. The respective influences of the impact velocity and micro-cell structural parameters on the in-plane macro-/micro-deformation behaviors, densification strains, the dynamic plateau stresses and the specific energy absorption of chiral honeycombs are discussed in detail. Numerical results show that there will appear three different types of deformation modes for hexachiral honeycombs with increasing the impact velocity, that is, “> <” mode, “transition” mode and “I” mode. Under low or moderate velocity crushing, the hexachiral honeycombs display the particular lateral compression “shrinkage” phenomenon of auxetic materials, which mainly depends upon the rotation deformation of the ligament on the central node. By introducing a non-dimensional “dynamic sensitivity index”, the in-plane dynamic enhancement effect of hexachiral honeycombs is also investigated in this paper.