基于二重对称剪纸的新型超材料胞元结构的设计与特性分析

Design and Characteristic Analysis of a New Metamaterial Cell Structure Based on Twofold-sym Kiri Pattern

新型机械超材料结构通常由一些简单的单元(称之为胞元)通过三维规则阵列组合而成。得益于超常的物理特性,这些机械超材料结构往往具有轻质高强度、多稳态、优异能量吸收能力等优点,正成为众多领域的热门研究方向。为进一步丰富超材料结构种类,需探索更多优质胞元结构。折纸结构具有结构简单、便于折叠等优势,为构建超材料胞元提供了一种重要方式。利用一种具有较好对称的剪纸图案--二重对称剪纸图案,提出一种具有负泊松比特性且单自由度折展的二重对称剪纸胞元。通过分析胞元结构的几何参数对折展运动的影响,发现胞元具有一定的拉胀(即负泊松比)特性,当剪纸的设计变量γ趋近于0时,该胞元趋于经典的内凹蜂窝结构。相较于后者,所提出的胞元还具备单自由度折展特性,为快速搭建吸能结构提供了便利。该胞元结构利用折叠后的物理干涉产生的自锁效应,使得其处于折叠极限状态下具有负载能力。通过静态压缩试验,发现二重对称剪纸芯比内凹蜂窝结构具有更优异的负载能力,是一种优异的纸质超材料结构。该胞元的提出,为探索更多新型超材料结构提供了可能,还为之奠定了理论分析基础。

Novel mechanical metamaterial structures usually consist of a number of simple cells combined by three-dimensional regular arrays.Due to their extraordinary physical properties,these mechanical metamaterial structures often have the advantages of light weight,high strength,multi-stability,excellent energy absorption capability,etc.,and are becoming a research focus in many fields.In order to further enrich metamaterial structures,more high-quality cellular structures need to be explored.Origami structure has the advantages of simple structure and easy folding,which provides an important way to construct metamaterial cells.In this paper,a twofold-symmetric kirigami(Twofold-sym Kiri)patern with good symmetry is adopted,and a cell with negative Poisson's ratio and single degree of freedom folding is proposed.By analyzing the influence of the geometric parameters of the cell structure on the folding motion,it is found that the cell has a stretching characteristic,namely negative Poisson's ratio.When the variable y of the kirigami pattern approaches O,the cell tends to the classical reentrant honeycomb structure.Compared to the classical reentrant honeycomb structure,the proposed cell has the advantage of single DOF which will benefit to construct large deployable energy-absorption structures quickly.With the usage of the self-locking function caused by the physical interference during folding,the cellular structure in the folding limit state has the load capacity.Through the static compression test,it is found that the Twofold-sym Kiri structure has better load capacity than the reentrant honeycomb structure,which is an excellent origami metamaterial structure.The proposed cell provides the possibility for exploring more new metamaterial structures and lays the theoretical analysis foundation for it.