Three-Dimensional Trampolinelike Behavior in an Ultralight Elastic Metamaterial
Three-Dimensional Trampolinelike Behavior in an Ultralight Elastic Metamaterial
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DOI：
10.1103/physrevapplied.16.024015
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发表时间：
2021-08-09
影响因子：
4.6
通讯作者：
Jing, Yun
中科院分区：
文献类型：
--
作者：
Gerard, Nikhil Jrk;Oudich, Mourad;Jing, Yun
弹性超材料具有禁止波传播的带隙或频率范围。阻碍三维 (3D) 波传播的现有解决方案很大程度上依赖于高体积分数的质量夹杂物，这些夹杂物会诱发和调整基于负有效密度的局部共振。这项研究引入了一类弹性超材料，其体积分数低至3%（质量密度低至0.034 g/cm(3)），可实现低频带隙。该设计的工作原理取决于 3D 蹦床模式行为，尽管质量密度非常低，但弹性波仍能产生宽、全向和低频带隙。这种 3D 蹦床效应源自悬垂节点微架构网络，该网络充当局部谐振元件，在低频下产生带隙。对超材料的动态有效特性进行了数值研究，结果表明与蹦床效应相关的带隙是由负有效模量与接近零但正的有效密度相结合产生的。然后，通过基于光的打印系统制造超材料，从而实现实验表征，该系统能够实现具有悬垂微观特征的微结构。这种设计策略对于需要同时实现轻量化和振动控制的应用非常有用。
Elastic metamaterials possess band gaps, or frequency ranges that are forbidden to wave propagation. Existing solutions for impeding three-dimensional (3D) wave propagation largely rest on high-volume fractions of mass inclusions that induce and tailor negative effective density-based local resonances. This study introduces a class of elastic metamaterials that achieve low-frequency band gaps with a volume fraction as low as 3% (mass density as low as 0.034 g/cm(3)). The working of the proposed design hinges on a 3D trampolinelike mode behavior that gives rise to wide, omnidirectional, and low-frequency band gaps for elastic waves despite very low-mass densities. Such a 3D trampoline effect is derived from a network of overhanging nodal microarchitectures that act as locally resonating elements, which give rise to band gaps at low frequencies. The dynamic effective properties of the metamaterial are numerically examined, which reveal that the band gap associated with the trampoline effect is resulted from a negative effective modulus coupled with a near-zero yet positive effective density. The experimental characterization is then made possible by fabricating the metamaterial via a light-based printing system that is capable of realizing microarchitectures with overhanging microfeatures. This design strategy could be useful to applications where simultaneous light weight and vibration control is desired.