Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial
Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial
复制标题
单相超材料中深亚波长尺度弹性波的负折射
DOI：
10.1038/ncomms6510
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发表时间：
2014-11-01
影响因子：
16.6
通讯作者：
Huang, G. L.
中科院分区：
文献类型：
--
作者：
Zhu, R.;Liu, X. N.;Huang, G. L.
弹性波的负折射已在三维和二维声子晶体中得到研究和实验验证，但由于需要将结构缩放到可控制的尺寸，布拉格散射对于低频波的控制是不切实际的。在此，我们提出一种由单相固体材料制成的具有手性微观结构的弹性超材料，旨在实现弹性波的亚波长负折射。由于同时存在平移和旋转共振，观察到了负有效质量密度和负有效模量。我们通过实验证明了在不锈钢板中制造的超材料中，纵向弹性波在深亚波长尺度上的负折射。实验测量结果与数值模拟吻合良好。此外，还揭示和讨论了与负折射相关的波模式转换。因此，所提出的弹性超材料可用作弹性波聚焦的平面透镜。
Negative refraction of elastic waves has been studied and experimentally demonstrated in three- and two-dimensional phononic crystals, but Bragg scattering is impractical for low-frequency wave control because of the need to scale the structures to manageable sizes. Here we present an elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves. Both negative effective mass density and modulus are observed owing to simultaneous translational and rotational resonances. We experimentally demonstrate negative refraction of the longitudinal elastic wave at the deep-subwavelength scale in the metamaterial fabricated in a stainless steel plate. The experimental measurements are in good agreement with numerical simulations. Moreover, wave mode conversion related with negative refraction is revealed and discussed. The proposed elastic metamaterial may thus be used as a flat lens for elastic wave focusing.