Li Qi, Vipperman Jeffrey S
Department of Mechanical Engineering & Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
J Acoust Soc Am. 2019 Mar;145(3):1372. doi: 10.1121/1.5093622.
Acoustic cloaking is an important application of acoustic metamaterials. Pentamode acoustic cloaks have isotropic mass density and anisotropic stiffness. A different kind of pentamode material is proposed in this paper. It is composed of three-dimensional hexagonal unit cells built with double-cone structures. The structure is amenable for creating spherical pentamode geometries, which might be used for acoustic cloaking. The band structures show that there are band gaps for shear waves, where only compressional waves exist. The effective compressional wave velocities are calculated from the band structures for various parameters. The effective properties can be varied by changing the parameters independently. High anisotropy and large variation of effective properties are demonstrated, suggesting good potential for acoustic cloaking. The geometry of the unit cell can be designed to give the appropriate properties required for cloaking.
声学隐身是声学超材料的一项重要应用。五模声学隐身衣具有各向同性的质量密度和各向异性的刚度。本文提出了一种不同类型的五模材料。它由具有双锥结构的三维六边形晶胞组成。这种结构适合创建球形五模几何形状，可用于声学隐身。能带结构表明存在剪切波的带隙，其中仅存在压缩波。根据能带结构计算了各种参数下的有效压缩波速度。有效特性可以通过独立改变参数来改变。结果表明该材料具有高各向异性和有效特性的大变化，这表明其在声学隐身方面具有良好的潜力。晶胞的几何形状可以设计成具有隐身所需的适当特性。
