Chen Yi, Kadic Muamer, Guenneau Sébastien, Wegener Martin
Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe, Germany.
Institut FEMTO-ST, UMR 6174, CNRS, Université de Bourgogne Franche-Comté, 25000 Besançon, France.
Phys Rev Lett. 2020 Jun 12;124(23):235502. doi: 10.1103/PhysRevLett.124.235502.
The elastic properties of three-dimensional (3D) crystalline mechanical metamaterials, unlike those of amorphous structures, are generally strongly anisotropic-even in the long-wavelength limit and for highly symmetric crystals. Aiming at isotropic linear elastic wave propagation, we therefore study 3D periodic approximants of 3D icosahedral quasicrystalline mechanical metamaterials consisting of uniaxial chiral metarods. Considering the increasing order of the approximants, we approach nearly isotropic effective speeds of sound and isotropic acoustical activity. The latter is directly connected to circularly polarized 3D metamaterial chiral acoustic phonons-for all propagation directions in three dimensions.
与非晶结构不同，三维（3D）晶体机械超材料的弹性特性通常具有很强的各向异性——即使在长波长极限情况下以及对于高度对称的晶体也是如此。因此，为了实现各向同性的线性弹性波传播，我们研究了由单轴手性超棒组成的三维二十面体准晶机械超材料的三维周期近似体。考虑到近似体的阶数不断增加，我们得到了接近各向同性的有效声速和各向同性的声学活性。后者直接与三维超材料手性声子的圆偏振相关——适用于三维空间中的所有传播方向。
