Wang Wei, Bonello Bernard, Djafari-Rouhani Bahram, Pennec Yan, Zhao Jinfeng
Sorbonne Université, UPMC Université Paris 06 (INSP-UMR CNRS 7588), 4, place Jussieu, 75005 Paris, France.
Sorbonne Université, UPMC Université Paris 06 (INSP-UMR CNRS 7588), 4, place Jussieu, 75005 Paris, France.
Ultrasonics. 2020 Aug;106:106142. doi: 10.1016/j.ultras.2020.106142. Epub 2020 Apr 9.
We report on a new mechanism involving the torsional resonance of stubs to achieve the negative effective shear modulus of an elastic metamaterial plate. Combined with a mechanism to create a negative mass density, we develop a general method to set up and enlarge a shear-horizontal-polarized double-negative branch in the elastic metamaterial plate with stubs on both sides. We explore the capabilities of this structure for polarization filtering, mode conversion and abnormal refraction. It is shown that, this metamaterial plate behaves divergently against the polarization of incident waves propagating along ΓX direction in a square lattice crystal: it behaves as a double-negative system for zero-order shear horizontal (SH) wave but as a single-negative one for zero-order antisymmetric (A) or symmetric (S) Lamb waves. Mode conversion is achieved when the propagation deviates from ΓX direction. Moreover, we observe abnormal refracted patterns with both positive and negative refraction occurring at the interface between a prism-shaped supercell and the surrounding plate. Furthermore, we propose a chiral pillar to efficiently couple the torsional resonance with an incident A Lamb wave.
我们报道了一种涉及短柱扭转共振的新机制，以实现弹性超材料板的负有效剪切模量。结合一种产生负质量密度的机制，我们开发了一种通用方法，用于在两侧带有短柱的弹性超材料板中建立和扩大水平剪切极化双负分支。我们探索了这种结构在偏振滤波、模式转换和异常折射方面的能力。结果表明，这种超材料板对于沿正方形晶格晶体中ΓX方向传播的入射波的偏振表现出不同的特性：对于零阶水平剪切（SH）波，它表现为双负系统，而对于零阶反对称（A）或对称（S）兰姆波，它表现为单负系统。当传播偏离ΓX方向时，可实现模式转换。此外，我们在棱柱形超胞与周围板的界面处观察到了同时出现正折射和负折射的异常折射图案。此外，我们提出了一种手性柱，以有效地将扭转共振与入射A兰姆波耦合。
