Abstract
The polarization anomaly refers to the polarization transition from longitudinal to shear modes along an equi-frequency contour of the same branch, which occurs only in some anisotropic elastic media, but the lack of natural materials exhibiting desired anisotropy makes its utilization impossible for potential novel applications. In this paper, we present a unique, non-resonant type elastic metamaterial made of off-centered, double-slit unit cells. We show that its wave polarization characteristics that determine the desired anomalous polarization for a certain application are tailorable. As an application, a mode converting wedge that transforms pure longitudinal into pure shear modes is designed by the proposed metamaterial. The physics involved in the mode conversion is investigated by simulations and experiments.
Highlights
Polarization is an important wave characteristic of vector waves like electromagnetic and elastic waves
Anisotropic material property; it requires smaller normal stiffness than shear stiffness for specific material axes while normal stiffness should be larger than shear stiffness for other material axes[5,6,7]
We first propose an elastic metamaterial the rectangular unit cell of which consists of off-centered double slits
Summary
Hyung Jin Lee[1], Je-Ryung Lee[2], Seung Hwan Moon[2], Tae-Jin Je2, Eun-chae Jeon[2], Kiyean Kim3 & Yoon Young Kim[4]. The polarization anomaly refers to the polarization transition from longitudinal to shear modes along an equi-frequency contour of the same branch, which occurs only in some anisotropic elastic media, but the lack of natural materials exhibiting desired anisotropy makes its utilization impossible for potential novel applications. Unlike two orthogonal transverse modes in electromagnetics, the dissimilar, longitudinal and shear, modes in elasticity involve far different physical behaviors Such behaviors are dilatation (volume change) and dilatation-less (shape change) deformations where their relative properties are restrictively tailorable. Some simulations were implemented to show how the slit dimensions affect the effective characteristics of the metamaterial and experiments with the metamaterial-based mode-converting wedge were performed to verify the realization of polarization anomaly for the desired wave manipulation
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