Study on SH wave propagation in the elastic metamaterial layer

Abstract

Elastic metamaterial (EM) is a new type of structured material mainly built with repeatedly arranged sub-wavelength unit cells. EMs have shown many surprisingly new dynamic properties and provided us with a new idea for elastic wave/vibration control. Although a large amount of work has been conducted by researchers, wave behaviors in some important waveguides constructed with EM remain for further investigation. In this work, SH (shearing horizontal) wave propagating in the EM layer is studied. The effects of the abnormal properties of effective medium parameters (EMPs) on the SH wave dispersion features are discussed by comparison with a classical elastic layer. Our study shows that the behavior of EMPs can significantly influence the dispersion properties of SH wave propagation within the EM layer. Moreover, no SH surface wave mode could be supported near the stress-free surface of the EM layer, and the SH wave traveling in the EM layer must be composed of bulk wave components, and hence it will be blocked completely in those EM layers with imaginary effective transverse wave velocity which can be realized by single negative effective density or shear modulus. This work may serve as a theoretical reference for relevant metamaterial-based elastic wave/vibration control.