Complete mode conversion for elastic waves reflected by elastic metamaterial slab with double hexapole resonances

TL;DR

This paper demonstrates a metamaterial slab with coupled hexapole resonances that achieves complete elastic wave mode conversion between longitudinal and transverse waves over a broad frequency range.

Contribution

It introduces a novel elastic metamaterial design with double hexapole resonances enabling efficient and broadband mode conversion of elastic waves.

Findings

Achieves complete mode conversion between longitudinal and transverse elastic waves.

Broadens the frequency range for elastic wave mode conversion.

Uses coupled hexapole resonances in a novel metamaterial structure.

Abstract

In this study, we investigate the phenomenon of mode conversion in elastic bulk waves using coupled hexapole resonances. A metamaterial slab is proposed enabling the complete conversion between longitudinal and transverse modes. Each unit of the elastic metamaterial slab comprises a pair of scatterers, and their relative direction is oriented at an oblique angle. The interaction between the coupled hexapoles and the background results in oblique displacements, which are responsible for the mode conversion. Moreover, this conversion exhibits a broader frequency range compared to the quadrupole resonance. This innovative design significantly broadens the range of possibilities for developing mode-converting metamaterials.