Elastic metamaterials with simultaneously negative effective shear modulus and mass density

TL;DR

This paper introduces elastic metamaterials with fluid-solid composites that exhibit negative shear modulus and mass density, enabling unique wave phenomena like negative refraction and mode conversion.

Contribution

It presents a novel elastic metamaterial design with simultaneous negative shear modulus and density, demonstrating unique wave propagation properties.

Findings

Negative dispersion for transverse waves

Negative refraction demonstrated with a wedge sample

Mode conversion from transverse to longitudinal waves

Abstract

We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess negative shear modulus and negative mass density over a large frequency region. Such a solid metamaterial has a unique elastic property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample, and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids.