Elastic metamaterials for independent realization of negativity in density and stiffness

TL;DR

This paper introduces an elastic metamaterial that independently controls negative density and stiffness, enabling advanced manipulation of elastic waves, achieved through innovative design supported by theoretical, numerical, and experimental validation.

Contribution

The paper presents the first realization of an elastic metamaterial with independent tunability of negative density and stiffness, overcoming tensorial coupling challenges.

Findings

Successful independent tuning of negative density and stiffness.

Validated through numerical simulations and experimental tests.

Potential applications in elastic wave control and metamaterial design.

Abstract

In this paper, we present the realization of an elastic metamaterial allowing independent tuning of negative density and stiffness for elastic waves propagating along a designated direction. In electromagnetic (or acoustic) metamaterials, it is now possible to tune permittivity (bulk modulus) and permeability (density) independently. Apparently, the tuning methods seem to be directly applicable for elastic case, but no realization has yet been made due to the unique tensorial physics of elasticity that makes wave motions coupled in a peculiar way. To realize independent tunability, we developed a single-phased elastic metamaterial supported by theoretical analysis and numerical/experimental validations.