Design of tunable acoustic metamaterials with periodic piezoelectric microstructure

TL;DR

This paper presents a novel design for tunable acoustic metamaterials using periodic piezoelectric microstructures, enabling real-time control of wave propagation and filter properties through electrical circuit tuning.

Contribution

It introduces a new class of tunable metamaterials with adjustable acoustic properties via shunted piezoelectric elements, expanding capabilities beyond classical materials.

Findings

Effective control of pass and stop bands demonstrated.

Tunable properties achieved by adjusting electrical circuit impedance.

Potential for real-time adaptive acoustic filtering shown.

Abstract

An innovative special class of tunable periodic metamaterials is designed, suitable for realising high-performance acoustic filters. The metamaterial is made up of a phononic crystal coupled to local resonators. Such local resonators consist of masses enclosed into piezoelectric rings, shunted by either dissipative or non-dissipative electrical circuit. By tuning the impedance/admittance of such electrical circuits, it is possible to fully adjust the constitutive properties of the shunting piezoelectric material. This feature paves the way for unconventional behaviours, well beyond the capabilities achievable with classical materials. It follows that the acoustic properties of the periodic metamaterial can be adaptively modified, in turn, opening new possibilities for the control of pass and stop bands. By exploiting a generalization of the Floquet-Bloch theory, the in-plane free wave propagation in the tunable metamaterial is investigated, by varying a certain tuning parameter, to show the efficiency of the proposed shunting piezoelectric system as a wave propagation control device. Particular attention is devoted to the determination of the in-plane constitutive equations of the shunting piezoelectric phase in the transformed Laplace space. Finally, broad design directions of tunable acoustic filters aiming to a changing performance requirement in real-time, is also provided.