Electroelastic metasurface with resonant piezoelectric shunts for tunable wavefront control

Abstract

In this paper, we design a tunable phase-modulated metasurface composed of periodically distributed piezoelectric patches with resonant-type shunt circuits. The electroelastic metasurface can control the wavefront of the lowest antisymmetric mode Lamb wave (A0 mode) in a small footprint due to its subwavelength features. The fully coupled electromechanical model is established to study the transmission characteristics of the metasurface unit and validated through numerical and experimental studies. Based on the analysis of the metasurface unit, we first explore the performance of electroelastic metasurface with single-resonant shunts and then extend its capability with multi-resonant shunts. By only tuning the electric loads in the shunt circuits, we utilize the proposed metasurface to accomplish wave deflection and wave focusing of A0 mode Lamb waves at different angles and focal points, respectively. Numerical simulations show that the metasurface with single-resonant shunts can deflect the wavefront of 5 kHz and 6 kHz flexural waves by desired angles with less than 2% deviation. In addition, it can be tuned to achieve nearly three times displacement amplification at the designed focal point for a wide range of angles from −75◦ to 75◦. Furthermore, with multi-resonant shunts, the piezoelectric-based metasurface can accomplish anomalous wave control over flexural waves at different positions. multiple frequencies (i.e., simultaneously at 5 kHz and 10 kHz), developing new potentials toward a broad range of engineering applications such as demultiplexing various frequency components or guiding and focusing them at different positions.

Elastic wave manipulation implemented using a locally resonant metasurface with digitally tunable piezoelectric shunts

“…Waveguiding refers to the intentional manipulation of wave propagation within a medium of interest and has been gaining attention in the field of elastodynamics. Examples of waveguiding phenomena include anomalous and negative refraction [3], wave focusing [4], source illusion [5], and cloaking [16], among others. Here the locally resonant piezoelectric unit cell discussed in Section 2 is patterned into a metasurface boundary and tuned to facilitate the anomalous refraction of incident elastic waves.…”

“…The most widely used approach for waveguide design is the phase-gradient method, relying on the implementation of precise, localized phase-shifts to reconstruct the transmitted wavefield and produce a specified waveguiding behavior [1]. Various designs have been proposed with implementations including anomalous refraction [3], focal lensing [4], source illusion [5], wave-mode conversion [6], and non-reciprocal wave propagation [7], among others.…”

“…Because the structural dynamics of each unit cell primarily depends on the electrical shunt, numerous circuit configurations have been proposed to enable passive, semi-active, and fully active control of elastic waveguiding. The scope of research has broadened considerably in recent years, evolving from established concepts of locally resonant and negative capacitance metasurfaces to include proposals for multibranch circuits [4], non-local coupling [9], digital switching [10], and non-linear circuitry [11]. Lin and Tol explored a multibranch locally resonant metasurface for simultaneous wave focusing at multiple frequencies [4].…”

“…The scope of research has broadened considerably in recent years, evolving from established concepts of locally resonant and negative capacitance metasurfaces to include proposals for multibranch circuits [4], non-local coupling [9], digital switching [10], and non-linear circuitry [11]. Lin and Tol explored a multibranch locally resonant metasurface for simultaneous wave focusing at multiple frequencies [4]. Bao et al proposed a piezoelectric metamaterial with synchronized switching between neighboring unit cells to enhance wave attenuation and modulate incident wavefronts [10].…”

A programmable metasurface based on acoustic black hole for real-time control of flexural waves

“…17 Piezoelectric materials have shown potential as a new method for designing reconfigurable elastic metasurfaces. 18,19 Through realtime sensing and wave manipulation based on piezoelectric metasurfaces, various peculiar control effects of elastic waves have been achieved. 4,20,21 However, the interaction between piezoelectric elements and the design of robustness affects the regulation of elastic waves.…”