Analytical coupled modeling of a magneto-based acoustic metamaterial harvester

Abstract

Membrane-type acoustic metamaterials (MAMs) have demonstrated unusual capacity in controlling low-frequency sound transmission, reflection, and absorption. In this paper, an analytical vibroacoustic-electromagnetic coupling model is developed to study MAM harvester sound absorption, energy conversion, and energy harvesting behavior under a normal sound incidence. The MAM harvester is composed of a prestressed membrane with an attached rigid mass, a magnet coil, and a permanent magnet coin. To accurately capture finite-dimension rigid mass effects on the membrane deformation under the variable magnet force, a theoretical model based on the deviating acoustic surface Green's function approach is developed by considering the acoustic near field and distributed effective shear force along the interfacial boundary between the mass and the membrane. The accuracy and capability of the theoretical model is verified through comparison with the finite element method. In particular, sound absorption, acoustic-electric energy conversion, and harvesting coefficient are quantitatively investigated by varying the weight and size of the attached mass, prestress and thickness of the membrane. It is found that the highest achievable conversion and harvesting coefficients can reach up to 48%, and 36%, respectively. The developed model can serve as an efficient tool for designing MAM harvesters.

A metamaterial structure capable of wave attenuation and concurrent energy harvesting

“…A metamaterial composed of an array of multi-functional resonators is shown to convert stored kinetic energy into electric energy by employing spring-load magnets and copper coils (Mikoshiba et al, 2012). The concept of magneto-based energy harvester has also been applied to acoustic metastructures (Nguyen et al, 2018). Besides using magnet-coil systems, the transformation of vibrations into electricity can be achieved by employing piezoelectric materials.…”

A Fano-based acoustic metamaterial for ultra-broadband sound barriers

“…The effective channel behaves as a linear resonator supporting both monopolar and dipolar local resonances [8,34]; however, the ventilation channels only support resonances at higher frequencies and the acoustic pressure is linear in terms of phase change at lower frequencies. The transmission is the radiation from channels to the downstream, while the reflection is the combination of the radiation from the channels to the upstream and the reflection by the external hard wall of the coupling unit [29,38] as ptfalse(x,yfalse)=pd1emand1emprfalse(x,yfalse)=Pi eikx+pu, where p u and p d are the radiation fields in the upstream and downstream, respectively. They are related to the velocities at the inlet ( x = 0) and outlet ( x = L ) of the channels via Green’s functions [13], right left right left right left right left right left right left3pt0.278em 2em 0.278em 2em 0.278em 2em 0.278em 2em 0.278em 2em 0.278empu(x,y)=−iρ0c0kve1∫−b/2b/2Gufalse(x,y|0,y0false) dy0−2iρ0c0kvv1∫a/2−d/2a...…”

“…G u ( x , y |0, y 0 ) and G d ( x , y | L , y 0 ) are the Green’s functions of the upstream ( x < 0) and downstream ( x > L ). They can be presented in terms of the mode shape functions of the waveguide [38,39], Gufalse(x,y|0,y0false)=1ika{eikx+i∑n=1∞φnfalse(yfalse)φnfalse(y0false)αn⟨φn2(y)⟩ eαnx} and Gdfalse(x,y|L,y0false)=1ika{e−ik(x−L)+i∑n=1∞φnfalse(yfalse)φnfalse(y0false)αn⟨φn2(y)⟩ …”

Enhancement of energy harvesting using acoustical-black-hole-inspired wave traps

“…The targeted applications concern structural stability, acoustic attenuation, health monitoring, and energy harvesting [2] to ensure the robustness and autonomy of active subsystems. Recent studies have shown the potential of sound energy harvesting using acoustic metastructures [3][4][5].…”