Abstract
In this article, a magnetomechanical metamaterial structure capable of simultaneous vibration attenuation and energy harvesting is presented. The structure consists of periodically arranged local resonators combining cantilever beams and permanent magnet-coil systems. A prototype of the metamaterial dual-function structure is fabricated, and models are developed. Results show good agreement between model simulation and experiment. Two frequency bandgaps are measured: 205–257 Hz and 587–639 Hz. Within these bandgaps, vibrations are completely attenuated. The level of vibration attenuation in the first bandgap is substantially larger than the level of vibration attenuation observed in the second bandgap. Mode shapes suggest that bending deformations experienced by the local resonators in the second bandgap are less than the deformations experienced in the first bandgap, and most vibrational energy is localized within the first bandgap where the fundamental resonant frequency is located, i.e., 224 Hz. The ability of the fabricated metamaterial structure to harvest electric power in these bandgaps is examined. Results show that vibration attenuation and energy harvesting characteristics of the metamaterial structure are coupled. Stronger vibration attenuation within the first bandgap has led to enhanced energy harvesting capabilities within this bandgap. Power measurements at optimum load resistance of 15 Ω reveal that maximum power generated within the first bandgap reaches 5.2 µW at 245 Hz. Compared with state-of-the-art, the metamaterial structure presented here shows a significant improvement in electric power generation, at considerably lower load resistance, while maintaining the ability to attenuate undesired vibrations within the frequency bandgap.
Highlights
Elastic mechanical metamaterials have shown extraordinary properties including bandgap phenomenon [1,2,3]
When the mechanical metamaterial structure is subject to excitations from external source, the kinetic energy contained in these oscillations is trapped in the local resonators. is results in the unique capability of generating frequency bandgaps within which oscillations are prevented from passing through. e generated bandgaps are formed at frequency matching the fundamental resonant frequency of the local resonators that are acting as local absorbers within the metamaterial structure [2, 10]
Zhu et al built a chiral lattice-based metamaterial beam that is embedded with local resonators to achieve broadband vibration attenuation in the frequency range of, approximately, 210–700 Hz [12]
Summary
Elastic mechanical metamaterials have shown extraordinary properties including bandgap phenomenon [1,2,3]. E fabricated structure recovered approximately 0.5 μW across 200 kΩ at 348 Hz. Power was only measured and reported within the first bandgap, i.e., at 348 Hz. a recent study by Li et al reported a mechanical metamaterial structure for simultaneous vibration isolation and energy harvesting [15]. E current state-of-the-art literature reveals that a growing number of researchers have recently attempted to use elastic mechanical metamaterials for simultaneous vibration attenuation and energy harvesting. Erefore, the work we present in this article is focused on investigating a magnetomechanical-based metamaterial structure for simultaneous vibration attenuation and energy harvesting. Compared with other efforts and available literature, the metamaterial structure we present in this work is shown to generate, significantly, more electric power while maintaining its ability to attenuate undesired vibrations.
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