A Phononic Crystal with Differently Configured Double Defects for Broadband Elastic Wave Energy Localization and Harvesting

Abstract

Several previous studies have been dedicated to incorporating double defect modes of a phononic crystal (PnC) into piezoelectric energy harvesting (PEH) systems to broaden the bandwidth. However, these prior studies are limited to examining an identical configuration of the double defects. Therefore, this paper aims to propose a new design concept for PnCs that examines differently configured double defects for broadband elastic wave energy localization and harvesting. For example, a square-pillar-type unit cell is considered and a defect is considered to be a structure where one piezoelectric patch is bonded to a host square lattice in the absence of a pillar. When the double defects introduced in a PnC are sufficiently distant from each other to implement decoupling behaviors, each defect oscillates like a single independent defect. Here, by differentiating the geometric dimensions of two piezoelectric patches, the defects’ dissimilar equivalent inertia and stiffness contribute to individually manipulating defect bands that correspond to each defect. Hence, with adequately designed piezoelectric patches that consider both the piezoelectric effects on shift patterns of defect bands and the characteristics for the output electric power obtained from a single-defect case, we can successfully localize and harvest the elastic wave energy transferred in broadband frequencies.

Elastic wave harvesting in piezoelectric-defect-introduced phononic crystal microplates

“…For ambient vibrational energies in low-frequency ranges [20,21], defective local-resonance type PnCs (often referred to as metamaterials) seem to be more suitable relative to Bragg type [22]. Single defects have a narrow operating bandwidth, while multiple defects (e.g., decoupled double defects [23,24], coupled double defects [25] and L-shape defects [26]) can broaden the energy harvesting bandwidth. Multiplefield techniques (e.g., thermal tuning [27,28], electrical tuning [29] and magnetic tuning [30]) allow efficient dynamic adjustment of the energy harvesting operating frequency for adaptation to random environmental frequencies.…”

L-shape triple defects in a phononic crystal for broadband piezoelectric energy harvesting

“…The weakened interaction between the double defects makes them appear independent. One peak frequency corresponding to each defect is independently manipulated at this point by varying the geometric dimensions of piezoelectric devices attached to each defect [ 42 ] or unit cells surrounding each defect [ 43 ]. Therefore, closely placing the defect band of each isolated defect successfully doubles the bandwidth of a PEH system as shown in Fig.…”

Designing a phononic crystal with a large defect to enhance elastic wave energy localization and harvesting

“…Deng et al 30) showed that a magnetoelastic PnC with a point defect could tune its resonance frequency to achieve variablefrequency energy harvesting. Jo et al [31][32][33][34] investigated the influence of the circuit connection between two defects, the supercell size and defect location, and dual-defect decoupling on energy localization. Lee et al 35) investigated the high output performance of a PnC-assisted PEH device by tuning the geometric parameters of the device.…”