Perforated auxetic honeycomb booster with reentrant chirality: A new design for high-efficiency piezoelectric energy harvesting

The present study develops an auxetic meta-structure booster to advance piezoelectric energy harvesting (PEH). The model comprised a three-dimensional (3D) cantilever beam equipped with an auxetic substrate bonded to a piezoelectric (PZT) point defect using an epoxy layer. The substrate used in this proposed energy harvester possesses an auxetic region responsible for generating auxetic behavior and concentrating stress in the PZT layer. The auxetic model called auxetic structure (AS)-II is inspired by ancient motifs and is designed based on the combination of several promising mechanisms, including reentrant, chiral, perforation, and honeycomb supercell. The finite element method is employed to create numerical models whose accuracy is confirmed by mesh convergence and available experimental data. A parametric study is conducted on the AS-II harvester to examine the influence of geometry and PZT material type on the harvested electrical power. Our research efforts stem from both mechanical and electrical circuit fields to fulfill the broadband design target within the desired ultra-low-frequency range of 1–20 Hz, regardless of the resonance condition. As a result, the impact of other factors, such as load resistance, frequency, load amplitude, and bonding stiffness, on the PEH performance is further investigated. The reason behind such outstanding performance of AS-II is explained in terms of geometrical physics and stress distribution. The effect of geometrical dimensions on the auxetic behavior is also analyzed using Poisson's ratio (PR) study. Subsequently, we demonstrate that this innovative adapter can advance the system's performance in terms of harvested power and lightweight by a magnification factor of 14.61 and 5.8 times that of a plain substrate and 2.25 and 3.16 times that of a conventional auxetic harvester, respectively. The present harvester is strain controllable, where it can set PR between −2 and 0, resulting in robust PEH even if switching input vibration from high to low levels. This new idea enables us to serve cantilever-type resonators at frequencies far lower than their resonant frequencies with small portions of incident excitement.