Vibration energy scavenging via piezoelectric bimorphs of optimized shapes

Abstract

Compact autonomous power sources are one of the prerequisites for the development of wireless sensor networks. In this work vibration energy harvesting via piezoelectric resonant bimorph beams is studied. The available analytical approaches for the modeling of the coupled electromechanical behavior are critically evaluated and compared with a finite element (FEM) numerical model. The latter is applied to analyze thoroughly the stress and strain states, as well as to evaluate the resulting voltage and charge distributions in the piezoelectric layers. The aim of increasing the specific power generated per unit of scavenger volume is pursued by optimizing the shape of the scavengers. Two optimized trapezoidal configurations are hence identified and analyzed. An experimental set-up for the validation of the proposed numerical model and of the obtained optimized structures is developed. Results of a preliminary experimental assessment, confirming the improved performances of optimized scavengers, are finally given

Bimorph piezoelectric vibration energy harvester with flexible 3D meshed-core structure for low frequency vibration

“…Therefore, the approach for making the elastic layer flexible is effective for the bimorph-type PVEHs. Moreover, as reported in previous studies [19–21], the output power can be further improved by optimizing the shape and size and the resonance frequency can be further decreased by adjusting the weight of the proof mass.…”

“…meandered or spiral structure [9,16])’ for reducing the resonance frequency, and 2D shapes (e.g. trapezoid, triangle [20,21]) for improving power generation. (3) The design and the fabrication process to make a complex 3D mesh structure are relatively simple when using 3D inclined exposure.…”

“…Although PVDF has an inferior piezoelectric constant compared to ceramics’ inorganic piezoelectric materials such as PZT and barium titanate [21,23], it enables large deformation and exhibits excellent flexibility [24]. Since the materials used in the proposed PVEH, except for the electrodes, are made of polymer materials, the proposed bimorph cantilever is flexible.…”

“…Hence, the amount of strain in the piezoelectric layers increases under certain deflection, and consequently, the amount of generated power increases as compared to the unimorph type. In addition, several methods have been reported for increasing the output power by optimizing the cantilever shape and thickness of each layer have been reported [19–21]. Hence, the bimorph configuration is effective in improving the amount of output power.…”

Comparative Analysis of One-Dimensional and Two-Dimensional Cantilever Piezoelectric Energy Harvesters

“…These resonant motions result in maximum deflection of the structure, straining the piezoelectric material and producing electrical charge, which can be channeled as an alternating current across an electrical load resistance. Different strategies and techniques have been applied to design efficient, low-frequency, piezoelectric energy harvesters, such as considering different shape geometries (Abdelkefi et al 2011;Apo et al 2014;Ben Ayed et al 2014;Benasciutti et al 2010;Berdy et al 2012;Inman 2011, 2012a), developing bistable configurations (Daqaq 2011;Mann and Sims 2009), and including magnetic coupling (Abdelkefi and Barsallo 2014;Tang and Yang 2012). As for shape geometries, simple and complex systems have been proposed in order to design energy harvesters that can operate effectively at an excitation frequency that matches their resonant frequency.…”