A flextensional piezo-composite structure for energy harvesting applications

Abstract

A piezoelectric energy harvester (PEH) consisting of two cymbal electromechanical transducers and a cantilever beam structure designed and manufactured. The PEH under test is a novel design that aims to keep the transducers permanently under compression forces. Keeping the transducers under compression forces increases the life-time of the piezoelectric ceramics. A parametric study was performed in order to select design variables such as beam length and tip mass subject to constraint that the resonance frequency of the system would not exceed 200Hz. A mathematical model representing the PEH was derived, a finite element (FE) model was built and a parametric study was performed for the optimization of the PEH. The derived mathematical model and the FE model were validated experimentally by the manufactured PEH. DC voltage and power obtained from the PEH were evaluated experimentally for low acceleration levels of 2g (1g=10m/s2). The effect of stacking the piezoelectric disks on energy harvesting performance was also evaluated experimentally. The two type of transducers used are cymbals with single layer (C-PZT1) and two-layer-stacked (C-PZT2) PZT 5H (lead zirconate titanate) disks. Under sinusoidal vibrations of 2g acceleration amplitude, the structure with C-PZT2 transducers (B-PZT2) was able to generate 141.61μW of power at 153Hz across a resistive load (RL) of 40kΩ while the one with C-PZT1 transducers (B-PZT1) generated 104.04μW of power at 166Hz across an RL of 80kΩ.