Experimental study of the variations in the electromechanical properties of piezoelectric energy harvesters and their impact on the frequency response function

Abstract

This work presents a comprehensive study of the uncertainties involved in the FrequencyResponse Function (FRF) of Piezoelectric Energy Harvesters (PEHs) based on experimentalresults. A proper experimental setup is designed facilitating the FRF identification for dif-ferent PEHs. The test protocol consists in three test that quantify the aleatoric and epis-temic uncertainties by the study of repeated measurements, variation in the mountingprocess, and variations in the electromechanical properties of the materials employed inthe harvester. The experimental setup and the test protocol are tested employing two dif-ferent bimorph-type harvesters identified as Model A and B. 20 harvesters correspondingto Model A and 10 to Model B are tested multiples times under the test protocol proposed.Results clearly indicate that the most important source of uncertainties deals with the vari-ability of the electromechanical properties of the PEH, which is particularly greater than: (i)the noise on the measurements, (ii) the variations introduced by the clamping condition,and (iii) the dimensional variations in the geometry. The results are also compared withpredictions performed by adopting a recent numerical framework to propagate uncertain-ties in PEHs. The present work is particularly important since it presents the experimentalevidence of the variations in the electromechanical properties of PEH and their influence onthe FRF. Additionally, the results not only validate the uncertainty propagation procedurespreviously proposed but also suggest that their use is mandatory to estimate the FRF. Thiswork presents, to the best of the authors’ knowledge, the first effort to experimentallyquantify the uncertainties in PEHs.