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

Abstract

Abstract This work presents a comprehensive study of the uncertainties involved in the Frequency Response Function (FRF) of Piezoelectric Energy Harvesters (PEHs) based on experimental results. A proper experimental setup is designed facilitating the FRF identification for different PEHs. The test protocol consists in three test that quantify the aleatoric and epistemic uncertainties by the study of repeated measurements, variation in the mounting process, and variations in the electromechanical properties of the materials employed in the harvester. The experimental setup and the test protocol are tested employing two different bimorph-type harvesters identified as Model A and B. 20 harvesters corresponding to 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 variability 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 with predictions performed by adopting a recent numerical framework to propagate uncertainties in PEHs. The present work is particularly important since it presents the experimental evidence of the variations in the electromechanical properties of PEH and their influence on the FRF. Additionally, the results not only validate the uncertainty propagation procedures previously proposed but also suggest that their use is mandatory to estimate the FRF. This work presents, to the best of the authors’ knowledge, the first effort to experimentally quantify the uncertainties in PEHs.