Abstract
Conventional energy harvester typically consists of a piezoelectric element, which is sandwiched between a proof mass and a base subjected to sinusoidal excitation. The resulting relative motion between the proof mass and the base produces a mechanical strain in the piezoelectric element, which is converted into electrical power by virtue of the direct piezoelectric effect. In this study, harvester is provided with a dynamic magnifier consisting of a spring-mass system which is placed between the piezoelectric element and the moving base. The main function of the dynamic magnifier, as the name implies, is to magnify the strain experienced by the piezo-element in order to amplify the electrical power output of the harvester. With proper selection of the design parameters of the magnifier, the harvested power can be dramatically enhanced and the effective bandwidth of the harvester can be improved. The theory governing the operation of this class of energy harvesters with dynamic magnifier (EHDM) is developed using the Lagrangian dynamics approach. Numerical examples are presented to illustrate the performance characteristics of the EHDM in comparison with the conventional energy harvesters. The obtained results demonstrate the feasibility of the EHDM as a simple and effective means for enhancing the magnitude and spectral characteristics of conventional harvesters.