Nonlinear dynamic response of an L-shaped beam-mass piezoelectric energy harvester

Piezoelectric energy harvesters (PEHs) have been taken considerable attention in decades. To evaluate the performance of the harvester in large deformation and high electric field conditions, nonlinear effects (geometric, material and damping nonlinearities) should be involved in analyzing the characteristic of the harvesters. In this article, the unimorph Lshaped harvester is investigated and influence of the geometric and material nonlinearities to the responses of the proposed L-shaped harvester is also studied. Based on extended Hamilton principle and Gauss law, the distributed parameter model of the L-shaped harvester is established and validated with experiments. Moreover, influence of some key parameters such as excitation amplitude a(bx) and nonlinear material coefficients alpha(1)-alpha(4) to the dynamic responses and voltage outputs of the L-shaped harvester are also analyzed. Besides, four different harvesters, which contain linearity only, geometric nonlinearity only, material nonlinearity only and both geometric and material nonlinearities, are investigated to embody the difference and importance of the two nonlinearities (geometric and material nonlinearities). Results show that as the excitation amplitude a bx increases, effect of geometric nonlinearity becomes more obvious and leads to the softening phenomenon, and part of nonlinear material coefficients have greater influence to the peak value of the dynamic responses and the nonlinear phenomena (softening or multiple-frequency). Thus, consideration of nonlinear effects (geometric and material nonlinearities) can improve the prediction accuracy of the performance of the harvester which will be helpful for design and application of the harvester in large amplitude excitation and high electric field conditions. (C) 2021 Elsevier Ltd. All rights reserved.