Nonlinear characteristic of a circular composite plate energy harvester: experiments and simulations

A piezoelectric energy harvester is investigated with the focus on its nonlinear behavior. The harvester consists of a circular composite plate with the clamped boundary, a proof mass and two steel rings. A reduced-order model of the harvester is established, and the parameters are identified from the experimental data. A technique is proposed to identify electrical parameters with the outcomes agreeing with the theoretical values, and a fifth-order polynomial is employed to approximate the nonlinear restoring force. Both the experimental and the numerical results demonstrate that the harvester changes its characteristic from linearity to a softening nonlinearity and finally to a combined softening and hardening nonlinearity as the excitation increases from low to high.