Insights on the performance and dynamical characteristics of piezoelectric energy harvesters with dissipative viscoelastic impacts

The effectiveness and dynamical characteristics of a cantilevered-piezoelectric energy harvester with a tip mass is investigated. The harvester is connected to an electrical load resistance and is subjected to harmonic excitations. A one-sided stopper with a nonlinear viscoelastic contact force model is used to represent the vibro-impact dynamics during collision. The coefficient of restitution is considered in order to model the energy dissipation in the form of viscoelastic effects. Two different discretization techniques, which are the long-time integration and finite difference methods, are employed in order to estimate the dynamical responses of the system and its levels of harvested power. The mathematical model is first verified with existing experimental data in the literature. The nonlinear collision stiffness was parameterized from soft to rigid, in order to investigate its effects on the maximum output power and bandwidth frequency. The influences of the base acceleration and restitution coefficient on the vibro-impact dynamics of the energy harvesting system are investigated. The results indicate the presence of period doubling, chaotic, and multi-stable responses with higher base acceleration values. The coefficient of restitution is varied from perfectly elastic to inelastic impacts to model the collision events as well as energy dissipation. It is demonstrated that the restitution coefficient affects the dynamics of the harvester and its levels of generated voltage. In fact, lower peaks of the harvested power and smaller regions of the resonant frequency are observed at low values of the coefficient of restitution. The results indicate the strong dependence of the energy harvester’s performance and its dynamics on the stiffness and restitution coefficient of the impact force as well as the level of input force to the system.