Harvesting Energy From the Nonlinear Oscillations of a Bistable Piezoelectric Inertial Energy Generator

Piezoelectric materials constitute an efficient transduction medium for passive power generation from ambient vibrations. As such, the unimorph and bimorph piezoelectric laminate linear beam is a prolifically researched energy harvesting device. The linear modeling framework is amenable to analytical solutions and frequency matching inertial energy generators to environmental oscillations is a seemingly ideal solution. Realistically, however, environmental disturbances are rarely of one particular frequency and linear oscillators are capable of strong responses only within a limited frequency range about system resonance. In view of these shortcomings, this paper builds upon a new research direction and shift in design philosophy toward purposefully incorporating nonlinearity into energy harvesting systems. In particular, the nonlinear magnetic forces of repulsion are introduced at the free end of a cantilevered bimorph piezoelectric beam, where the separation distance between two opposing permanent magnets doubles as a controllable bifurcation parameter. The numerical results demonstrate the efficacy of the nonlinear responses to yield markedly increased power levels when subject to deterministic excitations of varying forcing frequency and amplitude.