Large Strokes of a Piezocomposite Energy Harvester with Interdigitated Electrodes Accounting for Geometric and Material Nonlinearities

Piezocomposite materials are characterized by high flexibility and large displacements when used for energy harvesting applications. However, for beam-based designs, geometric and material nonlinearities are often neglected because of their complexity. Within this context an analytically model of the system is proposed including the geometric nonlinearities and relatively large electric fields. The proposed device is composed of unimorph cantilever beam used as energy harvester. A metallic layer is used as substrate for an AFC piezocomposite patch. The beam is excited transversely using a harmonic displacement at the clamped side. The Hamilton principle is applied to obtain the mathematical model of the proposed device. Galerkin procedure is used for space discretization and limit-cycle solutions are calculated using a continuation technique based on the finite difference approach. The simulated frequency-response of the harvested voltage across a purely resistive load shows a softening behavior. A hardening behavior is also observed if the material nonlinearity are taken into account. The results are compared and validated with a finite element model developed using ANSYS and accounting for large displacements. The influence of the number of electrode and the dimensions of the device are also analyzed and compared with previously published linear simulations.