Role of the structural nonlinearity in enhancing the performance of a vibration energy harvester based on the electrets materials

Films of electret material are currently used to cover the surface of electrodes of some vibration capacitive harvesters based on deformable beams, clamped at both ends. Nevertheless, performance of this device is often predicted through some simplified electromechanical model, which neglects the effect of geometric nonlinearity due to a mechanical coupling between the axial and flexural behaviors of the clamped beam. Stiffening of beam and nonlinear behavior are herein investigated, by resorting to a distributed model of electromechanical coupling of the vibration harvester, based on the finite element method. Influence upon the performance of energy conversion is then analyzed and an optimization of the configuration is proposed to assess some suitable design criteria.