Experimental Study on Performance Enhancement of a Piezoelectric Vibration Energy Harvester by applying Self-Resonating Behavior

This paper introduces a passive self-tuning energy harvester by applying self-resonating behavior. Under certain operating conditions, self-resonating systems have the capability to passively adjust their dynamical characteristics until the whole system becomes resonant. A clamped-clamped beam with an attached mass sliding freely with a slight gap showed self-resonating behavior. Under a harmonic input excitation and a well-defined operating regime, the mass moved along the beam thus causing a change in the natural frequency of the structure, and then stopped at the position where the natural frequency matched the excitation frequency, resulting in a significant increase in the vibration amplitude. For harvesting energy, a piezoelectric element was glued at one end of the beam. The operating regime of the self-resonating behavior was found experimentally in the two halves of the beam. In the half containing the piezoelectric element, self-resonating behavior was achieved between 126 Hz and 143 Hz. In the other half, it was achieved between 135 Hz and 165 Hz. Maximum power output of 2.5 mW was obtained under an input excitation of 4.92 m/s2 and 148 Hz. It is to be concluded that applying self-resonating behavior on energy harvesting provides a promising broadband technique.