A magnet-induced buckled-beam piezoelectric generator for wideband vibration-based energy harvesting

This article presents a magnet-induced buckled-beam piezoelectric generator developed for broadband vibration-based energy harvesting at low frequencies (<60 Hz) and small excitations (\0.5g). The harvester is made of a clamped- clamped piezoelectric beam, with one end movable and subjected to a magnet-induced compressive force. Due to the magnetic force, the beam becomes buckled and bistable. The harvester works as a double-well potential oscillator under excitations, where large-amplitude inter-well oscillation is produced to enhance the energy harvesting functionality. Numerical simulations show that the proposed harvester exhibits strong nonlinearities under harmonic excitations, including snap-through motions, large-amplitude voltage outputs, and broad frequency bandwidth. A prototype harvester is fabricated and experimentally investigated to confirm the findings from numerical simulations. It is observed that for a small base excitation of 0.35g, the harvester can produce a broad frequency bandwidth of 25.0 Hz (24.0-49.0 Hz) to constantly trigger inter-well snap-through motions and to maintain a peak-to-peak voltage of >10 V over a 1.3 MΩ load resistor. For a relatively larger base excitation of 0.5g, such a frequency bandwidth can be further widened to 29.5 Hz.