Vibro-impact energy harvester for low frequency vibration enhanced by acoustic black hole

In this Letter, we propose an enhanced vibro-impact energy harvester using acoustic black holes (ABHs) for scavenging low-frequency vibration energy. The energy harvester involves two beams: a relatively rigid piezoelectric generating beam with ABH profile and a flexible driving beam with a tip mass mounted at the end. The tip mass and the generating beam collide repeatedly under low-frequency excitations. Experimental studies are conducted to investigate the output performance of the energy harvester by comparing the output power and voltage of generating beams with different tailored ends. Finite element analysis is also carried out to evaluate the influence of electrode number of the piezoelectric sheet attached to the ABH beam on the output performance of the energy harvester. It is shown that the impacts between the tip mass and generating beam are capable of transferring vibration energy from the low-frequency band to high-frequency band, where ABH gets a desirable energy focalization effect to improve the output performance of the energy harvester. The energy harvester achieves the best output performance when its electrode is divided into two parts with the excellent power of 0.7 mW at the low frequency range from 5 to 13 Hz.