Energy harvesting of beam vibration based on piezoelectric stacks

Abstract

Piezoelectric stacks demonstrate excellent properties for energy harvesting owing to the high energy conversion efficiency and long lifetime. However, force amplification frames are commonly required to amplify the load applied to piezoelectric stacks. This paper proposes an energy harvester based on piezoelectric stacks without force amplification frames. The piezoelectric stacks are composed of annular piezoelectric sheets separated into several conductive sectors on the surface and mounted on a beam through a threaded sleeve and a nut. Experiments and simulations are carried out to evaluate the output performance of the energy harvester when the beam vibrates in transverse direction. The effects of excitation frequency, sector number, preload level, mounting position and piezoelectric sheet number on the output voltage are evaluated. Results from experiments and simulations show that the energy harvester gets the highest output gain as the excitation frequency reaches the resonant frequency of beam. When the piezoelectric sheets are divided into two insulated semi-circular regions, the best output performance can be obtained under the same loading conditions. Increasing the preload level is also beneficial for achieving high output voltage. However, this effect gets insignificant when the preload reaches to a certain value. The output gain of the energy harvester increases with the number of piezoelectric sheets. The output voltage is higher when the energy harvester is mounted at the beam center than that mounted at the beam ends.