Damped forced bending vibration of a vibration power generation element under base excitation

Abstract

Energy harvesting has been attracting attention as a power source for wireless sensors. It is a technology to obtain electric power from energy sources in the ambience. Vibration energy harvesting is one of the methods using piezoelectric materials. Piezoelectric materials have the ability to mutually convert between mechanical energy and electrical one. Vibration energy harvesting is a highly added value alternative power source that has the ability to reduce environmental impact and costs associated with battery disposal. Power generation characteristics of piezoelectric energy harvester have been treated theoretically. To predict the output power accurately, it is important to create a model suited to actual phenomenon. We have been studying the bending vibration of a vibration power generation element fabricated by forming thin films of lead zirconate titanate, PZT on the surfaces of stainless-steel substrate. So far , the effects of tip mass and inertia on the bending vibration response of the element have been investigated. Since viscous damping is not considered in our present model, especially the vibration response near the resonance point does not reproduce actual phenomenon. Therefore, damped forced bending vibration of a vibration power generation element under base excitation is conducted in this study. The element is modeled as a three-layered cantilever beam consisted of a stainless-steel base and PZT layers. Numerical calculations are conducted based on the exact solution of deflection to investigate the effect of damping on the dynamic response of the beam. On the other hand, excitation experiments of the element are also conducted to measure the time response of the deflection. Vibration in the form of sinusoidal time variation is applied to the element by a shaker. Analytical results and experimental ones of deflection are compared to evaluate the change in the deflection amplification factor with frequency of the element under base excitation.