Abstract

This paper describes the electricity generation characteristics of a new energy-harvesting system with piezoelectric elements.
The proposed system is composed of a rigid cylinder and thin plates at both ends. The piezoelectric elements are installed at the centers of both plates, and one side of each plate is subjected to a harmonic point force. In this system, vibration energy is converted into electrical energy via electro-mechanical coupling between the plate vibration and piezoelectric effect. In addition, the plate vibration excited by the point force induces a self-sustained vibration at the other plate via mechanical-acoustic coupling between the plate vibration and an internal sound field into the cylindrical enclosure. Therefore, the electricity generation characteristics should be considered as an electro- mechanical-acoustic coupling problem. Actually, the plate on the excitation side is lower than that on the non-excitation side in the natural frequency because of the influence of a vibrator to apply the point force to the plate, so that both natural frequencies are not identical and the effect of mechanical-acoustic coupling is not clarified very well. Then both frequencies are close by tuning the natural frequency due to thinning the plate on the non-excitation side. As a result, it is expected that the electricity generation characteristics are improved by promoting mechanical-acoustic coupling in comparison with the inherent situation.