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 electromechanical 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 vibrations and an internal sound field into the cylindrical enclosure. Therefore, the electricity generation characteristics should be considered as an electromechanical-acoustic coupling problem. The characteristics are estimated theoretically and experimentally from the electric power in the electricity generation, the mechanical power supplied to the plate, and the electricity generation efficiency that is derived from the ratio of both power. In particular, the electricity generation efficiency is one of the most appropriate factors to evaluate a performance of electricity generation systems. Thus, the effect of mechanical-acoustic coupling is principally evaluated by examining the electricity generation efficiency.
Highlights
To deal with depletion of fossil fuels and to materialize a low-carbon society, the improvement of energy saving technologies and the creation of new energy sources has been attempted in a lot of studies
The flexural stiffness of a beam structure is considerably intensified in comparison with that of a piezoelectric element, so that most of the strain energy is stored in the beam structure
To further improve the conversion efficiency, mechanical impedance matching method, which was derived from using spacers between the piezoelectric element and beam structure and tuning for the size of the piezoelectric element, was proposed [2]
Summary
To deal with depletion of fossil fuels and to materialize a low-carbon society, the improvement of energy saving technologies and the creation of new energy sources has been attempted in a lot of studies. To further improve the conversion efficiency, mechanical impedance matching method, which was derived from using spacers between the piezoelectric element and beam structure and tuning for the size of the piezoelectric element, was proposed [2]. These structural vibrations are caused by vibrators and various power sources. A self-sustained oscillation caused by placing a plate into a flow whose critical velocity was overpassed (socalled fluttering) is a well-known phenomenon To utilize such a fluttering phenomenon for energy-harvesting, the plate on which the piezoelectric elements were arranged was used, and the effect of their arrangement along the flow axis was considered. An optimization of the arrangement was performed among some positions and dimensions of piezoelectric elements [3]
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