This chapter presents the development of an acoustic energy harvester using the sonic crystal and the piezoelectric material. A point defect is created by removing a rod from a perfect sonic crystal. The point defect in the sonic crystal acts as a resonant cavity; thus, the acoustic waves at resonant frequency can be localized within the cavity of the sonic crystal. The piezoelectric material is put into the cavity to convert the ambient mechanical energy into electrical energy. The power generation from acoustic energy is based on the effect of the wave localization in the cavity and the direct piezoelectric effect of the piezoelectric material. The plane wave expansion method is employed to calculate the resonant frequency of the sonic crystal, and the finite element method is adopted to obtain the pressure and particle velocity field of the defect mode at the resonant frequency in the sonic crystal. A model for energy harvesting of the piezoelectric curved beam is also developed to predict the output voltage and power of the harvester. The larger voltage output of the piezoelectric material is associated with the larger pressure in the cavity of the sonic crystal. Two kinds of piezoelectric PVDF films (LDT4-028k and LDT2-028k) are placed inside the cavity of the sonic crystal and attached on rods. When the frequency of the incident acoustic wave is at 4.2/4.21kHz, a maximum power is generated under a load resistance 3.9/15kΩ for LDT4-028k/LDT2-028k PVDF film, respectively. Piezoelectric materials with higher electromechanical coupling should be selected to improve the output power. In addition, the piezoelectric beam can be designed to have the same resonant frequency with the cavity. By using properties of band gaps and wave localizations of the sonic crystal, the noise control and energy harvesting can be achieved simultaneously.
|Title of host publication||Advances in Energy Harvesting Methods|
|Publisher||Springer New York|
|Number of pages||25|
|ISBN (Print)||1461457041, 9781461457046|
|Publication status||Published - 2013 Sep 1|
All Science Journal Classification (ASJC) codes