STUDY ON THE BANDGAPS OF DEFECT STATES AND APPLICATION OF ENERGY HARVESTING OF LOCAL RESONANT PHONONIC CRYSTAL PLATE

A local resonant phononic crystal plate, which is composed by quadrangular epoxy resin matrix embedded with cylindrical scatterers, is proposed to study the vibration energy harvesting performance. The bandgaps and energy concentration characteristics for the defect state structure are analyzed in detail. Firstly, the bandgap curve and energy transmission characteristics are analyzed for perfect and point defect phononic plate with 5 \times 5 array structure based on supercell theory and finite element method. Considering the energy concentration characteristics of the point defect local resonance phononic crystal structure, piezoelectric material is used to replace the scatterer material of defect point, and the vibration energy characteristics are then analyzed. The results show that it has narrow resonance frequency band for the 5 \times 5 point defect supercell structure. In order to improve the energy capture efficiency, two kind of new phononic crystal plate composed of three 5 \times 5 supercells with different defect numbers and layout are proposed as the vibration energy harvester. According to the results of the electromechanical coupling analysis, it shows that the proposed local resonant phononic crystal plate overcomes the disadvantages of the single point defect supercell structure, such as too few defect modes and too narrow resonance frequency band. The working frequency band of the energy harvester is widened and the output voltage is increased. Additionally, it can further broaden the energy harvesting bandwidth and achieve better efficiency by introducing different number and configuration of defect states.