Thermally-induced transitions of multi-frequency defect wave localization and energy harvesting of phononic crystal plate

Abstract

Defect mode of phononic crystals has presented superiority in vibration energy harvesting with its ability in wave localization. For defect-based harvesters, harvesting performance is directly determined by the wave manipulation behavior of the defect structure which is affected by design parameters and thermal environment. In this paper, multi-frequency wave localization and harvesting characters are studied for heated binary phononic crystal plates with a single defect. Considering the stress stiffening effect of thermal load, variations in the multiple defect modes are investigated for varying defect dimensions at different heating levels. From the perspective of stiffness and mass matrices of the PC plate, the transition of defect modes is explained with considering the driving effects of both changes in the defect configuration and structural temperature. Thermally-induced local non-periodic perturbation of stiffness is the essential factor that prompts the transition of defect wave manipulation behavior. Discrepancy in sensitivity to the perturbation results in different thermal responses of defect modes. It leads to the variation in multi-frequency wave localization of the defect PC plate. Accordingly, thermal load shifts the harvesting band of the defect-based harvester toward the lower frequency range, and may convert the discrete harvesting points into a continuous band. Temperature could be a potential means to tune the multi-frequency wave localization behavior and the defect-based harvesting performance.