In this paper, a low-frequency broadband energy harvesting structure is proposed based on locally resonant phononic crystals (LRPCs). The low-frequency LR characteristics and energy harvesting capabilities of the proposed structure are investigated by using the finite element method. Energy localization effects are verified when local resonances occur, making the proposed LR structure work as an energy collector. Structure modifications are performed to improve the low-frequency energy collecting performance. For the suggested structure with composite units, sixteen resonant frequencies are found in the frequency range below 250 Hz, at which vibration energy is localized intensively in the piezoelectric folded beams. Based on the frequency response analysis, the composite structures are proved to have good energy harvesting capabilities over a broadband low frequency range, due to the multiple resonances and the high concentration of localized energy. These structures will be helpful for the self-powered microsystems, such as portable electronic devices, wireless sensors, microelectromechanical systems (MEMS) and so on, to extract energy from ambient low frequency vibrations.
Hybrid Signal Processing Technique to Improve the Defect Estimation in Ultrasonic Non-Destructive Testing of Composite Structures