Design, analysis and experimental study of a T-shaped piezoelectric energy harvester with internal resonance

In this paper, a T-shaped piezoelectric energy harvester (TPEH) is proposed by taking advantages of internal resonance and multimodal techniques. The developed TPEH is composed of a clamped-sliding main beam and a branched vertical cantilever beam at the center. The sliding end of the clamped-sliding beam could move freely along the axial direction, and two piezoelectric patches are attached at both sides of the substrate near the sliding end. An electromechanical coupling model was established based on the extended Hamilton's method. The simulation results are in good agreement with the experimental results. The simulation and experimental results indicate that the 1:3 internal resonance phenomenon of the TPEH occurs when the excitation frequencies are close to the first resonance of the TPEH. As a result, the energy conversion efficiency can be significantly increased through the high-frequency response at the low-frequency excitation. Meanwhile, the operational bandwidth is widened with the hardening nonlinear response of the proposed TPEH within the first resonance bandwidth. Finally, it was demonstrated that the proposed TPEH is able to harvest practical vibration energy with low-amplitude and low frequency.