A magnetically coupled nonlinear T-shaped piezoelectric energy harvester with internal resonance

This letter originally presents a magnetically coupled nonlinear T-shaped piezoelectric energy harvester with multiple resonance bands based on internal resonance principle. The proposed harvester consists of a clamped-clamped buckled beam and a vertical cantilever with tip magnetically coupled. The corresponding theoretical model is established. Two resonance bands with hardening nonlinear phenomenon are obtained. 1:2:3:4 internal resonance characteristics with the peak amplitude ratio of 1:1.81:0.56:0.31 are found for the generated voltage of the first resonance. The energy conversion efficiency can be enhanced by utilizing high frequency response under low-frequency excitations. The bandwidth of full width at half maximum output power reaches 13.8 Hz within the excitation between 5∼30 Hz. The response of random excitations is also investigated and an average power of 9.64 μW is achieved at the random excitation intensity of 0.001 g²Hz^-1. Overall, the proposed harvester can achieve ultra-wide working frequency range under low-level excitations and is suitable for low-frequency random vibrations.