Modeling of a horizontal asymmetric U-shaped vibration-based piezoelectric energy harvester (U-VPEH)

In this paper, we present a new horizontal asymmetric U-shaped vibration-based piezoelectric energy harvester (U-VPEH), which collects and converts destructive vibration energy into useful electrical energy. The finite element analysis is conducted on modal shape, the displacement, the mechanical energy, and the strain for both the linear and nonlinear U-VPEH models. Mathematical governing equations are derived to investigate dynamic characteristics of the model. The harmonic balance method and state space form are utilized to conduct the analytical and theoretical analysis. The results show that the first and second eigenfrequencies are 17.167 Hz and 22.951 Hz for the nonlinear U-VPEH model while those are only 17.366 Hz and 25.124 Hz for the linear model. The nonlinear energy harvester model can narrow frequency band gap between the first two resonance modes. Moreover, the maximum voltage response is 8.743 V@16.5 Hz under the up-sweeping signals while the maximum voltage response is 14.18 V@15.41 Hz under the down-sweeping signals. The experimental results demonstrate that the voltage response and the resonance frequency of the U-VPEH agree with the analytical and theoretical analysis. The nonlinear horizontal asymmetric U-VPEH model exhibits a good performance on the energy transfer. This higher energy output, lower resonance frequency, and closer resonance peak can broaden the flexibility and practical usage of the energy harvester.