Nonlinear Dynamics of Two-degree-of-freedom Vortex-induced Vibration Energy Harvester

Vortex-induced vibrations (VIV) often occur in many engineering situations, such as offshore structures, large-span bridges, and fluid piping systems. Harnessing energy from VIV, on the one hand, can provide a sustainable power supply to the essential sensing devices for structural health monitoring; on the other hand, it can dissipate the vibration energy and help protect the structural integrity. This paper presents the dynamic analysis of a two-degree-of-freedom (2DOF) VIV piezoelectric energy harvester (PEH). The governing equations of the 2DOF VIVPEH are developed by using the wake oscillator model to describe the aerodynamic force. The dynamic response of the 2DOF VIV-PEH is compared with that of a traditional one-degree-of-freedom (1DOF) counterpart. It is found that the 2DOF VIV-PEH can generate two lock-in regions for broadband energy harvesting. Further analysis shows that the 2DOF VIVPEH undergoes in-phase and out-of-phase motions in the first and second lock-in regions, respectively. The fast Fourier transform (FFT) and modal analyses unveil that the two lock-in regions are related to and determined by the two resonances of the 2DOF VIV-PEH. Based on the understanding of the above fact, a parametric study is conducted to explore how to adjust the two resonances of the 2DOF VIV-PEH for customizing the two lock-in regions. Some design guidelines for tuning the system parameters are summarized according to the parametric study. Finally, the maximum power analysis is performed. Optimal resistances for obtaining the maximum power outputs are identified for the 2DOF VIV-PEH in different lock-in regions. © SMASIS 2023.All rights reserved.