The idea of generating electricity from ambient environmental energy sources has drawn great attention in recent decades. Harnessing energy from different environmental energy sources, such as pre-existing base motion, wind flow, radio frequency, solar and heat, etc., have been enthusiastically studied. In particular, extensive research has been conducted on piezoelectric energy harvesting relying on pre-existing base motions which excite energy harvesters to vibrate through inertial forces. Meanwhile, in a separate body of work, small-scale aeroelastic wind energy harvesting has attracted growing interests where the vibrational energy is extracted from a piezoelectric energy harvester driven by aeroelastic instabilities. Examples of aeroelastic instabilities include galloping, wake galloping, flutter and vertex-induced vibration (VIV). In fact, in many environmental conditions, wind and base motion are coexisting where these two types of kinetic energy can be simultaneously utilized for electricity generation. However, previous findings from energy harvesting with a single type of source are not applicable since interaction between the two coexiting excitations varies the overall mechanical and electrical dynamics. Very recently, researchers have started to analyze response characteristics of concurrent wind flow and base vibration energy harvesting and reported several strategies for power enhancement. Especially, for concurrent galloping and base vibration energy harvesters, it has been found that there is only a very narrow frequency bandwidth where the two sources are truly concurrently contributing to energy harvesting with the two frequency components associated with the inertial and aeroelastic oscillations synchronize with each other.&nbsp;For the purpose of increasing this bandwidth, we propose to employ the internal resonance effect in a 2DOF concurrent galloping and base vibration energy harvester. The analytical solutions of the nonlinear mechanical and electrical responses are derived for the first time using harmonic balanced method by incorporating the aero-electro-mechanical coupling and inertial-aeroelastic coupling effects. Stability analysis is carried out for the effective frequency synchronization range. The analytical results are validated by numerical simulation. Subsequently, parametric study is carried out to analyze the effects of several key factors on the internal resonance behavior as well as the power output level, including electro-mechanical coupling, load resistance, magnetic force, wind speed and base acceleration. Results show that the nonlinear stiffness terms, especially the quadratic stiffness term, significantly influences the 2:1 internal resonance behavior and the overall power extraction performance. The analytical solution and parametric analysis form a theoretical guideline for further designing and optimizing concurrent wind and base vibration energy harvesters with enhanced performance.

Parametric Study of a 2dof Concurrent Galloping and Base Vibration Energy Harvester With Internal Resonance

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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