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Nonlinear metastructures for simultaneous vibration suppression and energy harvesting

This project is funded by the Australian Research Council. In this project, we investigate dual-functional locally resonating metastructures for simultaneous vibration suppression and energy harvesting. The aim is to widen low-frequency vibration suppression gaps and maximise energy capture by manipulating the dynamics of nonlinear unit cells. This will promote the development of next-generation multifunctional metastructures. Knowledge produced should improve the durability of structural components and empower sustainable wireless monitoring with self-powered sensors.

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Advanced energy harvesting structures

Unlike large-scale wind energy, which exists only in wind farms or offshore environments, small-scale wind energy in low-speed (e.g., 1~10 m/s) wind flows is omnipresent. For example, in outdoor environments, wind exists on the sides of highways, surrounding moving cars, around unmanned aerial vehicles, and in almost any highly urban area; while in indoor environments, wind exists inside the heating, ventilation and air conditioning (HVAC) systems, as an example. Considerable kinetic energy is carried by such small-scale wind flows yet remains mostly untapped. One of the primary interests in our research group is to develop aeroelasticity-based piezoelectric energy harvesters to harness kinetic energy from small-scale wind flows, which can be used to power remote wireless sensors for sustainable sensing and monitoring applications. Common aeroelastic instability includes translational galloping, vortex-induced vibration, flutter, wake galloping, buffeting, etc.. The goal of this research is to enhance the converted power level toward achieving self-powered capabilities in low-power microelectronics as a part of the future Internet of Things.

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               Video for (b)                                                           Video for (d)                                             Video for (e)

(a) A galloping piezoelectric wind energy harvester with a bluff body of different cross sections, (b) a 2DOF nonlinear galloping energy harvester, (c) vortex-induced vibration (upper) and airfoil flutter (bottom) based energy harvester, enhanced with a beam stiffener, (d) a flap harveser with flexoelectric material, (e) Trinity: a self-sustaining indoor wireless sensing network capable to carry out energy harvesting, synchronous duty-cycling, and sensing.

Dual-source energy harvesting

In many circumstances, wind and base vibratory excitations coexist, such as in the case of bridges, railway tracks, aircrafts and ocean buoys. We investigate dual-source power generation from concurrent base vibratory and aeroelastic excitations. The research was motivated by the realisation that it is insufficient and incorrect to consider excitation sources individually when energy harvesters are exposed to coexisting thus unavoidably interacting dual excitations. We explore how to develop adaptive and broadband nonlinear structures to overcome the frequency-dependent susceptibility challenge associated with existing techniques. Approaches include mono- and multi-stable structures, internal resonance, mechanical stoppers with frequency up-conversion, and other nonlinearity techniques.

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Dual-source energy harvester with (a) an impact mechanical stopper, (b) softening monostable nonlinearity, (c) internal resonance. 

Energy harvesting interface circuit

In an electro-mechanically or aero-electro-mechanically coupled kinetic energy harvesting system, the power extraction efficiency is dependent on the advancements in both mechanical structure and interface circuit. The power conditioning interface circuit has been shown to have a significant impact on the energy harvesting efficiency in both base vibration and wind energy harvesting systems. We investigate the power enhancing capability of the synchronous switching technique (SCE, SSHI, etc.) in various nonlinear base vibration and aeroelasticity-induced vibration energy harvesting through experiment, theoretical analysis and equivalent circuit simulation. 


Nonlinear mass and stiffness enhanced smart structures

Utilizing smart dampers with nonlinear mass and stiffness effects is a new way to enhance the performance of mechanical and structural systems. Example applications include car suspension systems, vibration absorbers in buildings, etc. We are motivated to understand its role in enhancing other nonlinear and smart structures with potential applications in mechanical, aerospace, civil and other areas.

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