Research On Vortex-induced Vibration Energy Harvesting Using A Piezoelectric Cantilever Beam Undergoing Torsion And Bending-torsion

In nature, low speed flowing water is widely existed. Many scholars focu s on researches on converting these water energy contained in the low speed fluid into electricity.Vortex induced vibration(VIV) will occur when water flows through the cylinder in a low speed and excites the cylinder ’s low periodical frequency vibration, the piezoelectric beam is rigidly connected with the cylinder, then it will periodically vibrate together with the cylinder, polarizing and generating. Single harvester can power i ntermittent low-power, wireless and small electronic devices, meanwhile, array combinations of multigroup harvesters can continuously supply energy for large electronic equipment s. By reading related documents and eccentric designing of cylinders, designing vortex-induced vibration energy harvesting from low-velocity water using piezoelectric cantilever beams undergoing torsion and bending-torsion, morever, a series of numerical analysis and experimental studies have been finished to research the harvesters.Based on the theories of fluid vortex induced vibration, mechanical vibration, mechanics of materials, elasticity, piezoelectricity, Euler-Bernoulli beam and discrete methods of Galerkin, the mathematical models of the piezoelectric beam are established, combined with Lagrange’s equations, the nonlinear energy control equations of vortex induced vibration harvester are created.The harvesters designed by using the energy control equations are numerically analyzed, then compared their vibration characteristics, choosing the vortex-induced vibration energy harvester using piezoelectric cantilever beams undergoing bending-torsion as our subjects. Meanwhile, the affects of flow velocity, load resistance, width of piezoelectric beam, cylinder diameter and it’s mass eccentricity distance and cylind er mass on the harvesting characteristics of harvesters are researched. Under the condition of a certain flow velocity, we should reasonably select the external load resistance, size of the piezoelectric beam and the eccentric cylinder as far as possible to maximize the harvesting energy.Finally, an experimental platform was developed. The harvesters were assembled, we verified the results of numerical analysis by experiments. Both experimental and numerical analysis results are in good agreement in terms of trend and values, verifying the correctness of the mathematical model, which can be used to guide the design and processing of efficient energy harvester. Meanwhile, the vortex-induced vibration energy harvester using piezoelectric cantilever beams undergoing bending-torsion with a maximum output power 0.4133 m W was developed. Compared to the harvester undergoing bending vibration, the maximum output power has a increase of 130%.In this paper, vortex-induced vibration energy harvesters using piezoelectric cantilever beams undergoing torsion and bending-torsion are studied. Verifying the correctness of the theoretical model established through the experiment s, which can be used for guiding the design and machining the efficient energy harvesting devices using low speed water.