An energy harvester using piezoelectric cantilever beams undergoing coupled bending–torsion vibrations

Abstract

Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple of asymmetric tip masses; the latter convert part of the base excitation force into a torsion moment. This structure can be tuned to be a broader band energy harvester by adjusting the first two global natural frequencies to be relatively close to each other. We develop a distributed-parameter model of the harvester by using the Euler-beam theory and Hamilton's principle, thereby obtaining the governing equations of motion and associated boundary conditions. Then, we calculate the exact eigenvalues and associated mode shapes and validate them with a finite element (FE) model. We use these mode shapes in a Galerkin procedure to develop a reduced-order model of the harvester, which we use in turn to obtain closed-form expressions for the displacement, twisting angle, voltage output, and harvested electrical power. These expressions are used to conduct a parametric study for the dynamics of the system to determine the appropriate set of geometric properties that maximizes the harvested electrical power. The results show that, as the asymmetry is increased, the harvester's performance improves. We found a 30% increase in the harvested power with this design compared to the case of beams undergoing bending only. We also show that the locations of the two masses can be chosen to bring the lowest two global natural frequencies closer to each other, thereby allowing the harvesting of electrical power from multi-frequency excitations.

Maximum Power of Thermally and Electrically Coupled Thermoelectric Generators

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Performance enhancement of piezoelectric energy harvesters from wake galloping

“…Many investigations have focused on ambient vibration-based energy harvesting. [1][2][3][4][5][6] On the other hand, harvesting energy from fluid flows at low speed is desirable in many applications including the deployment of self-powered sensors or batteries in buildings, rivers, and airstreams. Several recent studies [7][8][9][10][11][12][13] have focused on the conversion of aeroelastic vibrations in airfoil sections to electrical power.…”

Design and Experimental Study of an L Shape Piezoelectric Energy Harvester

“…The torsional moment is occurred by rotational mode. Abdelkefi et al [20,21] conducted the numerical study for the T shape piezoelectric energy harvester which undergoes coupled bending and torsion by unbalanced proof masses. Similarly, a self-excited fluidic energy harvester is proposed and investigated [22,23].…”