Abstract
Vibration-based energy harvesting technology is the most promising method to solve the problems of self-powered wireless sensor nodes, but most of the vibration-based energy harvesters have a rather narrow operation bandwidth and the operation frequency band is not convenient to adjust when the ambient frequency changes. Since the ambient vibration may be broadband and changeable, a novel V-shaped vibration energy harvester based on the conventional piezoelectric bimorph cantilevered structure is proposed, which successfully improves the energy harvesting efficiency and provides a way to adjust the operation frequency band of the energy harvester conveniently. The electromechanical coupling equations are established by using Euler-Bernoulli equation and piezoelectric equation, and then the coupled circuit equation is derived based on the series connected piezoelectric cantilevers and Kirchhoff's laws. With the above equations, the output performances of V-shaped structure under different structural parameters and load resistances are simulated and discussed. Finally, by changing the angle θ between two piezoelectric bimorph beams and the load resistance, various comprehensive experiments are carried out to test the performance of this V-shaped energy harvester under the same excitation. The experimental results show that the V-shaped energy harvester can not only improve the frequency response characteristic and the output performance of the electrical energy, but also conveniently tune the operation bandwidth; thus it has great application potential in actual structure health monitoring under variable working condition.
Highlights
Wireless sensor networks (WSNs) have received much attention
It can be concluded that the V-shaped structure has a better voltage output performance and wider operation bandwidth than the L-shaped structure in these cases
Since the ambient vibration is usually broadband and changeable, a novel V-shaped vibration energy harvester is proposed based on the cantilevered piezoelectric bimorph structure
Summary
Wireless sensor networks (WSNs) have received much attention. WSNs technology has been recognized as an effective technique for the various industrial fields [1], such as environmental monitoring [2], fire detection [3], body area networks [4], and fault diagnosis [5]. The most commonly used piezoelectric energy harvester configuration is a cantilever with piezoceramic layers located on a vibrating host structure for electrical power generation from bending vibrations under resonance excitation [12,13,14,15]. As an alternative to conventional multiresonant piezoelectric beams, Erturk A et al [38] proposed an L-shaped beam-mass structure as a new piezoelectric energy harvester configuration, which can broaden the operation bandwidth and overcome the shortcomings of the single frequency excitation. Based on the above considerations, a new V-shaped piezoelectric low frequency vibration energy harvester which can arbitrarily tune the angle between the two piezoelectric bimorph beams is explored in this study.
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