No abstract

This letter proposes an energy harvester with dynamic multistability to harvest the wind energy. In this design, a piezoelectric beam is integrated with a rectangular wing to initiate the flutter; the multistable mechanism is realized by oppositely placing a tip magnet and two fixed magnets. It is found that the proposed energy harvester has the dynamic stability that can execute and sustain the snap-through motion over a wide range of wind speeds. A prototype of the harvester was fabricated, and the validation experiment was carried out. The harvester exhibited the bistable characteristic at low wind speed and the tristable characteristic at high wind speed. The experimental results showed that the presented system could realize snap-through (even coherence resonance) and produce high output power for the wind speed ranging from 1.5 m/s to 7.5 m/s.

In this work, a hybrid energy harvester is proposed to broaden the working bandwidth of vibration energy harvesting. This design consists of two piezoelectric polyline beams standing with a gap distance, of which one is bonded with a piezoelectric patch and covered by an electret layer, while an electrode covers the other. The two polyline beams are coupled through the electret and electrode effect, which is beneficial for extending the working bandwidth. The motion with which the two beams bump into each other could extend the harvester’s working bandwidth in the low-frequency area. If replacing the second beam with an inverted beam, the working bandwidth will also be extended. To understand the underlying mechanisms and compare their performance, corresponding theoretical and experimental studies are carried out. The results show that the proposed harvester consists of two polyline beams that possess broader bandwidth with the coupling and collision impact design. Parameter analysis of the tip mass position on the auxiliary beam is conducted. The proposed hybrid energy harvester excited by stochastic excitation could generate an output power of 69.1 µW under an excitation level of 0.0041g2 Hz−1 with an active surface area of 280 mm2.

Large-amplitude snap-through motion might happen between two equilibria of a buckling inverted piezoelectric beam under vibration excitation, therefore enhancing the energy harvesting performance of system significantly. However, in practical application, owing to the deep potential well of a buckling beam, relatively large excitation amplitude is needed to trigger such snap-through motion. To overcome this limitation, we herein propose an improved inverted beam harvester that comprises an inverted beam with an affixed tip magnet and two additional magnets mounted in the vicinity of the equilibrium positions. By introducing this repulsive magnetic force, the potential energy could be tailored to promote the occurrence of snap-through motion. Numerical simulation is conducted and it is shown that with the proposed design the harvester would be able to realize snap-through motion more easily compared to the original buckling system. This has also been validated by the experiment in which large deflection and voltage output are both observed when snap-through motion is activated under low excitation frequency.

No abstract