Abstract
In response to the defects of bi-stable energy harvester (BEH), we develop a novel quad-stable energy harvester (QEH) to improve harvesting efficiency. The device is made up of a bimorph cantilever beam having a tip magnet and three external fixed magnets. By adjusting the positions of the fixed magnets and the distances between the tip magnet and the fixed ones, the quad-stable equilibrium positions can emerge. The potential energy shows that the barriers of the QEH are lower than those of the BEH for the same separation distance. Experiment results reveal that the QEH can realize snap-through easier and make a dense snap-through in response under random excitation. Moreover, its strain and voltage both become large for snap-through between the nonadjacent stable positions. There exists an optimal separation distance for different excitation intensities.
Highlights
Energy harvesting from ambient vibrations has received a great research interest in many fields, such as wireless sensor, self-powered microelectronics and autonomous battery recharging
The potential energy shows that the barriers of the quad-stable energy harvester (QEH) are lower than those of the bi-stable energy harvester (BEH) for the same separation distance
Cottone et al.[7] studied the stochastic dynamics of BEH subjected to Gaussian random excitation and their results showed that BEH can outperform the linear ones under random excitation
Summary
Energy harvesting from ambient vibrations has received a great research interest in many fields, such as wireless sensor, self-powered microelectronics and autonomous battery recharging. Vibration-based energy harvester using piezoelectric material is widely adopted owing to its high energy density, simple structure and easy miniaturization.[1,2,3,4,5] Conventional linear piezoelectric energy harvesting devices only work optimally near their resonance frequencies with a narrow frequency bandwidth around a particular resonant frequency.[6] vibration existing in environments generally has a wide band of frequency. Numerous nonlinear piezoelectric energy harvesters based on the traditional linear ones have been introduced, including mono-stable Duffing, impact and bi-stable oscillator designs. The results showed that there exists an optimal potential shape which maximizes the output power under a given noise intensity and bandwidth He and Daqaq[9] investigated the influence of potential function asymmetries on the performance of nonlinear energy harvesters under white noise.
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