<p class="MsoNormal" style="text-align: justify; text-indent: .5in; line-height: 150%">Vibration based energy harvesting techniques have been extensively studied over the past decade because of the dramatically reduced power requirement of small electronic device. Among different vibrational energy conversion mechanisms, piezoelectric transduction based configurations have been most favored due to the high energy density and easily miniaturized fabrication. In the last decades, piezoelectric energy harvesters based in traditional resonance mechanism have been widely investigated.&nbsp; As an effective means to overcome the shortcomings of linear systems only performing well near the resonance frequency, bistable piezoelectric energy harvesters have been investigated widely in the area of energy harvesting.&nbsp; As ambient vibrations are always with the characteristics of randomness and distributed in a wide frequency range, it is significant to consider the output performance of multistable harvesters under different types of random excitations. Although much effort has been devoted to determining approximately the response characteristics of multistable harvesters under different types of random excitations, previous studies almost focused on the system with nonlinear forces cannot be manipulated arbitrarily.&nbsp; It is very promising if the nonlinear forces can be customized according to requirements, in which the performance of the energy harvester can be further optimized. The nonlinear force customization device consists of a pre-compressed spring, a miniature bearing, and a raceway, which are designed according to the nonlinear forces. As an example, the device is installed at the end of a piezoelectric cantilever beam, and mono-stable, bi-stable and tri-stable energy harvesters are customized, respectively. In this work, nonlinear energy harvesters with customized nonlinear force subjected to external Gaussian white noise excitations is studied. The probability density functions of mechanical states are obtained by method of moment differential equation and the good agreement between numerical simulation and analytical results demonstrates the effectiveness of the proposed method. Mean square power is presented to illustrate the device output performance. The simulations show that beyond certain critical amplitude of excitation, the harvesters undergo inter-well oscillations and harvest more power. This implies that if the variance of the random ambient excitation is known, then the harvester could be optimized so that the mean harvested power is maximized. As an example, the device is installed at the end of a piezoelectric cantilever beam, and mono-stable, bi-stable and tri-stable energy harvesters are customized, respectively. The nonlinear force customization device enables designers to obtain the desirable nonlinear forces for the vibration energy harvesters. For the bistable piezoelectric energy harvester, the influence of external excitation intensity and internal system parameters on the outputs is firstly analyzed theoretically and numerically.</p>

Probabilistic Response of a Vibration Energy Harvester With Customized Nonlinear Force Driven by Random Excitation

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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