Multifunctional piezoelectric metastructures for vibration attenuation and energy harvesting
Khattak, Mohid Muneeb
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Over the past two decades, there has been a substantial increase in research conducted on energy harvesting techniques. With the developments in low-power electronic devices and sensors, such as wearable electronics and wireless sensors used in structural health monitoring, energy harvesting is expected to become a viable solution to overcome the need for battery replacement or recharging as well as relevant maintenance efforts. In most applications, vibrations are unwanted and may result in damage or failure of structures. This opens up a pathway to research into VEH techniques which simultaneously can harness useful energy as well as attenuate these harmful vibrations. Locally resonant (LR) metastructures are metamaterial-based finite structures with engineered properties that exhibit local resonance. Bandgap formation is a dynamic property exhibited by these LR metastructures where, for a range of frequencies, wave propagation is forbidden (and this bandgap can be tuned for wavelengths larger than the lattice size for low-frequency applications). This thesis discusses multifunctionality of these structures for concurrent vibration mitigation and low-power energy harvesting. Specifically, the work detailed in this thesis focuses on piezoelectric energy harvesting utilizing the inherent property of piezoelectric elements for converting mechanical strain into electrical energy. Electromechanical models are developed and analyzed numerically for various LR vibrating structures including linear and non-linear cantilever beams. LR metastructures made from (1) linear mechanical resonators with piezoelectric elements, (2) linear electromechanical (piezoelectric) resonators with resistive inductive shunts, and (3) bistable attachments with piezoelectric elements are explored both experimentally and numerically. Conclusions are drawn based on the results obtained in this work.