Study on piezoelectric energy generation under high frequency excitation
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Date
2024-08-20
Authors
Xiao, Yu
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Abstract
The development of energy technology has stimulated the application of low-power wireless electronic devices. Batteries are commonly used to supply power for these devices, however, the limited lifespan and expensive replacement cost necessitate the development of generating electricity from waste energy. Energy generation, which collects wasted energy from external sources, has become a popular research topic. Over the past decades, the low cost and easy-to-apply characteristics of piezoelectric material have spurred various research endeavors aiming at developing piezoelectric energy generators based on different energy sources.
This thesis aims to develop piezoelectric energy generators (PEGs) under various working conditions using high frequency excitation, validate the accuracy of the corresponding models, investigate their dynamic behaviors, and evaluate their energy generation performance. A vehicle brake pad with embedded PEGs is developed by utilizing high-speed rotation of vehicle brake rotor. Charge dissipation from the measuring device is considered to accurately calculate the generated voltage from the piezoelectric patch during operation. Inspired by frictional contact during the braking process between the rotor and frictional layer, a shear mode PEG is proposed to explore its performance under self-excited friction-induced vibration (FIV). The dynamic voltage responses from experiment, closely matched with the analytical results, demonstrate the great performance from vibrations close to the resonant frequency of the system. A modified PEG employing bi-linear and impact techniques is then proposed, modeled, and tested through experiment to examine the improved performance and verify the continuous FIV under these conditions. To understand the mechanism and dynamic responses of nonlinear PEGs considering different connections between magnetic spring and piezoelectric element, mathematical models are proposed and solved through numerical iteration. The results from parameter studies demonstrate enhanced frequency bandwidth and operating velocity range using harmonic excitation and FIV, respectively. Furthermore, PEG using FIV has been extended to continuum structures, and a piezoelectric coupled continuum beam using FIV is modeled, described, and studied for the first time to characterize its dynamic response and energy generation performance. Following that, a piezoelectric coupled stepped beam is modeled using a modified method, tested through experiment, and utilized as a case study of geometric optimization.
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Mechanical Engineering