SUBJECT: M.S. Thesis Presentation
BY: Sihong Zhao
TIME: Friday, October 19, 2012, 2:00 p.m.
PLACE: Love Building, 109
TITLE: Energy Harvesting from Random Vibrations of Piezoelectric Cantilevers and Stacks
COMMITTEE: Dr. Alper Erturk, Chair (ME)
Dr. Aldo Ferri (ME)
Dr. Laurence Jacobs (COE)


The main component of this thesis presents analytical and numerical electroelastic modeling, simulations, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given PSD or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first one of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H cantilever bimorph under different random excitation levels. In addition to base-excited cantilevered configurations, a second study is presented on energy harvesting using prismatic piezoelectric stack configurations. Electromechanical modeling and numerical simulations are given and validated through experiments for a multi-layer PZT-5H stack. Both broadband and bandwidth-limited random excitation cases are investigated theoretically and experimentally. After validating the electromechanical models for specific experimentally configurations and samples, various piezoelectric materials are compared theoretically for energy harvesting from random vibrations.