MSc Mechanical ENG Defense Notice (Haining Li)
MSc Mechanical Engineering Defense
Friday, January 22, 2021
2:30 PM Via zoom
Presented by: Haining Li
Supervisor: Dr. Kefu Liu
Join Zoom Meeting
https://lakeheadu.zoom.us/j/97929392265?pwd=MStOYVgyZDRuazJyTnpFeGtHTyt3...
Meeting ID: 979 2939 2265
Passcode: 073029
A Tunable Multi-Stable Piezoelectric Vibration Energy Harvester
ABSTRACT
The vibration energy harvester is intended to convert ambient environmental energy into electrical energy. It has great potential to be an alternative to the conventional battery in low-power electric devices. A traditional vibrating energy harvester consists of a linear oscillator that operates in a narrow frequency band. Nonlinear energy harvesters provide a promising solution to widen the operating bandwidth. Based on the system stability states, the nonlinear vibration energy harvesters can be classified as mono-stable and multi-stable. In this study, a tunable multi-stable piezoelectric energy harvester is proposed. The apparatus can be manually tuned to achieve three states, namely tri-stable, bi-stable, and mono-stable. It has a compact structure compared to the existing designs.
Firstly, the apparatus’s design is presented. The analytical model for the restoring force due to the magnetic interaction is developed by using the magnetic dipole approach. Then the model is validated experimentally. Using the measured data, the model optimization is conducted by using the genetic algorithm. Based on the optimized model, the stability state regions versus the tuning parameters are identified. Secondly, the electromechanical model of the developed apparatus is developed. By linearizing the model, the optimum resistance value of the linear system under harmonic excitation and colored noise excitation is studied, respectively. Thirdly, the output performance of the bi-stable energy harvester under colored noise excitation is investigated numerically and experimentally. Fourthly, the output performance of the tri-stable energy harvester is studied numerically and experimentally as well. The results show that the frequency analysis method is insufficient to determine the optimum resistance when the tri-stable energy harvester is engaged in the high orbit inter-well oscillation. In addition, when the multi-stable energy harvester system is at resonance, the output performance will be largely improved by the separation between each well.