Chase Ray successfully defended his Masters of Science degree in Mechanical Engineering entitled “Piezoelectret Foam in a Multilayer Stack Configuration for Vibration Energy Harvesting” on April 14, 2015. Congratulations Chase!
Abstract:
Electronic devices are high demand commodities in today’s world, and such devices will continue increasing in popularity. Currently, batteries are implemented to provide power to these devices; however, the need for battery replacement, their cost, and the waste associated with battery disposal present a need for advances in self- powered technology. Energy harvesting technology has great potential to alleviate the drawbacks of batteries. In this work, a novel piezoelectret foam material is investigated for low-level vibration energy harvesting. Specifically, piezoelectret foam assembled in a multilayer stack configuration is explored. Modeling and experimentation of the stack behavior when excited in compression at low frequencies are performed to investigate piezoelectret foam as a multilayer energy harvester. An examination of modeling piezoelectret foam as a stack with an equivalent circuit is made following recently published work and is used in this study. Two 20-layer prototype devices and a 40-layer prototype device are fabricated and experimentally tested via harmonic base excitation. Electromechanical testing is performed by compressing the foam stacks to obtain output electrical energy; consequently, allowing the frequency response between input mechanical energy and output electrical energy to be developed. Modeling results are compared to the experimental measurements to assess the fidelity of the model at resonance. Lastly, energy harvesting experimentation in which the devices are subject to harmonic base excitation at the natural frequency is conducted to determine the ability of the piezoelectret foam stack to successfully charge a capacitor. For a 20-layer stack, a 100 F capacitor is charged to 1.45 V in fifteen minutes, and produces a peak power of 0.45 W. A 40-layer stack can charge a 100 F to 1.7 V in iffteen minutes, and produce a peak power of 0.89 W.