Investigations on beam geometries effect of placement of piezoelectric material and proof mass on the performance of energy harvester

Abstract

Vibration energy harvesting is the process of converting natural and human-made vibrations into usable electrical energy. Electromagnetic, electrostatic, and piezoelectric materials are the conversion techniques used to convert mechanical vibration energy into electrical energy. Among these techniques, piezoelectric material has more power density compared to others. Smart electronic devices and wireless sensors use electrochemical batteries and external power supplies to power themselves. In the last few decades, the performance of electronic devices grow steadily but the performance of batteries remains stagnant. The batteries need charging, maintenance and replacement over the time. Researchers found that piezoelectric energy harvesting is one of the ways to overcome this problem. In this thesis, investigation on different geometries of the beam for piezoelectric energy harvesting has been done. The effect of placement of piezoelectric material on the beam for energy harvesting and analysis of effect of proof mass (material, shape, size, and orientation) on frequency, optimal load, voltage and power was done. Analysis of unimorph and bimorph energy harvesters with multipatch piezoelectric materials was also done. Among the various beam geometries proposed for piezoelectric energy harvesting, the selected beams were Rectangle (REC), Triangle (TRI), Taper in width (TAP W), Taper in thick (TAP T), Taper in thick and width (TAP TW), Inverted taper in width (INTAP W), Inverted taper in thick (INTAP T) and Inverted taper in thick and width (INTAP TW) based on stress and strain analysis. Five beams namely REC, TRI, TAP W, TAP TW, and INTAP TW beams were considered and the resonant frequency, open circuit voltage, optimal load, voltage, and power under load were determined by experimentaland numerical methods. Since the deviation between the experimental and numerical method is less, the same methodology was applied for numerical analysis of the other beams. From numerical analysis, it was found that the INTAP TW beam pr