Energy harvesting from piezoelectric stacks via impacting beam

Özpak, Yiğit
Piezoelectric materials can be used for energy harvesting from ambient vibration due to their high power density and ease of application. Two basic methods, namely, tuning the natural frequency to the operational frequency and increasing the operation bandwidth of the harvester are commonly employed to maximize the energy harvested from piezoelectric materials. Majority of the studies performed in recent years focus mostly on tuning the natural frequency of the harvester. However, small deviations in operating frequency from the natural frequency can cause excessive loss in the power output. It is then advantageous to design a harvester which is capable operating in a wide frequency band. This goal could be achieved both by expanding effective bands of natural frequencies and introducing a frequency-rich external input to the system. The main idea is to supply constant excitation energy into the harvester system to obtain high energy levels by changing system characteristics. In this study, an analytical model of an impacting beam with piezoelectric stack at its tip is developed, in order to investigate the effects of impacts on energy harvested. Experimental validation of analytical results is also performed. Analytical expressions to obtain response of harvester and impact forces occurred during motion are generated for solution in MATLAB® platform by iterative solution methodology. Validation of the analytical model is performed upon comparisons with test results. Moreover, harvester efficiency for broadband frequency excitations is tested and its characteristic properties are investigated in detail.
Citation Formats
Y. Özpak, “Energy harvesting from piezoelectric stacks via impacting beam,” M.S. - Master of Science, Middle East Technical University, 2014.