Parametric Study and Effect of Beam Material on a Unimorph Piezoelectric Energy Harvester with Tip Mass

Piezoelectric energy harvesting devices are attracting interest to minimize the consumption and use of batteries which are considered expensive, harmful to the environment, and have limited life. The modification of the properties of the structural material and geometrical shape of a piezoelectric harvester can be of interest to increase the output power and broaden the frequency bandwidth. One possible approach of improving the performance of energy harvesters is to use energy harvester with dynamic magnifier (EHDM) which is described in this work by employing a piezoelectric unimorph cantilever (PVDF) integrated at the end of a structural cantilever beam. A model of the system is developed which can be considered as coupled linear resonators which can be solved approximately using a lumped parameter model. A carbon fiber reinforced plastic (CFRP) cantilever beam has been connected to the piezoelectric harvester element and the output voltage and power have been investigated both experimentally and theoretically. The output voltage and power at optimal resistance was 1.08 V and 2.73 mW respectively at the first resonance frequency of approximately 49 Hz of a single UCB. Also, the output voltage and average power at optimal resistance was 1.18 V and 2.78 mW respectively at first resonance frequency of 54 Hz, at the second resonance frequency of 120 Hz was 0.43 V and 0.36 mW, respectively of a UCB with magnifier beam. Finally, comparisons between the experimental results of coupled beam or EHDM and theoretical results of coupled linear oscillators showed a good agreement of a first and second peak under specific conditions