Performance of a Cantilever Energy Harvester under Harmonic and Random Excitations
The technique of harvesting the energy from base structural vibration through a piezoelectric transducer attached at an appropriate location on the vibrating structure is gaining popularity in recent years. Although the amount of energy harvested depends on the type and magnitude of base excitation, the energy harvest under random excitation as compared to equivalent harmonic excitations is not yet well understood and is investigated in this paper through a cantilever energy harvester. Initially, the energy harvested under harmonic excitations is numerically simulated and experimentally validated under increasing base accelerations with different load resistances. Subsequently, the performance of this energy harvester is experimentally studied under random excitations. The results demonstrate that the harvested energy (a) reaches maximum value when the base excitation matches the natural frequency of the harvester, (b) increases with the increase in base accelerations irrespective of the type of excitation, and (c) increases by 2-14 times under random excitations as compared to equivalent harmonic excitations i.e. under same energy input. It is recommended that the energy harvester be used in aerospace structures where random vibration amplitude is higher, to harvest more energy.
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