An energy harvesting dynamic vibration absorber is studied to suppress undesirable vibrations in a host structure as well as to harvest electrical energy from vibrations using piezoelectric transduction. The present work studies the feasibility of using vibration absorber for harvesting energy under random excitation and in presence of parametric uncertainties. A two degrees of freedom model is considered in the analytical formulation for the host along with the absorber. A separate equation is used for energy generation from piezoelectric material. Two studies are reported here, (i) with random excitation where the base input is considered to be Gaussian; (ii) parametric uncertainty is considered with harmonic excitation. Under random base excitation the analytical results show that, with the proper selection of parameters, harvested electrical energy can be increased along with the reduction in vibration of the host structure. Graphs are reported showing trade-off between harvested energy and vibration control. Whereas, Monte Carlo simulations are carried out to analyze the system with parametric uncertainty. This showed that the mean harvested power decreases with an increase in uncertainties in the natural frequency as well as damping ratio. In addition, optimal electrical parameters for obtaining maximum power for the case of uncertain parameters are also reported in this study.
A hybrid energy harvester combining piezoelectric and electromagnetic transduction mechanisms is designed to scavenge vibration energy. The system comprises of a cantilever beam, a piezoelectric harvester and a magnetic mass hung through a spring at the free end. The beam with piezoelectric harvests electrical energy due to the strain induced in the piezoelectric patch. The hung mass oscillates in and out a solenoid to harvest energy due to electromagnetic induction. The system can generate power from any vertically oscillating vibrating host structure. This paper studies the power harvested from the hybrid harvester under harmonic excitation using experimental and analytical evaluations. Comparisons are made with the standalone piezoelectric and electromagnetic harvester under the same excitation environment. The study shows that the present hybrid harvester can harvest energy at a broad range of frequencies. Furthermore few parametric studies are carried out for understanding the device performance. Finally, the efficiency of the proposed hybrid energy harvester is compared with the existing hybrid energy harvester.
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