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Rouhollah Hosseini,Mohsen Hamedi,임종범,김재환,Jedol Dayou 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.3
Electrical energy is normally generated through different sources such as hydroelectric, wind, heat, nuclear transformation, chemical reactions or vibrations. Nowadays, harvesting power from mechanical vibration is one of the novel technologies that usually can be done by systems based on electromagnetic, electrostatic, piezoelectric and combination of them. Piezoelectric systems can convert motion from the vibrating structures into electrical power. Cellulose Electro-active paper (EAPap) has been recognized as a novel smart piezoelectric material that can be used for energy harvesting purposes. One of the most prevalent method for vibration energy harvesting is using unimorph piezoelectric cantilever beams. In this paper, an analytical solution based on distributed parameter model is presented to calculate the generated energy from vibration of cantilever substrate that is partially covered by EAPap material. In the studied structure, piezoelectric layer thickness in comparison to the length of the beam and thickness of substrate material can be considered very thin. Thus its effect on the vibration behavior of structure is negligible. The results are validated by experimental values. The analytical data was found to be very close to experimental results and finite element simulation values. Findings from this study provide guidelines on system parameters that can be manipulated for more efficient performance in different ambient source conditions.
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Mohamad Hossein Fatahi,Mohsen Hamedi,Majid Safarabadi 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.2
The low specific power of mechanical energy harvesters is the biggest shortcoming prevents these harvesters from becoming a viable replacement for batteries used in monitoring structures. In this paper, increasing the output voltage of the mechanically excited piezoelectric harvester beams was investigated. A composite beam consisting of an auxetic honeycomb, skin, piezo layer and end mass was optimally designed and subjected to base excitation. Two samples with homogenous and honeycomb substrates were fabricated and tested. The measured natural frequencies showed good agreement with the FE model results with 7% average error. The equivalent properties of the honeycomb were extracted and verified and formed a homogenous orthotropic layer. Geometry of honeycomb and beam was considered for the optimization process. The length of the beam, as an input parameter, was used in an inner loop inside the optimization cycle to set the natural frequency near 50 Hz. Measuring the performance of the two beams with the same size of the piezoelectric layer showed that auxetic honeycomb substrate improves the open-circuit voltage above 25% and the specific voltage above 30% compared with the simple substrate.
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