Abstract
This paper proposes an approach for designing an efficient vibration energy harvester based on a vibro-impacting piezoelectric microcantilever with a geometric shape that has been rationally modified in accordance with results of dynamic optimization. The design goal is to increase the amplitudes of higher-order vibration modes induced during the vibro-impact response of the piezoelectric transducer, thereby providing a means to improve the energy conversion efficiency and power output. A rational configuration of the energy harvester is proposed and it is demonstrated that the new design retains essential modal characteristics of the optimal microcantilever structures, further providing the added benefit of less costly fabrication. The effects of structural dynamics associated with advantageous exploitation of higher vibration modes are analyzed experimentally by means of laser vibrometry as well as numerically via transient simulations of microcantilever response to random excitation. Electrical characterization results indicate that the proposed harvester outperforms its conventional counterpart (based on the microcantilever of the constant cross-section) in terms of generated electrical output. Reported results may serve for the development of impact-type micropower generators with harvesting performance that is enhanced by virtue of self-excitation of large intensity higher-order mode responses when the piezoelectric transducer is subjected to relatively low-frequency excitation with strongly variable vibration magnitudes.
Highlights
Interest in the field of vibration energy harvesting has been continuously increasing over the last decade
Measurements were performed with the freely-vibrating microcantilevers of the microcantilever
Equations (4) and (5) indicate that an increase in vibration frequency of the piezoelectric transducer aim of this study was to validate an approach on improves the effective of intrinsic leadsThe to stronger electrical damping, whichbased in turn its exploitation efficiency. This means modal characteristics of frequencies, elastic structures for increasing efficiency of that, with higher vibration more mechanical energy isenergy removedharvesting from vibration energy harvesters (VEHs) during energy microcantilever-type
Summary
Interest in the field of vibration energy harvesting has been continuously increasing over the last decade. Many vibration energy harvesters (VEHs) are designed to power wireless sensors, thereby aiming to replace batteries which suffer from a finite lifespan and pose environmental issues. The vast majority of reported VEH designs are based on elastic structures covered with piezoelectric layers, commonly configured as uni- or bi-morphs. A literature review reveals that relatively little research has been conducted on structural optimization of microcantilever-type vibro-impacting VEHs with thorough dynamic response studies being scarce. Investigation of dynamics-related performance parameters of vibro-impact systems (VIS), such as operation speed, stability, reliability, and longevity, is a high priority topic among the other research work conducted in the field of VEHs. Designing a commercially viable device is possible only through in-depth understanding and accurate prediction of its vibrational behavior
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