Abstract
This work presents a simple and innovative piezoelectric energy harvester, inspired by fractal geometry and intrinsically including dynamic magnification. Energy harvesting from ambient vibrations exploiting piezoelectric materials is an efficient solution for the development of self-sustainable electronic nodes. After an initial design step, the present work investigates the eigenfrequencies of the proposed harvester, both through a simple free vibration analysis model and through a computational modal analysis. The experimental validation performed on a prototype, confirms the accurate frequency response predicted by these models with five eigenfrequencies below 100 Hz. Despite the harvester has piezoelectric transducers only on a symmetric half of the top surface of the lamina, the rate of energy conversion is significant for all the investigated eigenfrequencies. Moreover, by adding a small ballast mass on the structure, it is possible to excite specific eigenfrequencies and thus improving the energy conversion.
Highlights
Harvesting energy from ambient vibrations, exploiting the direct piezoelectric effect, is an efficient solution for powering self-sustainable electronic devices and remote sensors.The integration of an energy harvester in these devices, eliminates the need for external power sources, ensuring continuous operation over a long period of time.Among the large number of piezoelectric energy harvesters proposed in the literature, a peculiar approach consists in equipping the harvester with a dynamic magnifier
Dynamic magnification consists in constraining the harvester to an intermediate spring-mass system, which is fixed to the vibrating base structure
Zhou et al [14] propose a highly efficient piezoelectric energy harvester composed by a multi-mode intermediate beam with a tip mass, and by an energy harvesting beam
Summary
Harvesting energy from ambient vibrations, exploiting the direct piezoelectric effect, is an efficient solution for powering self-sustainable electronic devices and remote sensors.The integration of an energy harvester in these devices, eliminates the need for external power sources (i.e. batteries or connection to the power grid), ensuring continuous operation over a long period of time.Among the large number of piezoelectric energy harvesters proposed in the literature, a peculiar approach consists in equipping the harvester with a dynamic magnifier. Cornwell et al [2], Rastegar et al [3] and Ma et al [4] propose harvesters which incorporate an intermediate elastic system between the oscillating base and a cantilevered piezoelectric structure. Erturk et al [7] propose a new L-shaped beam-mass structure piezoelectric energy harvester exhibiting two very close natural frequencies. Zhou et al [14] propose a highly efficient piezoelectric energy harvester composed by a multi-mode intermediate beam with a tip mass (acting as a dynamic magnifier), and by an energy harvesting beam. Vasic and Costa [15] investigate a similar configuration, of a piezoelectric energy harvester consisting of an intermediate beam with a tip mass acting as dynamic magnifier. Sharma et al [19] study the influence of the cross-section of the dynamic magnifier on energy harvesting
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