Extended frequency bandwidth through multi-degree-of-freedom nonlinear magneto-mechanical energy harvesting

Abstract

Energy harvesting from different vibration sources is typically designed by means of a single degree of freedom approach and implementing both linear and nonlinear principles and techniques. In this paper, starting from the experience of the authors in different applications and using linear magneto-inductive electromechanical oscillators, a two-degree-of-freedom energy harvester is designed with the aim of supplying sensors in a wing typical section. The energy harvester can be modelled as a system of two masses with linear springs or nonlinear elastic interactions due to magneto-static forces. The equivalent mechanical dampers of the same device are four coils that can be connected to the electric interface and then to the electric load circuit. The strong improvement of this simple extension of a linear generator with two degrees of freedom relies on the dynamic improvements of the coupling to the source that can be tuned in order to increase the frequency bandwidth of the device. The simulations show that, although the limited stroke of the magnets and the undesired mechanical friction can reduce the energy harvested, the nonlinearities of the magnetic forces and fluxes can represent an effective advantage, in particular, in a multi-degree of freedom system subject to a large frequency bandwidth input or random excitations. Potential perspectives could be also implemented through semi-active or active strategies obtained through the electric interface.

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ORCID for A. Da Ronch: orcid.org/0000-0001-7428-6935

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