Design enhancement and non-dimensional analysis of magnetically-levitated nonlinear vibration energy harvesters

Abstract

Over the past decade, there has been special interest in developing nonlinear energy harvesters capable of operating over a wideband frequency spectrum. Chief among the nonlinear energy harvesting techniques is magnetic levitation–based energy harvesting. Nonetheless, current nonlinear magnetic levitation–based energy harvesting approaches encapsulate design challenges. This work investigates some of the design issues and limitations faced by traditional magnetic levitation–based energy harvesters such as damping schemes and stiffness nonlinearities. Both experiment and model are used to quantify and evaluate damping regimes and stiffness nonlinearities present in magnetic levitation–based energy harvesters. Results show that dry friction, mostly ignored in magnetic levitation–based energy harvesting literature, contributes to the overall energy dissipation. Measured and modeled magnetic forces–displacement curves suggest that stiffness nonlinearities are weak over moderate distances. An enhanced design utilizing a combination of mechanical and magnetic springs is introduced to overcome some of these limitations. A non-dimensional model of the proposed design is developed and used to investigate the enhanced architecture. The unique potential energy profile suggests that the proposed nonlinear energy harvester outperforms the linear version by steepening the displacement response and shifting the resonance frequency, resulting in a larger bandwidth for which power can be harvested.

Magnetostatic Spring Softening and Stiffening in Magneto-Mechanical Resonator Systems

“…where I is the cross-sectional moment of inertia, κ represents the torsional mechanical restoring spring constant, and c is the viscous damping coefficient. In this paper, we do not consider the effects of dry friction [28]. Since τ 12 = 0 for θ 1 = θ 2 = 0, the system is not at equilibrium for zero deflections, and to obtain the magnetic effect, we must linearize the system around the new equilibrium deflections θ eq,1 , θ eq,2 .…”

A Dimensionless Parameter Analysis of a Cylindrical Tube Electromagnetic Vibration Energy Harvester and Its Oscillator Nonlinearity Effect

“…In this section, a nondimensional analysis method is developed to investigate the characteristics of the proposed energy harvester, although the dimensionless performance analysis of nonlinear electromagnetic vibration energy harvesting was also conducted by [64,65]. In order to solve Equations (5) and (6), it is assumed that…”

Investigation on a broadband magnetic levitation energy harvester for railway scenarios

“…Aldawood et al ( 2019) presented an enhanced energy harvester based on magnetic springs, using dual-mass and geometrically non-linear mechanical planar springs to increase the power of the harvester. Nammari and Bardaweel (2017) proposed a type of magneto-mechanical non-linear vibration energy harvester, which used four tilt springs to guide the movement of the suspended magnet. The broadband and low-frequency energy collection characteristics of the designed harvester were verified through experiments.…”