Dynamic Characteristics of Galfenol Cantilever Energy Harvester

Abstract

Based on the Armstrong model and the established electromechanical model of a Galfenol cantilever energy harvester, a nonlinear dynamic model is proposed to describe the mechanical-magneto-electro coupled characteristics of the device. Comparisons between the experimental and calculated results show that the proposed model can provide a reasonable qualitative indication of data trends, and can predict the effects of the acceleration excitation, the load resistance, and the bias magnetic field on the output performance of the device, thus has very strong practicability.Index Terms-Armstrong model, energy harvester, Galfenol, inverse magnetostrictive effect.

Modeling and Characterization of a Kinetic Energy Harvesting Device Based on Galfenol

“…These conditions are quite unreal for standard applications. Indeed, when such approximation is adopted, notable errors in outputs, with respect to the magnetic bias, are obtained [36,37,38].…”

Equivalent Strain and Stress Models for the Effect of Mechanical Loading on the Permeability of Ferromagnetic Materials

“…It still has to be determined whether the plus or minus sign has to be chosen in (10). Let's first consider a case with no shear strain/stress with respect to b, meaning that (b T d 2 b) = (b T db) 2 . This is the case with all other states in (3), except for σsh2.…”

“…This result corresponds exactly to the equivalent stress derived in [7], where the effect of shear stress on the equivalent stress was not considered. The above rule for choosing the sign in (10) will result in a discontinuity in teq around b T db = 2r/3 when shear is present such that (b T d 2 b) ≠ (b T db) 2 . However, since the minimum of ψ(B, teq) occurs at teq = r, the energy and permeability are symmetric with respect to teq = r, and thus the selection of the sign does not cause discontinuities in the permeability obtained from the model.…”

“…The equivalent strain model t = ε requires first transforming the stress configurations of (3) into equivalent strains by inverting the Hooke's law (2) and then applying (14). This needs to be done also for the uniaxial case, since the strain tensor is not uniaxial under uniaxial stress due to the Poisson effect.…”

“…AGNETO-MECHANICAL interaction causes additional losses and permeability degradation in electrical machine cores [1]. On the other hand, the same effects can be utilized for harvesting electrical energy from mechanical vibration [2], [3]. Complex multiaxial strains and stresses may occur in such applications, but identification measurements are most commonly available only under uniaxial stress parallel to the magnetic field [4]- [5].…”