Magnetomechanical coupling and elastic moduli of polymer-bonded Terfenol composites

Abstract

The dependence of coupling coefficient (k) and elastic moduli (EH and EB) on particle size and volume fraction of Terfenol powder in polymer-bonded composites has been investigated. Materials were prepared with powder in five size ranges between 106 and 710 μm and in three volume fractions (VF). The moduli show a ΔE effect, which is negative for small bias fields and positive for larger fields. EH is found to be independent of particle size and to vary with VF in agreement with model predictions. The maximum value of k, for each sample, is found to be independent of both particle size and VF and a simple model is presented which predicts this behavior and indicates that the low values of kmax arise mainly from the low modulus of the epoxy binder.

Effect of the elastic modulus of the matrix on the coupling of magnetostrictive composites

“…Fig. 3 shows the measured as a function of bias field, , for epoxy-bonded ( = 60%) [6], phenol-bonded ( = 50%) and glass-bonded ( = 30% and 60%) composite Terfenol-D. Also shown for comparison is the dependence of on for a typical sample of bulk Terfenol-D.…”

“…Several studies have shown that the high frequency performance can be substantially improved by fabricating metal/epoxy resin composites [3]- [5]. Although the saturation magnetostrain of these composites is unaffected by the volume fraction provided that the limit of percolation is reached, the coupling coefficient is generally low ( 0.2) due to the significant difference between the elastic modulii of the metal phase and the epoxy phase [6]. It has recently been suggested that better performance could be expected by using materials for the matrix phase in which the mechanical properties more closely match those of the metal phase [7].…”

Longitudinally driven giant magneto-impedance effect enhancement by magneto-mechanical resonance

“…Hence, the ribbon's anisotropy field changed when the temperature was above 340 1C. It can be found from the inset that the sample annealed at 340 1C has the optimal MMC k 33 ; the amplitude peaked at 340 1C accordingly [11]. Based on above analysis, the maximal resonance amplitude appeared after 340 1C annealing.…”

Interfacial stiffness dependence of the effective magnetostriction of particulate magnetostrictive composites

“…Some adequately manipulated magnetostrictive composites can greatly reduce the eddy-current loss and improve mechanical properties while keeping relatively large magnetostriction. The magnetostrictive composite with resin matrix can be operated till several hundred kilohertz, which greatly extends frequency limit of magnetostrictive materials (Hudson et al, 1998).…”