| Popis: |
We investigated the dynamic behavior of 1-3 type magnetostrictive particulate composites as a function of both bias field (5-140 kA/m) and frequency (1-100 kHz). The composites consist of approximately 0.5 volume-fraction Terfenol-D particles embedded and magnetically aligned in a passive epoxy matrix. The measured properties include elastic moduli (E/sub 3//sup H/ and E/sub 3//sup B/), dynamic relative permeability (/spl mu//sub r33/), dynamic strain coefficient (d/sub 33/), magnetomechanical coupling coefficient (k/sub 33/), and the ratio of the dynamic strain coefficient to the dynamic susceptibility (d/sub 33///spl chi//sub 33/). We observed the dependence of these properties on bias field and explain it here in terms of domain-wall motion followed by saturation near 40 kA/m. The spectra of /spl mu//sub r33/, d/sub 33/, and d/sub 33///spl chi//sub 33/ indicate that the magnetization process is independent of frequency and that the effect of eddy-current losses is insignificant up to 100 kHz. The observations agree with predictions made by classical eddy-current theory and suggest that the composites can be operated at significantly higher frequencies than monolithic Terfenol-D. |
