Magnetostrictive 1-3 composites with internal field biasing

Owen Thomas, Simon Busbridge, George Tomka

Research output: Contribution to journalArticle

Abstract

1-3 composites comprising an array of square Terfenol-D rods continuous in the direction of actuation and separated by an epoxy matrix have been produced. The benefits of a Terfenol-D 1-3 composite over bulk Terfenol-D and powder composites has been investigated. A higher frequency capability is realized while maintaining a greater coupling coefficient, k33, to that of powder composites. 1-3 composites were produced containing between 40% and 70% volume fraction of Terfenol-D. Magnetic biasing was achieved using Nd2Fe14B powder located within the epoxy matrix at 40% volume fraction. Internal bias fields of 75 and 45 kA/m were measured for the 1-3 composites containing 40% and 70% Terfenol-D, respectively. A coupling coefficient of 0.53 was measured for the composites filled with epoxy alone while the coupling coefficient varied from 0.33 to 0.48 for the biased composites with between 40% and 70% volume fraction of Terfenol-D, respectively. The acoustic impedance was determined using the radial resonance and observed to decrease with decreasing Terfenol-D volume fraction. A 50% volume fraction Terfenol-D 1-3 composite containing microspheres within the epoxy had the lowest measured acoustic impedance of 6.8 Mrayl, making this composite the most suitable for coupling acoustic energy into tissue/water for ultrasound/SONAR applications.
Original languageEnglish
Pages (from-to)2763-2765
Number of pages3
JournalIEEE transactions on magnetics
Volume40
Issue number4
DOIs
Publication statusPublished - 24 Aug 2004

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