Magneto-thermo-mechanical characterization of 1–3 type polymer-bonded Terfenol-D composites

Abstract This paper describes magneto-thermo-mechanical test results for 1–3 type magnetostrictive composites incorporating Terfenol-D (Tb 0.3 Dy 0.7 Fe 2 ) particulate in an epoxy binder. The purpose of this study is to evaluate the behavior of magnetostrictive composites under combined magnetic, thermal, and mechanical loading, and to determine fundamental properties used for design of sonar transducers that incorporate these materials. Two different tests were performed both at room temperature and under thermal loading: (1) constant magnetic field with cyclically varying mechanical load around a bias load, and (2) constant mechanical pre-load with cyclically varying magnetic field. Testing was performed on five different volume fraction ( V p ) composites, namely, 13%, 23%, 31%, 37%, and 50%. Parameters that were evaluated include strain output ( e 3 ) and elastic modulus ( E 3 H ). Detailed analysis, including relative permeability ( μ 33 σ / μ 0 ) and the piezo-magnetic coefficient ( d 33 ), is only presented for the composite with 50% V p . Results indicate that composite properties, as pertaining to sonar transducers, are comparable to monolithic Terfenol-D while reducing brittleness, providing higher operational frequencies and easier manufacturability. Moreover, results for composite Terfenol-D can be explained well using theory developed for monolithic Terfenol-D.