Magnetomechanical properties of terfenol-D 2-2 composites with internal field biasing

Two self-biased Terfenol-D 2-2 composites have been produced with laminations perpendicular to (112) and an internal magnetic field along [112]. The characteristic frequency of a sample of dimensions 2.5 ×7.0×10.0 mm has been increased to 53 kHz compared to 0.2 kHz for the bulk material by increasing the resistivity to 1×10^-5 Ωm. The static strain along [1~1~1] was found to be 752 and 647 ppm for the two samples when [1~1~1] was parallel to the externally applied field H_appl. When [1~1~1] was perpendicular to H_appl the internal field H_int must be added to H_appl thereby giving an asymmetrical strain versus H_appl curve. Eddy currents have been reduced by the introduction of a thin insulating layer, the mechanical properties of which critically control the magnetoelastic performance of the composite.