Experimental characterization of the sensor effect in ferromagnetic shape memory Ni-Mn-Ga

The characterization of a commercial Ni-Mn-Ga alloy for use as a deformation sensor is addressed. The experimental determination of flux density as a function of strain loading and unloading at various fixed magnetic fields gives the bias field needed for maximum recoverable flux density change. This bias field is shown to mark the transition from irreversible (quasiplastic) to reversible (pseudoelastic) stress-strain behavior. A reversible flux density change of 145 mT is observed over a range of 5.8% strain and 4.4 MPa stress at a bias field of 368 kA/m. The alloy investigated shows potential as a high-compliance, high-displacement deformation sensor.