Experimental characterization of NiMnGa ferromagnetic shape memory alloy bars under variable loading conditions

A comprehensive experimental characterization of single crystal, martensite, NiMnGa rods is the current subject of study. Preliminary actuator force-displacement curves for DC magnetic fields up to 0.6 T in the static regime have been developed. A peak static actuation force of 5.5N at 0.4 mm in was observed. The effects AC magnetic fields below magnetic saturation were also examined. The dynamic force-displacement characteristics of the NiMnGa alloy in the presence of mechanical preloads was studied. Dynamic testing at AC fields of 0.3 T yielded strains of up to 1.2% and dynamic loads of up to 7 N. A possible material dependence on strain-rate and was observed from the experimental dynamic stress-strain curves.