Behaviors of Ferromagnetic Shape Memory Alloy Ni–Mn–Ga Under Incomplete Magneto-Mechanical Loading–Unloading Cycles



In order to investigate the behaviors of ferromagnetic shape memory alloys (FSMAs) under incomplete magneto-mechanical loading–unloading cycles, a single crystal Ni–Mn–Ga specimen is studied with the use of specially designed and manufactured test equipment. Characterization of the specimen is done, and simple experiments are conducted to approve validity of the findings and measurements by the prepared test rig. Stress–strain responses under different constant magnetic fields as well as strain–magnetic field responses under different amounts of a constant pressure are obtained for several complete and incomplete loading–unloading cycles to investigate behaviors of an FMSA when different kinds of interruptions are imposed in the course of loading or unloading. The so-called phenomena of strain hardening and return point memory are observed in the alloy, and similarities and differences between interruption during loading and unloading are investigated.