Phenomenological Analysis on Subloops in Shape Memory Alloys Due to Incomplete Transformations

The subloops in the shape memory alloys, the stress-strain-temperature hysteresis loops due to the incomplete transformation, are analyzed from the phenomenological point of view. The transformation kinetics formulated by the same authors is generalized by introducing the transformation start conditions, both martensitic and reverse, which are assumed to be dependent on the extent of prior transformation and be determined from the isothermal or isostatic experiment. The theory developed is successfully applied to the simulations on the subloop behavior in the alloys under the various mechanical and/or thermal loads.