PARTIAL HYSTERESIS CYCLES IN SHAPE-MEMORY ALLOYS : EXPERIMENTS AND MODELLING

Abstract
This work presents a collection of experimental pseudoelastic hysteresis cycles associated with the isothermal stress-induced martensitic transition of a Cu-Zn-Al single crystal. It is found that stress-strain trajectories retain memory of loading and unloading points, as observed for polycrystals. A particular version of the Preisach model for hysteresis is used to predict partial loops, using a limited number of experimental trajectories as input data and no adjustable parameters. Comparison between measured and predicted trajectories reveal that energy dissipation in the forward transition is different than in the reverse transition ; this is confirmed by a distinct evolution with transformed fraction of the energy losses computed from two different (loading and unloading) kinds of partial cycles.