Relaxation and creep phenomena in shape memory alloys. Part I: Hysteresis loop and pseudoelastic behavior

摘要

To describe the behavior of SMA we use a thermomechanical model, founded on a free energy which is a convex function with respect to the strain and to the martensitic volume fraction, and a concave one with respect to the temperature. The material parameters of the model are experimentally determined. In part I we prove that the model can describe the existence of the hysteresis loop and the pseudoelastic behavior of the SMAs. In part II we show that the model can predict stress relaxation and strain creep during martensitic transformation, and we compare this predictions with the corresponding experimental results obtained by us.