SMA Constitutive Modeling Backed Up by 3D-XRD Experiments: Transformation Front in Stretched NiTi Wire

It has been known for a long time that martensitic phase transformation in NiTi shape memory alloys loaded in tension develops inhomogeneously via formation and propagation of macroscopic deformation bands resembling well-known Luders bands. Growing literature evidence supports the view that NiTi, in fact, develops a variety of localized deformation phenomena in particular geometries and loading modes. Coupling of cutting-edge experimental methods with dedicated modeling techniques can bring new insight into such a type of behavior. In this short review of our recent study, we demonstrate this synergic approach on the investigation of the martensite band in a stretched NiTi superelastic wire, in which the advanced technique of three-dimensional X-ray diffraction was complemented by NiTi-tailored constitutive model. We focus mainly on the modeling part, but the experimental background motivating and validating the chosen numerical approach is also briefly presented.