Thermodynamical model of NiTi SMA including plastic deformation mechanisms
Besides the inclusion of mechanisms of plastic deformation in both austenitic and martensitic phases in an independent manner, the model newly captures also more complex coupled phenomena of martensitic transformation and plastic deformation, such as transformation-induced plasticity, stabilization of martensite by plastic deformation, or plastic-induced microstrain heterogeneity leading to functional fatigue. Despite a large number of different mechanisms involved in the model, which is reflected by a considerable number of internal parameters introduced for the description of evolving microstructure, the model still brings a basic, simple phenomenological understanding of the coupled transformation-plasticity proceeding in NiTi, and, after its successful implementation to FEM software, it may open many new possibilities for simulations of NiTi components' behavior and processing.
We will present a comparison of several experimental and simulated data and discuss how the understanding and description of coupled transformation and plasticity can allow tailoring of strain heterogeneity on both micro and macro scales inside NiTi components.