Three types of constitutive models have been developed during the past decades including the phenomenological model, the micromechanical model and the microscopic thermodynamical model. In these phenomenological model type, we may find the cosine model (Liang and Rogers, 1990), the modified cosine model with decomposed Martensite volume fraction for the twinned part and the detwinned part (Brinson and Lammering, 1993), the exponential model (Boyd and Lagoudas, 1994) and the polynomial model. The microscopic thermodynamical model provides a unified constitutive framework from which many models can be derived (Qidwai and Lagoudas, 2000).