“…As is shown in these studies the thermomechanical response of SMAs is extremely complex, a fact that in conjunction with the continuously increasing use of SMAs in several innovating applications in many engineering fields results in a greater need for a better understanding of these materials. For the past decades several constitutive models have appeared within the literature (e.g., Raniecki et al, 1992;Abeyaratne and Knowles, 1993;Ivshin and Pence, 1994;Boyd and Lagoudas, 1996;Lubliner and Auricchio, 1996;Panoskaltsis et al, 2004), which within the context of a geometrical linear theory can capture several aspects of the experimentally observed response. Nevertheless, the physics of the problem (e.g., see Smallman and Bishop, 2000), together with some basic results of the crystallographic theory of martensitic phase transformations (e.g., Ball and James, 1987;James and Hane, 2000;Abeyaratne et al 2001), suggest that a geometrically non -linear approach is more appropriate.…”