Constitutive model for shape memory alloys including phase transformation, martensitic reorientation and twins accommodation

This paper deals with the thermomechanical modeling of the macroscopic behavior of NiTi shape memory alloys (SMAs). A phenomenological 3D-model, based on thermodynamics of irreversible processes is presented. Three main physical mechanisms are considered: the martensitic transformation, the reorientation of martensite and the inelastic accommodation of twins in self-accommodated martensite. The description of such strain mechanisms allow an accurate analysis of SMA behavior under complex thermomechanical paths, especially when transformation occurs at low stress level. Moreover, some key characteristics such as tension–compression asymmetry and internal loops inside the major hysteresis loop are taken into account. Numerical simulations for various theromechanical loading paths are presented to illustrate the present model capability to capture the complex behavior of SMAs

Research highlights► Constitutive model for SMA developed to capture transformation and reorientation, suitable for non–proportional loadings. ► Include the effect of the accommodation of twins and features such tension-compression asymmetry amd internal loops during transformation. ► Capture the superelastic behavior, shape memory effect, thermal actuation under strain, and stress recovery.