Phenomenological modeling on cyclic deformation of superelastic NiTi shape memory alloy

Abstract

In the present work, a phenomenological constitutive model for the cyclic behavior of superelastic NiTi shape memory alloy is established. Various inelastic mechanisms, i.e. martensitic transformation, martensitic reorientation, transformation-induced plasticity and reorientation-induced plasticity, are included in the model. Within the framework of thermodynamics, the evolution equations of internal variables are derived from Clausius-Duhem inequality. Via finite-element implementation, the mechanical response and the configuration of the specimen subjected to cyclic uniaxial and multiaxial loadings can be obtained. As for uniaxial loading, the degradation of superelasticity, i.e. the increase of residual strain, the drop of transformation stress and the decrease of stress hysteresis, can be reproduced with high fidelity. As for multiaxial loading, the necessity of incorporating martensitic reorientation into the model is substantiated. Satisfactory agreement between simulation and experiment confirms the validity of the proposed approach.