A thermo-mechanical constitutive equation for shape memory alloy

The thermomechanical macro-processes of super elasticity and shape memory effect occurring in shape memory alloy(SMA) are directly described using the concept of shape memory factor. A three-dimensional constitutive equation is developed based on thermodynamics and the assumption that SMA is an isotropic material. It overcomes both limitations that the previous three-dimensional constitutive equations are not available to predict the mechanical behaviors of SMA in the complex stress state and fail to express the mechanical behaviors of SMA with initial stress and strain. All material constants in the proposed constitutive equation can be determined through macroscopic experiments, which make it easily to be applied. Numerical results illustrate that it predicts the thermomechanical behaviors of SMA in the complex stress state very well. This paper can provide a theoretical basis for the applications of SMA.