Analysis of the Parameters and Capabilities of a Three-Dimensional Transformation-Plasticity Coupled Shape Memory Alloy Material Model and Subroutine

A shape memory alloy material model with coupled transformation-plasticity and anisotropic constitutive behavior is implemented as a user subroutine (UMAT) in the commercial finite element code Abaqus. This phenomenological formulation accounts for micromechanical mechanisms using energetic definitions of elasticity, transformation initiation, transformation kinetics, transformation saturation, plastic yield, latent heat of transformation and coupled interactions of transformation and plasticity. The model is capable of anisotropic material symmetry and both isotropic and kinematic hardening through the definition of three elastic limit hypersurfaces: transformation initiation, transformation saturation, and plasticity. The model can analyze complex problems such as low temperature compression, stress-ratcheting, and fatigue; and for simulating some of these more complex behaviors, provides an improvement from other industry-standard models. In this presentation, the abilities of this model are demonstrated by presenting model parameters that features large temperature changes, large superelastic tension-compression asymmetry ratios and non-isotropic material assumptions and their numerical consequences. The mechanistic abilities of the material model are demonstrated using Abaqus simulations of complex loadings, including assessments against literature data.