The stiffness of the material model is generally unsymmetrical, but a symmetric matrix is used in the solution by default. If convergence difficulty occurs during the solution, specify the unsymmetric solver option (NROPT,UNSYM).

SMA phase transformation involves a transformation stage and the saturated transformation. Because convergence is more difficult to achieve during the transformation stage, break the transformation loadstep up into smaller ones and use smaller time steps.

The superelasticity option (TBOPT = SUPE) of the material model (TB,SMA) supports only 3D, plane strain, and axisymmetric stress states. The memory option (TBOPT = MEFF) of the material model supports most of the stress states including beam, shell, plane strain, axisymmetric, and 3D stress states. The LINK180 element is not supported for either material option.