说明：  This is an Abaqus user material subroutine UMAT in fortran language of a new 3D strain based constitutive model for shape emory alloys developped by Ben Jaber and coauthors in 2008 [1] and improved recently by Ben Jaber 2014 [2] This subroutine in Fortran language allows users to simulate thermomechanical behaviors of SMA products. More details about material parameters and internal variables are availables in The file UMAT_SMA_benjaber_ET_AL_ReadMe.pdf . [1] Ben Jaber M, Smaoui H and Terriault P (2008) Finite element analysis of a shape memory alloy three-dimensional beam based on a finite strain description Smart materials and structures 17(4), 045005. [2] Ben Jaber M (2014) Numerical implementation of a 3D strain-based constitutive model for shape memory alloys under a finite strain description Submitted to Smart materials and structures.