ABSTRACT
Several examples in the preceding chapters are solved with the aid of Abaqus programmable features such as UMAT and UGENS. Because of the complexity of FORTRAN and PYTHON coding, the programming required by those examples is deferred to this chapter. Programmable features require additional software such as compilers and libraries, necessitating detailed installation instructions that are included in a new Appendix. In this chapter, detailed descriptions are given on how to write the FORTRAN code for UMAT and UGENS in various flavors depending on the type of elements required (1D, plane stress, 3D solid) and implementing new capabilities that native Abaqus does not have. Furthermore, details about how to provide the augmented Abaqus solver with the data needed by these new capabilities and how to visualize their novel results is also provided. All of this is illustrated by examples including custom-coded failure criteria, orthotropic viscoelasticity, continuum damage mechanics (CDM), non-local constitutive models (DDM), and fatigue. Furthermore, interaction with Abaqus CAE and MATLAB is best done by using PYTHON scripts that CAE can execute. This is illustrated with examples on how to write constraint equations (CE), calculate volume average of stresses and strains, simulate discrete damage mechanics, and evaluate thermal fatigue.
