The following user subroutines allow you to create user-defined material models:
UMAT for mechanical material models in Abaqus/Standard.
VUMAT for mechanical material models in Abaqus/Explicit.
UMATHT for thermal material models in Abaqus/Explicit.
“User-defined mechanical material behavior,” Section 26.7.1 of the Abaqus Analysis User's Guide
“User-defined thermal material behavior,” Section 26.7.2 of the Abaqus Analysis User's Guide
To define material constants for a user material:
From the menu bar in the Edit Material dialog box, select GeneralUser Material.
(For information on displaying the Edit Material dialog box, see “Creating or editing a material,” Section 12.7.1.)
If you are performing an Abaqus/Standard analysis, click the arrow to the right of the User material type field, and select the type of user material for which you are defining constants.
If you are performing an Abaqus/Standard analysis, toggle on Use unsymmetric material stiffness matrix if the material stiffness matrix, , is not symmetric or, in the case of a thermal constitutive model, if is not symmetric. This parameter causes Abaqus/Standard to use its unsymmetric equation solution procedures.
If you are defining a mechanical or thermomechanical material, enter the Mechanical Constants in the Data table.
For detailed information on how to enter data, see “Entering tabular data,” Section 3.2.7.
If you are defining a thermal or thermomechanical material, enter the Thermal Constants in the Data table.
For detailed information on how to enter data, see “Entering tabular data,” Section 3.2.7.
Click OK to close the Edit Material dialog box. Alternatively, you can select another material behavior to define from the menus in the Edit Material dialog box (see “Browsing and modifying material behaviors,” Section 12.7.2, for more information).