The Mechanical APDL program activates many UPFs via a specific user action. This can be through a command option or a user selection. Below is a list of specific actions required for several types of UPF.
To activate user elements created using the method described in Creating a New Element via the User-Defined Element API, you need USRELEM and USRDOF commands, as well as ET and TYPE commands.
To activate a user element created using the method described in Creating a New Element by Directly Accessing the Program Database, you must select it as one of the element types in a model using the ET command, then set the element attribute pointer using the TYPE command, and define elements using the solid modeling or direct generation method.
To define a user material described in Subroutine UserMat (Creating Your Own Material Model), Subroutine UserCreep (Defining Your Own Implicit Creep Material Behavior), and Subroutine userswstrain (Defining Your Own Swelling Laws), you need to activate it with the corresponding TB commands.
To customize contact interfacial behaviors as described in Subroutine USERFRIC (Writing Your Own Friction Laws) and Subroutine USERINTER (Writing Your Own Contact Interactions), you need to activate them with the corresponding TB commands.
To program history-dependent contact properties described in Subroutine USERCNPROP (Defining Your Own Real Constants for Contact Elements), you need to activate the user routine with the R, RMORE, or RMODIF command. The real constant must be defined by the Mechanical APDL reserved table name _CNPROP and enclosed in % signs (that is, %_CNPROP%).
UPFs that are not activated by the means described above must be activated by either of the following methods:
Issuing the USRCAL command
Choosing menu path or .
To activate or deactivate the routines, issue the command
USRCAL,Rnam1,
...Rnam9, where Rnam1 and
Rnam9 are the names of specific routines. You can specify up to
nine routines with one USRCAL command, or you can issue multiple
USRCAL commands.
Issue the command USRCAL,NONE to deactivate all valid user subroutines. To list the status of the routines, issue the command USRCAL,STAT.
For a list of the user routines that the USRCAL command (or its equivalent menu paths) affects, see the USRCAL command description in the Command Reference.
If you do not activate the UPFs in this manner, standard Mechanical APDL logic is used by default. For example, when you apply a convection load, standard Mechanical APDL logic is the default even if you have a user convection routine linked in. The user convection routine must be activated by the USRCAL command or its menu equivalent.