Contact interaction (TB,INTER) can be used to specify the type of interaction between general contact surfaces. These interactions are defined via the GCDEF command. TB,INTER can also be used to specify a user-defined interaction for pair-based contact elements or for general contact definitions.
Contact interactions for general contact definitions are specified
via the TB,INTER command instead of using KEYOPT(12)
(as for pair-based contact definitions). The interaction option is
specified by the TBOPT field as shown in
the table below.
| TBOPT Label | Interaction Behavior | Description |
|---|---|---|
| STANDARD | Standard unilateral contact | Normal pressure equals zero if separation occurs. (Similar to KEYOPT(12) = 0 for pair-based contact elements.) |
| ROUGH | Rough (no sliding) | Perfectly rough frictional contact where there is no sliding. (Similar to KEYOPT(12) = 1 for pair-based contact elements.) |
| NOSEPE | No separation (sliding permitted) | No separation contact in which the target and contact surfaces are tied for the remainder of the analysis once contact is established (although sliding is permitted). (Similar to KEYOPT(12) = 2 for pair-based contact elements.) |
| BONDED | Bonded contact (no separation, no sliding) | Bonded contact in which the target and contact surfaces are bonded in all directions (once contact is established) for the remainder of the analysis. (Similar to KEYOPT(12) = 3 for pair-based contact elements.) |
| ANOSEP | No separation (always) | No separation contact in which contact detection points that are either initially inside the pinball region or that once involve contact always attach to the target surface along the normal direction to the contact surface (sliding is permitted). (Similar to KEYOPT(12) = 4 for pair-based contact elements.) |
| ABOND | Bonded (always) | Bonded contact in which contact detection points that are either initially inside the pinball region or that once involve contact always attach to the target surface along the normal and tangent directions to the contact surface (fully bonded). (Similar to KEYOPT(12) = 5 for pair-based contact elements.) |
| IBOND | Bonded (initial contact) | Bonded contact in which the contact detection points that are initially in a closed state will remain attached to the target surface, and the contact detection points that are initially in an open state will remain open throughout the analysis. (Similar to KEYOPT(12) = 6 for pair-based contact elements.) |
All of the above options use one material constant (C1) on the TBDATA command. The value of C1 defines the effect of initial penetration or gap, as described in the table below.
| C1 Value | Description |
|---|---|
| 0[a] | Include both initial geometrical penetration or gap and offset. (Similar to KEYOPT(9) = 0 for pair-based contact elements.) |
| 1[b] | Exclude both initial geometrical penetration or gap and offset. (Similar to KEYOPT(9) = 1 for pair-based contact elements.) |
| 2 | Include both initial geometrical penetration or gap and offset, but with ramped effects. (Similar to KEYOPT(9) = 2 for pair-based contact elements.) |
| 3 | Include offset only (exclude initial geometrical penetration or gap). (Similar to KEYOPT(9) = 3 for pair-based contact elements.) |
| 4 | Include offset only (exclude initial geometrical penetration or gap), but with ramped effects. (Similar to KEYOPT(9) = 4 for pair-based contact elements.) |
| 5 | Include offset only (exclude initial geometrical penetration or gap) regardless of the initial contact status (near-field or closed). (Similar to KEYOPT(9) = 5 for pair-based contact elements.) |
| 6 | Include offset only (exclude initial geometrical penetration or gap), but with ramped effects regardless of the initial contact status (near-field or closed). (Similar to KEYOPT(9) = 6 for pair-based contact elements.) |
Note that the effects of C1 input are dependent on which TBOPT label was previously defined. The indicated initial
gap effect is considered only if TBOPT =
ANOSE or TBOPT = ABOND is defined.
As an alternative to the program-supplied interface behaviors,
you can define your own interaction model with the user-programmable
subroutine, USERINTER. You can specify a number
of properties or constants associated with your interaction model,
and you can introduce extra solution-dependent state variables that
can be updated and used within the subroutine. User-defined interaction
is applicable to 2D and 3D contact elements used in pair-based contact
definitions or general contact definitions.
After writing a USERINTER subroutine to
program your interaction model, you incorporate the model in your
analysis by using the command TB,INTER with TBOPT = USER and specifying the interaction properties
on the TBDATA command as shown below.
TB,INTER,1,,2,USER ! Activate user defined contact interaction; NPTS = 2 TBDATA,1,PROP1,PROP2 ! Define interaction properties
For detailed information on using the USERINTER subroutine, see Defining Your Own Contact Interaction (USERINTER) in the Contact Technology Guide.