CNTSTB
Bulk Data Entry Defines parameters for stabilization control of contact (S2S and N2S) and gap elements (CGAP/CGAPG). This entry is supported with nonlinear static and nonlinear transient analysis types for both small and large displacement cases.
A CNTSTB Bulk Data Entry should be referenced by a CNTSTB Subcase Information entry to be applied in a particular subcase.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
CNTSTB | ID | APSTB | LMTGAP | S0 | S1 | ||||
SCALE | TFRAC |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
CNTINT | CTID | APSTB | LMTGAP | SO | S1 | ||||
SCALE | TFRAC |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
GAPINT | PID | APSTB | LMTGAP | SO | S1 | ||||
SCALE | TFRAC |
CNTINT and GAPINT continuation lines can coexist in one CNTSTB card. CTID and PID can be identical in one CNTSTB card, as well.
Example
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
CNTSTB | 99 | NO | |||||||
CNTINT | 51 | YES | |||||||
0.01 | |||||||||
CNTINT | 52 | YES | |||||||
10.0 | 0.01 | ||||||||
GAPINT | 52 | YES | |||||||
1.0E4 | 0.25 | ||||||||
GAPINT | 58 | YES | 1.0 | 0.001 | |||||
1.0E4 | 0.05 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
ID | Each
CNTSTB Bulk Data Entry should have a unique
identification number. No default (Integer > 0) |
|
APSTB | Head flag indicating if
contact stabilization is activated.
Note: All the fields following
APSTB should be blank, if
APSTB is set to
NO. |
|
LMTGAP | Contact opening threshold
for stabilization. Stabilization becomes zero when contact opening
is greater than or equal to this value.
There is no default for the GAPINT continuation line. You are required to provide a value for LMTGAP field, if the GAPINT continuation line is specified. (Real > 0.0 - specified threshold value) |
|
S0 | Scale factor for
stabilization coefficient at the start of a subcase. Default = 1.0 (Real ≥ 0.0) |
|
S1 | Scale factor for
stabilization coefficient at the end of a subcase. Default = 0.0 (Real ≥ 0.0) |
|
SCALE | Stabilization coefficient
scale factor. Default = 1.0 (Real ≥ 0.0) |
|
TFRAC | Factor for scaling
tangential stabilization with respect to normal
stabilization. Default = 0.1 (Real ≥ 0.0) |
|
CNTINT | Defines the start of a continuation line used to specify another set of stabilization parameters, which overrides the set of parameters defined above, for a specific contact interface (CTID). It can be repeated as required. | |
CTID | Contact interface
identification number. No default (Integer > 0) |
|
GAPINT | Defines the start of a continuation line used to specify another set of stabilization parameters, which overrides the set of parameters defined above, for specific CGAP/CGAPG elements (PID). It can be repeated as required. | |
PID | Gap property
identification number. No default (Integer > 0) |
Comments
- The CNTSTB Bulk Data Entry is selected by the CNTSTB Subcase Information Entry.
- When APSTB is YES, the contact
normal stabilization stiffness
is calculated as:Where,
- Reference stiffness for contact stabilization.
- Time-dependent scale factor.
For time, in a subcase, is calculated as:
Where,- Time at the start of the subcase.
- Time at the end of the subcase.
is calculated using and as .
- When APSTB is YES, the contact
tangent stabilization stiffness
is calculated as:
- The defaults and priority information in conjunction with PARAM,EXPERTNL,CNTSTB for different contact types are:
Table 1. Contact Stabilizationstabilization is not applicable to FREEZE or TIE Contact LGDISP or (LGDISP+SMDISP) g SMDISP N2S b/S2S CGAP/CGAPG N2S c (CGAPG-core)
S2S CGAP/CGAPG PARAM,EXPERTNL,CNTSTB Damping d Artificial Spring e Artificial Spring e Damping d Artificial Spring e CNTSTB (Priority a) (Bulk card referenced by Subcase Entry)
Damping (‘CNTINT’ or the first line of CNTSTB Bulk card)
Damping f (‘GAPINT’)
Damping (‘CNTINT’ or the first line of CNTSTB Bulk card)
Damping (‘CNTINT’ or the first line of CNTSTB Bulk card)
Damping f (‘GAPINT’)
- When both CNTSTB Subcase/Bulk Data pair and PARAM,EXPERTNL,CNTSTB are defined in a subcase, the CNTSTB Subcase/Bulk Data pair takes priority. For other subcases, the stabilization with the PARAM is effective.
- When there are LGDISP subcases in a deck file, N2S contact will be converted to Internally generated contact (different from CGAPG), and the stabilization on N2S contact will be conducted in this category.
- CGAPG-core N2S is generated, when N2S contact is defined and there is no LGDISP subcases defined in a deck file. The stabilization on N2S contact will be conducted in this category.
- In this case, the stabilization activated with the PARAM is consistent with the stabilization activated with default settings of the CNTSTB Bulk Data Entry.
- The artificial spring stiffness is
determined by: Where,
- Artificial spring stiffness used to stabilize the gap elements.
- Reference gap stiffness, generally it represents the stiffness of surrounding elements.
- Global analysis time.
- The data defined in the first line of this card does not apply on CGAP/CGAPG elements. In order to apply damping stabilization on these elements, continuation lines with ‘GAPINT’ flag must be defined and referenced.
- SMDISP+LGDISP indicates models which contain both SMDISP subcases and LGDISP subcases in the same model.
- Contact stabilization introduces artificial energy that can delay the open-to-close and close-to-open transitions, and it should be used with caution.
- This card is represented as a load collector in HyperMesh.