TIE

Bulk Data Entry Defines a tied contact in Linear Static Analysis (STATICS) and Small Displacement Nonlinear Analysis (NLSTAT).

PENALTY-based and MPC-based TIE contacts are available and can be selected using CONTPRM, TIE. 7

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
TIE TID PID SSID MSID DOF SRCHDIS ADJUST    
  DISCRET     GSETID ROT        

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
TIE 5   7 8   0.01      
  N25     2          

Definitions

Field Contents SI Unit Example
TID Tied interface identification number. 1

(Integer > 0)

  
PID Identification number of a Property entry defined in Geometric Nonlinear Analysis ( Radioss Integration). This field is only valid for Geometric Nonlinear Analysis (ANALYSIS=EXPDYN).

(Integer > 0)

  
SSID Slave entity identification number. 2 3

(Integer > 0)

  
MSID Master entity identification number. 2 3

(Integer > 0)

  
DOF Defines the degrees-of-freedom (component numbers) that are tied together in MPC-based TIE contact.

Default = 123 (Integer, up to six unique digits (0 < digit ≤ 6) may be placed in the field with no embedded blanks for grid points. The components are in the output coordinate system referenced by the slave grid points).

  
SRCHDIS Search distance criterion for creating contact condition. When specified, only slave nodes that are within SRCHDIS distance from master surface will have contact condition checked.

Default = Half of the master element size (Real > 0 or blank)

For Node-to-Node (N2N) discretization, the default is 0.0.

  
ADJUST Adjustment of slave nodes onto the master surface at the start of a simulation. 5
NO (Default)
No adjustment.
AUTO
A real value equal to 5% of the average edge length on the master surface is internally assigned as the depth criterion.
Real ≥ 0.0
Value of the depth criterion which defines the zone in which a search is conducted for slave nodes (for which contact elements have been created). These slave nodes (with created contact elements) are then adjusted onto the master surface. The assigned depth criterion is used to define the searching zone in the pushout direction.
Integer > 0
Identification number of a SET entry with TYPE=GRID. Only the nodes on the slave entity, which also belong to this SET, will be selected for adjustment.

For Node-to-Node (N2N) discretization, the default is NO and Real value can be specified for the depth criterion, similar to other discretization types. AUTO and Integer do not apply for N2N discretization.

  
DISCRET Discretization approach type for the construction of contact elements. 2 3
N2S
Node-to-surface discretization.
S2S
Surface-to-surface discretization.
N2N
Node-to-node discretization. 3 9
blank (Default)
Surface-to-surface discretization if the slave is not a set of grids and there is no heat transfer analysis; node-to-surface discretization, otherwise.
  
GSETID Identifies a SET entry that references grid points of the slave entity that are to be included in the TIE contact regardless of the search distance. Therefore, for any grid points identified via GSETID, if a corresponding master surface is available, then a corresponding TIE contact is generated regardless of the SRCHDIS field value.

This grid set should always be a subset of the grids in the slave entity (identified by the SSID field).

The GSETID field is not supported for N2N discretization.

(Integer > 0 or blank)		  
ROT Constraining rotational degrees of freedom for Node-to-Surface Tie contact (this is only supported for Large Displacement).
YES (Default)
Rotational degrees of freedom are constrained.
NO
Rotational degrees of freedom are not constrained.
  

Comments - Small Displacement Nonlinear Analysis

  1. A TIE Bulk Data Entry should have a unique ID when compared to all CONTACT Bulk Data Entries. TIE Bulk Data Entry is internally converted to CONTACT Bulk Data with FREEZE option.
  2. The slave entity (SSID) always consists of grid nodes. It may be specified as:
    • a set of grid nodes defined using SET card
    • a surface defined using SURF card (the slave nodes are picked from the respective nodes of the SURF faces)
    • a set of elements (shells or solids) defined using SET card. Slave nodes are picked from the respective nodes of the elements in the set. For 3D solids, only nodes on the surface of the solid body are selected; internal nodes are not considered.
    • OptiStruct will error out, if the structural side is set as Slave in MPC-based TIE contact for Fluid-Structure model.
    • DISCRET=N2S is recommended if the slave entity is a set of grids (nodes) or a set of solid elements. For further information, refer to Contact Discretization in the User Guide.
  3. The master entity (MSID) may be defined as:
    • a surface defined using SURF card
    • a set of elements (shells or solids) defined using SET card. For sets of 3D solids, element faces on the surface are automatically found and selected as master surface.
    • For N2N discretization, MSID should refer to a GRID set defined by the SET entry.
  4. TIE element is created with the same structure as a CONTACT element of TYPE=FREEZE. TIE element enforces zero relative motion on the contact surface - the contact gap opening remains fixed at the original value and the sliding distance is forced to be zero. Also, rotations at the slave node are matched to the rotations of the master patch. For further information, refer to Contact Discretization in the User Guide.
  5. For further information regarding SRCHDIS and ADJUST, refer to Contact Interface Parameters (Contact Control) in the User Guide.
  6. Contact stabilization for surface-to-surface contact and node-to-surface contact can be activated using the CNTSTB Subcase Information and CNTSTB Bulk Data Entries. Additionally, the PARAM, EXPERTNL can be used to activate contact stabilization. The CNTSTB Bulk Data parameters override the parameter values for a particular subcase.
  7. Two types of TIE contact are available, PENALTY-based and MPC-based. The two types can be switched using CONTPRM, TIE, PENALTY/MPC. The MPC-based TIE uses Multi-point Constraints to define a tied contact between the master and slave surfaces. Additionally, the MPC's can be output to <filename>_contmpc.fem using CONTPRM, CONTMPC, YES. If CONTPRM, TIE, MPC is specified, all the TIE contacts in the model are defined using the MPC-based method. For further information regarding SRCHDIS and ADJUST, refer to Lagrange Multipliers (MPC-based) in the User Guide.
  8. N2S option should be used to activate large shape change during shape optimization. Currently, large shape change is activated if the model has N2S contact or CGAP/CGAPG/CWELD/CFAST/CSEAM elements.
  9. N2N discretization is currently only supported for Small Displacement Nonlinear Analysis.
  10. For Implicit Analysis, PENALTY-based TIE is the default. Whereas, for Explicit Analysis, MPC-based TIE is the default. For Explicit Analysis, if OptiStruct detects the model contains over-constraint conditions, then the related TIE is switched to PENALTY-based TIE automatically.
  11. This card is represented as a group in HyperMesh.