TIE

Bulk Data Entry

TIE – Tied Contact Definition

Description

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 (Comment 8).

Format

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

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

Field	Contents
TID	Tied interface identification number. See Comment 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. See comments 2 and 3. (Integer > 0)
MSID	Master entity identification number. See comments 2 and 3. (Integer > 0)
DOF	Defines the degrees-of-freedom (component numbers) that are tied together in MPI-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 = All slave nodes checked (Real > 0 or blank)
ADJUST	Adjustment of slave nodes onto the master surface at the start of a simulation. See Comment 5. <NO, AUTO, Real > 0.0, or Integer > 0> Default = NO. NO – 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.
DISCRET	Discretization approach type for the construction of contact elements. See Comments 2 and 3. <N2S, S2S, blank> Default = blank. N2S – node-to-surface discretization. S2S – surface-to-surface discretization. blank – 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.

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's 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.

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's Guide.

5.	For further information regarding SRCHDIS and ADJUST, refer to Contact Interface Parameters in the User's Guide.

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,CNTSTB can be used to activate contact stabilization. The CNTSTB bulk data parameters override the parameter values for a particular subcase.

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's Guide.

8.	This card is represented as a group in HyperMesh.