# PCNTX2

Bulk Data Entry Defines properties TYPE2 tied CONTACT interface for geometric nonlinear analysis.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PCNTX2 PID
IGNORE FSPOT LEVEL ISRCH IDELG
If FSPOT = 20, 21, or 22, two continuation lines
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RUPT IFILT SRTID SNTID STTID   MAXND MAXTD
FSTR FSTRATE FDIST ALPHA
If FSPOT = 25, one continuation line
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
STFAC VISC

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PCONT 34
PCNTX2 34

## Definitions

Field Contents SI Unit Example
PID Property identification number of the associated PCONT.

No default (Integer > 0)

IGNORE Flag to ignore secondary nodes if no main segment found for TIE contact. 6
0
No deletion of secondary nodes.
1
Secondary nodes with no main segment found are deleted from the interface.
2
Secondary nodes with no main segment found are deleted from the interface, if SRCHDIS is blank, then it would be new calculated internally.

Default as defined by CONTPRM (Integer)

FSPOT Spot weld formulation flag.
1
Formulation is optimized for spot weld or rivets.
2
Same formulation as standard formulation. Required when using hierarchy levels. Not compatible with nodal time step (TSTYP= GRID, TSC = CST).
4
Rotational degrees-of-freedom are not transmitted (if shells are used).
5 (Default)
Standard formulation.

(Integer)

20, 21, 22 - formulation with failure. Not compatible with nodal time step GRID(CST) on XSTEP card. The stress is computed for each secondary node according to the "equivalent" surface around the node. The equivalent surface is defined accordingly:
20
Surface computed using shell and brick faces attached to the node.
21
Surface computed using only the shell attached to the node.
22
Surface computed using only the brick faces attached to the node.
25
Penalty formulation.
30
Formulation with cubic curvature of main segment. Not compatible with nodal time step GRID(CST) on XSTEP card.

LEVEL Hierarchy level of the interface.

No default (Integer > 0)

ISRCH Search formulation flag for the closest main segment.
1
Old formulation (only used for previous version).
2 (Default)
New improved formulation.

(Integer)

IDELG Node deletion flag.
0
No deletion.
1
The kinematic condition is suppressed on secondary node, if the main element is deleted. (The secondary node is removed from the interface).

RUPT Failure model (only available with FSPOT = 20, 21, or 22) 6
0
Failure when MAXND or MAXTD are reached.
1
See Comment 10.

(Integer)

IFILT Filter flag. 12
0 (Default)
No filtering.
1
Filtering (alpha filter).

(Integer)

SRTID TABLEDi entry identification number defining stress factor versus stress rate. 8

No default (Integer ≥ 0)

SNTID TABLEDi entry identification number defining maximum normal stress versus normal relative displacement (ND).

This function must be defined. 8

No default (Integer > 0)

STTID TABLEDi entry identification number defining maximum tangential stress versus tangential relative displacement (TD).

This function must be defined. 8

No default (Integer > 0)

MAXND Maximum normal relative displacement.

Default = 1.0E20 (Real)

MAXTD Maximum tangential relative displacement.

Default = 1.0E20 (Real)

FSTR Stress scale factor. 8

Default = 1.00 (Real)

FSTRATE Stress rate scale factor. 8

Default = 1.00 (Real)

FDIST Distance scale factor. 8

Default = 1.00 (Real)

ALPHA Stress filter alpha value.

Default = 1.00 (Real)

STFAC Interface stiffness scale factor. (Only used with FSPOT = 25).

Default = 1.00 (Real)

VISC (Optional) Critical damping coefficient on interface stiffness (Only used with FSPOT = 25).

Default = 0.05 (Real)

1. The property identification number must be that of an existing PCONT Bulk Data Entry. Only one PCNTX2 property extension can be associated with a particular PCONT.
2. PCNTX2 is only applied in geometric nonlinear analysis subcases which are defined by ANALYSIS = EXPDYN. It is ignored for all other subcases.
3. PCNTX2 is only valid for tied contact specified using the TIE Bulk Data Entry. The PID field on the TIE entry can be used to reference the PCNTX2 entry.
4. Interface TYPE2 is a kinematic condition, no other kinematic condition should be set on any nodes of the secondary surface.
5. The default value for SRCHDIS is the average of the main segments.
6. If IGNORE = 1 or 2, the secondary nodes without a main segment found during the searching are deleted from the interface;

If IGNORE = 1 and SRCHDIS is blank, then the default value of the distance for searching closest main segment is the average size of the main segments;

If IGNORE = 2 and SRCHDIS is blank, then the distance for searching closest main segment is computed as follows for each secondary node:

d1 = 0.6 * (Ts + Tm)

d2 = 0.05 * Tmd

SRCHDIS = max(d1 , d2)

Where,
Ts
Thickness of the element connected to the secondary node, for solids Ts = 0.0
Tm
Thickness of main segment, for solids Tm = Element volume / Segment area
Tmd
Main segment diagonal
7. Main nodes of an interface TYPE2 may be secondary nodes of another interface TYPE2 if the hierarchy level of the first interface is lower than the hierarchy level of the second interface. Hierarchy levels are only available with FSPOT=2.
8. For failure (FSPOT = 20, 21, or 22), it could model glue connection. In this case, the force in secondary node will be scaled by reduced force coefficient ${f}_{N}$ ( ${f}_{T}$ ), which is computed as:(1)
$\begin{array}{l}{f}_{N}=\text{min}\left\{\sqrt{\frac{{\left({\sigma }_{N}^{\text{max}}\right)}^{2}}{\text{max}\left[{\left({\sigma }_{N}\left(t\right)\right)}^{2},{10}^{-20}\right]}},1\right\}\hfill \\ {f}_{T}=\text{min}\left\{\sqrt{\frac{{\left({\sigma }_{T}^{\text{max}}\right)}^{2}}{\text{max}\left[{\left({\sigma }_{T}\left(t\right)\right)}^{2},{10}^{-20}\right]},1}\right\}\hfill \end{array}$

The reduced force is compared to the maximum value:

If ${\sigma }_{N}<{\sigma }_{N}^{\text{max}}$ , then ${f}_{N}$ = 1, which means the force will not be reduced.

If ${\sigma }_{N}<{\sigma }_{N}^{\text{max}}$ , then ${f}_{N}=\sqrt{\frac{{\left({\sigma }_{N}^{\text{max}}\right)}^{2}}{\text{max}\left[{\left({\sigma }_{N}\left(t\right)\right)}^{2},{10}^{-20}\right]}}$ , which means the force will then be reduced.

Here the maximum value will be defined by you with:

$\begin{array}{l}{\sigma }_{N}^{\text{max}}=f\left(\stackrel{˙}{\sigma }\right)\cdot \text{SNTID}\left(\frac{\Delta {X}_{N}}{\text{FDIST}}\right)\hfill \\ {\sigma }_{T}^{\text{max}}=f\left(\stackrel{˙}{\sigma }\right)\cdot \text{STTID}\left(\frac{\Delta {X}_{N}}{\text{FDIST}}\right)\hfill \\ f\left(\stackrel{˙}{\sigma }\right)=\text{FSTR}\cdot \text{SRTID}\left(\frac{\stackrel{˙}{\sigma }}{\text{FSTRATE}}\right)\hfill \end{array}$

Where,
${\sigma }_{N}^{\text{max}}$
Maximum normal stress value defined by SNTID
${\sigma }_{N}\left(t\right)$
Normal stress
${\sigma }_{N}^{\text{max}}$
Maximum tangential stress value defined by STTID
${\sigma }_{T}\left(t\right)$
Tangential stress
FSTR
Input constant stress factor
SRTID
Input variable coefficient
SNTID and STTID
Input stress-displacement tables

Once the rupture criterion (defined by Rupt) is reached, the contact will be deleted.

9. If RUPT = 1, the failure criterion is:(2)
$\sqrt{{\left(\frac{\text{ND}}{\text{MAXND}}\right)}^{2}+{\left(\frac{\text{TD}}{\text{MAXTD}}\right)}^{2}}>1$
10. If FSPOT = 30, secondary mass/inertia/stiffness distribution to the main node is based on the Kirschoff model: bi-cubic form functions are used instead of linear (standard formulation). It allows a softer contact behavior since the element shape curvature is taken into account in the force/moment transmission.
11. If IDELG = 1, then when a 4-node shell, a 3-node shell or a solid element is deleted, it is also removed from the main side of the interface (kinematic condition is suppressed on relative slasecondaryve nodes).
12. If IFILT is set to 1, the normal and tangential stresses are filtered with an alpha filter, as: (3)
${\sigma }_{N}\left(t\right)=\text{ALPHA}×{\sigma }_{N}\left(t\right)+\left(1-\text{ALPHA}\right)×{\sigma }_{N}\left(t-1\right)$
(4)
${\sigma }_{T}\left(t\right)=\text{ALPHA}×{\sigma }_{T}\left(t\right)+\left(1-\text{ALPHA}\right)×{\sigma }_{T}\left(t-1\right)$
13. FSPOT = 25 (penalty formulation) will keep the penalty formulation during the whole run. The secondary node (of this contact) could also be the secondary node of another kinematic option, like rigid body. The penalty stiffness is constant, calculated as the mean nodal stiffness of main and secondary side. The stiffness factor, STFAC, may be used to modify it, if needed. The penalty stiffness will be multiplied by STFAC. A critical viscous damping coefficient (VISC) allows damping to be applied to the interface stiffness.