# PCNTX11

Bulk Data Entry Defines properties TYPE11 of a CONTACT interface for geometric nonlinear analysis.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PCNTX11 PID   ISTF   IGAP     IDEL
STMIN STMAX MESHSIZE DTMIN
STFAC FRIC GAP TSTART TEND STF1
IBC     INACTI VISS VISF BMULT

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PCONT 34
PCNTX11 34

## Definitions

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

No default (Integer > 0)

ISTF Stiffness definition flag. 5
0
STFAC is a stiffness scale factor and the stiffness is computed according to the main side characteristics.
1
STIF1 is used as interface stiffness.
2, 3, 4 and 5
STFAC is a stiffness scale factor and the interface stiffness is computed from both main and secondary characteristics.

Default as defined by CONTPRM (Integer = 0, ..., 5)

IGAP Gap definition flag.
CONST
Gap is constant and equal to GAP.
VAR
Gap is a variable (in space, not in time) according to the characteristics of the impacted main line and the impacting secondary nodes. 6
VAR3
Gap is a variable according to the characteristics of the impacted main line and impacting secondary node + gap is taken into account the size of the elements.

Default as defined by CONTPRM (Character)

IDEL Node and segment deletion flag.
0
No deletion.
1
When all the elements (shells, solids) associated to one segment are deleted, the segment is removed from the main side of the interface. Additionally, non-connected nodes are removed from the secondary side of the interface.
2
When a shell or a solid element is deleted, the corresponding segment is removed from the main side of the interface. Additionally, non-connected nodes are removed from the secondary side of the interface.

Default as defined by CONTPRM (Integer)

STMIN Minimum stiffness (Only with ISTF > 1).

Default as defined by CONTPRM (Real ≥ 0)

STMAX Maximum stiffness (Only with ISTF > 1).

Default as defined by CONTPRM (Real ≥ 0)

MESHSIZE Percentage of mesh size (Used only when IGAP = VAR3).

Default = 0.4 (Real, 0.0 < MESHSIZE ≤ 1.0)

DTMIN Limiting nodal time step. 8

No default (Real ≥ 0)

STFAC Interface stiffness scale factor (Only with ISTF1).

Default as defined by CONTPRM (Real ≥ 0)

FRIC Coulomb friction.

Default as defined by CONTPRM (Real ≥ 0)

GAP Gap for impact activation. 6

Default as defined by CONTPRM (Real ≥ 0)

TSTART Start time.

Default = 0.0 (Real ≥ 0)

TEND Time for temporary deactivation.

Default = 1030 (Real ≥ 0)

STIF1 Interface stiffness (Only with ISTF = 1).

Default = 0.0 (Real ≥ 0)

IBC Flag for deactivation of boundary conditions at impact applied to the secondary grid set.

Default as defined by CONTPRM (Character = X, Y, Z, XY, XZ, YZ, or XYZ)

INACTI Handling of initial penetrations flag. 7
0
No action.
1
Deactivation of stiffness on nodes.
2
Deactivation of stiffness on elements.
3
Change secondary node coordinates to avoid small initial penetrations.
5
GAP is variable with time and initial gap is adjusted as:
${\text{gap}}_{0}=\text{gap}-{\text{P}}_{0}$
6
Gap is variable with time but initial gap is slightly de-penetrated as:
${\text{gap}}_{0}=\text{gap}-{\text{P}}_{0}-0.05*\left(\text{gap}-{\text{P}}_{0}\right)$

Invalid entries are ignored.

Default as defined by CONTPRM (Integer)

VISS Critical damping coefficient on interface stiffness.

Default as defined by CONTPRM (Real ≥ 0)

VISF Critical damping coefficient on interface friction.

Default as defined by CONTPRM (Real ≥ 0)

BMULT Sorting factor. Can be used to speed up the sorting algorithm and is machine-dependent.

Default as defined by CONTPRM (Real ≥ 0)

## Comments

1. The property identification number must be that of an existing PCONT Bulk Data Entry. Only one PCNTX11 property extension can be associated with a particular PCONT.
2. PCNTX11 is only applied in geometric nonlinear analysis subcases which are defined by ANALYSIS = EXPDYN. It is ignored for all other subcases.
3. If FRIC is not explicitly defined on the PCONTX/PCNTX# entries, the MU1 value on the CONTACT or PCONT entry is used for FRIC in the /INTER entries for Geometric Nonlinear Analysis. Otherwise, FRIC on PCONTX/PCNTX# overwrites the MU1 value on CONTACT/PCONT.
4. PCNTX11 defines the properties of contact interface type CONTX11, it describes the edge to edge or line to line interface. This interface simulates impact between lines, a line can be a beam or truss element or a shell edge or spring elements. The interface properties are:
• impacts occur between a main and a secondary line
• a secondary line can impact on one or more main lines
• a line can belong to the main and the secondary side. This allows self impact.
• this interface can be used in addition to the interface TYPE7 PCNTX7 to solve the edge to edge limitation of interface TYPE7
5. If ISTF1, the interface stiffness K is computed from the main segment stiffness Km and/or the secondary segment stiffness Ks.

The main stiffness is computed from Km = STFAC * B * S * S/V for solids, Km = 0.5 * STFAC * E * t for shells.

The secondary stiffness is an equivalent nodal stiffness computed as Ks = STFAC * B * V-3 for solids, Ks = 0.5 * STFAC * E * t for shells.

In these equations, B is the Bulk Modulus, S is the segment area, and V is the volume of a solid. There is no limitation to the value of stiffness factor (but a value larger than 1.0 can reduce the initial time step).

The interface stiffness is K = max (STMIN, min (STMAX, K1)) with:
• ISTF = 0, K1 = Km
• ISTF = 2, K1 = 0.5 * (Km + Ks)
• ISTF = 3, K1 = max (Km, Ks)
• ISTF = 4, K1 = min (Km, Ks)
• ISTF = 5, K1 = Km * Ks / (Km + Ks)
6. If IGAP = VAR, the variable gap is computed as: gm + gs
with:
• gm - main element gap with

gm = t/2, t: thickness of the main element for shell elements.

gm = L/10, L - length of the smallest side of a solid element.

gm = 1/2√ for truss and beam elements, with S being the cross section of the element.

gm = 0 for spring elements.

• gs - secondary element gap is computed as the same way.

If the secondary node is connected to multiple shells and/or beams or trusses, the largest computed secondary gap is used.

The variable gap is always at least equal to GAP.

7. INACTI = 3, is only recommended for small initial penetrations and should be used with caution because:
• the coordinate change is irreversible
• it may create other initial penetrations, if several surface layers are defined in the interfaces
• it may create initial energy, if the node belongs to a spring element

INACTI = 5 is recommended for airbag simulation deployment.

INACTI = 6 is recommended instead of INACTI = 5, in order to avoid high frequency effects into the interfaces.
8. Secondary segment is deactivated from the contact when the segment kinematic time step calculated for this contact becomes smaller than DTMIN.