PCNTX5

Bulk Data Entry

PCNTX5 – Extended CONTACT Property type 5 for Geometric Nonlinear Analysis

Description

Defines properties type 5 of a CONTACT interface for geometric nonlinear analysis.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PCNTX5	PID					IBAG	IDEL
	STFAC	FRIC	GAP	TSTART	TEND
	IBC		IRM	INACTI
	IFRIC	IFILT	FFAC
	FRICDAT	C1	C2	C3	C4	C5	C6

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
PCONT	34
PCNTX5	34

Field	Contents
PID	Property identification number of the associated PCONT. No default (Integer > 0)
IBAG	Airbag vent holes closure flag in case of contact. Default = 0 (Integer) 0 - No closure 1 - Closure
IDEL	Flag for node and segment deletion. Default as defined by CONTPRM (Integer = 0, 1, or 2) 0 - No deletion. 1 - When all the elements (shells and solids) associated to one segment are deleted, the segment is removed from the master side of the interface. Additionally, non-connected nodes are removed from the slave side of the interface. Has a CPU cost higher than IDEL = 2. 2 - When a shell or a solid element is deleted, the corresponding segment is removed from the master side of the interface. Additionally, non-connected nodes are removed from the slave side of the interface.
STFAC	Interface stiffness scale factor. Default = 0.2 (Real > 0)
FRIC	Coulomb friction. Default as defined by CONTPRM (Real > 0)
GAP	Gap for impact activation (See comment 4). Default as defined by CONTPRM (Real > 0)
TSTART	Start time Default = 0.0 (Real > 0)
TEND	Time for temporary deactivation. Default = 1030 (Real > 0)
IBC	Flag for deactivation of boundary conditions at impact applied to the slave grid set. Default as defined by CONTPRM (Character = X, Y, Z, XY, XZ, YZ, XYZ)
IRM	Renumbering flag for segments of the master surface (Integer = 0, 1, or 2). 0 - If segment is connected to a solid element its normal is reversed if entering the solid element (the segment is renumbered). 1 - Normal is always reversed (segment 1234 is read 2143). 2 - Normal is never reversed (segment connected to a solid element are not renumbered).
INACTI	Handling of initial penetrations flag (See comment 5). Default as defined by CONTPRM (Integer = 0, 3, or 4) 0 - No action. 3 - Change slave node coordinates to avoid small initial penetrations. 4 - Change master node coordinates to avoid small initial penetrations. Invalid entries are ignored.
IFRIC	Friction formulation flag (See comment 6). Default as defined by CONTPRM (Character = COUL, GEN, DARM, or REN) COUL - Static Coulomb friction law. GEN - Generalized viscous friction law. DARM - Darmstad friction law. REN - Renard friction law.
IFILT	Friction filtering flag (See comment 7). Default as defined by CONTPRM (Character = NO, SIMP, PER, or CUTF) NO - No filter is used. SIMP - Simple numerical filter. PER - Standard -3dB filter with filtering period. CUTF - Standard -3dB filter with cutting frequency.
FFAC	Friction filtering factor. Default as defined by CONTPRM (Real = 0.0 < FFAC < 1.0)
FRICDAT	Indicates that additional information for IFRIC will follow. Only available when IFRIC = GEN, DARM or REN.
C1, C2, C3, C4, C5, C6	Coefficients to define variable friction coefficient in IFRIC = GEN, DARM, or REN. 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 PCNTX5 property extension can be associated with a particular PCONT.

2.	PCNTX5 is only applied in geometric nonlinear analysis subcases which are defined by ANALYSIS = NLGEOM or IMPDYN. 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.	In implicit analysis, different contact formulations are used for contact where slave and master set do not overlap and where they overlap (self-contact).

In the case of self-contact, the gap cannot be zero and a constant gap is used. For small initial gaps, the convergence will be more stable and faster, if GAP is larger than the initial gap.

In implicit analysis, sometimes a stiffness with scaling factor reduction (for example, STFAC = 0.01) or reduction in impacted thickness (if rigid one) might reduce unbalanced forces and improve convergence, particularly in shell structures under bending where the effective stiffness is much lower than membrane stiffness; but it should be noted that too low of a value could also lead to divergence.

5.	INACTI = 3 or 4 are 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

6.	IFRIC defines the friction model.

IFRIC = COUL – Coulomb friction with FT < FRIC * FN.

For IFRIC > 0 the friction coefficient is set by a function (µ = µ (p, V)), where p is the pressure of the normal force on the master segment and V is the tangential velocity of the slave node.

The following formulations are available:

•	IFRIC = 1 - Generalized viscous friction law

µ = FRIC + C1 * p + C2 * V + C3 * p * v + C4 * p2 + C5 * v2

•	IFRIC = 2 - Darmstad law

µ = C1 * e(C2V) * p2 + C3 * e(C4V) * p + C5 * e(C6V)

•	IFRIC = 3 - Renard law

	0 < V < C5
	C5 < V < C6
	C6 < V

where:

renard4

•	The first critical velocity Vcr1 must not be 0 (C5 ≠ 0). It also must be lower than the second critical velocity Vcr2 (C5 < C6).

•	The static friction coefficient C1 and the dynamic friction coefficient C2, must be lower than the maximum friction C3 (C1 < C3 and C2 < C3).

•	The minimum friction coefficient C4, must be lower than the static friction coefficient C1 and the dynamic friction coefficient C2 (C4 < C1 and C4 < C2).

7.	IFILT defines the method for computing the friction filtering coefficient. If IFILT ≠ NO, the tangential friction forces are smoothed using a filter:

FT = α * F'T + (1 - α) * F'T-1

where,

FT is the tangential force

F'T is the tangential force at time t

F'T-1 is the tangential force at time t-1

α is the filtering coefficient

IFILT = SIMP – α = FFAC

IFILT = PER – α = 2dt/FFAC, where dt/T = FFAC, T is the filtering period

IFILT = CUTF – α = 2 * FFAC * dt, where FFAC is the cutting frequency

8.	This card is represented as an extension to a PCONT property in HyperMesh.