This option is used to modify the default hard contact pressure-overclosure relationship in a mechanical contact analysis. Mechanical interactions normal to the surfaces are influenced by this option. It must be used in conjunction with the *SURFACE INTERACTION option or in an ABAQUS/Standard analysis with the *GAP option or the *INTERFACE option. By default, ABAQUS/Standard will determine whether the contact constraint will be enforced with or without a Lagrange multiplier. You can use the *CONTACT CONTROLS option to override the default.
Products: ABAQUS/Standard ABAQUS/Explicit
Type: Model data in ABAQUS/Standard; Model or history data in ABAQUS/Explicit
Level: Part Part Instance Assembly Model in ABAQUS/Standard; Step in ABAQUS/Explicit
This parameter applies only to ABAQUS/Standard analyses with a default “hard” pressure-overclosure relationship.
Include this parameter to choose the augmented Lagrange method for enforcement of the contact constraint. See “Constraint enforcement methods for ABAQUS/Standard contact pairs,” Section 29.2.3 of the ABAQUS Analysis User's Manual, for a discussion of the default penalty stiffness and penetration tolerance associated with this method (the default penalty stiffness used by this method is often stiffer than that with the straight penalty method). You can specify or modify the penalty stiffness on the data line.
This parameter applies only to ABAQUS/Standard analyses with a default “hard” pressure-overclosure relationship.
Include this parameter to choose the penalty method for enforcement of the contact constraint. See “Constraint enforcement methods for ABAQUS/Standard contact pairs,” Section 29.2.3 of the ABAQUS Analysis User's Manual, for a discussion of the default penalty stiffness. You can specify or modify the penalty stiffness on the data line.
Include this parameter to prevent any separation of the two surfaces once contact has been established.
Use this parameter to choose a contact pressure-overclosure relationship other than the default hard contact.
Set PRESSURE-OVERCLOSURE=HARD (default) to choose a pressure-overclosure relationship without physical softening. Note that some numerical softening will occur if a penalty or augmented Lagrange constraint enforcement method is used.
Set PRESSURE-OVERCLOSURE=EXPONENTIAL to define an exponential pressure-overclosure relationship.
Set PRESSURE-OVERCLOSURE=LINEAR to define a linear pressure-overclosure relationship.
Set PRESSURE-OVERCLOSURE=SCALE FACTOR to define a piecewise linear pressure-overclosure relationship based on scaling the default contact stiffness. This option is available only for the general contact algorithm in ABAQUS/Explicit.
Set PRESSURE-OVERCLOSURE=TABULAR to define a piecewise linear pressure-overclosure relationship in tabular form.
If a contact area is not defined, such as may occur for node-based surfaces or for GAP- or ITT-type contact elements, “pressure” should be interpreted as force. For contact with three-dimensional beams or trusses, “pressure” should be interpreted as force per unit length.
When used to modify the default surface behavior, the PRESSURE-OVERCLOSURE parameter cannot be used with the NO SEPARATION parameter in an ABAQUS/Standard analysis.
First (and only) line:
User-defined penalty stiffness. If this field is left blank, the penalty stiffness has the default value or is multiplied by the scale factor given in the third field of the data line.
Clearance at which the contact pressure is zero. The default is zero.
Scale factor for the default penalty stiffness or for the penalty stiffness if specified in the first field of the data line. The default is one.
First (and only) line:
Clearance at which the contact pressure is zero, 
(see Figure 18.47–1).
Pressure at zero clearance, 
.
The following data item is available only in ABAQUS/Explicit analyses:
Value of the maximum stiffness, 
. When using penalty contact, large stiffness values obtained from the exponential law may significantly lower the stable time increment size. Choose a suitable maximum stiffness to mitigate this effect (see Figure 18.47–1). By default, is set equal to infinity for kinematic contact and the default penalty stiffness for penalty contact.
First (and only) line:
Slope of the pressure-overclosure curve. This value must be positive.
First (and only) line:
Overclosure factor, 
(see Figure 18.47–2), which defines the overclosure measure (used to delineate the segments of the pressure-overclosure curve) as a percentage of the minimum element size in the contact region. This value must be greater than zero. Leave blank if an overclosure measure (second data item) is specified.
Overclosure measure, 
(see Figure 18.47–2), which defines the overclosure measure (used to delineate the segments of the pressure-overclosure curve) directly. This value must be greater than zero. Leave blank if an overclosure factor (first data item) is specified.
Stiffness scale factor, 
(see Figure 18.47–2), which defines the geometric scaling of the “base” stiffness and must be greater than one.
Initial stiffness scale factor, 
(see Figure 18.47–2), which defines an additional scale factor for the “base” default contact stiffness and must be greater than zero. The default value is one.
First line:
Pressure.
Overclosure.
Repeat this data line in ascending order of overclosure value as often as necessary to define the overclosure as a function of pressure. A minimum of two data lines are required. The pressure-overclosure relationship is extrapolated beyond the last overclosure point by continuing the same slope (see Figure 18.47–3).
