*CONTACT CONTROLS

Specify additional controls for contact.

This option is used to provide additional optional solution controls for models involving contact between bodies. The standard solution controls are usually sufficient, but additional controls are helpful to obtain cost-effective solutions for models involving complicated geometries and numerous contact interfaces, as well as for models in which rigid body motions are initially not constrained.

The CONTACT CONTROLS option can be repeated to set different control values for different contact pairs. It must be used in conjunction with the CONTACT PAIR option in Abaqus/Explicit analyses.

This page discusses:

See Also
*CONTACT PAIR
In Other Guides
Adjusting Contact Controls in Abaqus/Standard
About Contact Pairs in Abaqus/Explicit
Contact Controls for Contact Pairs in Abaqus/Explicit

ProductsAbaqus/StandardAbaqus/Explicit

TypeHistory data

LevelStep

Specifying additional controls for contact in an Abaqus/Standard analysis

Optional, mutually exclusive parameters applicable to augmented Lagrangian constraint enforcement

ABSOLUTE PENETRATION TOLERANCE

Set this parameter equal to the allowable penetration. Only contact constraints defined with augmented Lagrangian surface behavior will be affected by this parameter.

RELATIVE PENETRATION TOLERANCE

Set this parameter equal to the ratio of the allowable penetration to the characteristic contact surface face dimension. Only contact constraints defined with augmented Lagrangian surface behavior will be affected by this parameter. By default, the RELATIVE PENETRATION TOLERANCE parameter is set to 0.1% except for finite-sliding, surface-to-surface contact, in which case the default setting is 5%.

Optional parameters

MAIN

Set this parameter equal to the main surface name to apply the controls to a specific contact pair. This parameter must be used in conjunction with the SECONDARY parameter to specify a contact pair.

PERTURBATION TANGENT SCALE FACTOR

Set this parameter equal to the factor by which Abaqus/Standard will scale the default tangential stiffness used for the contact pairs in a particular linear perturbation step. Only contact constraints enforced with penalty methods will be affected by this parameter. This tangential scale factor is activated when a nonzero friction is specified on the data line of the FRICTION option.

PRESSURE DEPENDENT PERTURBATION

Set this parameter equal to the value of the p1 coefficient controlling the base state contact pressure–dependent enforcement of contact constraints in a particular linear perturbation step. This parameter allows you to relax or remove both normal and tangential contact constraints with low pressure.

RESET

Include this parameter to reset all contact controls to their default values. This parameter cannot be used with any other parameters, except for the SECONDARY and MAIN parameters. When this parameter is used in conjunction with the SECONDARY and MAIN parameters, the controls applied to the specific contact pair are removed.

SECONDARY

Set this parameter equal to the secondary surface name to apply the controls to a specific contact pair. This parameter must be used in conjunction with the MAIN parameter to specify a contact pair.

STABILIZE

Include this parameter to address situations where rigid body modes exist as long as contact is not fully established. This parameter activates damping in the normal and tangential directions based on the stiffness of the underlying mesh and the time step size. If no value is assigned to this parameter, Abaqus calculates the damping coefficient automatically. If a numerical value is assigned to this parameter, Abaqus multiplies the automatically calculated damping coefficient by this value. If the damping coefficient is defined directly on the data line, any numerical value assigned to this parameter is ignored.

Set STABILIZE =USER ADAPTIVE to scale the automatically calculated damping coefficient or the damping coefficient specified on the data line by a factor that decreases over iterations within one increment, according to the pattern specified on the second data line.

The STABILIZE parameter can be used to specify damping for the whole model or for an individual contact pair by using the SECONDARY and MAIN parameters. Values specified for a specific contact pair override the values for the whole model, if given.

STIFFNESS SCALE FACTOR

Set this parameter equal to the factor by which Abaqus/Standard will scale the default penalty stiffness to obtain the stiffnesses used for the contact pairs.

Set STIFFNESS SCALE FACTOR=USER ADAPTIVE to scale the default penalty stiffness by a factor that increases over iterations of the first increment and remains constant (equal to the last specified value) for subsequent increments.

This scale factor acts as an additional multiplier on any scale factor specified on the data line of the SURFACE BEHAVIOR option.

TANGENT FRACTION

Set this parameter equal to a fraction of the damping in the normal direction as specified with the STABILIZE parameter. By default, the tangential and normal stabilization are the same.

Optional data line if the PRESSURE DEPENDENT PERTURBATION parameter is included

First (and only) line

  1. The p0 coefficient. Default is equal to p1.

Optional data lines if the STABILIZE parameter is included

First line

  1. Damping coefficient to be used in the contact interface. The value entered overrides the damping coefficient calculated by Abaqus.

  2. Fraction of the damping that remains at the end of the step. The default is zero. Set to one to keep the damping constant over the step. If a nonzero value is specified, convergence problems may occur in a subsequent step if stabilization is not used in that step.

  3. Clearance at which the damping becomes zero. By default, the clearance is calculated by Abaqus based on the facet size associated with the contact pair. Set to a large value to obtain damping independent of the opening distance.

Second line (required if STABILIZE=USER ADAPTIVE)

  1. Up to eight values in descending order. For example, 1.0, 0.0.

For STABILIZE without the USER ADAPTIVE setting, omitting the first data line can have different effects than specifying a blank data line. A blank data line causes parameters of the data line to be set to default values; whereas prior values of these parameters will persist if the data line is omitted and RESET is not in effect.

Optional data line if STIFFNESS SCALE FACTOR=USER ADAPTIVE

Third line if STABILIZE=USER ADAPTIVE; otherwise, first line

  1. Up to eight scale values in ascending order. By default, the stiffness scale factors are 10-7,10-5,10-3,10-1,1.

Specifying additional controls for contact in an Abaqus/Explicit analysis

Warning: These controls are intended for experienced analysts and should be used with care. Using nondefault values of these controls may greatly increase the computational time of the analysis or produce inaccurate results.

Required parameters

CPSET

Set this parameter equal to the name of the contact pair set associated with this contact controls definition. The contact controls defined with this option will be applied to all contact pairs having this contact pair set name.

Optional parameters

FASTLOCALTRK

Set FASTLOCALTRK=NO if contact is not being enforced appropriately. A more conservative local tracking method will be used that may resolve the error. The default is FASTLOCALTRK=YES, which uses a more computationally efficient local tracking method.

GLOBTRKINC

Set this parameter equal to the maximum number of increments between global contact searches. The default is 100 increments for two-surface contact and 4 increments for self-contact.

RESET

Include this parameter to reset all of the optional controls to their default values. Those controls that are explicitly specified with other parameters on the same CONTACT CONTROLS option are not reset. If this parameter is omitted, only the explicitly specified controls will be changed in the current step; the others will remain at their previous settings.

SCALE PENALTY

Set this parameter equal to the factor by which Abaqus/Explicit will scale the default penalty stiffnesses to obtain the stiffnesses used for the penalty contact pairs within the contact pair set specified with the CPSET parameter. Penalty contact constraints defined with softened surface behavior and kinematic contact constraints will not be affected by this parameter. By default, the SCALE PENALTY parameter is set to unity.

WARP CHECK PERIOD

Set this parameter equal to the number of increments between checks for highly warped facets on main surfaces. By default, this check is performed every 20 increments. More frequent checks will cause a slight increase in computational time.

WARP CUT OFF

Set this parameter equal to the out-of-plane warping angle, measured in degrees, at which a facet will be considered to be highly warped. The out-of-plane warping angle is defined as the amount of variation of the surface normal over a facet. The default is WARP CUT OFF=20.

There are no data lines associated with this option.