This option is used to introduce friction properties into a mechanical surface interaction model governing the interaction of contact surfaces, a contact pair, or connector elements. It must be used in conjunction with the *SURFACE INTERACTION option, the *CONNECTOR FRICTION option, or in an ABAQUS/Standard analysis with the *CHANGE FRICTION, the *GAP, the *INTERFACE, or the *ITS options.
Products: ABAQUS/Standard ABAQUS/Explicit
Type: Model or history data in ABAQUS/Standard; 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.
In a steady-state transport analysis set this parameter equal to the absolute magnitude of the allowable elastic slip velocity (
) to be used in the stiffness method for sticking friction. In all other analysis procedures set this parameter equal to the absolute magnitude of the allowable elastic slip (
) to be used in the stiffness method for sticking friction. If this parameter is omitted, the elastic slip (or elastic slip velocity) is defined by the SLIP TOLERANCE value.
This parameter applies only to ABAQUS/Standard analyses and cannot be used when friction is defined for connector elements.
Include this parameter to choose the Lagrange multiplier formulation for friction.
This parameter cannot be used when friction is defined for connector elements.
Include this parameter to specify completely rough (no slipping) friction.
This parameter applies only to ABAQUS/Standard analyses.
Set this parameter equal to the value of 
(defined as the ratio of allowable maximum elastic slip velocity to angular velocity times the diameter of the spinning body in a steady-state transport analysis or as the ratio of allowable maximum elastic slip to characteristic contact surface face dimension in all other analysis procedures). The default is SLIP TOLERANCE=.005.
When friction is defined for connector elements, is defined (when possible) as the ratio of of allowable maximum elastic slip to a characteristic element dimension in the model. In this case the default is SLIP TOLERANCE=.0001.
This parameter cannot be used when friction is defined for connector elements.
Include this parameter if the friction model is to be defined in user subroutine FRIC in an ABAQUS/Standard analysis or in user subroutine VFRIC in an ABAQUS/Explicit analysis.
This parameter applies only to ABAQUS/Standard analyses and cannot be used when friction is defined for connector elements.
Include this parameter if anisotropic friction is being defined.
Set this parameter equal to the number of field variable dependencies included in the definition of the friction coefficient in addition to slip rate, contact pressure, and temperature. If this parameter is omitted, it is assumed that the friction coefficients have no dependencies or depend only on slip rate, contact pressure, and temperature. See “Specifying field variable dependence” in “Material data definition,” Section 9.1.2 of the ABAQUS Analysis User's Manual, for more information.
This parameter is valid only if the USER parameter is included.
Set DEPVAR equal to the number of state-dependent variables required for user subroutine FRIC in an ABAQUS/Standard analysis or for user subroutine VFRIC in an ABAQUS/Explicit analysis. The default is DEPVAR=0.
Include this parameter to specify separate static and kinetic friction coefficients with a smooth transition zone defined by an exponential curve.
The ANISOTROPIC and TAUMAX parameters cannot be used with this parameter.
This parameter is valid only if the USER parameter is included.
Set this parameter equal to the number of property values needed as data to define the friction model in user subroutine FRIC in an ABAQUS/Standard analysis or in user subroutine VFRIC in an ABAQUS/Explicit analysis. The default is PROPERTIES=0.
This parameter applies only to ABAQUS/Explicit analyses.
Set this parameter equal to the slope of the curve that defines the shear traction as a function of the elastic slip between the two surfaces. If this parameter is omitted or frictional forces are not present, shear softening will not be activated. This parameter cannot be used in conjunction with user subroutine VFRIC.
Set this parameter equal to the equivalent shear stress limit, 
; that is, the maximum achievable value of the equivalent shear stress. If no value is given or TAUMAX=0 in an ABAQUS/Standard analysis, there is no limit on the equivalent shear stress. A value of zero is not allowed in an ABAQUS/Explicit analysis.
This parameter is valid only if the EXPONENTIAL DECAY parameter is used.
Include this parameter if the exponential decay coefficient, 
, is to be computed by ABAQUS. If this parameter is omitted, the decay coefficient must be given directly on the data line.
First line:
Friction coefficient, 
.
Slip rate, 
. If this value is omitted, the friction coefficient is assumed to be independent of the slip rate.
Contact pressure, 
. If this value is omitted, the friction coefficient is assumed to be independent of the contact pressure.
Average temperature at the contact point, 
, between the two contact surfaces. If this value is omitted, the friction coefficient is assumed to be independent of the surface temperature.
Average value of the first field variable, 
.
Average value of the second field variable, 
.
Etc., up to four field variables.
Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):
Average value of the fifth field variable, 
.
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the friction coefficient as a function of contact pressure, slip rate, average surface temperature, and other predefined field variables.
First line:
Friction coefficient in the first slip direction, 
.
Friction coefficient in the second slip direction, 
.
Slip rate, . If this value is omitted, the friction coefficient is assumed to be independent of the slip rate.
Contact pressure, . If this value is omitted, the friction coefficient is assumed to be independent of the contact pressure.
Average temperature at the contact point, , between the two contact surfaces. If this value is omitted, the friction coefficient is assumed to be independent of the temperature.
Average value of the first field variable, .
Average value of the second field variable, .
Etc., up to three field variables.
Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than three):
Average value of the fourth field variable, 
.
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the friction coefficient as a function of contact pressure, slip rate, average surface temperature, and other predefined field variables.
First (and only) line:
Static friction coefficient, 
.
Kinetic friction coefficient, 
.
Decay coefficient, .
First line:
Friction coefficient for the first data point, . This value corresponds to the static friction coefficient.
Second line:
Friction coefficient for the second data point, . This value corresponds to the dynamic friction coefficient measured at the reference slip rate, 
.
Slip rate of the second data point, . This value corresponds to the reference slip rate used to measure the dynamic friction coefficient.
Third line (optional):
Kinetic friction coefficient, 
. This value corresponds to the asymptotic value of the friction coefficient at infinite slip rate, 
. If this data line is omitted, ABAQUS/Standard automatically calculates such that 
.
There are no data lines in this case.
First line:
Enter the values of the friction properties, eight per line.
Repeat this data line as often as necessary to completely define all of the properties needed by user subroutine FRIC or VFRIC, as indicated by the value of PROPERTIES.