ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE
TypeModel or history data in Abaqus/Standard; History data in Abaqus/Explicit
LevelPartPart instanceAssemblyModel in Abaqus/Standard; Step in Abaqus/Explicit
Abaqus/CAEInteraction module
Optional, mutually exclusive parameters
 ELASTIC SLIP

This parameter applies only to
Abaqus/Standard
analyses.
In a steadystate transport analysis set this parameter equal to the
absolute magnitude of the allowable elastic slip velocity
($\dot{{\gamma}_{i}}$)
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 (${\gamma}_{i}$)
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.
 LAGRANGE

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.
 ROUGH

This parameter cannot be used when friction is defined for connector
elements.
Include this parameter to specify completely rough (no slipping) friction.
 SLIP TOLERANCE

This parameter applies only to
Abaqus/Standard
analyses.
Set this parameter equal to the value of ${F}_{f}$
(defined as the ratio of allowable maximum elastic slip velocity to angular
velocity times the diameter of the spinning body in a steadystate 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, ${F}_{f}$
is defined (when possible) as the ratio of allowable maximum elastic slip to a
characteristic element dimension in the model. In this case the default is SLIP TOLERANCE=.0001.
 USER

This parameter cannot be used when friction is defined for connector
elements.
In an
Abaqus/Standard
analysis, set USER=FRIC (default) if the friction
model is to be defined in user subroutine
FRIC. Set USER=COEFFICIENT if the friction
coefficient is to be defined in user subroutine
FRIC_COEF.
In an
Abaqus/Explicit
analysis, set USER=FRIC (default) if the friction
model is to be defined in user subroutine
VFRIC. Set USER=FRICTION if the friction model
is to be defined in user subroutine
VFRICTION.
VFRIC is applicable to contact pairs, whereas
VFRICTION is applicable to general contact. Set USER=COEFFICIENT if the friction
coefficient is to be defined in user subroutine
VFRIC_COEF.
VFRIC_COEF can be used only with general contact.
Optional parameters
 ANISOTROPIC BEHAVIOR

Include this parameter if anisotropic friction is being defined. This
parameter cannot be used when friction is defined for connector elements.
Set ANISOTROPIC BEHAVIOR=LEGACY to specify anisotropic friction with directional preference
associated with a contact orientation. This parameter value applies only to
Abaqus/Standard
analyses.
Set ANISOTROPIC BEHAVIOR=SURFACE PROPERTY to specify anisotropic friction with directional preference as
a surface property. This parameter value applies only to
Abaqus/Explicit
analyses.
 DEPENDENCIES

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 Material data definition for more information.
 DEPVAR

This parameter is valid only if the USER parameter is included.
Set DEPVAR equal to the number of statedependent variables required for
user subroutine
FRIC in an
Abaqus/Standard
analysis or for user subroutines
VFRIC and
VFRICTION in an
Abaqus/Explicit
analysis. The default is DEPVAR=0.
 EXPONENTIAL DECAY

Include this parameter to specify separate static and kinetic friction
coefficients with a smooth transition zone defined by an exponential curve.
The ANISOTROPIC BEHAVIOR and TAUMAX parameters cannot be used with this parameter.
 NOMINAL

This parameter applies only to
Abaqus/Explicit
analyses and is meaningful only when ANISOTROPIC BEHAVIOR=SURFACE PROPERTY.
Set NOMINAL=AVERAGE (default) to specify
an average friction coefficient on the data lines.
Set NOMINAL=MINIMUM to specify a minimum
friction coefficient on the data lines.
Set NOMINAL=MAXIMUM to specify a maximum
friction coefficient on the data lines.
 PROPERTIES

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 and
FRIC_COEF in an
Abaqus/Standard
analysis or in user subroutines
VFRIC,
VFRIC_COEF, and
VFRICTION in an
Abaqus/Explicit
analysis. The default is PROPERTIES=0.
 SHEAR TRACTION SLOPE

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
subroutines
VFRIC,
VFRIC_COEF, and
VFRICTION.
 TAUMAX

Set this parameter equal to the equivalent shear stress limit; that is, the
maximum achievable value of the equivalent shear stress. The value given must
be greater than zero.
 TEST DATA

This parameter is valid only if the EXPONENTIAL DECAY parameter is used.
Include this parameter if the exponential decay coefficient,
${d}_{c}$,
is to be computed by
Abaqus.
If this parameter is omitted, the decay coefficient must be given directly on
the data line.
 WEIGHT

This parameter is valid only if ANISOTROPIC BEHAVIOR=SURFACE PROPERTY is used.
Set WEIGHT=BALANCED to specify a balanced weighting method for combining
surfacebased directional preferences for the anisotropic friction model.
Set WEIGHT=PROPORTIONAL to specify an epsilonproportional weighting method for
combining surfacebased directional preferences for the anisotropic friction
model.
Set WEIGHT=DOMINANT to specify the maximumepsilondominant weighting method for
combining surfacebased directional preferences for the anisotropic friction
model.
Data lines to
define the coefficient of friction if the USER, ROUGH, EXPONENTIAL DECAY, and ANISOTROPIC BEHAVIOR parameters are omitted
 First line

Friction coefficient, $\mu $.

Slip rate, ${\dot{\gamma}}_{eq}$.
If this value is omitted, the friction coefficient is assumed to be independent
of the slip rate.

Contact pressure, p. If this value is omitted, the
friction coefficient is assumed to be independent of the contact pressure.

Average temperature at the contact point, $\overline{\theta}$,
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, ${\overline{f}}^{1}$.

Average value of the second field variable, ${\overline{f}}^{2}$.

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, ${\overline{f}}^{5}$.

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.
Data lines to
define the coefficient of friction if the ANISOTROPIC BEHAVIOR=LEGACY parameter is used and the USER, ROUGH, and EXPONENTIAL DECAY parameters are omitted
 First line

Friction coefficient in the first slip direction, ${\mu}_{1}$.

Friction coefficient in the second slip direction, ${\mu}_{2}$.

Slip rate, ${\dot{\gamma}}_{eq}$.
If this value is omitted, the friction coefficient is assumed to be independent
of the slip rate.

Contact pressure, p. If this value is omitted, the
friction coefficient is assumed to be independent of the contact pressure.

Average temperature at the contact point, $\overline{\theta}$,
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, ${\overline{f}}^{1}$.

Average value of the second field variable, ${\overline{f}}^{2}$.

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, ${\overline{f}}^{4}$.

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.
Data lines to
define the coefficient of friction if the ANISOTROPIC BEHAVIOR=SURFACE PROPERTY parameter is used and the USER, ROUGH, and EXPONENTIAL DECAY parameters are omitted
 First line

Average (${\mu}_{nom}$),
minimum (${\mu}_{\mathrm{min}}$),
or maximum (${\mu}_{\mathrm{max}}$)
friction coefficient, depending on the parameter used at the keyword level.

Slip rate, ${\dot{\gamma}}_{eq}$.
If this value is omitted, the average friction coefficient is assumed to be
independent of the slip rate.

Contact pressure, p. If this value is omitted, the
average friction coefficient is assumed to be independent of the contact
pressure.

Average temperature at the contact point, $\overline{\theta}$,
between the two contact surfaces. If this value is omitted, the average
friction coefficient is assumed to be independent of the temperature.

Average value of the first field variable, ${\overline{f}}^{1}$.

Average value of the second field variable, ${\overline{f}}^{2}$.

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, ${\overline{f}}^{4}$.

Etc., up to eight field variables per line.
Repeat this set of data
lines as often as necessary to define the average friction coefficient as a
function of contact pressure, slip rate, average surface temperature, and other
predefined field
variables.
Data line to
define the static and kinetic friction coefficients if the EXPONENTIAL DECAY parameter is used and the decay coefficient is specified
directly First (and only)
line

Static friction coefficient, ${\mu}_{s}$.

Kinetic friction coefficient, ${\mu}_{k}$.

Decay coefficient, ${d}_{c}$.
The default value is zero.
Data lines if the EXPONENTIAL DECAY and TEST DATA parameters are used
 First line

Friction coefficient for the first data point, ${\mu}_{1}$.
This value corresponds to the static friction coefficient.
 Second line

Friction coefficient for the second data point, ${\mu}_{2}$.
This value corresponds to the dynamic friction coefficient measured at the
reference slip rate, ${\dot{\gamma}}_{2}$.

Slip rate of the second data point, ${\dot{\gamma}}_{2}$.
This value corresponds to the reference slip rate used to measure the dynamic
friction coefficient.
 Third line (optional)


Kinetic friction coefficient, ${\mu}_{\mathrm{\infty}}$. This
value corresponds to the asymptotic value of the friction coefficient at
infinite slip rate, ${\dot{\gamma}}_{\mathrm{\infty}}$. If this
data line is omitted,
Abaqus/Standard
automatically calculates ${\mu}_{\mathrm{\infty}}$ such
that $\left({\mu}_{2}{\mu}_{\mathrm{\infty}}\right)/\left({\mu}_{1}{\mu}_{\mathrm{\infty}}\right)=0.05$.
There are no data lines when the ROUGH parameter is used
Data lines to
define the user subroutine properties if the PROPERTIES parameter is used
 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
subroutines
FRIC,
FRIC_COEF,
VFRIC,
VFRIC_COEF, and
VFRICTION as indicated by the value of PROPERTIES.
There are no data lines when the USER parameter is used without the PROPERTIES
parameter
