ProductsAbaqus/StandardAbaqus/Explicit
TypeModel or history data in Abaqus/Standard; History data in Abaqus/Explicit
LevelPartPart instanceAssemblyModel in Abaqus/Standard; Step in Abaqus/Explicit
Optional, mutually exclusive parameters
- ELASTIC SLIP
-
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.
- 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
(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 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
-
This parameter cannot be used if the USER parameter is included.
If this parameter is omitted in an
Abaqus/Standard
analysis and the USER parameter is included, the user subroutine determines whether
directional preference exists in resistance to sliding. Otherwise, the friction
model remains isotropic.
If this parameter is omitted in an
Abaqus/Explicit
analysis, anisotropic frictional behavior occurs if directional preference is
specified as a surface property.
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 and cannot apply to friction associated with connector elements.
Set ANISOTROPIC BEHAVIOR=NONE to specify that the friction model remains isotropic, even if
directional preference is assigned as a surface property.
Set ANISOTROPIC BEHAVIOR=SURFACE PROPERTY to allow anisotropic frictional behavior to occur if
directional preference is specified as a surface property. This parameter value
applies only to
Abaqus/Explicit
analyses.
- COEFFICIENT PRECEDENCE
-
This parameter applies only to
Abaqus/Explicit
analyses and is used to control the precedence of specifying friction
coefficients.
Set COEFFICIENT PRECEDENCE=CONTACT PROPERTY (default) to indicate that friction coefficients assigned as
contact properties take precedence over friction coefficients derived from
values specified as surface properties.
Set COEFFICIENT PRECEDENCE=SURFACE PROPERTY COMBINATION to indicate that friction coefficients derived from values
specified as surface properties take precedence over friction coefficients
assigned as contact properties.
- 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 state-dependent variables required for
user subroutines
FRIC and
FRIC_COEF 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 significant only if directional preferences are introduced as
surface properties.
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,
,
is to be computed by
Abaqus.
If this parameter is omitted, the decay coefficient must be given directly on
the data line.
Data lines to
define the coefficient of friction if the USER, ROUGH, EXPONENTIAL DECAY, and ANISOTROPIC BEHAVIOR parameters are omitted
- 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, p. 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.
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, .
-
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, p. 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.
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 (),
minimum (),
or maximum ()
friction coefficient, depending on the parameter used at the keyword level.
-
Slip rate, .
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, ,
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, .
-
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 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, .
-
Kinetic friction coefficient, .
-
Decay coefficient, .
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, .
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 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
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