Products
Abaqus/Standard
Abaqus/Explicit
Abaqus/CAE
Type
Model data
LevelModel
Abaqus/CAE
Property module
Required, mutually exclusive parameters
-
FREQUENCY
-
This parameter applies only to frequency domain procedures in Abaqus/Standard analyses.
Use this parameter to choose the frequency domain definition. In this case the
material's long-term elasticity must be defined using the ELASTIC or the HYPERELASTIC option. If a
frequency-domain viscoelastic response is specified for a time domain procedure, the
viscoelastic response is ignored and the material response is based on the long-term
elastic moduli.
Set
FREQUENCY=CREEP TEST DATA
to define the frequency domain response using a Prony series representation of the
relaxation moduli, if the Prony series parameters are to be computed from shear and
volumetric creep test data.
Set
FREQUENCY=FORMULA
to define the dissipative material parameters by the power law formulæ.
Set
FREQUENCY=PRONY
to define the frequency domain response using a Prony series representation of the
relaxation moduli by specifying the Prony series parameters.
Set
FREQUENCY=RELAXATION TEST DATA
to define the frequency domain response using a Prony series representation of the
relaxation moduli, if the Prony series parameters are to be computed from shear and
volumetric relaxation test data.
Set
FREQUENCY=TABULAR
to provide tabular definition of the frequency domain response.
-
NONLINEAR
-
Include this parameter to define a nonlinear viscoelastic network within the parallel
rheological framework.
-
TIME
-
This parameter applies only to time domain procedures.
Use this parameter to choose the time domain definition. In this case the material's
elasticity must be defined using the ELASTIC, the HYPERELASTIC, or the HYPERFOAM option. If a
time-domain viscoelastic response is specified for a frequency domain procedure, the
viscoelastic response is ignored and the material response is based on the
instantaneous elastic moduli.
Set
TIME=CREEP TEST DATA
if the Prony series parameters are to be computed by Abaqus from data taken from shear and volumetric creep tests.
Set
TIME=FREQUENCY DATA
if the Prony series parameters are to be computed by Abaqus from frequency-dependent cyclic test data.
Set
TIME=PRONY
to define a linear, viscoelastic material by giving the parameters of the Prony series
representation of the relaxation moduli.
Set
TIME=RELAXATION TEST DATA
if the Prony series parameters are to be computed by Abaqus from data taken from shear and volumetric relaxation tests.
Required parameters when the
NONLINEAR parameter is included
-
LAW
-
Set
LAW=BB POWER LAW
to choose the preferred form of the Bergstrom-Boyce power law. It is recommended that
you use this parameter setting rather than
LAW=BERGSTROM-BOYCE.
Set
LAW=BERGSTROM-BOYCE
to choose a Bergstrom-Boyce law. This parameter setting is superseded by
LAW=BB POWER LAW.
Set
LAW=HYPERB
to choose a hyperbolic-sine law.
Set
LAW=POWER LAW
to choose a power law. It is recommended that you use this parameter setting rather
than
LAW=STRAIN.
Set
LAW=STRAIN
to choose a strain hardening law. This parameter setting is superseded by
LAW=POWER LAW.
Set
LAW=USER
to input the creep law using user subroutine UCREEPNETWORK or user subroutine
VUCREEPNETWORK.
-
NETWORKID
-
Set this parameter equal to the network id. This number must be greater than or
equal to 1 and smaller than or equal to the number of networks. The network ids must
consist of consecutive integers.
-
SRATIO
-
Set this parameter equal to the stiffness ratio for the network. The sum of the
ratios for the networks must be smaller than or equal to 1. If the sum is smaller than
1, an additional elastic network is defined with the value of the stiffness ratio such
that the condition is satisfied.
Optional parameters
-
DEPENDENCIES
-
This parameter can be used only when the
NONLINEAR parameter is included.
Set this parameter equal to the number of field variable dependencies included in the
definition of the creep constants in addition to temperature. If this parameter is
omitted, it is assumed that the creep constants have no dependencies or depend only on
temperature. See Specifying Field Variable Dependence for more
information.
-
PRELOAD
-
This parameter applies only to Abaqus/Standard analyses.
This parameter can be used only in conjunction with
FREQUENCY=TABULAR
to specify the nature of preload used for defining frequency-domain viscoelastic
material properties or effective thickness-direction gasket properties.
Set
PRELOAD=UNIAXIAL
to specify that the frequency-domain viscoelastic material properties correspond to a
uniaxial test.
Set
PRELOAD=VOLUMETRIC
to specify that the frequency-domain viscoelastic material properties correspond to a
volumetric test. This setting is not meaningful when used with gasket elements to
define effective thickness-direction properties.
-
PROPERTIES
-
This parameter applies only to Abaqus/Standard analyses and can be used only when
LAW=USER
is used.
Set this parameter equal to the number of property values needed as data in user
subroutine UCREEPNETWORK or user subroutine
VUCREEPNETWORK. The default is
PROPERTIES=0.
-
TYPE
-
This parameter cannot be used in conjunction with the
NONLINEAR parameter.
Use this parameter to define whether the VISCOELASTIC option is being
used to define continuum material properties or effective thickness-direction gasket
properties.
Set
TYPE=ISOTROPIC
(default, and only option for Abaqus/Explicit) to define continuum material properties. This choice is appropriate when the
viscoelastic material model is used for any continuum, structural, or special-purpose
elements whose material response is modeled using continuum material properties
(examples of such special-purpose elements include modeling cohesive elements with a
continuum response—see Modeling of an Adhesive Layer of Finite Thickness or gasket
elements with a material response—see Defining the Gasket Behavior Using a Material Model). In Abaqus/Explicit this parameter should also be used for the definition of viscoelastic properties
for cohesive elements with elastic traction-separation behavior (Modeling Viscoelastic Traction-Separation Behavior in Abaqus/Explicit).
Set
TYPE=TRANSVERSELY ISOTROPIC
to define a linear, transversely isotropic, viscoelastic material. This option can be
used only with
TIME=PRONY
or
FREQUENCY=PRONY.
Set
TYPE=ORTHOTROPIC
to define a linear,orthotropic, viscoelastic material. This option can be used only
with
TIME=PRONY
or
FREQUENCY=PRONY.
Set
TYPE=TRACTION
to define effective thickness-direction gasket properties. This option is supported
only for gasket elements whose behavior is modeled directly using a gasket behavior
model (Defining the Gasket Behavior Using a Material Model).
Optional parameters when test data are given to define time domain viscoelasticity with
TIME=CREEP TEST DATA,
TIME=RELAXATION TEST DATA,
or
TIME=FREQUENCY DATA
or when test data are given to define frequency domain viscoelasticity with
FREQUENCY=CREEP TEST DATA
or
FREQUENCY=RELAXATION TEST DATA
-
ERRTOL
-
Set this parameter equal to the allowable average root-mean-square error of the data
points in the least-squares fit. The default is 0.01 (1%).
-
NMAX
-
Set this parameter equal to the maximum number of terms N in the
Prony series. Abaqus will perform the least-squares fit from
N=1
to
N=
NMAX until
convergence is achieved for the lowest N with respect to
ERRTOL. The default and maximum
value is 13.
Data line to define continuum material properties for
FREQUENCY=FORMULA
- First (and only) line
-
-
Real part of
g*1
.
(g*(ω)=g*1f-a)
-
Imaginary part of
g*1
.
-
Value of a.
-
Real part of
k*1
.
(k*(ω)=k*1f-b)
If the material is incompressible, this value is ignored.
-
Imaginary part of
k*1
. If the material is incompressible, this value is ignored.
-
Value of b. If the material is incompressible, this value is
ignored.
Data lines to define continuum material properties for
FREQUENCY=TABULAR
without the PRELOAD parameter or for
TIME=FREQUENCY DATA
- First line
-
-
Real part of
ωg*
.
(ωℜ(g*)=Gℓ/G∞)
-
Imaginary part of
ωg*
.
(ωℑ(g*)=1-Gs/G∞)
-
Real part of
ωk*
.
(ωℜ(k*)=Kℓ/K∞)
If the material is incompressible, this value is ignored.
-
Imaginary part of
ωk*
.
(ωℑ(k*)=1-Ks/K∞)
If the material is incompressible, this value is ignored.
-
Frequency, f, in cycles per time.
Repeat this data line as often as necessary to define the dissipative
part of the material behavior.
Data lines to define continuum material properties for
FREQUENCY=TABULAR,
PRELOAD=UNIAXIAL
- First line
-
-
Uniaxial loss modulus.
-
Uniaxial storage modulus.
-
Frequency, f, in cycles per time.
-
Uniaxial nominal strain (defines the level of uniaxial preload).
Repeat this data line as often as necessary to define the uniaxial
loss and storage moduli as functions of frequency and preload.
Data lines to define continuum material properties for
FREQUENCY=TABULAR,
PRELOAD=VOLUMETRIC
- First line
-
-
Bulk loss modulus.
-
Bulk storage modulus.
-
Frequency, f, in cycles per time.
-
Volume ratio, J (current volume/original volume; defines the
level of volumetric preload).
Repeat this data line as often as necessary to define the bulk loss
and storage moduli as functions of frequency and preload.
Data lines to specify continuum material properties with the Prony series
parameters directly using
TIME=PRONY
or
FREQUENCY=PRONY
with
TYPE=ISOTROPIC
- First line
-
-
ˉgP1
, the modulus ratio in the first term in the Prony series
expansion of the shear relaxation modulus.
-
ˉkP1
, the modulus ratio in the first term in the Prony series
expansion of the bulk relaxation modulus.
-
τ1
, the relaxation time for the first term in the Prony series
expansion.
Repeat this data line as often as necessary to define the second,
third, etc. terms in the Prony series. There is no restriction on the number of terms
in the Prony series.
Data lines to specify continuum material properties with the Prony series
parameters directly using
TIME=PRONY
or
FREQUENCY=PRONY
with
TYPE=TRANSVERSELY ISOTROPIC
- First line
-
-
ˉrP(1,1111)
, the modulus ratio in the first term in the Prony series
expansion of the
D1111
component of the relaxation modulus.
-
ˉrP(1,2222)
, the modulus ratio in the first term in the Prony series
expansion of the
D2222
component of the relaxation modulus.
-
ˉrP(1,1122)
, the modulus ratio in the first term in the Prony series
expansion of the
D1122
component of the relaxation modulus.
-
ˉrP(1,2233)
, the modulus ratio in the first term in the Prony series
expansion of the
D2233
component of the relaxation modulus.
-
ˉrP(1,1212)
, the modulus ratio in the first term in the Prony series
expansion of the
D1212
component of the relaxation modulus.
-
τ1
, the relaxation time for the first term in the Prony series
expansion.
Repeat this data line as often as necessary to define the second,
third, etc. terms in the Prony series. There is no restriction on the number of terms
in the Prony series.
Data lines to specify continuum material properties with the Prony series
parameters directly using
TIME=PRONY
or
FREQUENCY=PRONY,
TYPE=ORTHOTROPIC
- First line
-
-
ˉrP(1,1111)
, the modulus ratio in the first term in the Prony series
expansion of the
D1111
component of the relaxation modulus.
-
ˉrP(1,1122)
, the modulus ratio in the first term in the Prony series
expansion of the
D1122
component of the relaxation modulus.
-
ˉrP(1,2222)
, the modulus ratio in the first term in the Prony series
expansion of the
D2222
component of the relaxation modulus.
-
ˉrP(1,1133)
, the modulus ratio in the first term in the Prony series
expansion of the
D1133
component of the relaxation modulus.
-
ˉrP(1,2233)
, the modulus ratio in the first term in the Prony series
expansion of the
D2233
component of the relaxation modulus.
-
ˉrP(1,3333)
, the modulus ratio in the first term in the Prony series
expansion of the
D3333
component of the relaxation modulus.
-
ˉrP1,1212
, the modulus ratio in the first term in the Prony series
expansion of the
D1212
component of the relaxation modulus.
-
ˉrP(1,1313)
, the modulus ratio in the first term in the Prony series
expansion of the
D1313
component of the relaxation modulus.
- Second line
-
-
ˉrP(1,2323)
, the modulus ratio in the first term in the Prony series
expansion of the
D2323
component of the relaxation modulus.
-
τ1
, the relaxation time for the first term in the Prony series
expansion.
Repeat this set of data lines as often as necessary to define the
second, third, etc. terms in the Prony series. There is no restriction on the number
of terms in the Prony series.
Data lines to define viscoelastic properties for cohesive elements with elastic
traction-separation behavior using
TIME=PRONY
in Abaqus/Explicit
- First line
-
-
ˉgP1
, the modulus ratio in the first term in the Prony series
expansion of the shear traction relaxation modulus.
-
ˉkP1
, the modulus ratio in the first term in the Prony series
expansion of the normal traction relaxation modulus.
-
τ1
, the relaxation time for the first term in the Prony series
expansion.
Repeat this data line as often as necessary to define the second,
third, etc. terms in the Prony series. There is no restriction on the number of terms
in the Prony series.
Data lines to define viscoelastic properties for cohesive elements with elastic
traction-separation behavior using
TIME=FREQUENCY DATA
in Abaqus/Explicit
- First line
-
-
Real part of
ωg*
.
(ωℜ(g*)=Gℓ/G∞)
-
Imaginary part of
ωg*
.
(ωℑ(g*)=1-Gs/G∞)
-
Real part of
ωk*
.
(ωℜ(k*)=Kℓ/K∞)
-
Imaginary part of
ωk*
.
(ωℑ(k*)=1-Ks/K∞)
-
Frequency, f, in cycles per time.
Repeat this data line as often as necessary to define the dissipative
part of the material behavior.
To specify viscoelastic behavior via test data
No data lines are used with this option when either
TIME=CREEP TEST DATA
or
TIME=RELAXATION TEST DATA
is specified. The test data are given by the SHEAR TEST DATA and the VOLUMETRIC TEST DATA options or by the
COMBINED TEST DATA
option.
Data lines to define effective thickness-direction gasket properties for
PRELOAD=UNIAXIAL
- First line
-
-
Effective thickness-direction loss modulus.
-
Effective thickness-direction storage modulus.
-
Frequency, f, in cycles per time.
-
Closure (defines the level of preload).
Repeat this data line as often as necessary to define the effective
thickness-direction gasket loss and storage moduli as functions of frequency and
preload.
Data lines to define effective thickness-direction gasket properties if
PRELOAD=UNIAXIAL
is not included
- First line
-
-
Real part of
ωk*
.
(ωℜ(k*)=kℓ/k∞)
, where
k*
represents the complex effective thickness direction dynamic
stiffness.
-
Imaginary part of
ωk*
.
(ωℑ(k*)=1-ks/k∞)
, where
k*
represents the complex effective thickness direction dynamic
stiffness.
-
Frequency, f, in cycles per time.
Repeat this data line as often as necessary to define the normalized
effective thickness-direction gasket loss and storage moduli as functions of
frequency.
Data lines for
LAW=BB POWER LAW
- First line
-
-
q0
. (Units of FL−2.)
-
m.
-
C.
-
E, a constant used for regularizing the creep strain rate
near the undeformed state. The value of E should be
non-negative. If this field is left blank, the default value of 0.01 is used.
-
˙ε0
. The default is 1.0. (Units of T−1.)
-
Temperature.
-
First field variable.
-
Second field variable.
- Subsequent lines (only needed if the
DEPENDENCIES parameter has a value
greater than two)
-
-
Third field variable.
-
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the
dependence of the creep constants on temperature and other predefined field
variables.
Data lines for
LAW=BERGSTROM-BOYCE
- First line
-
-
Creep parameter, A.
-
Effective stress exponent, m.
-
Creep strain exponent, C.
-
E, a constant used for regularizing the creep strain rate
near the undeformed state. The value of E should be
non-negative. If this field is left blank, the default value of 0.01 is used.
-
Temperature.
-
First field variable.
-
Second field variable.
-
Third field variable.
- Subsequent lines (only needed if the
DEPENDENCIES parameter has a value
greater than three)
-
-
Fourth field variable.
-
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the
dependence of the creep constants on temperature and other predefined field
variables.
Data lines for
LAW=HYPERB
- First line
-
-
A. (Units of T−1.)
-
B. (Units of F−1L2.)
-
n.
- Temperature.
-
First field variable.
-
Second field variable.
-
Etc. up to four field variables.
- Subsequent lines (only needed if the
DEPENDENCIES parameter has a value
greater than four)
-
-
Fifth field variable.
-
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the
dependence of the creep constants on predefined field variables.
Data lines for
LAW=POWER LAW
- First line
-
-
q0
. (Units of FL−2.)
-
n.
-
m.
-
a. The default is 0.0.
-
˙ε0
. The default is 1.0. (Units of T−1.)
-
Temperature.
-
First field variable.
-
Second field variable.
- Subsequent lines (only needed if the
DEPENDENCIES parameter has a value
greater than two)
-
-
Third field variable.
-
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the
dependence of the creep constants on temperature and other predefined field
variables.
Data lines for
LAW=STRAIN
- First line
-
-
A. (Units of F
-n
L
2n
T
-1-m
.)
-
n.
-
m.
-
Temperature.
-
First field variable.
-
Second field variable.
-
Etc., up to four field variables.
- Subsequent lines (only needed if the
DEPENDENCIES parameter has a value
greater than four)
-
-
Fifth field variable.
-
Etc., up to eight field variables per line.
Repeat this set of data lines as often as necessary to define the
dependence of the creep constants on temperature and other predefined field
variables.
Data lines for
LAW=USER
- No data lines are needed if the
PROPERTIES parameter is omitted or set
to 0. Otherwise, first line
-
-
Give the properties, eight per line.
Repeat this data line as often as necessary to define the material
properties.
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