ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE
TypeModel or history data LevelModelStep
Abaqus/CAEAmplitude toolset; bubble loading is
not supported. Similar functionality is available in the
Interaction
module.
Required parameters
 NAME

Set this parameter equal to a label that will be used to refer to the
amplitude curve.
Optional parameters
 DEFINITION

Set DEFINITION=TABULAR (default) to give the amplitudetime (or amplitudefrequency)
definition in tabular form.
Set DEFINITION=EQUALLY SPACED, PERIODIC, MODULATED, DECAY, SMOOTH STEP, SOLUTION DEPENDENT, or BUBBLE to define the amplitude according to the definitions given in
Amplitude Curves.
Set DEFINITION=USER to define the amplitude via user subroutines
UAMP and
VUAMP.
Set DEFINITION=ACTUATOR to define the amplitude via cosimulation with a logical
modeling program.
 INPUT

Set this parameter equal to the name of the alternate input file containing
the data lines for this option. See
Input Syntax Rules
for the syntax of such file names. If this parameter is omitted, it is assumed
that the data follow the keyword line.
This parameter cannot be used if DEFINITION=USER or DEFINITION=ACTUATOR.
 SCALEX

Set this parameter equal to the value by which the time values are to be
scaled. The default is 1.
This parameter cannot be used if DEFINITION=SOLUTION DEPENDENT, BUBBLE, USER, or ACTUATOR.
 SCALEY

Set this parameter equal to the value by which the amplitude values are to
be scaled. The default is 1.
This parameter cannot be used if DEFINITION=SOLUTION DEPENDENT, BUBBLE, or USER.
 SHIFTX

Set this parameter equal to the value by which the time values are to be
shifted. The default is 0.
This parameter cannot be used if DEFINITION=SOLUTION DEPENDENT, BUBBLE, USER, or ACTUATOR.
 SHIFTY

Set this parameter equal to the value by which the amplitude values are to
be shifted. The default is 0.
This parameter cannot be used if DEFINITION=SOLUTION DEPENDENT, BUBBLE, or USER.
 TIME

Set TIME=STEP TIME (default) for step time. If the step in which the amplitude is
referenced is in the frequency domain, STEP TIME corresponds to frequency.
Set TIME=TOTAL TIME for total time accumulated over all nonperturbation analysis
steps.
See
Conventions
for a discussion of these time measures.
 VALUE

Set VALUE=RELATIVE (default) for relative magnitude definition.
Set VALUE=ABSOLUTE for direct input of absolute magnitudes. In this case the data
line values in the load option are ignored. Because the values given in the
field definition are ignored, the absolute amplitude value will be used to
define both the temperature and the gradient. For this reason, VALUE=ABSOLUTE should not be used when temperatures or predefined field
variables are specified for nodes connected to beam and shell elements whose
section definition includes TEMPERATURE=GRADIENTS (default).
Required parameter for DEFINITION=EQUALLY SPACED
 FIXED INTERVAL

Set this parameter equal to the fixed time (or frequency) interval at which
the amplitude data will be given.
Optional parameter for DEFINITION=EQUALLY SPACED
 BEGIN

Set this parameter equal to the time (or lowest frequency) at which the
first amplitude is given. The default is BEGIN=0.0.
Optional parameter for DEFINITION=TABULAR or DEFINITION=EQUALLY SPACED
 SMOOTH

Set this parameter equal to the fraction of the time interval before and
after each time point during which the piecewise linear time variation is to be
replaced by a smooth quadratic time variation in any case when time derivatives
of the amplitude definition are required. The defaults are SMOOTH=0.25 in
Abaqus/Standard
and SMOOTH=0.0 in
Abaqus/Explicit.
The allowable range is 0.0 $<$SMOOTH$\le $
0.5. A value of 0.05 is suggested for amplitude definitions that contain large
time intervals to avoid severe deviation from the specified definition. This
parameter is applicable only when time derivatives are needed (for displacement
or velocity boundary conditions in a direct integration dynamic analysis) and
is ignored for all other uses of this option.
Optional parameters for DEFINITION=USER
 PROPERTIES

Set this parameter equal to the number of properties being entered. The
properties are available for use in user subroutines
UAMP and
VUAMP. They can be defined on the data lines or directly within
the user subroutine. The default is PROPERTIES=0.
 VARIABLES

Set this parameter equal to the number of solutiondependent state variables
that must be stored with this amplitude definition. Its value must be greater
than 0. The default is VARIABLES=1.
Data lines for DEFINITION=TABULAR or DEFINITION=SMOOTH STEP with four data points (eight entries) per line
 First line


Time or frequency.

Amplitude value (relative or absolute) at the first point.

Time or frequency.

Amplitude value (relative or absolute) at the second point.

Etc., up to four pairs per line.
Repeat this data line as often
as necessary. Each line (except the last one) must have exactly four
time/magnitude or frequency/magnitude data
pairs.
Data lines for DEFINITION=TABULAR or DEFINITION=SMOOTH STEP with one data pair (two entries) per line
 First line


Time or frequency.

Amplitude value (relative or absolute) at the first point.
Repeat this data line as often
as necessary. Each line must have exactly one time/magnitude or
frequency/magnitude data
pair.
Data lines for DEFINITION=EQUALLY SPACED with eight values per line
 First line

Amplitude value at the time or frequency given on the BEGIN parameter.

Amplitude value at the next point.

Etc., up to eight values per line.
Repeat this data line as often
as necessary. Each line (except the last one) must have exactly eight amplitude
values.
Data lines for DEFINITION=EQUALLY SPACED with one value per line
 First line

Amplitude value at the time or frequency given on the BEGIN parameter.
Repeat this data line as often
as necessary. Each line must have exactly one amplitude
value.
Data lines to
define periodic data (DEFINITION=PERIODIC) First
line

N, the number of terms in the Fourier series.

$\omega $,
the circular frequency, in radians per time.

${t}_{0}$,
the starting time.

${A}_{0}$,
the constant term in the Fourier series.
 Second line

${A}_{1}$,
the first coefficient of the cosine terms.

${B}_{1}$,
the first coefficient of the sine terms.

${A}_{2}$,
the second coefficient of the cosine terms.

${B}_{2}$,
the second coefficient of the sine terms.

Etc., up to eight values per line.
Repeat this data line as often
as necessary. Each line (except the last one) must have exactly eight entries,
to a total of 2N
entries.
Data line to
define modulated data (DEFINITION=MODULATED) First (and
only) line

${A}_{0}$.

A.

${t}_{0}$.

${\omega}_{1}$.

${\omega}_{2}$.
Data line to
define exponential decay (DEFINITION=DECAY) First (and
only) line

${A}_{0}$,
the constant term.

A, the coefficient of the exponential function.

${t}_{0}$,
the start time of the exponential function.

${t}_{d}$,
the decay time of the exponential function.
Data line to
define a solutiondependent amplitude (DEFINITION=SOLUTION DEPENDENT) First (and
only) line

Initial amplitude value (default = 1.0).

Minimum amplitude value (default = 0.1).

Maximum amplitude value (default = 1000.).
Data lines to
define bubble loading (DEFINITION=BUBBLE) First
line

Charge material constant, K.

Charge material constant, k.

Charge material constant, A.

Charge material constant, B.

Adiabatic charge constant, ${K}_{c}$.

Ratio of specific heats for gas, $\gamma $.

Density of charge material, ${\rho}_{c}$.

Mass of charge material, ${m}_{c}$.

Depth magnitude of charge material, ${d}_{I}$.
 Second line

Fluid mass density, ${\rho}_{f}$.

Sound speed in fluid, ${c}_{f}$.

Xdirection cosine of fluid surface normal.

Ydirection cosine of fluid surface normal.

Zdirection cosine of fluid surface normal.
 Third line

Acceleration due to gravity, g.

Atmospheric pressure, ${p}_{atm}$.

Wave effect parameter, $\eta $.
Set to 1.0 for wave effects in the fluid and gas; set to 0.0 to neglect these
effects. The default is 1.0.

Flow drag coefficient, ${C}_{D}$.
The default is 0.0.

Flow drag exponent, ${E}_{D}$
(${E}_{D}\ge 0$).
The default is 2.0.
 Fourth line

Time duration, ${T}_{\mathrm{final}}$.

Maximum number of time steps for the bubble simulation,
${N}_{\mathrm{steps}}$.
The bubble amplitude simulation ceases when the number of steps reaches
${N}_{\mathrm{steps}}$
or the time duration, ${T}_{\mathrm{final}}$,
is reached. The default is 1500.

Relative step size control parameter, ${\mathrm{\Omega}}_{\mathrm{rel}}$.
The default is 1 × 10^{−11}.

Absolute step size control parameter, ${X}_{\mathrm{abs}}$.
The default is 1 × 10^{−11}.

Step size control exponent, $\beta $.
The step size, $\mathrm{\Delta}t$,
is decreased or increased according to the error estimate:
${\left({\mathrm{\Omega}}_{\mathrm{rel}}\leftx\right+{X}_{\mathrm{abs}}\right)}^{\beta}\le \mathrm{\Delta}t{\left\frac{dx}{dt}\right}^{\beta}$.
The default is 0.2.
Data lines to
define user amplitude properties when PROPERTIES is specified with DEFINITION=USER First
line

Enter the amplitude properties, eight per line.
Repeat this data line as often
as necessary to define all amplitude
properties.
There are no data lines if DEFINITION=ACTUATOR
