 AMPLITUDE

This parameter defines the default amplitude variation for loading
magnitudes during the step.
Set AMPLITUDE=STEP if the load is to be applied instantaneously at the start of
the step and remain constant throughout the step.
Set AMPLITUDE=RAMP if the load magnitude is to vary linearly over the step, from
the value at the end of the previous step (or zero, at the start of the
analysis) to the value given on the loading option.
If this parameter is omitted, the default amplitude choice depends on the
procedure chosen, as shown in
Defining an analysis.
The default amplitude variation can be overwritten for individual loadings by
using the AMPLITUDE parameter on the loading options (Amplitude Curves).
This parameter is rarely needed, and changing the defaults may cause
problems. For example, the automatic load incrementation scheme in procedures
without a real time scale (such as the
STATIC option) applies the loads gradually by incrementing the
normalized time scale. The use of AMPLITUDE=STEP specifies that the entire load will be applied immediately, so
Abaqus/Standard
may not be able to choose suitable small increments if the loading causes
strongly nonlinear response.
 CONVERT SDI

This parameter determines how severe discontinuities (such as contact
changes) are accounted for during nonlinear analysis.
Set CONVERT SDI=YES (default) to use local convergence criteria to determine
whether a new iteration is needed.
Abaqus/Standard
will determine the maximum penetration and estimated force errors associated
with severe discontinuities and check whether these errors are within the
tolerances. Hence, a solution may converge if the severe discontinuities are
small.
Set CONVERT SDI=NO to force a new iteration if severe discontinuities occur
during an iteration, regardless of the magnitude of the penetration and force
errors. This option also changes some time incrementation parameters and uses
different criteria to determine whether to do another iteration or to make a
new attempt with a smaller increment size.
If the CONVERT SDI parameter is omitted,
Abaqus/Standard
will use the value specified in the previous general analysis step. An
exception is the first new step of a restart analysis, which will use CONVERT SDI=YES by default regardless of the setting in the previous step.
This parameter has no relevance and will be ignored for heat transfer
analysis and linear perturbation steps.
 DSA

This parameter applies only to
Abaqus/Design.
Set DSA=YES to activate design sensitivity analysis for the step. Once
DSA is activated in a general step, it remains
active in all subsequent general steps until it is deactivated in a subsequent
general step by setting DSA=NO. Once DSA is activated in a
perturbation step, it remains active in all subsequent consecutive perturbation
steps until it is deactivated in a subsequent consecutive perturbation step.
However, if DSA is activated in a step whose
procedure is not supported for DSA,
DSA will be deactivated until it is activated
again by setting DSA=YES.
 EXTRAPOLATION

This parameter is useful only for nonlinear analyses.
Set EXTRAPOLATION=LINEAR (default for procedures other than
DYNAMIC, APPLICATION=TRANSIENT FIDELITY) to indicate that the process is essentially monotonic, so
that
Abaqus/Standard
should use a 100% linear extrapolation, in time, of the previous incremental
solution to begin the nonlinear equation solution for the current increment (a
1% extrapolation is used with the Riks method).
Set EXTRAPOLATION=PARABOLIC to indicate that the process should use a quadratic
displacementbased extrapolation, in time, of the previous two incremental
solutions to begin the nonlinear equation solution for the current increment.
Set EXTRAPOLATION=VELOCITY PARABOLIC (available for
DYNAMIC procedure only and default for the
DYNAMICAPPLICATION=TRANSIENT FIDELITY procedure) to indicate that the process should use a quadratic
velocitybased extrapolation, in time, of the previous incremental solutions to
begin the nonlinear equation solution for the current increment.
Set EXTRAPOLATION=NO to suppress any extrapolation.
 INC

Set this parameter equal to the maximum number of increments in a step (or
in a single loading cycle for direct cyclic analysis). This value is only an
upper bound. The default value is 100.
The INC parameter has no effect in procedures where automatic
incrementation cannot be used (for example,
BUCKLE,
STEADY STATE DYNAMICS, and
MODAL DYNAMIC).
 NAME

Set this parameter equal to a label that will be used to refer to the step
on the output database. Step names in the same input file must be unique. Step
names from the original input file can be reused in a restart input file.
 NLGEOM

Omit this parameter or set NLGEOM=NO to perform a geometrically linear analysis during the current
step. Include this parameter or set NLGEOM=YES to indicate that geometric nonlinearity should be accounted
for during the step (stress analysis, fully coupled thermalstress analysis,
and coupled thermalelectricalstress analysis only). Once the NLGEOM option has been switched on, it will be active during all
subsequent steps in the analysis.
 PERTURBATION

Include this parameter to indicate that this is a linear perturbation step.
For this type of analysis
Abaqus/Standard
expects that load, boundary, and temperature changes should be given and that
the results will be changes relative to the previous step. Please
read the discussions in
General and perturbation procedures,
Meshtomesh solution mapping,
and
About loads
before using this option.
 SOLVER

Set SOLVER=ITERATIVE to use the iterative linear equation solver.
Please read the discussion in
Iterative linear equation solver
before using this option.
If this parameter is omitted, the default direct sparse solver is used.
 UNSYMM

Set UNSYMM=YES to indicate that unsymmetric matrix storage and solution
should be used.
Set UNSYMM=NO to indicate that symmetric storage and solution should be
used.
The default value for this parameter depends on the model and procedure
options used. The user is allowed to change the default value only in certain
cases. If the UNSYMM parameter is not used in such cases,
Abaqus/Standard
will use the value specified in the previous general analysis step. See
Defining an analysis
for a more detailed discussion of the use of this parameter.