- ALLSDTOL
Include this parameter to indicate that an adaptive automatic damping
algorithm will be activated in this step. Set this parameter equal to the
maximum allowable ratio of the stabilization energy to the total strain energy.
The initial damping factor is specified via the STABILIZE parameter or the FACTOR parameter. This damping factor will then be adjusted through
the step based on the convergence history and the value of ALLSDTOL. If this parameter is set equal to zero, the adaptive automatic
damping algorithm is not activated; a constant damping factor will be used
throughout the step. If this parameter is included without a specified value,
the default value is 0.05. If this parameter is omitted but the STABILIZE parameter is included with the default value of dissipated
energy fraction, the adaptive automatic damping algorithm will be activated
automatically with ALLSDTOL=0.05.
This parameter must be used in conjunction with the STABILIZE parameter (see
Solving Nonlinear Problems).
- CETOL
Set this parameter equal to the maximum difference in the creep strain
increment calculated from the creep strain rates based on conditions at the
beginning and on conditions at the end of the increment, thus controlling the
accuracy of the creep integration. In general, the tolerance can be calculated
by choosing an acceptable stress error tolerance and dividing by a typical
elastic modulus. If the model consists of a linear viscoelastic material
characterized by the
VISCOELASTIC option, a looser tolerance of the order of the elastic
strains can be used. If CETOL is omitted, fixed time increments are used.
- CONTINUE
Set CONTINUE=NO (default) to specify that this step will not carry over the
damping factors from the results of the preceding general step. In this case
the initial damping factors will be recalculated based on the declared damping
intensity and on the solution of the first increment of the step or can be
specified directly.
Set CONTINUE=YES to specify that this step will carry over the damping factors
from the end of the immediately preceding general step.
This parameter must be used in conjunction with the ALLSDTOL and the STABILIZE parameters.
- CREEP
Set CREEP=EXPLICIT to use explicit integration for creep behavior throughout the
step, which may sometimes be computationally less expensive. The time increment
will be limited by the accuracy tolerance (CETOL) and by the stability limit of the forward difference operator.
See
Rate-Dependent Plasticity: Creep and Swelling
for details on the integration scheme.
- FACTOR
Set this parameter equal to the damping factor to be used in the automatic
damping algorithm (see
Solving Nonlinear Problems)
if the problem is expected to be unstable due to local instabilities and the
damping factor calculated by
Abaqus/Standard
is not suitable. This parameter must be used in conjunction with the STABILIZE parameter and overrides the automatic calculation of the
damping factor based on a value of the dissipated energy fraction.
- STABILIZE
Include this parameter to use automatic stabilization if the problem is
expected to be unstable due to local instabilities. Set this parameter equal to
the dissipated energy fraction of the automatic damping algorithm (see
Solving Nonlinear Problems).
If this parameter is omitted, the stabilization algorithm is not activated. If
this parameter is included without a specified value, the default value of the
dissipated energy fraction is 2 × 10−4 and the adaptive automatic
damping algorithm will be activated by default with ALLSDTOL=0.05 in this step; set ALLSDTOL=0 to deactivate the adaptive automatic damping algorithm. If
the FACTOR parameter is used, any value of the dissipated energy fraction
will be overridden by the damping factor.