STABILIZE, Key, Method, VALUE, SubStpOpt, FORCELIMIT
Activates stabilization for all elements that support
nonlinear stabilization.
KeyKey for controlling nonlinear stabilization:
OFF | — | Deactivate stabilization. This value is the default. |
CONSTANT | — | Activate stabilization. The energy-dissipation ratio or damping factor remains constant during the load step. |
REDUCE | — | Activate stabilization. The energy-dissipation ratio or damping factor is reduced linearly to zero at the end of the load step from the specified or calculated value. |
MethodThe stabilization-control method:
ENERGY | — | Use the energy-dissipation ratio
as the control. This value is the default when |
DAMPING | — | Use the damping factor as the control. |
VALUEThe energy-dissipation ratio (Method = ENERGY) or damping factor (Method =
DAMPING). This value must be greater than 0 when Method = ENERGY or Method = DAMPING. When Method = ENERGY, this value is usually a number between
0 and 1.
SubStpOptOption for the first substep of the load step:
NO | — | Stabilization is not activated for
the first substep even when it does not converge after the minimal
allowed time increment is reached. This value is the default when |
MINTIME | — | Stabilization is activated for the first substep if it still does not converge after the minimal allowed time increment is reached. |
ANYTIME | — | Stabilization is activated for
the first substep. Use this option if stabilization was active for
the previous load step via |
FORCELIMITThe stabilization force limit coefficient, such that
0 < FORCELIMIT < 1. The default value
is 0.2. To omit a stabilization force check, set this value to 0.
Once issued, the stabilization effects of the command remain until you issue either a STABILIZE command (with no arguments) or a STABILIZE,OFF command. If you issue the command with no arguments, the effect is to deactivate stabilization.
Once issued, a STABILIZE command remains in effect until you reissue the command.
For the energy dissipation ratio, specify VALUE = 1.0e-4 if you have no prior experience with the current model;
if convergence problems are still an issue, increase the value gradually.
The damping factor is mesh-, material-, and time-step-dependent; an
initial reference value from the previous run (such as a run with
the energy-dissipation ratio as input) should suggest itself.
Exercise caution when specifying SubStpOpt = MINTIME or ANYTIME for the first load step; ANSYS, Inc. recommends this
option only for experienced users. If stabilization was active for
the previous load step via Key = CONSTANT
and convergence is an issue for the first substep, specify SubStpOpt = ANYTIME.
When the L2-norm of the stabilization force
(CSRSS value) exceeds the L2-norm of the internal force multiplied
by the stabilization force coefficient, ANSYS issues a message displaying
both the stabilization force norm and the internal force norm. The FORCELIMIT argument allows you to change the default
stabilization force coefficient (normally 20 percent).
This command stabilizes the degrees of freedom for current-technology elements only. Other elements can be included in the FE model, but their degrees of freedom are not stabilized.
For more information about nonlinear stabilization, see Unstable Structures in the Structural Analysis Guide. For additional tips that can help you to achieve a stable final model, see Simplify Your Model in the Structural Analysis Guide.