stabilize

Mapdl.stabilize(key='', method='', value='', substpopt='', forcelimit='', **kwargs)

Activates stabilization for all elements that support nonlinear

APDL Command: STABILIZE stabilization.

Parameters
key

Key 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.

method

The stabilization-control method:

ENERGY - Use the energy-dissipation ratio as the control. This value is the default

when Key ≠ OFF.

DAMPING - Use the damping factor as the control.

value

The 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.

substpopt

Option 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 Key ≠ OFF.

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 Key = CONSTANT.

forcelimit

The 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.

Notes

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.