CNTNLSUB
Subcase Information Entry The CNTNLSUB command can be used to continue a nonlinear solution from a preceding nonlinear subcase, and thus create complex loading sequences.
Format
CNTNLSUB=option
Definitions
Argument | Options | Description |
---|---|---|
option | <YES,
NO, SID> Defaults: If CNTNLSUB does not exist in the input file, the default is NO. If CNTNLSUB exists in the input file, but a value is not specified, the default is YES. |
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Comments
- This command applies only to nonlinear subcases.
Nonlinear subcases may only be continued from other nonlinear subcases of the same analysis type. That is, Small Displacement Nonlinear Analysis subcases (ANALYSIS=NLSTAT) may only be continued from other Small Displacement Nonlinear Analysis subcases, Nonlinear Transient Dynamics Subcases (ANALYSIS=EXPDYN) may only be continued from other Nonlinear Transient Dynamics Subcases, and Large Displacement Nonlinear Analysis Subcases (PARAM, LGDISP, 1) may only be continued from other Large Displacement Nonlinear Analysis Subcases.
- Only one CNTNLSUB entry can be defined for each subcase.
- If CNTNLSUB = option is present above the first subcase, it is applied to all nonlinear subcases. (CNTNLSUB = SID is only allowed within a subcase).
- CNTNLSUB is mostly relevant in path-dependent problems, such as plasticity or gap/contact analysis with friction/stick. In these problems, subcase continuation can be used to create complex loading paths that will typically produce very different results than simple proportional loading of a single subcase. CNTNLSUB also affects the convergence history and, to some extent, the results in problems that typically are not path-dependent, such as gap/contact analysis without friction.
- If displacement boundary conditions (zero or non-zero SPC or SPCDs) or forces applied to a preceding subcase (Subcase 1) are removed in the continued nonlinear subcase (Subcase 2), then they are converted into equivalent internal forces at the beginning of Subcase 2 and are ramped down gradually. This effect can be observed in the SPCFORCE, TOTALFORCE, OLOAD and GPFORCE output requests.
- If the deformed shape resulting from the preceding subcase should be unchanged in the subsequent subcase, then the D field should be set to F on the SPC or SPCD entries. Retaining the deformed shape by setting the D field to F on the SPC/SPCD entry is supported for both analysis and optimization.