Release 11.0 Documentation for ANSYS
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PIVCHECK, KEY, PRNTCNTRL
Prevents a batch mode, linear static analysis from stopping when a negative or zero equation solver pivot value is encountered.
MP ME ST PR PRN <> <> <> EM <> <> PP <>
Determines whether to stop or continue an analysis when a negative or zero equation solver pivot value is encountered:
ON | — | Default value. ANSYS checks for negative or zero pivot values on linear static analyses performed with the frontal, sparse and PCG solvers. When one is encountered, an error is issued, stopping the job. A negative pivot value may be valid for some multiphysics analyses (e.g. Electromagnetic or Thermal); this key has no effect in these cases. |
OFF | — | Pivots will not be checked. This key continues the analysis in spite of a zero or negative pivot value. The program will proceed until other error checking routines are encountered. |
Provides print options. Print output with these options will be sent to the default output file, not to the files created by the nonlinear diagnostic tools (NLDIAG).
ONCE or blank | — | Default value. Print maximum and minimum pivot information once per loadstep if the SPARSE solver (the default solver) is used. |
EVERY | — | Print maximum and minimum pivot information every Newton-Raphson iteration or at every iteration within a substep of every loadstep. This option is provided for nonlinear diagnostics. |
This command is valid only for linear static analyses. In a nonlinear analysis, a negative pivot may be valid. Normally, rigid body motions in a nonlinear analysis will be trapped by error routines checking infinitely large displacements (DOF limit exceeded) or nonconvergence status. An under-constrained model may avoid the pivot check, but fail with a DOF limit exceeded error.
This command is applicable only to batch mode (not in the GUI). While in an ANSYS interactive session, it is generally desirable to remain in the session, even though a pivot error has occurred. Warning messages will be displayed on the screen, allowing the user to take corrective action.
Finally, machine precision will determine if a warning or an error is issued for the small pivot case. In all cases there will be some notification that the model needs to be checked closely for an accurate solution.
This command is also valid in PREP7.