NROPT
NROPT, Option1, Option2, Optval
Specifies the Newton-Raphson options in a static or full transient analysis.
MP ME ST <> PRN <> <> <> EM <> <> PP <> EME MFS
Option1

Option key:

AUTO   — 

Let the program choose the option (default).

FULL   — 

Use full Newton-Raphson.

MODI   — 

Use modified Newton-Raphson.

INIT   — 

Use the previously computed matrix (initial-stiffness).

UNSYM   — 

Use full Newton-Raphson with unsymmetric matrices of elements where the unsymmetric option exists.

Option2

Option key:

CRPL  — 

When applicable in a static creep analysis, activates modified Newton-Raphson with a creep-ratio limit. Valid only when Option1 = AUTO.

Optval

Adaptive descent key:

ON   — 

Use adaptive descent (default if frictional contact exists). Explicit ON is valid only if Option = FULL.

OFF   — 

Do not use adaptive descent (default in all other cases).

CRLIMIT   — 

The creep-ratio limit for use with the modified Newton-Raphson procedure. Typically, this value should not exceed 0.15. Valid only when Option1 = AUTO (default) and Option2 = CRPL.

Notes

The NROPT command specifies the Newton-Raphson option used to solve the nonlinear equations in a static or full transient analysis.

If used within the solution processor, this command is valid only within the first load step.

The automatic modified Newton-Raphson procedure with creep-ratio limit control (NROPT,AUTO,CRPL,CRLIMIT) applies to static creep analysis only. When the creep ratio is smaller than value of the creep ratio limit specified, the modified Newton-Raphson procedure is used. If convergence difficulty occurs during solution, use the full Newton-Raphson procedure.

The command NROPT,UNSYM is also valid in a linear non-prestressed modal analysis that is used to perform a brake squeal analysis. In this special case, the command is used only to generate the unsymmetric stiffness matrix; no Newton-Raphson iterations are performed.

The default values given for this command assume SOLCONTROL,ON (the default). See the description of SOLCONTROL for a complete listing of the defaults set by SOLCONTROL,ON and SOLCONTROL,OFF.

See Newton-Raphson Option in the Structural Analysis Guide for more information.

This command is also valid in PREP7.

Menu Paths

Main Menu>Preprocessor>Loads>Analysis Type>Analysis Options
Main Menu>Solution>Analysis Type>Analysis Options

Release 14.0 - © 2011 SAS IP, Inc. All rights reserved.