Let the program choose the option (default).
Use full Newton-Raphson.
Use modified Newton-Raphson.
Use the previously computed matrix (initial-stiffness).
Use full Newton-Raphson with unsymmetric matrices of elements where the unsymmetric option exists.
When applicable in a static creep analysis, activates modified Newton-Raphson with a creep-ratio limit. Valid only when Option1 = AUTO.
Adaptive descent key:
Use adaptive descent (default if frictional contact exists). Explicit ON is valid only if Option = FULL.
Do not use adaptive descent (default in all other cases).
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.
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.
This command is also valid in PREP7.