ARCTRM, Lab, VAL, NODE, DOF
Controls termination of the solution
when the arc-length method is used.
LabSpecifies the basis of solution termination:
OFF | — | Does not use ARCTRM to terminate analysis (default). |
L | — | Terminates the analysis if the first
limit point has been reached. The first limit point is that point
in the response history when the tangent stiffness matrix becomes
singular (i.e., the point at which the structure becomes unstable).
If |
U | — | Terminates the analysis when the displacement first equals or exceeds the maximum desired value. |
VALMaximum desired displacement (absolute value). Valid
only if Lab = U. The analysis terminates
whenever the calculated displacement first equals or exceeds this
value. For rotational degrees of freedom, VAL must be in radians (not degrees).
NODENode number corresponding to displacement used to
compare with displacement specified by VAL. If blank, the maximum displacement will be used. Valid only if Lab = U.
DOFValid degree of freedom label for nodal displacement
specified by NODE. Valid labels are UX,
UY, UZ, ROTX, ROTY, ROTZ. Valid only if NODE>0 and Lab = U.
The ARCTRM command is valid only when the arc-length method (ARCLEN,ON) is used.
It can be convenient to use this command to terminate the analysis when the first limit point is reached. In addition, the NCNV command should be used to limit the maximum number of iterations. If the ARCTRM command is not used, and the applied load is so large that the solution path can never reach that load, the arc-length solution will continue to run until a CPU time limit or a "maximum number of iterations" is reached.