ARCTRM
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 (that is, the point at which the structure becomes unstable). If
Lab= L, argumentsVAL,NODE,DOFare ignored.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,VALmust 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 ifLab= U.DOFValid degree of freedom label for nodal displacement specified by
NODE. Valid labels are UX, UY, UZ, ROTX, ROTY, ROTZ. Valid only ifNODE>0 andLab= U.
Notes
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.