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!CONVERG_PARAM

Specification of the convergence criteria parameters of the Newton-Raphson iteration. Referenced by CONVERGPARAM of !STEP.

Parameters

Parameter Type Description
NAME C Convergence criteria parameter name (required)

** Second and subsequent lines **

For each pair of the check quantity and the norm, specify whether it is used for the check and the threshold value. The order of the lines is arbitrary.

    (2nd and subsequent lines) QUANTITY, NORM, ACTION, TOL
Variable Type Description
QUANTITY C Check quantity. RESIDUAL (residual), CORRECTION (displacement correction), LAGRANGE (Lagrange multiplier correction)
NORM C Norm. L2 (L2 norm), MAX (maximum absolute value of the degree-of-freedom components)
ACTION C CHECK (used for the check) or SKIP (not used for the check)
TOL R Threshold value. Required for CHECK and must be a positive value. Can be omitted for SKIP

The default values for each pair of the check quantity and the norm are as follows. The default values for the L2 norm can be changed with the corresponding parameters of !STEP.

QUANTITY Default for NORM=L2 Default for NORM=MAX Parameter of !STEP corresponding to the L2 norm
RESIDUAL CHECK, 1.0e-3 SKIP CONVERG
CORRECTION CHECK, 1.0e-8 SKIP CONVERG_DDISP
LAGRANGE CHECK, 1.0e-2 SKIP CONVERG_LAG

Example

In the case of checking the residual with both the L2 norm and the maximum value, and not using the check by the displacement correction

    !CONVERG_PARAM, NAME=CP1
     RESIDUAL,   L2,  CHECK, 1.0e-6
     RESIDUAL,   MAX, CHECK, 1.0e-5
     CORRECTION, L2,  SKIP
    !STEP, CONVERGPARAM=CP1

The log per iteration in this case is as follows. The 2nd line is the check value by the maximum value, and for the residual, the node number (global number) and degree-of-freedom number at which the maximum value occurred are appended.

 iter:       3, res(force): 2.1034E-05, lag.corr.: 4.5600E-07
                res(force,max): 8.5120E-05 (node 1024, dof 2)

Notes

  • For the definitions of the check quantities and the convergence condition obtained by combining check quantities, refer to Convergence Criteria of the theory manual
  • For each pair of the check quantity and the norm, the default values are overridden by CONVERG, CONVERG_DDISP, and CONVERG_LAG of !STEP, and the lines of this card override them. Pairs not written on this card remain at the values of !STEP (the default values if not specified)
  • The lines for RESIDUAL and CORRECTION apply to both the translational degrees of freedom and the rotational degrees of freedom (only for 6-degree-of-freedom elements). The lines for LAGRANGE are not used for the check even if CHECK is specified, in analyses without Lagrange multipliers (such as ALAGRANGE contact analysis or analyses without contact)
  • When both the L2 norm and the maximum value of the same check quantity are set to CHECK, both must be satisfied
  • When MAX is set to CHECK, the check value by the maximum value is output on the 2nd line of the log per iteration. For the residual and the displacement correction, the node number and degree-of-freedom number at which the maximum value occurred are appended
  • The divergence check by MAXRES of !STEP is performed with the L2 norm of the residual, regardless of the specification of this card
  • !CONVERG_PARAM must be defined before the !STEP that references it
  • The following cases are input errors
    • There is no NAME
    • The values of QUANTITY, NORM, and ACTION are invalid
    • There are two or more lines for the same pair of the check quantity and the norm
    • There is no threshold value for CHECK, or it is 0 or less
    • The !CONVERG_PARAM with the name specified in CONVERGPARAM of !STEP does not exist before that !STEP
    • As a result of applying this card, all of RESIDUAL and CORRECTION become SKIP