 
 
 
 
 
 
 
  
Keyword type: step
This option is used to change the iteration control parameters. It should only be used by those users who know what they are doing and are expert in the field. There are two, mutually exclusive parameter: PARAMETERS and RESET. The RESET parameter resets the control parameters to their defaults. With the parameter PARAMETERS is used to change the defaults. It can take the value TIME INCREMENTATION, FIELD or LINE SEARCH. If the TIME INCREMENTATION value is selected, the number of iterations before certain actions are taken (e.g. the number of divergent iterations before the increment is reattempted) can be changed and effect of these actions (e.g. the increment size is divided by two). The FIELD parameter can be used to change the convergence criteria themselves.
Finally, LINE SEARCH can be used to change the line search parameters (only for face-to-face penalty contact). The line search parameter scales the correction to the solution calculated by the Newton-Raphson algorithm such that the residual force is orthogonal to the correction. This requires the solution of a nonlinear equation, and consequently an iterative procedure. In CalculiX this procedure is approximated by a linear connection between:
First line:
There are no subsequent lines if the parameter RESET is selected.
Following lines if PARAMETERS=TIME INCREMENTATION is selected:
Second line:
 iteration after which a check is made whether the
residuals increase in two consecutive iterations (default: 4). If so,
the increment is reattempted with
 iteration after which a check is made whether the
residuals increase in two consecutive iterations (default: 4). If so,
the increment is reattempted with  times its size.
 times its size.
 iteration after which a logarithmic convergence check is
performed in each iteration (default: 8). If more than
 iteration after which a logarithmic convergence check is
performed in each iteration (default: 8). If more than  iterations are needed, the increment is reattempted with
iterations are needed, the increment is reattempted with  its size.
 its size.
 iteration after which the residual tolerance
 iteration after which the residual tolerance 
 is used
instead of
 is used
instead of 
 (default: 9).
 (default: 9).
 maximum number of iterations allowed (default: 16).
 maximum number of iterations allowed (default: 16).
 number of iterations after which the size of the
subsequent increment will be reduced (default: 10).
 number of iterations after which the size of the
subsequent increment will be reduced (default: 10).
 maximum number of iterations allowed in two consecutive
increments for the size of the next increment to be increased
(default: 4).
 maximum number of iterations allowed in two consecutive
increments for the size of the next increment to be increased
(default: 4).
 Currently not used.
 Currently not used.
 Maximum number of cutbacks per increment (default: 5). A
cutback is a reattempted increment.
 Maximum number of cutbacks per increment (default: 5). A
cutback is a reattempted increment.
 Currently not used.
 Currently not used.
 Currently not used.
 Currently not used.
Third line:
 Cutback factor if the solution seems to diverge(default: 0.25).
 Cutback factor if the solution seems to diverge(default: 0.25).
 Cutback factor if the logarithmic extrapolation predicts
too many iterations (default: 0.5).
 Cutback factor if the logarithmic extrapolation predicts
too many iterations (default: 0.5).
 Cutback factor for the next increment if more than
 Cutback factor for the next increment if more than  iterations were needed in the current increment (default: 0.75).
iterations were needed in the current increment (default: 0.75).
 Cutback factor if the temperature change in two subsequent
  increments exceeds DELTMX (default: 0.85).
 Cutback factor if the temperature change in two subsequent
  increments exceeds DELTMX (default: 0.85).
 Currently not used.
 Currently not used.
 Currently not used.
 Currently not used.
 Factor by which the next increment will be increased if
less than
 Factor by which the next increment will be increased if
less than  iterations are needed in two consecutive increments (default: 1.5).
 iterations are needed in two consecutive increments (default: 1.5).
 Currently not used.
 Currently not used.
Following lines if PARAMETERS=FIELD is selected:
Second line:
 Convergence criterion for the ratio of the largest
residual to the average force  (default: 0.005). The average force is
defined as the average over all increments in the present step of the
instantaneous force. The instantaneous force in an increment is
defined as the mean of the absolute value of the nodal force
components within all elements.
 Convergence criterion for the ratio of the largest
residual to the average force  (default: 0.005). The average force is
defined as the average over all increments in the present step of the
instantaneous force. The instantaneous force in an increment is
defined as the mean of the absolute value of the nodal force
components within all elements.
 Convergence criterion for the ratio of the largest
solution correction to the largest incremental solution value (default: 0.01).
 Convergence criterion for the ratio of the largest
solution correction to the largest incremental solution value (default: 0.01).
 Initial value at the start of a new step of the
time average force (default:
 the time average force from the previous steps or 0.01 for the first step).
 Initial value at the start of a new step of the
time average force (default:
 the time average force from the previous steps or 0.01 for the first step).
 user-defined average force. If defined, the
calculation of the average force is replaced by this value.
 user-defined average force. If defined, the
calculation of the average force is replaced by this value.
 Alternative residual convergence criterion to be
used after
 Alternative residual convergence criterion to be
used after  iterations instead of
 iterations instead of 
 (default: 0.02).
 (default: 0.02).
 Criterion for zero flux relative to
 Criterion for zero flux relative to
 (default:
 (default:  ).
).
 Convergence criterion for the ratio of the
largest solution correction to the largest incremental solution value
in case of zero flux (default:
 Convergence criterion for the ratio of the
largest solution correction to the largest incremental solution value
in case of zero flux (default:  ).
).
 Convergence criterion for the ratio of the largest
residual to the average force for convergence in a single iteration (default:
 Convergence criterion for the ratio of the largest
residual to the average force for convergence in a single iteration (default:  ).
).
Following lines if PARAMETERS=LINE SEARCH is selected:
Second line:
 Maximum value of the line search parameter (default: 1.).
 Maximum value of the line search parameter (default: 1.).
 Minimum value of the line search parameter (default: 0.25).
 Minimum value of the line search parameter (default: 0.25).
Example: *CONTROLS,PARAMETERS=FIELD 1.e30,1.e30,0.01,,0.02,1.e-5,1.e-3,1.e-8
leads to convergence in just one iteration since nearly any residuals
are accepted for convergence (
 and
 and
 .
. 
Example files: beammrco.
 
 
 
 
 
 
