| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | All | ||
| Area: | Confirm Message | ||
| Original Author: | Bentley Technical Support Group |
Problem:
When analyzing a model the following occurs:
---------------------------
Confirm
---------------------------
The load case did not converge. Do you wish to continue iterating?
---------------------------
Yes No Cancel
---------------------------
What should I do?
Solution:
Selecting YES: The program will re-run the analysis for more iterations in hopes of converging below the non-linear tolerances specified.
The default number of iterations is 30, If it was determine that 31-99 iterations enabled the analysis to converge, make this a permanent change by changing the Nonlinear analysis> Maximum iterations settings, as shown below
Then each time an analysis is performed it will use the updated number of iteration thus reducing likely hood that the message above will be displayed.
Selecting No: Stops the analysis procedures and presents the following:
---------------------------
Confirm
---------------------------
Do you want to see .LOG file for magnitude of unbalance error?
---------------------------
Yes No Cancel
---------------------------
Selecting Yes: AutoPIPE Viewer is automatically displayed with the *.LOG for review.
Selecting No: The dialog is closed and user is able to enter the next AutoPIPE command.
Selecting Cancel: The dialog is closed and user is able to enter the next AutoPIPE command.
Additional Comments, Questions, and Answers:
Notes:
-
-
-
The first step for any model with non-convergence use slightly liberal tolerances to allow for convergence may resolve the non-convergence issue.
a. Increase the force tolerance
b. Increase the displacement tolerance (increase the displacement tolerance by factor of 10 until it converges, then ease off the tolerance until you avoid the errors)
-
Some more converging solutions for buried piping are to first try using nonzero K2 values in order to avoid unlimited displacements. Using larger K2 values temporarily (K2=K1/1000 or so) can help you see if P1 values are sufficient by checking displacements. By setting K1, K2, P1 to 0.01 N/m and 0.001 M/mm/mm, the model should converge with no problem
-
May need to add concentrated or distributed weight to submerged pipe to prevent it from uplifting (in practice concrete mats are added in some cases
-
Try using V-Stops at a reasonable spacing (that will make it pass the sustained stress check). You may have to use large friction factors (0.5 to 1.0) for these supports
- Under certain circumstances, when 2 analysis set should be the same but are different may be directly related to different number of iterations and tolerance settings that are too wide. Tightening up the tolerance may help the results become more consistent,
-
-
Item #1: What to do when "load case did not converge" message appears in AutoPIPE?
a: Model with gaps and friction does not converge after 5 iteration, should it continue to iterate or not?
b: Piping model with Wave does not converge
c: Piping model with beams and soil does not converge
d: Piping model with underwater piping resting on the seabed does not converge
Item #2: How to read a *.LOG file in AutoPIPE?
a: How to solve a friction force problem found in a Log file for AutoPIPE?
Item #3: Does AutoPIPE as a whole have the same type of converging issues as seen by other programs?
Item #4: How to change number of iterations for static analysis?
See Also
Confirm Messages displayed in AutoPIPE