Convergence problems in ANSYS batch mode but not in GUI

In summary: Hi,In summary, the problem is that the solution does not converge when the input file is run in batch mode.
  • #1
Vigardo
88
7
Dear experts,

I´m performing a non-linear buckling analysis under ANSYS Mechanical APDL (v14.5) using an input file that processes the last converged step to generate some etable output.

When run in GUI everything goes fine: the non-linear buckling analysis is performed until it becomes non-convergent, the previous to last step is selected, and the wanted etable is generated. However, if the input file is run in batch mode (command line) (*), it dumps the following convergence error and exits without generating the etable:
*** ERROR *** Solution not converged at time 0.6885 (load step 1 substep 71). Run terminated.

I´ve tried some workarounds using " NCNV,0 " (**) or " NERR,,,-1 " (***) commands. Both commands work in GUI, i.e. they do not exit non-linear analysis and continue execution, but only NERR does it in batch. The problem is that this way more non-convergent steps are performed than necessary so both runs will be slower and, more important, I can´t select the "previous to last step" to get the etable results I want.

PLEASE, WOULD YOU HELP ME ? Any help is highly appreciated! Thanks in advance!*Command to run ANSYS from windows 10 command line:
"c:\Program Files\ANSYS Inc\v145\ansys\bin\winx64\ANSYS145.exe" -b nolist -s noread -p ansys -i mynonlinear.txt -o mynonlinear.out

**NCNV sets the program behavior upon nonconvergence if the solution fails to converge: 0= Do not terminate analysis, 1= terminate program execution and analysis, or 2= terminate analysis but not execution (valid in SOLU processor).

***NERR,,,-1 Ignores all errors and performa all non-convergent steps in non-linear analyisis (valid in all processors).
 
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  • #2
hi,,, Ihave the problem ..the solution not converged run terminate ?how solve it
 
  • #3
Hi douaa, I'm sorry, but I haven't solve the problem yet... I hope you be more lucky!
 
  • Like
Likes douaa
  • #4
when i reduce load the solution is done .but i know that not ok
 
  • #5
Could be that the run is just timing out . Try setting a longer allowable run time .
 
  • Like
Likes FactChecker and douaa
  • #6
i active arc length and sub step equal=100 ,and i tried to increase substep but problem not solve ??
 
  • #7
Douaa, does your problem happen only running in batch mode (from command line) or it also occurs in GUI?
 

FAQ: Convergence problems in ANSYS batch mode but not in GUI

1. What could be causing convergence problems in ANSYS batch mode but not in the GUI?

One possible cause could be differences in the mesh quality. In batch mode, ANSYS may be using a coarser mesh compared to the GUI, which can lead to convergence issues. It is important to check and ensure that the mesh is consistent between batch mode and GUI runs.

2. Can the solver settings affect convergence in ANSYS batch mode?

Yes, the solver settings can greatly impact convergence in ANSYS. In batch mode, the default settings may be different compared to the GUI, which can affect the convergence of the solution. It is recommended to check and adjust the solver settings for batch mode runs.

3. How can I troubleshoot convergence problems in ANSYS batch mode?

Firstly, it is important to check the input files and make sure they are consistent between batch mode and GUI runs. It is also helpful to compare the solver settings and make any necessary adjustments. Additionally, checking for any errors or warnings during the batch mode run can provide insights into the cause of the convergence problems.

4. Are there any differences in the solution algorithms used in batch mode and the GUI in ANSYS?

Yes, there can be differences in the solution algorithms used in batch mode and the GUI in ANSYS. In batch mode, ANSYS may use a more simplified solution algorithm to save computational time. This can lead to convergence issues, especially for complex problems. It is important to compare and adjust the solution algorithms for batch mode runs if necessary.

5. Can the hardware or operating system affect convergence in ANSYS batch mode?

Yes, the hardware and operating system can play a role in convergence issues in ANSYS batch mode. If the hardware is not optimized for running ANSYS, it can lead to slower computations and potential convergence problems. It is important to ensure that the system meets the minimum requirements for running ANSYS and optimize the hardware and operating system if possible.

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