Learning Forum

[Sigurd]

I'm defining several external force sets for structures connected with hinges in Aqwa 2024R1.  With more than 11 structure force sets (i.e. at the 12th structure force set) I get this error message:  "ASCITH - External Force T/H file. Missing value(s) - Expected 73 Record#17". The number 73 is probably related to 1+6*12=73, I don't know what record#17 is related to.  This will be a problem in my analysis as I need 30 structure force sets.  Is there a limited number of external forces in Aqwa, and if it is any workaround?  Or is it simply a bug (that hopefully is fixed in 2024R2 - haven't loaded that yet).  Any tips or tricks are appreciated.

[Sigurd]

Some clarifications.  It is "Structural Force Definition Data" that seems to somehow be formatting trouble with, even when I in the GUI fill out the structure forces.  11 structure forces are OK, failure experienced from the 12th structure force.  For the time beeing I've replaced the structure force set with 30 Point Forces enabling the "force following structure" - not as flexible of course as the force has to be constant (apart from direction) during the time span. 

I've also installed 2024 R2 now, and experience the same error.  I've done some testing with reading from comma-separated .csv-file (the one Aqwa writes out TimeResponse.XFT is in fact not comma-separated, so when I copy and edit the .csv-copy I have to generate the commas), and the same error is observed.  I therefore suspect this to be a bug, though still I'm not 100% sure of that as my testing may not be fully waterproof.  If it turns out to be a bug I will report it so it hopefully can be fixed in next service pack / release. Still, I hope that there is a workaround other than the follower point force I've used this far - maybe I may edit the solver input-file (TimeResponse.dat) directly - unfortunately this far I've not found were this structure force input is found in that file.

Snap from TimeResponse.XFT that continues with a total of 1+6*12 (because of 12 structures) = 73 like it should.  For 11 structures this is OK (then there is 1+6*11 = 67 coloumns and no error...

[Mike Pettit]

Hello,

That does look like a bug in Aqwa (or Aqwa Workbench), I will log it and try to get it fixed for the next release.

As a workaround, you could alternatively use the Python user-defined force function to apply your time-varying loads to each structure. The Aqwa solver can be connected to a Python server (code is provided in the installation) so that a Python function is called at every time step. Please see the Aqwa Reference Manual for more info: 30.3. External Server for User-Defined Force Calculation (ansys.com)

Please let me know if you have any problems or questions.

Mike

[Sigurd]

Thanks a lot Mike for fixing this bug in next release (2025R1 ?) and the workaround.  Really appreciated! 

Sigurd