Learning Forum

[Clemens_C]

I did a mode-superposition transient analysis with a cantilever. In /post26 I can get the displacement of nodes (with NSOL,,,U, Y), which is nice.

But I also need the nodal acceleration. Unfortunately I don't have access to that data. I don't understand why, because I set (VAout=YES) in TRNOPT. I tried a few options with the OUTRES command:

OUTRES,ALL,ALL or OUTRES,NSOL,ALL or OUTRES,A,ALL

But nothing works when I try the command NSOL,,,ACC,Y. :(

[Erik Kostson]

Hi
So this should work.

Try to add this after you are done with /prep7
! *** SOLUTION CONTROLS FOR MODAL ANALYSIS ***
! --------------------------------------------
/SOLUTION
ANTYPE,MODAL
MODOPT,,5,,,, MXPAND,ALL
SOLVE
FINISH
! *** SOLUTION CONTROLS FOR MSUP TRANSIENT ANALYSIS ***
! ----------------------------------------------------
/SOLUTION
ANTYPE,TRANS
TROPT,MSUP
TIME,1 ! change the end time as needed
NSUB,200 ! change this as needed
DMPSTR,0.01
OUTRES,ERASE
OUTRES,ALL,ALL
OUTRES,NSOL,ALL
SOLVE
! *** TIME HISTORY POST PROCESSOR ***
! -----------------------------------
/POST26
NSOL,3,3,ACC,Y,AY_2,
XVAR,1
PLVAR,3
This works on my end.

All the best

Erik

[Clemens_C]

Hi Erik thank you for your fast response!
I'm sorry but that didn't solve my problem. :((
When I try your code, it says "The label ACC cannot be used, as the data is not available.Pleasecheck the OUTRES command.The NSOL command is ignored."

Why do I get that message? I used
"OUTRES,ERASE
OUTRES,ALL,ALL
OUTRES,NSOL,ALL"
right before solving the loadsteps.

For the Modal Analysis I used:
"/SOLU
ANTYPE,MODALMODOPT,LANB,number_modes,,,,off
MXPAND,number_modes,,,YES,,YES" -> is that ok?

I have 2 loadsteps and solve them with LSSOLVE -> It worked perfectly in the Full Transient Analysis...
I would be so grateful if you could help me again!

[Erik Kostson]

Hi

Can you try without lssolve so use only one step and just use the code above with solve only.

thank you

Erik

[Clemens_C]

Hi sorry, it didn't work with only 1 loadstep as well.
No I have 1 more problem: the time variable is equal to the computed frequencies from the modal analysis. -> only 10 values for 10 frequencies. :(

[Erik Kostson]

Not sure what is happening here . I would try to do a simple example of msup on beam and try it on something simple and add the first commands in my post because that worked fine.
Also read through the apdl manual:
5.4.4. Expand the Mode-Superposition Solution

See if that helps
-
all the best

Erik

[Clemens_C]

Thank you for your help but it still doesn't work. I won't do MSUP again.

[Erik Kostson]

Hi

I would look on the help manual
5.4 Mode-Superposition Solution
See if there are any points there.

I normally do this (MSUP) in Workbench where post26 is not used.
and it works fine.

Sometimes it can be tricky to get these results it seems in APDL.

All the best

Erik

[maimang]

By default in a mode-superposition transient analysis, reaction force and other force output contains only static contributions. If you want to postprocess the velocities, accelerations, and derived results (Lab = TOTAL, DAMP, or INERT on the FORCE command), set VAout = YES to activate velocity and acceleration output.