General Mechanical

General Mechanical

APDL: How to get access to nodal acceleration in mode-superposition transient analysis?

    • Clemens_C
      Subscriber

      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. :(

    • Rahul Kumbhar
      Ansys Employee
      Please try adding SET,.. command before NSOL command.
    • Clemens_C
      Subscriber
      thank you for message. It doesn't work. I still get the message: "The label ACC cannot be used, as the data is not avaiable. Please check the TRNOPT command (VAout) as well as the expansion pass OUTRES command. The NSOL command is ignored."

      To get the acceleration I used the DERIV command.
    • Ashish Khemka
      Ansys Employee


      Nodal velocity and acceleration are only written to the results file for a full transient and not an MSUP transient. You can use DERIV command for getting the acceleration.
      Regards Ashish Khemka
    • Clemens_C
      Subscriber
      Thank you a lot! But I'm very confused. Why does it say "The mode-superposition transient solution (the modal coordinates) is written to the reduced displacement file,Jobname.rdsp,[...]. Only the displacement, velocity, and acceleration solutions can be post-processed directly in POST26" in 5.4.3.1. Obtaining the Solution???
      So why is the acceleration not available?
      Regards Clemens
    • maimang
      Subscriber
      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.
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