General Mechanical

General Mechanical

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Calculating only Modal Coordinates from an MSUP Transient Analysis in Mechanical

    • kamilemre.atay
      Subscriber

      Hi everyone,

      As the title of the topic suggests, I am looking for a way of calculating / writing only a modal coordinate file (.MCF) from a mode-superposition based trasient analysis in Mechanical.

      I have tried OUTRES,ALL,NONE command snippet in transient analysis and also tried turning on the "On-Demand Expansion" in both modal in steps in my transient analyses to be able to write only the MCF file as an output, yet it seems that APDL solver still does some expansion-like thing behind the scenes (it says that it still calculates reduced displacements etc, even though I don't write them due to my OUTRES,ALL,NONE command in all steps.

      The reason I want to be able to just calculate and skip everything is that I have a fairly large 3D model (about 2 million elements, 4 million nodes) with some forces and moments applied with remote points( so there are nodal forces applied on the model), so with expansion step, even just writing the MCF file takes more than a few hours for a for a few thousand timestep-long data.

       

      Any help is much appreciated.

       

      Thanks in advance.

    • dlooman
      Ansys Employee

      That makes sense and should have worked.  I'm worried thought that Mechanical may have over-written your outres command.  You could verify that by looking at the ds.dat file.  The mode-sup analysis is a two step process.  An initial solution is done to set the time step and do a mode-sup static analysis of any non-zero loads.  The second solution is the transient analysis.  Mechanical reissues its own outres command at the beginning of every load step so your outres command may have only applied to the first load step.  There's an option in the commands details to issue the commands every load step.

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