Autodesk Simulation Mechanical overwhelmed?

[Petr.Krysl]

Hello all,

I have tried computing the heat-conduction steady-state solution to a trivial problem: non-zero uniform heat generation rate, fixed boundary conditions, square (plate-like) domain.

I use 1M quadrilateral 4-node elements (1000x1000). The simulation completes in around 3.5 minutes, and even after it completes the UI is mostly unresponsive. Dialogs take forever to open and close, and this lasts for minutes. Things become better only after I revert to a much smaller mesh (10x10).

Question:

1. Could anyone try to compute the solution on their own machine and tell me how things went? 

https://www.dropbox.com/s/y28px6a3creg1to/Poisson_fem.ach?dl=0

2. Would you have any pointers on how to make the software more responsive?

I think it is rather disappointing to see such poor performance. The model is not THAT large!

Thanks,

Petr

[Petr.Krysl]

Not sure what happened, but the machine and version info got chopped out of my original post:

ASM 2014 (student edition)

Windows 7, i7 w/ 16 GB of memory, Intel HD graphics

P

[AstroJohnPE]

Hi Petr,

Are you planning on doing hand-built models, or will you be working with CAD models? I believe there is a difference, especially with chunky CAD models where most of the elements are inside the volume, and Simulation may be programmed to handle the interior elements more efficiently. In other words, a 1 million (1E6) element brick model created from CAD and a 1E6 element plate element model created by hand may behave differently.

I tried a 1000x1000 hand mesh but gave up. The FEA Editor was too slow on my computer. A 500x500 hand mesh took time to create the mesh, but I was able to work on it in the FEA Editor without any frustration once it was done meshing. (I changed the surface number of the edge lines, assigned surface controlled temperature instead of nodal controlled temperature, etc.) Some things that you may want to try are these:

• hide the loads and constraints whenever possible.
• try setting the Visual Style to mesh only. Perhaps the UI will be more responsive if it does not need to shade the model.
• define the element type after creating the model. The UI should definitely not try to shade the model without knowing the element type. (You may not be able to apply some loads or constraints until the element type is defined, but see what you can do.)

The 500x500 model was more responsive in the Results environment, especially after I hid the loads and constraints ("View > " tab). I was able to rectangle select some nodes (maybe a few hundred), right-click, and Inquire Results. The dialog appeared within 1 second. You can also free some memory by closing the FEA Editor and leaving just the Results environment open. That may help. (Likewise, if you want to open a model to view the results, it is faster to open the results directly by setting the "Type of File" on the Open dialog rather than opening the FEA Model and then switching to the Results environment.)

P.S. I did notice one possible problem with your model. The perimeter of the model was created with 4 single lines, and the 10x10 mesh was overtop of the 4 lines. As a result, there was 1 large element overtop the 10x10 mesh. In the Results environment, use the "Results Options > View > Shrink Elements" to see what I mean.

[Petr.Krysl]

Hello John,

Thank you very much  for the information.  

 My purpose was to obtain performance data that could be compared with  a home-brew FE solver. The homebrew assembles and solves the equations in under 10 seconds.  I realize  that the poor response  of ASM   is to a certain degree  due to difficulties with graphics display (too many symbols for the loads and constraints),, but even then the solver reports something like 3 1/2 minutes solution time.

  I will follow your advice on the treatment of the graphics display to redo the calculation.  I'm curious to see how much of a difference that will make.

Not sure how a single element but overlaid over the  big mesh.   The geometry was meshed using the manual meshing tools.

Best regards,

Petr