Alex Bausk on engineering and unrelated learnings

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Oh Robot Blues

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Some people might tell it that the great grim motto of the STEM (Science-Technology-Engineering-Math) field is: sweat, tears, and pointless manual labor. So here’s just a small update on how things are for the Autodesk Robot Structural Analysis (ARSA) users out there.

The last week brought some new discoveries of problems that a Robot user should be aware of. I’ll just leave it here for future reference:

  • While ARSA is able to export 3D faces from DWG/DXF files, the export process is prohibitively slow, taking some 2 minutes per single 3Dface. This adds up to the horde of problems with structural calculations compatibility, which can be summarized as follows: if you ever switch to another structural analysis software (or sometimes even another preprocessing technique), you will have to rebuild your existing models nearly from the beginning in order to be able to use them.
  • The issue with response spectra analysis (namely, incorrect ZPA calculation) that has been plaguing dynamic analysis in ARSA at least since release 2011 (and possibly in earlier releases) is still there, after a major version update and three service packs. Serioualy, how do you get away with this crap? Am I the first person to ever use ARSA for dynamics? I don’t think so, since there are guys that are much more proficient with dynamics in ARSA than me.

These issues were discussed with the support team of ARSA (these guys do a really nice job, considering the negligence that they receive from our mighty ADSK overlords) and it was established that these issues are persistent and endemic to the ARSA application.

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Written by Alexander Bausk

November 16, 2011 at 1:48 pm

Posted in Программы, FEA, GUI

Modeling I

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I’ve just finished modeling geometry of a VVER-440 power reactor building. I’m completely bushed yet very glad I managed to do it.

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It’s just the steel part of it. Under the trusses will reside the concrete containment and auxiliary structures.

Now a lot of work has to be done further. It’s just an AutoCAD 3D model. It has to be imported to the FEA solver’s preprocessor, crunched a bit to mitigate some minor errors; then materials would be applied, sections specified. Then, a lot of work to specify coupled nodes, etc.
At last, static and dynamic loads will be applied, including seismic and aircraft impact, then comes solving the resulting finite element model, and a heck of messing with the apparently irrelevant results. After that, detailed analysis of structural members and writing about 80 pages of final safety assessment report. Man, I’m bushed.

When I’ll be finished, perphaps I’ll give a little more detail about how it was done.
Also, it’ll make for a great entry into the would-be portfolio.

Written by Alexander Bausk

October 18, 2009 at 10:10 pm

Posted in AutoCAD, CAD, FEA, Modeling

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A Blast from the Past

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Attached follows a screenshot of Robot SA 2009 documentation.

CBS_manual_example_eng_calculations_2009

The software to which this sheet pertains has been released by Autodesk in 2008 as I remember. Prior to this, Autodesk acquired RoboBAT, the developer of Robot finite element analysis package.
I posted this sheet to illustrate the current state of Robot documentation, which is frozen at a level of maybe v15. Since the acquisition, Autodesk did fairly nothing to improve the accompanying documentation and very little to improve the program itself.
I understand that their primary target is developing BIM technology and liaison with Revit, but this is no excuse to dump those wishing to have more control of the FE analysis process than the BIM allows.

Also, Autodesk charges four-digit numbers for the right to use Robot SA with documentation coming from pre-Windows 2000 era.

PS. Thus ends the Autodesk Rant Series.

Written by Alexander Bausk

October 6, 2009 at 8:43 am

Posted in FEA

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CalculiX Posts on structural.wordpress.com

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I’ve started a series about the stunning CalculiX FEA software in Russian:
http://structural.wordpress.com/category/calculix/.

When it will be over, I think I’ll compile a kind of lecture notes about how to use CalculiX efficiently. There is a heck to be done there; for example, I’m already dreaming of an AutoCAD – based preprocessor to make large models and a postprocessor to manipulate results.

One thing that CalculiX lacks to become a killer tool for structural engineering is a complete absence of any design modules. As you get the “raw” FE solution, you’re on your own to the most work-consuming part – actual design.
If we take any AutoCAD clone for say US$600 and make it work as pre/post for CalculiX, we practically get an ANSYS – level structural FE solution for less than thousand bucks. Lot to think about.

Written by Alexander Bausk

June 18, 2009 at 3:40 pm

Posted in all..., CalculiX, FEA

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