free-form surface - form finding with mesh using GSA (Oasys) - troubles

by Alessandro Liuti

May 20, 2011

Hi,

 

I've been trying to develop a free-form mesh surface through form finding procedure, by using Jon Mirtschin's very interesting GSA plugin (http://geometrygym.blogspot.com/).

I've studied some examples I found pretty useful, but I am kind of stuck, maybe in the final phase of the process; is anybody capable of checking the ghx file and try to help me solving the impasse?

I hereby enclose the ghx, and a sketchy snapshot of the result I've been seeking; thank you all so much in advance,

 

Alessandro.

  • up

    Jon Mirtschin

    Hi Alessandro,

     

    Here's some comments from my look at your model to keep you progressing.

     

    Your sketch shows continuous curvature over the lines of support, in reality a membrane or fabric would crease and hang over these support lines (as my image shows).  If you wish to "form find" this type of geometry, you will need to find a way to apply upwards pressure at these regions.

     

     

    It's easiest to work with a single mesh, so I reworked your line generation to loft a surface (there were some internal disjoint edges forming).  Also, I added an exaggerated gravity load case to give the surface shape (with settlement loads only, the surface will relax to a minimal surface, which will produce planar type surface in your example as it spans one way.  I also added an xy restraint to the internal nodes not vertically fixed, the surface was collapsing at some edges causing problems in calculating a result.

     

    One other tip, if you right click on an ssiBake component, you can disable the placement of data into Windows Clipboard that will help accelerate the process.

     

    I hope this helps you progress further closer to your objective, I'm happy to help advise further.

     

    Cheers,

     

    Jon

    4

    May 21, 2011

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