Unfold a surface (unloft?) to flat pattern?

Discussion in 'SolidWorks' started by DAS, Sep 9, 2003.

  1. DAS

    DAS Guest

    Can someone tell me of a Solidworks built-in capability to pattern a
    surface from a given model so that a piece of flat material can be cut
    accordingly and placed over an actual object, form-fitting? The
    computiong trick I want to perform is to know where to cut out
    material for folds that must occur in the finished product. A close
    analogy is cutting fabric so that it could be joined at fold cut-outs
    and simply slipped over an object, like upholstery. Is this too far
    out for Solidworks' basic package?
     
    DAS, Sep 9, 2003
    #1
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  2. I was able to do it on a rectangular part. Using surfaces. I would like to
    try your part. If you could send it to me.

    What I did was inserted the origional Part into an assembly and made a new
    part that contained the surfaces with zero offset. Then I thickened to
    ..001" and ripped the apropriate edges and inserted bends.

    Corey Scheich
     
    Corey Scheich, Sep 9, 2003
    #2
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  3. DAS

    DAS Guest

    Corey,

    That is exactly the kind of thing I am trying to do. My model is
    basically pure curves, so I am sure there are many ways to use your
    method on this problem, if the rip function will work with no exact
    corners. Thnx.
     
    DAS, Sep 9, 2003
    #3
  4. DAS

    Arlin Guest

    If everything is curves, more than likely, your surfaces are not
    gaussian surfaces.

    Gaussian surfaces are those which can be flattened without any
    stretching or tearing. Such surfaces include cylinders and cones.

    A non-gaussian surface is one which cannot be flattened without
    stretching or tearing. Think of an orange peel.

    Unless you are VERY careful about how you created your surfaces,
    ensuring that ALL surfaces are either perfectly flat, a perfect
    cylinder, or a perfect cone, flattening you surface cannot be
    accomplished with SWX, or almost any other "mainstream" software.

    To flatten a non-gaussian surface requires very detailed knowledge of
    both the mechanical properties of your material AND how it is formed
    from a flat. There are many programs used in the stamping industry to
    calculate flats from non-gaussian surfaces. They use FEA and complex
    analytical calculations to do this. I am not sure if similar packages
    exist for fabric material sheets. There probably are somewhere if you
    really need this functionality. It will be expensive, however.

    I believe there are some "simple" programs which can flatten non-
    gaussian surfaces (Rhino, perhaps???). But, AFAIK, they do not factor
    in material properties or the forming process. I really have no idea
    how they get it done (some sort of least energy method I would assume),
    but I would be willing to bet that it is not very accurate in the "real
    world."

    Note: SolidWorks does have a "Lofted Bend" feature in which non-gaussian
    sheetmetal shapes can be created and unbent. SolidWorks also includes
    tools to analyze deviations between the bent and flat state. However,
    the practical use of this tool is limited in many situations. For
    instance, the lofted bend must be the first feature in a part; you
    cannot thicken existing surfaces to create a lofted bend; and some
    others. Plus, like I said in the above paragraph, it does not factor
    material properties or process in the flattening process. Thus
    "highly" non-gausian lofted bends can be quite inaccurate. Of course,
    the closer the surface is to a gaussian surface, the more accurate a
    lofted bend can become.
     
    Arlin, Sep 9, 2003
    #4
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