Topics relate to geometry, meshing, and CAD

Meshing of body ?

    • maurya


               i am facing problem in meshing on one bone.

      Biggest doubt is this one day it mesh with terahedral mesh of 5mm element size.

      On next day when solution having problem i tried to decrease element size to 2mm it fails.

      Very funny why it mesh first day with large element size and next day for 2mm or even lesser, it fails.

      i am attaching file as well as showing pics.

      i split the screen into two : green(geometry with marked portion having problem) and yellow mesh with circle surrounded having problem.


    • peteroznewman

      Hello Deepak,

      This geometry has a lot of small spikes in it. This surface has a crack and the edges don't meet.



      ANSYS meshing software is brilliant in the way it can defeature geometry, in effect, ignoring small spikes and defects in order to use much larger elements that just span across that detail. I can understand why a 5 mm element can bridge over small details, and when the element size reduces, those details cannot be spanned  with a shorter bridge and they ruin the ability to mesh.



      Here is an idea, mesh the geometry with the largest elements that retain the detail at the scale you care about, while bridging the small details you don't care about. Then convert those elements to geometry. From that point on, the small details are GONE and you can mesh with as small an element as you wish, because the underlying geometry is the smooth shape function of the large elements, not the original spiky geometry you started with. I have a workflow that can export the deformed shape from an analysis as geometry along the lines shown below. 

      While simplification of the geometry occurred, there are some missing faces at the end of this process.


      The attached ANSYS 19.0 archive is presented for your entertainment.

    • peteroznewman

      Check my last post for updates and attachment.

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