Complex Shell Models Meshing

About the development of the FEM module/workbench.

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Complex Shell Models Meshing

Post by thomasstephen »

Hi Guys,

Meshing is done as single model either by making it a compound or fusion. The mesh element is single object. When the results are viewed I want to examine some critical part of the model. Other than clipping filter is there anyway to see different part of the meshes rather than a single mesh result object. Usually in FE tools, it is done by making a set for critical part in the modelling so that we can see the results of such part alone in post processing.

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Re: Complex Shell Models Meshing

Post by mac_the_bike »

This is a belated response to the Complex Shell Models Meshing post by thomasstephen

Is there a better place than this for this topic?

There are 2 topics in this post:
  • look at different parts of the mesh
  • making sets of element faces
The following is concerned with my interpretation of the first topic.
What is required for this is a series of operations that will enable the user to erase 1 or more of the surface faces, see Note 1. Erasing means "don't display", not delete.
This is an example of the operation:
  • move the model into some appropriate orientation
  • press a key, say E, and, with the mouse, sweep out a rectangle
  • all surface faces "inside" the rectangle will be erased, see Note 2
You will now be able to see inside the model because part of the surface has been erased, see the attachment "clipping.jpg". This has been generated using clipping planes but the picture is close to what you would get by erasing elements.

Multiple applications of this process must be possible.

Three additional options are required:
  • "undo" - undo the current selection, perhaps only undo 1 level
  • "restore display" - restore the display
  • "show cut face" - display the surface faces on the cut surface. This will give a surface which is not flat.
Note 1:
When a 3D model is displayed, in reality only the external faces are displayed. So erasing surface faces means erasing external faces.

Note 2:
There are at least 2 criteria for choosing which surface faces are to be erased:
  • if at least one, but not all, of the nodes of the surface face is/are inside the rectangle, then erase this surface face.
  • if all the nodes of of the surface face are inside the rectangle, then erase this surface face.
Only 1 of the criteria should be used.
In both cases only the position of the nodes in the undistorted mesh, i.e. without the displacements being added, should be considered.
If part of the surface face is inside the rectangle but the surface face is not to be erased then the display should show all of the surface face. This is different to clipping.

Now some points about the mesh quality which can be checked by erasing surface faces.

How do you check on the mesh "inside" the geometry?
You can have a good mesh on the geometry surface but what does it look like beneath the surface?
For example if you have a fillet radius you need to be able to see the size of the elements beneath the surface to make sure that they will be able to represent the stress distribution.

The modeller can view the shape of the internal surface faces by use of The "show cut face" option.
This display would give a good idea of the shape and size of these elements.

not Modal Assurance Criterion
clipping.jpg (77.21 KiB) Viewed 422 times
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