[Oct 17, 2020: I have discovered that this issue and the one posted as '"Missing "Rotate 3D" icon' are indistinguishable (at least by me). Here is what I think I have found: gmsh returns a 2D result for this geometry and it is displayed in a 3D context - can be rotated and zoomed as if it were a very thin 3D model. However, if the model is saved as a model file (.fea) and the re-opened, it is displayed as a 2D figure, thus with no "Rotate 3D" control.
So from my perspective there are two issues: First, what is it about the geometry that causes gmsh to return this seeming 2D model with a "grid cell mean quality" of "NaN" or "Inf"? The second issue is the way FEATool handles/displays this case both when it happens and after it is saved and reloaded.
I have added another post to this issue with an example that is captured from the ground up that will re-produce both issues from scratch. See below.]
This issue may well be caused by my ill formed model. But I submit it in hopes of at least learning where the problem lies.
It is similar to one provided in the second entry of the "Missing "Rotate 3D" icon" post:
Here is what the disk looks like inside the block:
When submitted to gmsh, here is the result:
Some time after I had moved on from the occurrence of this issue, I noticed the following error indications in the MATLAB Command Window, so I cannot be sure that they were associated with the creation and processing of the model, but I am including them in case they provide useful information:
Use these steps:
1. Create a new 3D model, Conductive Media.
2. Create 2D Workspace at (0,0,0)
3. Create an Ellipse x=.05, y=.1
4. Extrude 0.02 along 'z' axis
5. Chamfer 0.005
6. Chamfer 0.002
7. Create a block -2:2 -1:1 -1:1
... to produce this model geometry:
8. Generate grid using 0.21 (default)
... to produce a normal 3D grid:
Changing to the Geometry mode and zooming in on the 20mm thick disk:
9. Reduce 'z' dimenson of elliptical disc by transforming scale [1 1 .05].
...shrinks the disk in thickness ('z') by a factor of 20:
[So far everything seems normal. Problems begin to appear with the next step.]
10. Generate grid using grid size of 0.21 (default)
... to produces a 3D displayed grid that seems to be only 2D (in x, y):
Note FEATool Command log showing "grid cell mean quality: Inf".
11. At this point save Model, GUI Script, and MATLAB script files: