I am using utility skin solid elements which suppose to create shells with normals pointing outside solids. I noticed that for some solid meshes, produced skin has mixed normals. Is there a utility which can fix normals to point out without user interaction/inspection?
The branch message indicates that this is not a closed set of shell elements (outer surface).
If you verify the Hex mesh with a free face wireframe plot do you see any "faces" inside what you think of as the outer surface boundary. use Display/FEM/show only faces (in wireframe) , default normally, and look for internal edges using wireframe display. Sometimes I use shaded , which hides the internal faces, but then use clipping planes to look at a slice of the model and move the planes across the model checking for faces appearing in the interior.
There is a problem with the mesh where there are two tet elements going to a single hex face. This is causing a mesh junction when you create shell elements,. 2 trias on one quad . I've tried to point it out here:
a more serious problem is that a lot of the elements are inside out, these are failing the positive volume connectivity test and they are giving rise to shell elements that point the opposite way to what you expect if the hex had a positive volume.
Here is a fixed mesh with all positive volume elements and the tets overlying the hexes replaced with wedges. this now creates shells which all point outwards.