Exporting STL From SketchUp for Schools to SimScale

I’m trying to export a STL file from Sketchup for schools to do a force analysis in SimScale. When I export the STL file from Skethcup it is not recognized as a solid in Simscale. I’m trying to find out if this is something I need to fix in Sketchup or if it as issue in SimScale. I’ve attached my exported test project. Is there any reason this would not be a solid?

Test2.stl (684 Bytes)

Can you share the SKP file so we can see what you’re working from?

Also here’s the Sketchup file.

Test2.skp (136.3 KB)

I looked that the SKP file. It appears to be a simple box and SketchUp reports it as a solid component. The imported STL also shows as solid when I bring it into SketchUp. If there was a problem with the STL export, I would expect the imported STL to show as not solid in SketchUp. That would make me suspicious of how SimScale is importing it. Unfortunately I’m not much familiar with SimScale so I don’t have good advice for that.

Thanks for looking into it. I was thinking the same thing that it was a solid. I tried doing it with a more complex project which is why I wanted to create the simplest test case. If this particular project were sent to something like a 3D printer would it print a solid box or would it print a shell?

It should print as a solid box although the slicer software might create a a sort of fill mesh (the technical term escapes me at the moment) so it isn’t entirely solid.

In SketchUp, faces have no thickness so if you want a shell, you would need a box inside a box with proper face orientation on the inside.

I don’t want a shell. I want it to be a solid. I’m just trying to find out why another software program might interpret it as a shell and not a solid. Or if there’s any way to implicitly make sure the STL file shows as solid.

STL, like SketchUp, represents objects using a collection of faces (triangles exclusively for STL). It has no concept of “solid” in the sense of filling a volume with material. It is up to the 3D printer software (or other importer) to recognize that the faces surround a closed volume that can be interpreted as a “solid” and to choose how to fill that object. Usually they offer a choice of the fill factor, i.e. amount of material to put in a sort of web in the interior, because the cost and time to print go up dramatically as you increase the amount of material.