Meshing Tubular Structure

protontim

I have an extrusion model that I have tried to mesh from the STEP file with no real success. So to get a good model I decided to import a DXF, do a 2D mesh and then extrude. However, when I do the 2D meshing it meshes over the internal cavities (see attached). Is there any way to avoid this happening?

Ideally I would like to be able to mesh the STEP file but I have little success in that regard. I can get NETGEN to give me a mesh that has a couple bad elements, but I would really like a mesh in Mecway so I can use faces for my constraints. Right now I would be happy to get the DXF to mesh properly. Thanks.

Victor

Before meshing it, put the lines that define the holes in a different component, then the holes will end up in that component after meshing too so you can easily select and delete them.

To move the elements to a new component, select them, right click one, then click "Add elements to new component".

Sergio

For this kind of shapes I found very suitable work directly with the 3d solid and mesh only surfaces using the quad option, then create a named selection with one of the end faces. Then switch to element selection, select the named selection and reverse the selection (to select all the elements minus the one on the end face). Then delete this elements and you have then only the end face meshed with mostly quads, that you can easily extrude along the perfil lenght to get an almost full hexa mesh (the holly grial for FEA).

This mesh in my opinion will have the best elements shape and will be less elements than meshing directly with tetra elements.

Regards

VMH

Just some rough sketches, mesh, and screenshots (per Sergio comment).

protontim

Thanks so much for the help. Greatly appreciated. Sergio, I had tried something similar to your method and got to work, but your method is superior. Thank you and thanks to VMH for the informative illustrations. Problem resolved.

Sergio

Very nice meshes VMH, you are ready for the aluminum extrusion industry!

Would be very usefull an option to mesh onlys selected faces of solid parts.

Regards

protontim

Used the recommended method for both parts shown. Joined them with bonded contact. Made for a very clean mesh on a part that previously would not even mesh. Thanks again for the help.

[Deleted User]

that's a cool result, nice job guys

VMH

Great to hear that it's helpful. Just a comment that may not be your case. If the smaller part that are inserted into the groove of the larger part and are not welded together, it would be more accurate to use contact that allow interactions between the parts (like "New CCX Contact" from the nonlinear static analysis option). The bonded contact of the two parts if they are not fully welded yields a much stiffer section.