Hi all,

I would like to share an analysis of a steel tubular connection, like you could find in a major truss span of a bridge or roof. Of particular note is that (thanks to the great selection of tools and workbenches in FreeCAD) it only took me 1 hour or so to model and complete this whole analysis.

The dimensions are fictitious, but credible, i.e.: the horizontal tube has a diameter of 500mm and wall thickness of 10mm, whereas the diagonal braces have a diameter of 250mm and a wall thickness of 10mm. The diagonal loads are 1MN each.

The first picture shows the 4 solids used to create the tubulars and the region for mesh refinement

Next, the BooleanFragments of the combined solids are downgraded to faces in the Draft workbench, after which the model can be cleaned up by removing unwanted faces and stitched together with "Join Connect Objects" in the part workbench

This can be meshed in FEM work bench and the region where the braces meet the horizontal can be refined by creating a mesh region.

The results show the local deformation of the horizontal tube (scaled by a factor 50) and the high stresses the braces induce. This would be the starting point for designing local reinforcement of the node.

Finally a glossy Paraview picture of the same result

In my view FreeCAD is a great tool to quickly asses conceptual designs.