Not sure what do you mean sorry. I hope the example is useful to you.
As Xyont has confirmed, this assemblies requires a bunch of nodes to get reliable results but, not recommended doesn’t mean it is restricted.
i have checked the example,
very interesting. i have checked the buckling modes.
I prefere to work with beam cross-section created with solid elements.
how you fix the boundary, if you use a U-cross-section?
in connection with gravity and shear center!?
this what i found in 2016 for preliminary review. i did not refined the model and investigate further, it seems beam element in CalculiX mostly dependent on how user modeling.
please, don’t judge quickly about the reliability and accuracy or even a bugs cause your model may inappropriate to set (i.e mesh, element type & additional restraint) or limitation itself.
i seen many user direct compared to 1D/2D classical element were is not comparable due to expanding element in CalculiX and generates knot or MPC existence. user need different model approach to refined and set up properly.
To compare with the theoretical result I guess the same strategy. Idealization of a pure pinned support and rotation around the x axis constrained.
I have tested on a 6meters UPN160 with distributed Self weight and agreement with the theory is reached in this case with just 4xB32R. Not bad at all.
Too bad it doesn’t have even a simple GUI. Is rotating and merging built-in sections the only way to analyze non-standard shapes ? It would be great if there was any open-source software allowing users to import a drawing of the cross-section from CAD software like FreeCAD.
I used it in the past for the D-box structure of aircraft wings, the skin (leading edge structure) was imported from a *.dat file and merged onto an I-shaped member (stringers+spars). Today probably it is easier than before, but it was a relatively difficult task to do the first time. But the code was automated and parametrized so later changes were easier.
I have positioned two UPN160 one with respect to the center of gravity and the second with respect to the Shear Center.
I have not been able to completely avoid rotation without a minimum constrain (rotational spring).
That’s a good point for this technique as it seems able to model bending/twist. ¿Is that possible Xyont or am i reading incorrecftly the displacements?
it seems eccentricity and twist only considered by beam element in CalculiX when user defined the member distributed load transferred to webs. this assumption given correct assumption since any transversal load must resisted by stiff part.
above true assumption are ignored by many classical beam element. this what i mean before, another condition is required to test and validate.