Karamba 3d - Shell forces/stresses

Hi everyone,

I’m kinda new to grasshopper and Karamba…
I’m trying to get the tresses and forces out of a karamba 3d model (Shell with meshes).
I just don’t get it… The forces I get from the S-force component don’t add up with the support reactions…

The model in here is a small part of an bigger script. But it is a core structure and now I need to check what the stresses and forces are at certain points. Is there anyone who can help me?


Shell stresses-forces.gh (35.0 KB)

Hi @Bart_H,
you need to sum up the cross section forces at a specific section (see attached file:
Shell stresses-forces_cp.gh (44.3 KB)
The stress concentrations at the point-wise supports introduce an inaccuracy with respect to the resultant of the section forces. If there are no specific reasons for having point-wise supports it would be better to have all points at the base supported.
– Clemens

1 Like

Hi Clemens,
Thanks you for the response, this helps a lot!
I implemented this part to my main script and it gives me pretty accurate vallues!!

Thanks for taking the time to help me!

Hello. I have the same problem, but the reason may be different. I have a frame structure resting on four columns, all modelled with shell elements. The reaction forces are correct, but the shell section component at the base or mid-height of any column provides very low values in comparison. I think that I am making something wrong, but what!? Thank you!

shell section.gh (149.6 KB)

Hello @valbe363,
one reason for the inaccuracy could be the very stretched triangles used for modeling the lower beams. It would be interesting to see how the results change with a finer mesh in the region of the section.
Did you consider modeling the C-profiles as beams with I-sections?
– Clemens