Unplausible Deformation under Self-Weight

[Justin_Becker]

Hello everyone,

I’ve completed my geometry model and converted all lines into Karamba elements using the Line To Element component. I’ve also assigned Element IDs to distinguish different parts. The goal is to run a parameter study and optimize cross sections.

Issue: I’m already getting strange deformations under just the self-weight load case. As a check, I applied a sample load at the ridge – that deformation looks plausible. So something seems off in the way I applied the self-weight or defined the structure.

Second issue: I’m struggling with the workflow for cross-section optimization. What I want:

• Columns should be I-profiles
• Truss elements should be CHS profiles
• Ideally assignable via group IDs
• I want to define a range for CHS profiles, e.g. diameters only between 5 cm and 25 cm

Question: What’s the correct way to implement this in Karamba? Does anyone have a working example or can explain the step-by-step process?

Any help is appreciated. I’m happy to clarify if anything’s unclear.

This is the deformation under a uniform distributed Load:

And this one under the Dead-Load Case… this looks quiet odd to me:

I also find it strange that the deformation under self-weight is larger than under the uniform distributed load. Does anyone have an idea why that might be?

[matttam (Matthew Tam)]

It is hard to solve the issue from just screenshots, if you share your script, this might help.

Regarding cross section optimisation, you can do so by grouping your cross sections into families or using the default cross section library which have. An example you can refer to is Large Deformation of a Triangular Grid - Karamba3D More examples can be found on our website.