Custom section of multiple tube profiles


I’m trying to understand how to define a section of 2 parallel tubes running next to each other?

In my system model, they are displayed as a single curve which makes things easy but in reality it will be double tubes so I’m trying to bring my simulation as close as possible to the real setup. I can see there’s a deconstruct / construct section component, however my engineering knowledge is limited to calculate those values myself. Isn’t there a way to input a custom cross section geometry and let Kiwi calculate all the forces for the structure?

Hey, there is no possibility in Kiwi to compute the crosssectional values from e.g. a drawing of the cross section. You need to get the crosssectional values - either by another plugin or program or by computing on your own. In the case of two tubes, it would be quite simple to compute the values with R being the outer radius and r the inner one.
A=(R²-r²)* pi * 2
Iy=2* pi/4*(R^4-r^4)
Iz=2* pi/4*(R^4-r^4)+(A* R) if connected
It=4*(((R+r)/2)²* pi)²/((R+r)/2* 2* pi* 2)
The German wikipedia page provides also some examples for other cross sections: Flächenträgheitsmoment – Wikipedia

Wow, that’s great input!

What about Wy, Wz, Ay, Az? Do you know by any chance formulas to those too?

Ay and Az are not that clear.

But you do not need those values for the analysis. It’s only for the stress evaluation.

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Thanks Anna, this is really helpful!