Polyline beams in Karamba and Join elements

lea.dambrine · January 6, 2021, 2:37pm

Hi there !

Here I have a project for a tree that must be able to support its own weight.
At the morphological level it looks like this:

But on Karamba instead of having continuous branches from start to finish, I have to, since the beams are created from lines and not from curves, split them. So my shape is not right, because they are on Karamba assemblies of beams and not continuous branches from the ground to the top as in the morphological research. This gives completely wrong calculations.
In addition, I normally have connecting pieces between the different branches like this:

But I don’t know how to interpret them in the calculation on Karamba, because if I create supports it gives me pieces that are much too rigid. I cannot directly import circular elements that would surround the branches. I thought maybe to create concentric forces around these places but I don’t know how to model them on Grasshopper …

Any ideas for a solution?

matttam · January 6, 2021, 7:09pm

Hi @lea.dambrine,

can you explain your problem a bit clearer? f you split your curves at their insections and convert these to lines, they will still be intepreted as “continuous” elements in Karamba, unless you define joints between them.

I cannot see any results from Karamba in your screenshots so its hard to see where we could help you.

lea.dambrine · January 6, 2021, 9:00pm

(thanks for your help)

Well… It’s what I’ve done for the first part, but I was wondering if it was considering it as a continuous thing so… Great !

But then my real problem is how can i materialize that all thoose branches are linked where they are joins, that is to say, on the image below where there are the polygons :

because for the moment I did it as supports but it makes the structure too rigid :

And I tried to represent them as beams that would link the ends for the previous separated elements of the beams together then I have this as a result :

And the component tell me that there is a support problem that I don’t understand :

matttam · January 7, 2021, 7:40am

Hi @lea.dambrine,

you should include the connections as Beams as you have in your second image. There should not be supports there unless your structure is really supported there.

There seems to be an error with the Assembled Model - you can right click to see what the error message is. The Connected Parts components allow you to check if your geometry is really connected in one model - please refer to https://manual.karamba3d.com/3-in-depth-component-reference/3.1-model/3.1.4-connected-parts

lea.dambrine · January 7, 2021, 1:45pm

I included the connections as beams, but since I’ve done that, an error appears on the model that wasn’t here before :

Definition of my supports is the same as when the beams wasn’t there, based on the “flour” of the tree…

Before adding all thoose elements (and after deleting the bottom of the tree), it was working so I don’t understand…

matttam · January 8, 2021, 7:52am

Hi,
As the error message says, the support node is not defined in your model. This can be a couple of issues.

Flatten your inputs in the Elements - you might have multiple branches and therefore multiple models
Check to see if the nodes are actually end points of your line geometry input.

lea.dambrine · January 8, 2021, 9:46am

Thank you so much ! I just didn’t realize all the elements must be assembled in one component before connecting them to the “Assemble model” module !

Just one last question … I have obtained a very weird result (I know the structure isn’t that great but to that extend, it seems weird) and also thickness doesn’t appear on it:

My structure is 1m high and to have the thickness of the branches (which should normally be a few centimeters) , I have to put on the cross section a thickness of like a hundred :

While in the pipe component, outside of Karamba, I can let 1 as an input for the radius and see them

Can you help me again please ?

matttam · January 10, 2021, 3:24pm

Hi,
i see that your rhino file is in cm. Please note that 1.3.3 version of Karamba only works with meters, so any geometry you input into Karamba will simply interpreted as meters.

lea.dambrine · January 10, 2021, 8:12pm

Thanks a lot !!