Grasshopper

algorithmic modeling for Rhino

Hello there,

I´m pretty new at Karamba and i realy appreciate and like it.

At the moment I´m trying to generate some fibre-reinforced plastic for a freeform, that´s exposed to gravity. I would love to recieve the firbes arranged in number and direction, that they can cope with the loadcase and I would just have to glue them together with some kind of resin. Like in the linked Example http://www.achimmenges.net/?p=5561 .
I read in the Karmba 1.1.0 manual, that "In case you want to strengthen a structure with linear elements (e.g.fibres) align them with FF-lines to get the most e ective layout."

I tried to do so, but the solution seems a bit missleading. I guess i did a mistake somewhere. What do you guys think?



Thanks,
Dominik

PS. gh file attached

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Hello Dominik,

you could try this:

  • increase the density of the underlying mesh to make the curves smoother.
  • be more selective about the starting points of the force flow lines. I think the points at the supports would be a good choice or where concentrated loads act.
  • If the structures behavior is governed by gravity use the Z-direction as the force flow direction.

Best,

Clemens

Hello Clemens,

thank you very much for your response. It looks good now.

I have another Question now :) I did a shell crossection optimization on a triangular shell wich is supported on the 3 corner points and the next closest two points of ech corner point. The shell is a bit asymetrical.

Now i get a unusual crossection height for one face. It´s way bigger then the other ones. For me it´s difficult to comprhend, and i suspect it´s somehow a mistake. What do you think?

F

Furthermore i would like to know if its possible to let the crossection "grow" in only one direction instead of puting out the original form as a middle layer? So that i would be able to put the original shell on the "ground" and during the optimization process nothing would tend to reach underneath that level?

Best regards,

Dominik Simon

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The excessive shell thickness at the support of is due to the clamped support condition there which leads to bending moments. 

You could try to add short pieces of beams use only one support per edge. The purpose of the beam pieces is to distribute the support reactions so that a stress singularity is avoided.

In Karmba 1.1.0 it is not possible to define eccentric shell cross sections.

Best,

Clemens

Fun project :)

- I quess it would be possible to divide the shell into "slices" of shells/meshes and give these different thickness in whatever direction and style wanted?

I can't remember what egde conditions it is possible to set for shells in Karamba?

it is possible to set different thicknesses for the elements of a shell. In Karamba 1.1.0 an isotropic material is assumed - therefore it is not possible to define different thicknesses for different directions. I think what would be needed here is the possibility to define composite shell sections.

For vertexes of shells one can define six displacement constraints. Line supports result from fixing multiple, consecutive points. 

Best,

Clemens

Thanks again, and sorry for the late Response :)

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