Grasshopper

algorithmic modeling for Rhino

# K1 - Sail Anchored to Movable Rods + Testing Real Values of Stiffness

Hi everyone (hopefully also Daniel)!

Last week I discovered Kangaroo and I'm having a blast testing structures that until now I was only able to do with models.

One of the projects that I'm currently working on is a tensegrity structure that uses cables and a tensile fabric to apply traction. The basic cell of the structure is a sail with two parallel rods.

The easy one was the fabric anchored to the extremes of the rod. I got great results with the tensegrity model , very similar to physical models that I was working on.

But then I tried the same thing with the fabric anchored all along the rods, but it proved to be hard (read all the "rod discussion"). I tried the bending force, but was too unstable. The best model I got was by applying different stiffness to the mesh, specifically, to the lines that coincide with the anchors.

It's by no means the solution that I had in mind, but the next days I'll be testing it with the structure. I came across with the next thing to my ideal solution, Daniel's boat (https://vimeo.com/30128894), but I couldn't replicate it. Anyone has some idea of a different, more rigid  solution? Even in K2, which I really don't understand yet, but any clue would be helpful.

Aside of that, I was also having trouble applying real values of stiffness. The third archive has the same definition that the first, but with real stiff values (the rods are wood, k=10^7 N/m, cables are nylon k=2x10^5 N/m). I adjusted the timestep and the subiterations, but it doesn't work as stable and smooth as the whatever-stiffness-sail. I don't know if isn't correctly calibrated, or my computer its too old (it pretty old and slow) or simply isn't a good definition.

If anyone has any idea it would be very much appreciated!

Antonio

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