Grasshopper

algorithmic modeling for Rhino

In response to a recent comment on this video:

 

I'm posting the files here.

 

The same grasshopper definition should work with any collection of struts and cables you draw in Rhino.

 

This sort of thing does seem well suited to exploration in Kangaroo.

By making the cables elastic and giving them some pre-tension, the form can be allowed to relax into a position where all cables are in tension and it is stable, then it can be tested or fabricated with much stiffer cables.

 

btw - For inspiration I'd recommend Kenneth Snelson's website:

http://www.kennethsnelson.net/

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thank you Daniel!
Great! Thanks a lot for posting!

Here's another little example, plus a minor tweak to the grasshopper definition so it can output the formfound cables without subdivision.

 

This is useful if you want to relax, bake and then feed the result back into the starting curves.

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I have tried out the definition without any tweaking to rebuild our famous 2010 Christmas tree which we have made without any form finding. We just have made a 3D model for the member lengths and have prayed that it will stay in shape. And it stayed. The GH definition works great, the result is almost identical to what we have achieved. A fantastic GH plug-and-play tensegrity definition, Daniel!

Great to hear! Always nice to have these real world checks.

 

I had a little play myself:

Nice, looks like we are entering a new playground. Here is another one we have made a few years ago, works as well! I have tried to drop it on the floor (the Christmas tree is a bit too big for this kind of experiment), and the dropping sequence of the virtual and real structure was very similar. I have to go back to work now, leaving playground...

Hi, Daniel. I just joined the grasshopper group because of your fabulous animations.

 

I created a short YouTube video with a high-tension tensegrity model, How a Tensegrity Behaves Under Stress. I'm expecting to see the same symmetric contraction when your six-strut model impacts the plane. Do you agree that the computer model is not behaving the same way? Can you alter your computer model so that it behaves more like the physical model?

 

We had a discussion about the stress-strain response last year in the sculptors.com geodesic listserv. Professor Amy Edmondson (Fuller's last chief engineer) believes the icosahedron must have the behavior described in 724.34 of Synergetics to be characterized as a tensegrity. This functional requirement goes beyond the simple appearance of the structures.

 

Hi Phil,

The difference in behaviour you are referring to is simply because different forces are being applied. If you were to apply the same squeezing forces in the simulation as you do in the video, then the I believe the response of the virtual model would be the same.

This morning, I squeezed a single pair of endpoints in the tensiondesigns.com "vector equilibrium" model. The movement of the other struts is still almost completely symmetrical. I will post a video up on YouTube so you can see.

 

Do you have a straightforward means of altering the elastic modulus of your tensile elements? Also, can you provide a slow-motion animation of the impact? I am considering creating a CDF project in Mathematica showing this: allowing the user to alter the tensile element properties to see the changing behavior.

Hey Daniel. I'm sorry to bother you on such an old post, but I tried this script on the latest kangaroo and grasshopper and it says the file is corrupt. I then tried to recreate the script from scratch but the definition still does not function. I tried adjusting the cable tension and gravity but nothing happens. I was wondering if you knew why this is. Thank you for your time. 

Don't worry about it. You're good.

Hello

Could you tell me how to get compression forces in the struts and the tension in the cables please?

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