Steve Mould video on bistable auxetic material

Hi There,

Steve Mould’s latest video https://www.youtube.com/watch?v=vrOjy-v5JgQ is on bistable auxetic material, where he has a somewhat flexible material with slots cut into it such that the initially flat form will deform into a three-dimensional surface that is locally stable. He has examples of domes and various cylindrical tubes. He has some very interesting analysis of the strategy for making the cuts to match the required surface.

This reeks of Grasshopper! I wonder if anyone has done anything along these lines and would be prepared to post an illustration or model? I am really tempted to have a go.

Bob

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search “auxetic” on this forum…

https://discourse.mcneel.com/t/auxetic-expansion-and-simulation-of-deployable-structures/90895

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You also have this thread with lots of nice insights from @DanielPiker : Kangaroo Bipartite

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Tian Chen actually did the work in Grasshopper! Here’s the reop with all the files: GitHub - UH-AIM/bistable-auxetic-surface-structures

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Hi Steve,

Clearly my ‘reek’ detector was spot on! Laughing my head off.

Thank so much for replying and for pointing to the GitHub repository. I see the demo .gh files and will give it a whirl!

And thank you also for all the work you put into your channel - I watch all of them!

Bob

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The history of the use of Grasshopper in auxetics work goes back more than 10 years.
This blog post from 2012 was what lead to my collaboration with Mark Pauly and Keenan Crane that resulted in this 2016 paper https://dl.acm.org/doi/10.1145/2897824.2925944
(full paper available here)

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Hi there,

@bob.h.mackay, @Steve_Mould Did you manage to successfully output your own geometries into bistable cutting files?

I am trying to get this working for a university project and would really appreciate any advice!

How did you prep your input files? Did you manage to download the suggested boundary first flattening application or did you use the grasshopper bbf component in the ngon pluggin.

Did you have any issues with the 'BASS generation' python block at the very end of the 'demo-tri-bistable' programme? For the example files, everything else is working but I am getting errors from that final block which generates the cutting pattern.

Thank you so much for any help and advice

Hi Catherine,

I’m afraid I did not take this very far. I have a reasonably large CNC milling machine, but with the restriction to wood or perhaps aluminium, I don’t think I would get the necessary flexibility for this to work. In the longer term I am looking for a way to create minimal surfaces, such as the gyroid, but other projects have intervened.

Best wishes with your project.

Bob

If you use the input files that’s supplied, you dont need BFF. What’s the error you got?

The design files work for me, but the GH script which allows one to visualize the auxetic mesh through the deployment stages (generation_aux_bass) is very broken (see attached screenshots). This is the error message I get from the BASS generation ghphythonscript:

“1. Solution exception:‘NoneType’ object is not subscriptable”