Inflated Tension Structures in Kangaroo 2

Hello Everyone,

I am part of a small design collective experimenting with inflatable structures called pneuhaus. I have been dabbling with Kangaroo 1 for quite some time and am trying to make the jump across to Kangaroo 2, but I am still trying to wrap my head around it. I understand that it allows you to incorporate multiple forces dependent on one another a bit better, which is what my question pertains to...

We are currently developing a project around creating a tensile lattice structure within an inflatable. In mocking things up, I have been able to simply inflate forms with static anchor points. I was wondering if it would be possible to link the anchor points for the inflatable shell to tensioned cables or nets pulling on the interior that find equilibrium when the tension is changed?

Below are some illustrations of what I am trying to achieve that I did with a tetrahedron in Kangaroo 1. To get both the inflated form and the tensioned form I had to run two simulations and bake each. I am looking for a way to have to forces of both dependent on one another.

I'm isolating the interior tension member to cables for now, but I would eventually like to expand to suspending 3d netted volumes within the inflatable.

I have also attached my attempted gh file with Kangaroo 2. It kind of works but not as drastically as I would like, and it breaks down very easily. Any help/advice would be greatly appreciated!:)

Attachments:

iflated_tension.gh, 27 KB

Replies to This Discussion

Permalink Reply by Daniel Piker on October 25, 2016 at 1:18pm

Hi August,

Sorry for taking a while to reply.

The K2 definition looks good, but attached are a few possible modifications.

I think the main reason the form looks so different is that the interior cables were preserving their original length.

In K1, a spring without a specified rest length would default to a rest length of zero, whereas in K2, a length goal defaults to the starting length as rest length. To make it shrink, you can set the target length as zero.

The Volume goal is sometimes easier to work with, as it should be less likely to cause instability. If inflating a mesh with the Pressure goal, the force is proportional to the face area, and when inflating, the faces get bigger, meaning more force and so on... potentially causing a runaway expansion if the resisting forces are not strong enough. With a volume goal the pressure reduces as the mesh expands, avoiding this.

I also showed how you can also use the soapfilm goal and laplacian smoothing instead of using just the mesh edges. In this model the soapfilm solution is just a sphere, with the 4 spikes towards the centre collapsing to nothing, but perhaps in other models it can be interesting.

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