# Live hinges + kerfing of 3D objects — forces and constraints

Hi there!

Naturally, being a bit of a kangaroo novice, I’ve spent the last couple of days drifting about on forums, absorbing tutorial videos, and messing with grasshopper in an attempt to make the image in my head a reality. Not super successful as of yet, but it’s an interesting problem and I was wondering whether any of you might have some ideas.

The idea behind the project I’m working on is to manipulate rigid materials by incorporating voids/cuts. In a way it’s a kind of kerfing, but of 3D blocks rather than sheets. For the purpose of modelling the behaviour in grasshopper, I’m hoping to create simplified versions (2D) of these geometries (i.e. just having the blocks in plan rather than as 3D volumes — since they’re uniform in the z-axis I was thinking I just extrude them to get the volume simulation. We’re also working with blocks that are kerfed along the z as well as x axis, but… as far as the simulation goes I’ll be a little bit less ambitious until I have an idea of how I can even make one axis happen).

My hopes for the less ambitious simulation:

a) to create a constraint which allows a volume to bend in a way that the edges do not overlap (as in a kerf — you can only bend until the surface of the material touches the opposite surface, and that’s the limit of curvature.)
b) to have a bend on one edge, caused by some force, to be carried through the material to the other side. It would allow me to extrapolate the behaviour of spurs of material normal to the outside of the second edge.

I’m thinking parts of this could be achieved pretty easily with an elastic rod, since the material needs to have some resistance. I just wasn’t able to quite… figure out how that worked. (Maybe I’m actually going about this all wrong and should just use a mesh rather than trying to use surfaces, but I feel that meshes don’t have enough resistance? Questions abound).

My overall hopes:

… To be perfectly honest, the ideal thing would be to have a material I can cut holes into, apply a force to, and observe how the entire thing distorts depending on those holes and the constraints set by the edge conditions. Like, that would be… incredible.

I really hope that this made sense. I’ve attached some drawings for clarity (I hope), and a video showing one of the simpler 3d printed models we’ve made so far.

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