Rigidbodies for simulating auxetics

Hi, I’ve a Grasshopper simulation of a hexagonal unit cell that can tessellate to form a larger auxetic sheet. Currently I can just solve everything geometrically, but I wanted to ask if it is possible to simulate, in an alternative way, the opening of the sheet using Kangaroo.

HexCell_simple

Here I have created a single mesh and then made a rigidbody from it (with its vertices feeding into the points input)

image
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If i anchor some arbitrary points on the mesh, and then use the grab to pull other parts of the mesh away, should it not be able to expand? I thought that the vertices of the mesh may start to act as pivot/rotational points.

I have attached a Grasshopper file for reference. Thanks for any help.
Unit_cell_hex_internalised.gh (37.9 KB)

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Hi @jasonlim

If you input all the tiles joined together as a single mesh to RigidBody, it will treat that whole mesh as rigid.
To have the tiles able to move relative to each other, each tile needs to be a body.
Also, RigidBody defaults to the volume centroid of the meshes as the frame for that body, but here the meshes are open, so the frames need to be set directly:


Unit_cell_hex_internalised_dp.gh (32.4 KB)

Also, if you want to keep the deformation in one plane, you could add an OnPlane goal to all the points.

Unit_cell_hex_internalised_dp2.gh (31.0 KB)

Hi that makes sense. Thank you Daniel

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Hi Daniel, I am trying to prevent collisions between the tiles and have tried rigidbody collisions in Kangaroo. However, it doesn’t seem to be working. Am I doing it correctly?


Unit_cell_hex_internalised_dp3.gh (47.5 KB)

Have a look at this example

dissection

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Hi @DanielPiker ! This is beautiful. I’m testing this to map the kinematics on to a surface. Is there another way you would do this? If the surface curvature is too much the connections break.