Because triangles are stable. The shape persists when the lengths of 3 edges stay unchanged.

modatberkeley

Does this structure also encapsulate the idea that shearing on the / direction is stronger/weaker than in the \ direction?

Edit: Yes, it's the anisotropic bias.

Noppapon

If my understanding is correct, the structure will not resist out of plane bending because the triangle meshes are planar, meaning they lie in a single plane, so they can not bend out of plane without deforming or stretching

sharhar

@Noppapon, yes, I think your understanding is correct. If we allow the triangles to move through 3D space, then the "sheet" of triangles would definitely bend. It's only when we constrain their movement to 2D that we see the triangles behave as a cohesive mesh.

and why does this structure resist shearing?

Because triangles are stable. The shape persists when the lengths of 3 edges stay unchanged.

Does this structure also encapsulate the idea that shearing on the / direction is stronger/weaker than in the \ direction?

Edit: Yes, it's the anisotropic bias.

If my understanding is correct, the structure will not resist out of plane bending because the triangle meshes are planar, meaning they lie in a single plane, so they can not bend out of plane without deforming or stretching

@Noppapon, yes, I think your understanding is correct. If we allow the triangles to move through 3D space, then the "sheet" of triangles would definitely bend. It's only when we constrain their movement to 2D that we see the triangles behave as a cohesive mesh.