Month: March 2023

A Curious Helical Structure

Greg FrederickLeave a comment

I stumbled across a rigid structure that seems to be a cross between a tensegrity prism, a polyhedron, and a tetrahelix.

Eight vertex-bonded equilateral triangles arranged into one module of a structural helix with a twist of six degrees.
Eight vertex-bonded equilateral triangles arranged into structural helix with a twist of six degrees per module.

I find it curious because a) it doesn’t seem to conform to the triangulation rule for rigid structures, b) it looks like it ought to be tensegrity prism, but it isn’t obvious which of the vectors can be replaced with tendons, and c) the top and bottom triangles are twisted at exactly six degrees, or 1/60th of a full 360° cycle.

Top view of one module of the structural helix indicating the 6-degree rotation between the top and bottom triangles.
In each module of the structural helix, the top triangle is rotated six degrees from the bottom triangle

Stacking one on top of another is also quite beautiful.

Top view of the structural helix constructed from twenty modules.
Top view of the helix constructed from twenty modules with a combined rotation of 120 degrees.