Arnold Patrick Martin's tensegrity ring features a tiny 6 strut tensegrity, see below. Its 6 strut tensegrity is held by tension wires to a ring mount.
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| 6 strut tensegrity ring by Martin |
Martin's work inspires me to ask: what is the world's smallest tensegrity? I am not counting naturally occurring tensegrity. Frankly, if tensegrity theorists are correct, the entire world is structured on tensegrity principles, and the world's smallest tensegrity would be the up-quarks and down-quarks that constitute every proton and neutron. No, I am inquiring after the world's smallest deliberately, human-produced tensegrity.
Let's say we proposed a prize for the smallest tensegrity. How would we assess the candidates for winning such a prize?
Assessing Prize Candidates
We would begin with the classic definition of tensegrity.Classic tensegrity structures enforce a radical separation of compression and tension: compression is supplied by isolated or "islanded" struts, while tension is supplied by global, closed networks of tendons. The struts have good compressive characteristics and poor tension characteristics; when compressed, they bulge at their perimeter, but when tensed, they snap. In contrast with the struts, tendons have good tensile characteristics and poor compressive characteristics. When tensed, tendons become more narrow in circumference; but when compressed, they fold and offer no resistance.
Would we accept nucleated strut designs, such as the original X-tensegrity module by Snelson (below)? Or only linear struts?
Next, we would define how we will measure size. My first thought is to measure strut length. Since, by definition, tendons must be tension-stretched between struts, tendons should not add to the diameter of such a structure. However, multi-strut tensegrities start to bulge at the center, and the diameter exceeds the strut length.
Next, we would need to decide how to reward complexity. A team attempting the tiniest tensegrity will naturally choose the form with the least number of parts. The tiniest, least complex non-nuclear-strut tensegrity conforming with the above definitions, is a 3 strut tensegrity that outlines a three-sided antiprism. However, it would be more exciting to see a 4 strut tensegrity that outlines a truncated tetrahedron, since that is the module that most people use to create tensegrity masts. Such a mast is essential to the goal of creating a true, ultra-lightweight, fractal tensegrity.
Hmmm... This would make a great proposal to next year's BFI challenge. Well, that gives us to the end of the year to work out the details!
Links
- Martin's web page, Museum of Wisconsin: http://www.wisconsinart.org/archives/artist/arnold-patrick-martin/profile-9598.aspx
- XPrize site: http://www.xprize.org/
- Buckminster Fuller Challenge: http://challenge.bfi.org/
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