Tensegrity Structure

Posted On: August 14, 2014

While I’m on a long bus ride from JPL to Goldstone to visit the satellite compound for the Deep Space Network, I figure I should catch up on some blog entries!

Itching to make something cheap but visually and physically interesting for MIT CPW 2013, I searched for a solution. I recalled a structure I had seen that used rope and beams to form a free standing sculpture of sorts. The internet kindly gave up the answer: the structure was an example of tensegrity, or tensional integrity.

This is a class of structures made of beams which are stabilized only through tension elements that string everything together. They are curious because, properly designed, a force applied anywhere in any direction can only result in increasing tension. The structure seems to lock down instead of displacing/moving/bending/falling over!

cubic tensegrity 6 beam next make cpw build

A fine example of Cubic Tensegrity! Imagine a cube wedged in the very center, so every face was against a beam.

Designs can be tesselated to create towers or benches, but I figured it would be cooler to make a couple kinds. There are several simple shapes a tensegrity sculpture can take, I chose two for the prefrosh to try and assemble. One looks like three chopsticks tied together, and would be the fall-back “easy” one. The other has a beam across each face of an imaginary cube at its center, and is far more elegant of a structure.

On the day, we successfully completed the chopstick sculpture! A large number of prefrosh were interested and helped, making it a great team building and meet-new-people event. We finished it with time to spare and so moved on to the cubic sculpture. This one was a monster, and proved too tedious to tension/retension before people wanted to move on to a different event.

Fear not though, because in a style I’ve found to be typical here, we ended up finishing it at about 02:00. Never ones to leave something that close unfinished, we headed out to the courtyard with a mostly dismantled sculpture and started over. When Next House woke up in the morning, they found a magnificent example of tensegrity in the courtyard. It stayed up all through the summer, until we had bigger plans for the courtyard.

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