Tensegrity

Saturday, February 23, 2013 by Ji Su

The first quarter of my spring 2013 semester was absolutely crazy. Here’s a sampling from my to do list:

  • Launch rockets for E80 out in a gravel pit by Pitzer. We used an altimeter and inclinometers to gather flight data of three rockets with different motors, and wrote a lab report with complete data analysis in less than 24 hours. Talk about adrenaline!
  • Buy 8 different brands of cigarettes for Choice Lab, to examine cadmium levels in tobacco. My choice lab is Environmental Analysis: Anthropomorphic Cadmium in Leafy Foodstuffs. Our team will specifically focus on determining whether or not the cadmium levels depend on a company’s specific processing methods or geographic origin of the tobacco.
  • Read about being a Gang Leader for a Day for my sociology/ethnography class.
  • Figure out tensegrity structures for an art project.

Today’s post, though, will focus mainly on that last task (and will make for probably the most intriguing blog title I’ve ever come up with).

Tensegrity structures contain a network of bars in tension and compression. Several bars may coincide at any joint, but at each joint there is only one bar in compression and all other bars are in tension. The compressed bars also do not touch at any point. Artist Kenneth Snelson creates large tensegrity structures where some bars look like they’re floating.

Dragon, by Kenneth Snelson

How did I find out about tensegrity?

In my continuum mechanics class (E83) as well as my engineering math class (E72) we were introduced to trusses and how to analyze the forces in each of the bars and determine which ones are compressive and which are tensile. In the former class we examined simpler structures and how to analyze them using methods in statics, then in the latter we examined a larger, more complex model. We applied principles of linear algebra to simplify the problem then use MATLAB to solve the system. Then Prof Bassman brought in an example of a tensegrity structure that her students had created for an advanced mechanical engineering class. In their structure, the compressive components were black bars and the tensile components were elastic bands.

So how did I recreate my own version of this engineering ingenuity for an art class? And why?

This semester I’m taking a mixed media studio art class (Art 100B) at Scripps. Our first project of the semester was to create art that reflects back on your childhood memories from an adult perspective. In class we went through multiple exercises to jog our memories and to brainstorm ideas. Soon enough I began remembering names of friends long forgotten, my most absurd hobbies (like watching ants on a sidewalk for hours on end), and the smallest details of everywhere I had lived. The crazy variety of dreams I had came rushing back–artist, librarian, book illustrator, author, professional speaker, physicist, engineer. I thought about each move I had made–6 total before starting high school–and how hectic each move felt, how I always felt like I could never settle down, how with each move I felt as if I had to fix small parts of my behavior to fully fit into each setting. I remembered the culture shocks of Singapore and New York, and I remember the reverse culture shock returning to Korea after much time abroad. Somehow though, I couldn’t come up with an idea that could unify these memories.

It was then that Prof Bassman’s students’ structure hit me. The bars experience opposing types of forces, yet together they create a stable structure that can experience some amount of load. For myself, these forces represent the adjusting and readjusting I constantly put myself through, compressing some aspects of my behavior and stretching others to fit a new community’s standards. The combination of art and engineering in a single project also represented the push and pull between my different ambitions and interests. But through it all, I’ve now grown to be a young adult with her own views as a third culture kid and with a desire to eventually combine my interests in art and engineering.

Tensegrity turned out to be the perfect concept for my childhood and the adult perspective I have of it. So once I had run it by my art professor, I went about building the prototype like a good engineer, and decided on aesthetic choices for materials–bamboo and fishing wire.

Engineering mindset: every creation starts with a prototype. My very first tensegrity structure, made with fishing wire and popsicle sticks.
Engineering mindset: every creation starts with a prototype. My very first tensegrity structure, made with fishing wire and popsicle sticks.

My first prototype was made with popsicle sticks, connected at the holes at the ends with fishing wire. Notice that the popsicle sticks (in compression) never touch each other, so when I sent this picture around to all my friends, they asked me if this was an optical illusion. Once I had my prototype functional, I created three larger versions of the above to create a tower.

The completed project hanging in my art studio.
The completed project hanging in my art studio.

So there: an art piece representing my hectic childhood, with an adult perspective. How awesome is it that my engineering classes led me to create my first abstract 3D piece (yup that’s right, all art I’ve done so far is 2D)?

Although I may have started this blog post off emphasizing how busy I’ve been, I hope that I also conveyed in my to-do list how excited I am about what I’m learning – the depth and the breadth of all my classes and, as you can see from my art project, how interconnected the class material can be. Even if I’m sleeping late this semester, at the end of every week I still feel satisfied because every day I’m being challenged to think in new ways and digest new, relevant and exciting material.