All tensegrity structures have stored energy; the energy is in the form of stored mechanical energy. Other terms used to describe this energy are “spring energy” or prestress. This little-known feature is essential to the function of tensegrity structures. These articles will give clear examples of that spring energy and why stored energy important to understand the behavior of these structures.
The bicycle wheel with spokes, invented around 150 years ago, is a tensegrity structure. Buckminster Fuller noted the “evolution” from thick wooden spokes to thin metal spokes; Amy Edmondson comments on that in A Fuller Explanation:
The wheel’s use of tension enables a far more efficient and lightweight structure than could be produced with compression spokes. Tension materials are inherently smaller and lighter than compression materials carrying equivalent loads.The wheel was originally an exclusively compression structure starting with the cave man’s stone cylinder and progressing to slightly more sophisticated designs like “the old artillery wheel” cited by Fuller in Synergetics.
At first, language appears to us to be fixed and rigid. When we write, we seek the correct word to use. Over time, we realize that there are shades of gray: many words will work, but some have will add a particular color that we like.
One day, we realize that both the meaning and the emotional coloration of words are up for grabs. Language itself is fluid (or maybe viscous), and various individuals and tribes are constantly striving to alter both the meaning and connotation of words. Here are three of those skirmishes:
Buckminster Fuller created the word “tensegrity”. Its definition is documented in his 1975 book Synergetics:
700.011 The word tensegrity is an invention: it is a contraction of tensional integrity. Tensegrity describes a structural-relationship principle in which structural shape is guaranteed by the finitely closed, comprehensively continuous, tensional behaviors of the system and not by the discontinuous and exclusively local compressional member behaviors. Tensegrity provides the ability to yield increasingly without ultimately breaking or coming asunder.
Words rarely come into existence with a more precise definition than this! All was good, or was it?
Recently, the Chanel Company launched a marketing campaign and website for their Ultra Correction Lift. Their homepage for the product says:
Taking the architectural concept of tenesegrity as a starting point, Chanel Research made a major discovery: the key role of a critical protein in the aging process — Tensin. To stimulate the production of Tensin, Chanel developed an exclusive ingredient, Elemi PFA, to naturally lift the skin from within.
If you click on “The Science” link on that flash site, you’ll find the question: What if the skin were a structure?
Since the skin is a structure, that’s an excellent question to ask! Few adults ever spend any time thinking about structure, let alone biological structures. Understanding tensegrity requires that we reexamine our fundamental assumptions about structure. Unfortunately, things go downhill from there. Clicking on that question reveals the following:
1940: Structure and Tensegrity
Tensegrity, derived from “tension” and “integrity”, is a basic architectural concept. So what is it? The integrity and resilience of any structure results from the balanced distribution of the forces of tension and compression within itself.
Tensegrity models were invented in the 1940s by the artist Kenneth Snelson while studying under Buckminster Fuller. He called them floating compression structures: the compression elements of a structure do not touch but instead have a floating relationship with each other. If that doesn’t make sense, I recommend looking at the images on Snelson’s website.
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The secondary title of “The Living Matrix” is “A Film on the New Science of Healing”. The intent of the filmmakers was to establish a connection between established scientific theories, our health, and healing. How well did they do? As I noted in my review, the filmmakers have failed to provide links to existing science. Neither the DVD nor the website currently provide any links to published scientific papers. In the absence of anything to back it up, the film’s claim that there’s a new “viable scientific theory” is not credible.
One particular claim from the movie came from Dietmar Cimbal, DVM, who the filmmakers label as a “biophysics researcher”. Dr. Cimbal talks about direction shifts of flocks of birds:
“Every one of us has watched a flock of birds in flight and how it changes direction. Instantly, all birds in the flock change direction. So, it seems as if a superior bird-brain controls all the birds simultaneously. That only works with the help of those fields, since the fields are able to transfer, with no information loss, and, above all, instantaneously with no time delay.”
A skeptic would have several questions at this point: Why does Dr. Cimbal presume the shifts are instantaneous? What observations did he make of flocks, and what instruments did he use to measure them? Where did he publish his results? If he was using someone else’s research, where is that research?
VIS – co – e – LAS – tic
“Viscoelastic” is a term used by physicists to describe materials that behave in two different ways: a fluid (viscous) and a solid (elastic). Viscous materials are fluids like water, motor oil, or honey. Viscous substances have a great capacity to absorb energy. Amusement parks use water to safely slow down rides after a drop. This video shows a 131-foot drop on “Pilgrim’s Plunge” a new water ride at Holiday World in Santa Claus, Indiana. Will Koch is the president of Holiday World; he gets to ride with The Big Guy.
“The Living Matrix” (TLM) is a new documentary about a variety of “energy-based” alternative medicines. It’s directed in the style of “What the #$*! Do We (K)now!?” (2004) and “The Secret” (2006) with tight cuts of commentary from about a dozen experts. There are several testimonials from individuals who were healed (or healed themselves) without relying on traditional western medicine. The movie has had a variety of showings around the world and is now available on DVD. I saw a recent screening of the film at the end of the ISSSEEM conference and purchased the DVD.
While the experts are speaking, the “voice” of TLM is really the director and the editor: what questions are asked and what edited parts of the experts’ responses are used. TLM experts criticize a reductionist approach to understanding the world, but this film itself is fundamentally reductionist: pulling small parts of separate conversations and reassembling them outside of their original context. DVDs provide a means to archive massive amounts of low-resolution video; I would really like to have access to the original interview footage.
There are a variety of scientific claims made in the film. These claims may be backed up with research, but no references to published papers are provided (other than listing the books that the various experts have published). I attempt to stay current on a broad spectrum of scientific topics; when I see some new claim with no references, I tend to dismiss it. The website would be an ideal place for links to the scientific research, but the producers haven’t created this reference.
Why would a skeptic care? Because the documentary repeatedly claimed it was discussing was scientific theories. There are certain rules that one must follow for that claim to be legitimate. If someone is not going through this process—or reporting on a group of scientists who did—what they are doing is speculating or making conjectures. It’s not that one is good and the other is bad, but there is mischief in failing to distinguish between the two.
This kind of movie is not the best way to learn science. Watching tightly-cut commentary from a variety of experts overloads rational thought; viewing nonstop causes more of an emotional response rather than a rational one. Frequently pausing the movie and researching the science (or lack of science) behind the claims causes the movie to play very differently.
If you wanted to explore Mars, what kind of bridge would you take with you? How would you build the bridges? How would you make sure the bridge will work for a variety of terrain? Since you must carry the bridge all the way to Mars, it must be small, light, and highly reliable. Researchers from the Technical University of Munich have a wonderful answer: a tensegrity truss.
Tensegrity masts are also used for deploying a variety of instrumentation and solar panels on orbiting satellites. The tensile network is bearing the weight of the structure; by increasing the tension, the mast deploys. It’s a remarkably material-efficient way to “reach out” with structure. Tensegrity masts can even teach us how to reach out more effectively with our arms and legs.
What is graceful movement? How do everyday things move gracefully, and what can we learn to bring grace to our own movement? Consider three examples:
Power Transmission Lines are used to distribute electrical power from generation facilities to homes and businesses. They provide a redundant network for power distribution; everyone should get reliable power even if parts of the transmission line network are temporarily shut down.
In the US, overhead transmission lines come in sets of three, and they usually deliver three phase power. The three power cables are held at uniform tension, and the distance between the three cables is precisely maintained throughout the entire transmission network.
Wind can cause the individual cables to vibrate; those vibrations can wear the cables out much faster. Cables moving individually could also create electrical noise and lower the quality of power in the grid.
Engineers use Stockbridge dampers to control mechanical vibrations on each segment of the cable. In this picture, there are a total of eight stockbridge dampers visible. These dampers are “tuned” to optimally absorb the particular kinds of wind-induced vibrations that the cables encounter.
These dampers are a classic loosely-coupled design; it’s also a bit counterintuitive that such a small widget could effectively control the vibrations on a long length of cable, but they do the job. These dampers are ubiquitous on transmission lines, but they were invisible to me until I started researching damping systems. Next time you’re near a transmission line, look for the Stockbridge dampers. And watch how the transmission lines move so … gracefully.
Here’s the basics of what I’ve learned over the last five years or so boiled down to eight principles. The list is crafted in such a way that both body/mind and technical types should be OK with the language.
1. The best way to describe the relationship between the bones is a floating relationship.
2. The resiliency of our body is something we can consciously and deliberately alter over time.
3. The most important strength is the strength of the system as a whole.
4. Our superficial and deep muscles play fundamentally different roles.
5a. Stacking-based imagery is pervasive in our culture; such imagery literally holds us down.
5b. By carefully observing ourselves and nature, it is possible to realize a different metaphor: floating compression.
6. There is a brilliance to our bodies that is largely unexplored.
7. Body/mind disciplines are a systemic means of exploring the world of floating compression that somehow, strangely, we have forgotten.
8. A pattern of movement that strategically alters the tension in our bodies is a body/mind discipline.
(Example of #5a: a skeleton is used to represent our musculoskeletal structure, but lacks any tensile elements.)
Tensional integrity is a very recent concept for our civilization. In A Fuller Explanation, Amy Edmondson talks about its origins:
In the summers of 1947 and 1948, Fuller taught at Black Mountain College, and spoke constantly of “tensional integrity”. Universe seems to rely on continuous tension to embrace islanded compression elements, he mused; we must find a way to model this structural principle. Much to his delight, a student and later well-known sculptor, Kenneth Snelson, provided the answer. He presented his discovery to Fuller: a small structure consisting of three separated struts held rigidly in place with a few strings.
Most of us haven’t had an opportunity to play with a tensegrity; having one in hand helps tremendously to understand them. Fortunately, you can buy one of these at your local toy store or from Amazon.com: it’s called a Skwish Toy. Get a Skwish! Body/mind workers: get several of these toys; figure out ways to use them in your classes. Better yet, get one of the medical-grade models from Tom Flemons.