8.13.2007

On Spiders, Spinning and Elegance

It was a big deal for me when I figured out a way to keep my models from spinning. Actually, my youngest son did it for me when he designed a still-life teepee-of-sorts. From opposite legs of this "teepee," I can tie a horizontal thread at the level of the object and influence its rotation. I'm still planning to take a photograph of that and post it. Until I get around to doing that though, I thought I'd cut 'n' paste the following image and article from the National Center for Scientific Research in France - about spiders and their far more elegant solution to the spinning problem:

© Anthony Carré - CNRS 2006

"Fasten an object to the end of a vertically suspended thread. Give it a slight twist and let go. You will observe that the object rotates for a certain length of time and with a certain amplitude, depending on the material of the thread. Now observe a spider suspended from its thread: It is stable, doesn't move, spins its thread in a perfectly straight line and always recovers its balance after environmental disturbances.

By experimenting with a torsion pendulum to which they attached a mass equivalent to a spider's weight, researchers at the Laboratoire de physique des lasers(CNRS/University of Rennes) compared the dynamic reactions of different types of thread to a 90° rotation. The results are revealing: a KevlarTM filament (which is synthetic) behaves like an elastic, with reduced oscillations. A copper thread oscillates slightly but does not return to its original shape, and becomes more fragile as a result of these oscillations. Spider's thread, on the other hand, is very efficient at absorbing oscillations, regardless of air resistance, and retains its twisting properties during the experiments. It also returns to its exact original shape. Certain alloys, such as Nitinol, possess similar properties but must be heated to 90° to return to their original shape.

The amazing properties of spider's thread have been known for several years: its ductility, strength and hardness surpass those of the most complex synthetics fibers . It now also seems that through natural selection, spider's thread has evolved into a material with “self-shape memory effect” which allows it to return to its original configuration without outside stimulus. This complex dynamic process has recently been represented as a “stacked” model which the authors use to depict the relaxation of the different proteins in spider's thread." - from CNRS March, 2006

2 comments:

Steven LaRose said...

Very cool.
(sorry for the short two word comments).

mary klein said...

that's ok