Ordinary objects rely upon simple mechanics to maintain their integrity. A rock, for instance, has only intermolecular forces to hold it in shape. Squeeze it and it reacts in an obvious, predictable way: it compresses for a while, then shatters when the stresses get too extreme.

Complex artifacts can have more interesting feedback loops among their components. A bridge may use composite materials and be built with girders, braces, beams, and hinges to permit a graceful response to increasing loads, temperature changes, earthquake shocks, unanticipated windstorms, and other disturbances to its static shape. But even the cleverest such design is limited in its ability to react to perturbations.

A "smart structure" takes this concept a big step forward by adding sensors and actuators to a mechanical system. A central processor can monitor strains at various points and then react, quickly and precisely, with counter-forces --- jiu-jitsu fashion --- to neutralize any attack on the object's configuration.

The result: control and stability far beyond what a passive design could achieve. See, for example, FastForwardFiftyYears (4 Jun 2003) for notes on Robert L. Forward's work on active feedback as applied to large space structures. Similar systems are used to maintain the optical perfection of huge earth-based telescopes. And intelligent structures are, in a sense, what many animals already are as they move around, balance themselves, and adjust their skeletons and muscles to carry great loads.

But orbiting laboratories, astronomical observatories, and biomechanical analyses of ants are rather too far from everyday life. Why not apply modern know-how to a more immediate challenge, one which affects a large and ever-increasing percentage of athletes? Specifically, how about using sensor/processor/actuator technology to make a better brassiere for lady athletes?

The classic "Stress Analysis of a Strapless Evening Gown" ([1], Charles E. Siem, Journal of Irreproducible Results, 1956) focused on a related issue --- but was limited to passive mechanical elements in that pre-microelectronic era, as demonstrated by this excerpt:

Effective as the strapless evening gown is in attracting attention, it presents tremendous engineering problems to the structural engineer. He is faced with the problem of designing a dress which appears as if it will fall at any moment and yet actually stays up with some small factor of safety. Some of the problems faced by the engineer readily appear from the following structural analysis of strapless evening gowns.

If a small elemental strip of cloth from a strapless evening gown is isolated as a free body in the area of plane A in Figure 1, it can be seen that the tangential force F1 is balanced by the equal and opposite tangential force F2. The downward vertical force W (weight of the dress) is balanced by the force V acting vertically upward due to the stress in the cloth above plane A. Since the algebraic summation of vertical and horizontal forces is zero and no moments are acting, the elemental strip is at equilibrium.

Support for advanced engineering development in the field of active jogging bras should, arguably, be a top governmental research thrust. The nation that succeeds will see its athletes lifted to new heights of Olympic prowess, separated in competition from the sagging fortunes of countries less well endowed with technological sophistication.

At least, until the batteries run down ...

(see also NeedForSpeed (10 Aug 2002), MemorySupport (31 Oct 2002), RearAdmiralLowerHalf (1 Jul 2003), AwesomeProwess (17 Jul 2003), SuperfluousCoyness (22 Oct 2004), ...)

TopicHumor - TopicScience - TopicRunning - TopicRecreation - TopicLiterature - 2004-05-07

(correlates: PositiveAndNegativeChoice, NeedForSpeed, FastForwardFiftyYears, ...)

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