Lau, Gary wrote:
OK Jim, I'll bite. What's hoop stress? Maybe the thing that annihilates the work coil in quarter-shrinkers?
exactly. hoop stress, generically, is the circumferential force on something round (e.g. the stress on the wall of a pressure vessel or pipe is mostly hoop stress)
ANd, yes, that's what causes the work coil on a quarter shrinker to deform/explode.
It's funny, in basic E&M, you cover the fact that a current in a loop causes the coil to want to expand (heck, it was on the Physics AP test back in 1976), but none of the basic texts actually do a numerical example. That tells me it doesn't have a "nice" simple precise analytical solution. (hmm magnetic fields, it's round, the solution probably involves Bessel functions). But, just like the Wheeler formulas, I'm hoping someone has run across a simple approximation.
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