Posted by Joe Baker on October 16, 2003 at 14:42:05:
In Reply to: Re: ATT: Rick Denney posted by Mark Wiseman on October 16, 2003 at 13:02:08:
It also increases, assuming the normal case of tubing walls much thinner than the ID. Maybe for thick walls, but I haven't considered them.
Given a tube of 0.95" ID, and walls of 0.05" thickness, the "mean" diameter -- the average of the ID & the OD -- is 1". if the metal expands by 1%, "mean" circumference, 3.14", increases by 0.0314 to 3.1714; the 'centerline' radius (average of ID & OD) would increase from 1" to roughly 1.01" (DUH!! I should have been able to go to this directly, because the relationship between diameter & circumference is linear). Adding the new thickness of .0505 (or, really, half the thickness times 2), the ID is now 0.9595.
For empirical proof: remember when you got a ring stuck on your finger, or a jar lid was too tight? What did Mom tell you to do? PUT IT UNDER HOT WATER TO LOOSEN IT.
Joe Baker, who loves it when his math & his Mom agree.