LynnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnEubank (EUBANK@vaxb.acs.unt.edu)
writes, after pausing to take another breath:
> When I discovered the crack, it was already just under a half-inch long and
> looking very hungry. It just so happens, however, that my father was on the
> scene when I found the crack and he suggested a trick that he'd used on
> his old Aercoup (sp?): Drilling a stop hole. That I did, right at the end
> of the crack. [...] The crack is dead in its tracks.
This is intriguing. An acquaintance of mine from my days at the Cambridge
University Engineering Department in England was engaged in performing
assorted stress tests on various metals. They'd clamp the test piece in a
jig on a machine that was capable of inflicting stresses in various ways:
multi-ton pulling, either steady or pulsating; pushing; twisting; showing
it reruns of "Gilligan's Island"; having a small man named Nate explain
the virtues of time-sharing condominiums (*); etc. They would photograph
and track the progress of stress cracks appearing in the metal. And how
did they control where the crack was to start? They drilled a hole in it.
Guess the difference between their samples and your door was whether the
stress was being relieved by, or created at, the hole in question.
Andrew C. Green
Datalogics, Inc. Internet: acg@dlogics.com
441 W. Huron UUCP: ..!uunet!dlogics!acg
Chicago, IL 60610 FAX: (312) 266-4473
(*) This stress test courtesy of columnist Dave Barry
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