[TheForge] work hardening question

[lama]

It's just the opposite Terry,
Work hardening occurs when one compresses the molecules by
continuous hammering. Metal Fatigue occurs when the metal is 
gently stretched or bent. The molecules tend to break their bond.
Aircraft have problems of metal fatigue, those wings move up and
down a lot. I have seen semi-trailers, (18 wheel gravel trucks)
with nearly every weld cracked from hauling 80,000 lb of gravel.
dave m.
----- Original Message ----- 
From: <terrylr@blauedonau.com>
To: <theforge@mailman.qth.net>
Sent: Monday, January 28, 2002 9:06 AM
Subject: [TheForge] work hardening question


> hello;
> 
> this question occurred to me this past saturday and again yesterday
> while watching the antenna tower by the house sway back and forth in
> the wind.
> 
> i may be overlooking something rather simple but here is the question.
> 
> what keeps the metal in antenna towers, street light poles, even the
> sears building in chicago from work hardening after all the time of
> swaying from wind?
> 
> it would appear that after swaying back and forth over the years
> that the metal would be work hardened and become brittle.
> 
> -- 
> Terry L. Ridder