The only reason that I am commenting is so that I can learn. (Red talks
about fatigue but not hardening.)
I know that copper work hardens, never really though of fatigue, as the
hardening tends to cause brittleness, then rupture. So I thought that I
should find out something. Went to our son's Metals Handbook (metal and
materials engineer) Still not sure if I learned anything.
Definitions
work hardening same as strain hardening
strain hardening An increase in hardness and strength caused by plastic
deformation at temperatures below the recrystalization point.
fatigue The phenomenon leading to fracture under repeated or fluctuating
stresses having a maximum value less than the tensile strength of the
material. Fatigue fractures are progressive, beginning as minute cracks
that grow under the action of the fluctuating stress
extra
strain-age embrittlement A loss in ductility accompanied by an increase in
hardness and strength that occurs when low-carbon steel is aged following
plastic deformation.
stress force per unit of area
strain A messure of the relative change in the size or shape of a body.
At 08:32 AM 2002-02-08 -0600, Red wrote:
>Work hardening and metal fatigue are not the same.
>
>Metal fatigue affects aluminum, copper, steel, and other metals. It
>does not occur unless the applied stress exceeds a threshold value.
>Correct design prevents it.
>
>Metal fatigue causes steel, copper, or aluminum wire or other forms to
>break following repeated bending. The stress that bending causes is
>proportional to the dimension across the bend; hence, fine wire
>tolerates bending better than coarse wire.
>
>Universal has sold towers for a long time. I wonder if there is any
>history of failure of towers correctly installed, within load and other
>limits.
>
>73 de WOØW
>
>
>________________________________________________________________________
>Where do you get ICE bandpass filters & beverage matching boxes? The
>same place that pays for the hosting of this list: The eHam Store.
>Order online at http://store.eham.net.
>-----------------------------------------------------------------------
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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>Problems: owner-towertalk@contesting.com
________________________________________________________________________
Where do you get ICE bandpass filters & beverage matching boxes? The
same place that pays for the hosting of this list: The eHam Store.
Order online at http://store.eham.net.
-----------------------------------------------------------------------
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
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