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From: smit~rols.com (Scott Mitchell)
Date: Tue, 8 Oct 1996 00:09:05 -0400 (EDT)
Subject: In defense of the IronMan

While reading the whole breakin debate, I recalled hearing my father talk
about how slowly increasing the load on a part could extend its fatigue
life. Dad is a professor of Mechanical Engineering at Virginia Tech and
fatigue is one of his areas of expertice. So I sent him email requesting
a clarification. I've included his response below, but suffice it to say
there is scientific justification for harmonica reeds lasting longer after
a proper breakin.

Larry Mitchell wrote:
> Yes sir you did hear me talk of a strengthening phenomenon that
>makes a part stronger if one increasingly stresses a component cyclically
>from low stresses to high stresses. This is called coaxing. Very
>specifically I do not know whether this occurs in the brass used in the
>reeds. It is known in steels and I have two citations for this. They are
>both given on pages 93 & 94 of Sors book on "Fatigue Design of Machine
>Components", Pergamon Press, Oxford England, 1971. Both of these
>citation references are in German!!! To sum it up, the endurance limits
>have been coaxed up by 20-60%!!! and the lives have been extended by
>100x-6000x! It would seem that this should be a viable techniques to use
>on a Harp-L, if the metals are susectible to what I would guess would be a
>strain aging phenomenon. Without more to go on that is the best I can do
>without more specific material data or without a copy of the Lehr and
>Herold papers on this topic. Then I would have to get them translated to
>see if they explain the mechanism so that I could see if it checks with my
>guess. Bottomline: there certainly is a metallurgical reason to believe
>that this might actually, the people just don't know the fatigue
>literature. Admittedly these are obscure references in Germany, but maybe
>the idea has come out of Germany with German harmonicas.

Scott Mitchell

__________________________________________________________________________
Scott Mitchell smit~rols.com

"As always, real research is best but speculation, wild-assed
guessing, and utter nonsense are inevitable." - Bo Bradham