Stretching wire (guitar strings) question...

Hi,
As a guitarist I find I am having trouble with new strings and getting them to a stable point where they have stopped stretching (and therefore stay in tune better). I was wondering about the physics of this process. When stretching a wire (in this case 'drawn, high carbon steel', some axially wound with phosphor-bronze wire), will the string ever reach a point of stability ? - i.e. it's not going to stretch any further ?
...or do the physics dictate that it will eventually reach a stable point (i.e. stop stretching) for a specified tension - T kg and will remain stable from zero kg to T kg tension, only stretching further if
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is to stretch the strings with a tension slightly greater than that encountered in normal use.
...or will it just continue to stretch linearly until it snaps ?
I'm trying to work out the best way of stretching new strings so that they remain stable at normal 'operating' tension (i.e. stay in tune !), but without affecting it's 'oscillation qualities'. I exceeded a threshold of some sort earlier with one wound string by over-stretching, rendering it useless.
There are many theories in the guitarist community on how best to stretch strings, all of them apparently based on nothing more scientific than 'I do it this way and always have'. I'm just wondering what the science is behind it.
Many thanks in advance !
Cheers,
Kev.

snipped-for-privacy@hotmail.com wrote:
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The phenomena is almost certainly of the Snoek - type of aneelastic relaxation related to carbon or nitrogen interstitual elements in the steel of the wire.
The high stress causes these alloying agents to be able to move around just a little and find slightly lower energy positions.
These relaxations will occur near room temperature, and thus could be the most likely cause of the detuning to lower frequencies common to steel stringed instruments when new strings are first installed. Pianos, guitars, banjos,.......
Over tightening of the strings by mechanical reaction has probably small effect on the Rate of stress relaxation, but does affect the magnitude, wiht larger stresses being associated with larger amounts of strain relaxation (loosening).
OVertightening may help you get to the point of relaxation where if you released the overtension, to the correct tension, you might hope to achieve stability of the string length.
However, this may not work at all, because the atoms undergoing the relaxation under high stress will not all remain relaxed when the applied stress is reduced.
No studies popped up in Google searches with combinations of "anelasticity, schoek, music, wire, guitar, banjo, piano...." that I tried.
I suspect that you have to simly put up with the situation as you and other musicians have in the past.
Jim http://www.iop.org/EJ/article/0022-3735/14/10/027/jev14i10p1218.pdf This link may do you little good. But, there weren't any esily findable links for "beginners".

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Good and well thought out, question tho. :)
Alvin in AZ

snipped-for-privacy@XX.com wrote:
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and
Many thanks to Jim for the excellent reply and Alvin for the compliment !
Merry Christmas to you both.
Cheers
Kev.

snipped-for-privacy@XX.com wrote:
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I agree :-)
But wouldn't it be able to ask the manufacturer for a tensile tension test? Perhaps this is not easy, since the guitar string exhibits creep in the beginning, but they must know something? Creep-tests perhaps?
Read this:
http://www.instron.com/wa/applications/test_types/tension/default.aspx
There must be a certain recommended maximum-value for "epsilon", right?
Med venlig hilsen / Best regards Martin Jørgensen