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Jim Coleman's Data
> >Here are some examples of tests taken at the CGConn engineering
labs while
> >I was there.
> >
> >wire size yield point break point
> >
> >13 258 lbs 290
> >13.5 267 303
> >14 317 355
> >15
> >16 347 398
> >18 431 487
> >
> >
> >There can be as much as 10 to 20 pounds greater tension in the
segment
> >between the tuning pin and agraffe as there is in the speaking
length
> >while pulling pitch up.
I take it to mean the yield point is the same as elasticity limit.
Where the elasticity limit is that tension where "stretch" or
elongation occurs. The string gets pulled so much that intead of
returning to its original length, it stays "stretched". This happens
well below the breaking point. There are theories that strings
pulled beyond their elasticity limit,"no longer can be expected to
function as music wire". (the other explanation for false beats)
So two question, is yield point the same as elasticity limit? and
how is/was yield point measured?
Here are some historical records of string strength taken from
Dolge.
(wish I had a scanner)
1867 World's Exhibition, Paris
Moritz Poehlmann's wire Nos. 13 14 15 16 17 18
broke at a strain of .............Lbs. 226 264 292 296 312 348
1876 World's Exhibition, Philidelphia
Steinway & Sons' testing machine used.
Moritz Poehlmann's wire Nos. 13 14 15 16 17 18
Lbs 265 287 320 331 342 386
1893 Chicago World's Fair
Poehlmann's wire Nos 12.5 13 14.5 15 16
break point lbs 325 335 350 400 415
Jim Colman's tests Nos 13 13.5 14 15 16 18
break point lbs 290 303 355 398 487
This shows piano makers have had modern strength wire for 100 years.
Richard Moody
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