Here’s another test. Bend wire. Wait for it to cool. Bend it again. Wait for it to cool. If the wire never breaks, then the mechanism is microheating.
C’mon, we know that won’t happen.
Anyway, I sacrificed a coat hanger and snipped 2 pieces from it.
The first was bent 16 times in air (temp 67F, according to my joke of a thermometer), before it broke.
The 2nd was bent 11 times in water (temp 61F, ditto) before it gave way.
The experiment sucked. The wire was rigid enough so that I couldn’t make equally-sized bends with my bare hands. Halfway through the air test, I switched to the use of “plyers & hand”. I still couldn’t achieve bend homogeneity.
But it felt less painful so I stuck with the p&h method for the underwater test.
After the fact, I noticed that I probably counted more half bends in the air segment than in the underwater segment. Or was it visa versa?
Perhaps “fatigueing” would be a better term, although I don’t think that’s an actual form of the word. By bending the wire back and forth, it causes the material to fatigue, eventually reaching it’s failure point.
I watched a show on the History Channel a few days ago which talked about Galen the physician, and Roman couching needles. I wasn’t able to link hollow needles to Galen online, and I couldn’t find the show on the History Channel website. But another quick search yielded this page, whereon it says:
