At 18:14 -0700 13/04/2011, David Love wrote: >As I mentioned earlier the formula for safe BP% (60%) came from Sanderson as >.557*(d^1.667), d in mils which gave me 170 lbs for .031 or US 13 gauge. >The actual diameter in mils (.775 mm) is more like .0305 which yields your >166 lbs. OK, I've worked it out now and applied it to the published Ršslau breaking strains. The factor for Ršslau would need to be 0.515 instead of 0.557, and then the curve follows very closely 60% of the published Ultimate Tensile Strength (Paulello's 'mechanical resistance'), but that gives us, almost exactly, 80% of Paulello's 'practical breaking load', in other words spot on the elastic limit. No time to write more at the moment, but I'll explain more later. JD
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