The effect of thread dimensional conformance on yield and tensile strength

摘要

This paper presents the results from tests that investigate the effect of thread dimensional conformance of fasteners on yield and tensile strength. Test specimens include combinations of bolts and nuts within dimensional conformance as specified by ASME Standard B1.1-1992, as well as bolts with undersized pitch and major diameters and nuts with oversized pitch and minor diameters. Tensile tests were performed in accordance with ASTM F606-95b. Data from the tests show reduced yield and tensile strength for the fastener combinations with undersized pitch and major bolt diameters or oversized pitch and minor nut diameters compared to fastener combinations within conformance. Variations in bolt pitch diameter were found to affect the yield and tensile strength by about an order of magnitude more than variations in bolt major diameter or nut pitch and minor diameters. The mean tensile strength for conforming product was found to be as much as 20 percent greater than the tensile strength for nonconforming product.