The Stress and Strain Distribution at the Neck of a Tensile Specimen

Abstract

Some approximate solutions to the problem of stress distribution at the neck of a tensile specimen have been developed by Bridgman, and Davidenkov and Spiridonova, assuming the following conditions : (1) The elastic strain can be neglected. (2) The strains are uniform over the cross section of the neck. (3) The yielding stress, therefore, is constant over the cross section of the neck. The strains of the surface of the minimum section were measured from the elongations of circumferential lines drawn finely by a diamond tool. By these measurements, it has been made clear that the axial strains over the minimum section are considerably different. It will be reasonable, therefore, to consider that the yielding stress is not constant over the minimum cross section. Using the obtained strains, we calculated the stress distribution over the minimum section, considering the difference of strain hardening over the minimum section.