Construction of tensile stress-strain curves for solid bars pre-deformed by gradient shear strain

Abstract

Cai Chen, Beygelzimer Y., Kulagin R., Davydenko O. Construction of tensile stress-strain curves for solid bars pre-deformed by gradient shear strain. Material working by pressure. 2020. № 1 (50). P. 114-118.
 Strain hardening curves were derived for the first time for tension of cylindrical solid bars in the presence of a linear strain gradient produced by severely pre-straining by torsion. An analytical formula was obtained, which enables constructing the local stress-strain curve. Data obtained for pure copper samples pre-twisted to different levels of shear strain were used. A saturation stage not known hitherto was found for large strains.
 One particularity of the present results is that for low tensile strains the tensile flow stress after torsion agrees well with the flow stress in monotonic tension.
 Another particularity of the results is that the tensile flow stress is constant after torsion at large strains, starting from about 1.5 strain. This effect was observed for the first time because the present technique is the first one to provide access to tensile flow stress after large strain torsion.