An analysis on necking effect and stress distribution in round cross-section specimens of pure copper with different diameters

The size dependence of the tensile properties and necking effect of pure copper exposed to various heat treatments are investigated in this paper using round bar cross-section specimens through experimental and 3D finite element methods (FEM). The results show that the total and post-necking elongation increased dramatically as the specimen diameter increased. The size effects on necking and stress distribution of different diameter specimens are analysed. These results show that the post-necking deformation length is only dependent on the diameter of the specimens and is independent of the specimen’s gauge length, which results in the size dependence of the post-necking elongation. Moreover, FEM simulations show that the size dependence of the tensile properties can be eliminated when the ratio of the gauge length to the diameter is larger than 10.