The effect of void shape on void growth and ductility in axisymmetric tension tests

The effect of void growth and ductility in axisymmetric tension tests was examined theoretically. The inelastic response of periodic arrays of initially oblate spheroidal voids in a homogeneous isotropically hardening matrix was analyzed for loading histories representative of axisymmetric tension tests. The failure strains were taken as the point where the deformation mode became that of uniaxial strain. All subsequent deformation was localized to ligaments between the voids. The results showed that, for stress states with a low hydrostatic stress component, the void growth rates were governed primarily by the void dimension perpendicular to the tensile axis. They also indicated that the failure strains were proportional to the projected area of the voids onto a plane perpendicular to the tensile direction, in agreement with published experimental results. For stress states with higher triaxiality, the influence of the initial aspect ratio was diminished.