A modeling study of the effect of stress state on void linking during ductile fracture

The deformation and fracture behavior of sheet specimens containing either pairs of “pseudo”-random arrays of equi-sized holes has been examined in both uniaxial and equal-biaxial tension utilizing experiment as well as computer simulation. Our results show for this plane-stress situation that hole linking is always caused by flow localization within the ligaments between neighboring holes. The imposed strains to initiate flow localization and subsequent ligament failure are sensitive to stress state (uniaxial versus biaxial) and the location of the neighboring hole(s). A significant observation is the influence of stress state on the multidirectionality of hole linking paths: specifically, increasing the biaxial component of the stress state increases the number of holes that can participate in a hole-linking process. A related implication is that the strain range over which void linking occurs decreases with increasing triaxiality of the stress state; in effect, after the initiation of void linking, its propagation is accelerated under biaxial or triaxial tension.