Ankit Srivastava¹; ¹Texas A&M University

The onset of multiple localization/necking and fragmentation in expanding ductile structures is delayed due to the stabilizing effect of inertia, and with increasing expansion velocity, both the number of necks and fragments, increase. In general, neck retardation is expected to delay fragmentation as necking is often the precursor to fracture. However, in porous materials it is possible that fracture can occur without significant necking. Following this, we investigate the emergence of multiple necking in ductile porous materials subjected to dynamic stretching using finite element calculations and linear stability analysis. Our results reveal that, a heterogeneous distribution of defects (e.g. porosity) is needed to trigger the multiple necking pattern but it barely affects the average neck spacing, and low initial porosity levels favor necking before fracture while high initial porosity levels favor fracture before necking, at higher strain rates.