Experimental characterization of damage processes in aluminum AA2024-O

Much of the damage mechanics literature has focused on void growth due to tensile hydrostatic stress. To clarify the effect of combined shear stress and hydrostatic stress on the development of damage, specimens of various geometries were employed in an experimental program to cover a wide range of triaxiality and shear stress. Digital image correlation (DIC) is utilized to measure the fracture strain of the 2D specimens. Experiments are paired with simulations utilizing J2 plasticity theory to complement the experiments and relate the fracture strain with combined hydrostatic and shear stresses. The results display accelerated damage for cases dominated by shear at low triaxiality. Crystal plasticity simulations were carried out using boundary conditions based on the DIC displacement field. These simulations indicate that tensile hydrostatic stress develops due to grain-to-grain interaction.