Model of void nucleation on grain boundaries in dynamic failure of ductile metals incorporating interface incompatibility

Abstract

Void nucleation on grain boundary (GB) has been regarded as an important mechanism of damage initiation in ductile polycrystalline materials under dynamic loading. The high tensile stress induced by this loading mode enables interface incompatibility (i.e. the incompatibility of mechanical properties across the GB) to significantly affect intergranular spall damage initiation. In the present work, the concept of compatibility energy release rate is proposed to quantify the influence of interface incompatibility on interfacial failure. A tensor-formed criterion incorporating the compatibility energy release rate is established for modeling GB void nucleation in dynamic failure of ductile metals. We show that considering interface incompatibility enables the model to accurately describe the dependence of GB void nucleation on multiple factors reported by experiments and simulations, including the loading state and the GB characteristics. A statistical model on the basis of the criterion, aimed at further analyzing statistical features of GB void nucleation, provides a valid reference for quantitatively assessing the GB damage resistance and gives a physical explanation for the widely-adopted Weibull-form distribution of the nucleation stress.