title: Crack nucleation criterion and its application to impact indentation in glasses.
abstract: Molecular dynamics (MD) simulations are used to directly observe nucleation of median cracks in oxide glasses under indentation. Indenters with sharp angles can nucleate median cracks in samples with no pre-existing flaws, while indenters with larger indenter angles cannot. Increasing the tip radius increases the critical load for nucleation of the median crack. Based upon an independent set of simulations under homogeneous loading, the fracture criterion in the domain of the principal stresses is constructed. The fracture criterion, or "fracture locus", can quantitatively explain the observed effects of indenter angle and indenter tip radius on median crack nucleation. Our simulations suggest that beyond the maximum principal stress, plasticity and multi-axial stresses should also be considered for crack nucleation under indentation, even for brittle glassy systems.
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Luo
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: K Deenamma
authors.initials: KD
authors.lastname: Vargheese
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: Adama
authors.initials: A
authors.lastname: Tandia
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: Guangli
authors.initials: G
authors.lastname: Hu
authors.affiliation: Science and Technology Division, Corning Incorporated, Corning, New York 14831, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Mauro