Mixed-mode fracture toughness evaluation of a copper single crystal using atomistic simulations
CB Cui and GH Lee and HG Beom, COMPUTATIONAL MATERIALS SCIENCE, 136, 216-222 (2017).
The fracture toughness and kinking of a cracked Cu single crystal under mixed-mode loads are investigated via atomistic simulations. The embedded-atom-method potential is adopted for modeling the Cu single crystal. The displacement conditions imposed on the simulation cells are the near-tip K-field displacements of a crack in a cubic symmetry material obtained from linear elastic fracture mechanics (LEFM). For comparison, an asymptotic problem of a kinked crack in a Cu single crystal is solved by finite element analysis under the LEFM framework. The mixed-mode fracture toughness and preferred orientation of the crack extension for the LEFM approach are evaluated on the basis of a proposed mixed mode fracture criterion. The crack extension is determined by maximizing the crack extension force, which defined as the ratio of the normalized energy release rate to the normalized surface energy. The discrepancies between the results obtained from the atomistic simulations and the LEFM approach are discussed. The transition of fracture patterns from brittle fracture to fracture after dislocation emission with an increase in mode mixity is the primary reason for such discrepancies. (C) 2017 Elsevier B.V. All rights reserved.
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