Molecular dynamics simulation-based cohesive zone representation of fatigue crack growth in a single crystal nickel

摘要

Nanoscale fatigue crack growth was investigated by introducing a cohesive zone model based on molecular dynamics simulations. The evolutions of the microstructure and stress in fatigue crack growth over two different cyclic loading regimes were investigated using pre-existing centre crack specimens. Under increasing strain amplitude cyclic loading, dislocations emitted and persistent slip bands formed around the fatigue crack tip, which retarded crack propagation and changed the stress distributions; under constant amplitude cyclic loading, crack opening and closing was accompanied by void formation in the crack plane. Different fatigue loading regimes resulted in different crack propagation mechanisms and stress distributions; the peak stress was accompanied by microstructure evolution ahead of the crack tip, which induced the variation in fatigue crack growth rates and crack opening displacements. (C) 2015 Elsevier B.V. All rights reserved.