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MM: Fachverband Metall- und Materialphysik

MM 38: Topical Session: Fundamentals of Fracture - Atomistic Modelling

MM 38.3: Vortrag

Mittwoch, 13. März 2013, 15:45–16:00, H4

Atomistic Simulations of Cracks in α-Iron: 2D vs. 3D — •Johannes J. Möller and Erik Bitzek — Friedrich-Alexander-Universität Erlangen-Nürnberg, Department of Materials Science and Engineering, Institute of General Materials Properties, Martensstr. 5, 91058 Erlangen, Germany

Atomistic simulations play a crucial role in advancing our understanding of the crack tip processes taking place during fracture. As with all atomistic simulations, the results depend critically on the model of atomic interaction and on the boundary conditions. Here we present a systematic study of seven different embedded atom method (EAM) potentials applied to mode I cracks in α-iron and compare the results of straight crack fronts in quasi-two-dimensional (2D) set-ups with curved crack fronts in three-dimensional (3D) set-ups.
Infinitely long, straight crack fronts were studied in a cylindrical geometry where the atoms are displaced according to the anisotropic linear-elastic solution and periodic boundary conditions are applied along the crack front direction. Comparison of the fracture behavior and critical stress intensity factors to experimental data allows us to rank the potentials according to their capability to realistically model fracture in α-iron. The results of these quasi-2D simulations are compared to large-scale 3D molecular statics and -dynamics simulations of penny shaped cracks. The plastic deformation mechanisms and changes in crack morphology are analyzed in detail and related to the curvature of the crack front and the 3D simulation set-up. The results highlight the importance of 3D models to study microstructurally short cracks.