Dislocation emission and crack growth in 3D bcc iron crystals under biaxial loading by atomistic simulations

0508315 - ÚT 2020 RIV US eng J - Journal Article
Uhnáková, Alena - Machová, Anna - Hora, Petr
Dislocation emission and crack growth in 3D bcc iron crystals under biaxial loading by atomistic simulations.
Journal of Applied Physics. Roč. 126, č. 7 (2019), č. článku 075115. ISSN 0021-8979. E-ISSN 1089-7550
R&D Projects: GA ČR(CZ) GA17-12925S; GA MŠMT(CZ) EF15_003/0000493
Institutional support: RVO:61388998
Keywords : nano-cracks * dislocation emission * ductile-brittle transition * T-stress * bcc iron * molecular dynamics
OECD category: Materials engineering
Impact factor: 2.286, year: 2019
Method of publishing: Limited access
https://aip.scitation.org/doi/pdf/10.1063/1.5109949?class=pdf

This paper is devoted to the study of the ductile-brittle behavior of a central nanocrack (1¯10)[110] (crack plane/crack front) under biaxial loading via free 3D molecular dynamics (MD) simulations, as well as the comparison of MD results with continuum predictions concerning T-stress. The so called T-stress is a constant stress component acting along the crack plane, which should be considered (together with the stress intensity factor K) in the assessment of brittle-ductile behavior, namely, in the case of the short cracks. Previous 2D atomistic simulations under plane strain conditions indicated that the level of T-stress (controlled by the biaxiality ratio σB/σA from the external loading) affects dislocation emission from the crack and can cause the ductile-brittle transition. The plane strain simulations using the periodic or translational boundary conditions in the bcc lattice have certain limitations: they enable the in-plane dislocation emission (Burgers vector lies in the observation plane), but they do not allow the complete dislocation emission on the all slip systems favored by the shear stress. As presented, our new free 3D atomistic simulations (without periodic or symmetry conditions) enable the activity of the all favored slip systems. Thus, they offer a more realistic insight into the microscopic processes generated by the crack itself in dependence on the T-stress level.
Permanent Link: http://hdl.handle.net/11104/0299625