Comparison of anisotropic crack tip behavior in hcp titanium by two-dimensional and three-dimensional atomistic simulations. (June 2021)

• Record Type: Journal Article
• Authors: Chang, Le; Kitamura, Takayuki; Zhou, Chang-Yu; He, Xiao-Hua
• Is Part Of: Theoretical and applied fracture mechanics. Volume 113(2021)
• Publication Date: 2021-06
• Subjects: hcp titanium -- Crack tip -- 2D simulation -- 3D simulation -- Dislocation emission; Fracture mechanics -- Periodicals; 620.1126
• DOI: 10.1016/j.tafmec.2021.102938
• Languages: English
• ISSNs: 0167-8442

Abstract

Highlights: Anisotropic crack tip behavior in hcp titanium is studied by 2D and 3D atomistic simulations. The stress triaxiality around the crack tip is lower in 3D simulations. The activation of the oblique slip mode improves crack tip plasticity in 3D simulations. The critical stress intensity factor for dislocation emission is lower in free 3D simulations. Abstract: As three-dimensional (3D) atomistic simulations require much higher computational costs, two-dimensional (2D) atomistic simulations under plane strain condition are widely used to study dislocation emission from the crack tip. In order to study the difference of crack tip behavior in 2D and 3D simulations, both 2D and 3D atomistic simulations of the anisotropic crack tip response in hcp titanium were performed, as well as the comparison of simulation results with linear elastic fracture mechanics (LEFM) predictions. The comparing results find significant discrepancies of the near tip stress fields, incipient crack tip deformation and critical stress intensity factor in 2D and 3D simulations. In consistent with the theoretical predictions, crack tip plasticity is solely contributed by the inclined slip mode with a lower critical stress intensity factor than that for cleavage, otherwise an artificial cleavage behavior may be observed in 2D simulations. In contrast to this, the lower stress triaxiality near the free surface leads to an easier dislocation nucleation in free 3D simulations. Besides, the participation of the oblique slip mode improves crack tip plasticity and facilitates the activation of the inclined slip mode that cannot be activated in 2D simulations. In general, the incipient crack tip behavior observed in 3D simulations shows more consistency with experimental results.