Multi-scale numerical simulation of fracture behavior of nickel-aluminum alloy by coupled molecular dynamics and cohesive finite element method (CFEM)

J Ding and HR Zheng and Y Tian and X Huang and K Song and SQ Lu and XG Zeng and WS Ma, THEORETICAL AND APPLIED FRACTURE MECHANICS, 109, 102735 (2020).

DOI: 10.1016/j.tafmec.2020.102735

In the current study, a mull-scale investigation on the crack propagation of B-2-NiAl alloy was performed by using coupled molecular dynamics (MD) and the cohesive finite element method (CFEM). In particular, by using python programming, a FE model with a zero- thickness cohesive element for batch insertion was established. The T-S curve obtained from MD simulation was adopted as the material input parameter for the zero-thickness cohesive element to investigate the micro crack propagation mechanism and realize the macro crack random propagation simulation. The results showed that in micro-scale, the crack propagation behavior of single crystal B-2-NiAl was primarily caused by continuous coalescence of the main cracks and microvoids generated from the stress concentration at the crack front. Furthermore, the single crystal B-2-NiAl experienced phase transition and followed the Bain path. Moreover, the T-S curves at different temperatures were compared with Needleman classical theoretical models, demonstrating the properness of the Needleman model. Afterwards, the macroscopic fracture toughness values of B-2-NiAl alloys at different temperatures were calculated and compared with those obtained from experiments. Such comparisons demonstrated good agreement with each other and indicated that the T-S curve obtained via MD can be applied to the FE method. These results validated the rationality of this mull-scale method, which offers an alternative approach for fracture behavior simulation across macro and micro scales.

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