Stress intensity factors, T-stresses and higher order coefficients of the Williams series expansion and their evaluation through molecular dynamics simulations

• Published in: Mechanics of advanced materials and structures 2023-10, Vol.30 (19), p.3862-3884
• Main Authors: Stepanova, L. V., Belova, O. N.
• Format: Article
• Language: English
• Subjects: classical fracture mechanics; Crack tips; Finite element analysis; Finite element method; Fracture mechanics; higher order terms of the Williams series expansion; Linear elastic fracture mechanics; Mathematical models; Metal plates; mixed mode loading; Molecular dynamics; Molecular dynamics simulation; Power series; Series expansion; Simulation; Singular stress fields; Stress intensity factors; T-stresses; Thermal expansion
• ISSN: 1537-6494; 1537-6532
• DOI: 10.1080/15376494.2022.2084800

Molecular dynamics method and finite element analysis are applied for the analysis of the stress field in the neighborhood of the crack tip in a copper plate with a single edge notch. The molecular dynamics simulations implemented in a classical molecular dynamics code LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) are aimed at evaluating classical continuum linear elastic fracture mechanics parameters such as stress intensity factors, T-stresses and higher order coefficients of the Williams power series expansion of the near crack stress field for Mode I, Mode II and Mixed Mode (Mode I + Mode II) loadings of the cracked specimen in isotropic linear elastic materials. The key objective of the study is the comparison of continuum and atomistic approaches for the estimation of the near crack tip fields using the example of one of the most common cracked configurations. Stress intensity factors, T-stresses and higher order coefficients of the Williams series expansion for a copper plate with the single edge notch under Mode I and Mixed Mode loadings are evaluated by atomistic modeling and by finite element method. The wide class of the computations in LAMMPS is performed. The atomistic values of stress intensity factors and higher order terms of the Williams series expansion are compared with the values obtained from the numerical solutions given by finite element method. It is shown that the continuum fracture theory successfully describes fracture and the near crack tip fields even at extremely confined singular stress field of only several nanometers. The angular distributions of the stress components from atomistic modeling are retrieved and compared with the angular distributions of the stresses from continuum linear elastic fracture mechanics. The comparison shows good agreement between two approaches.