Abstract The overarching objective of the paper is to analyze the mixed-mode crack propagation direction angles by molecular dynamics method and to investigate the validity of continuum-based linear elastic fracture mechanics crack growth criteria. For this purpose, an embedded atom potential (EAM) available in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) molecular dynamics (MD) software is utilized to accurately pinpoint mixed-mode crack growth. The study is focused on the application of the different approaches for determination of the initial crack propagation angle. Copper and aluminum plates with the central crack under complex mechanical stresses (Mode I and Mode II loading) are studied by extensive MD simulations. Williams’ expansion for the crack tip fields containing the higher-order terms is used. The crack propagation direction angles for combinations of Mode I and Mode II loadings are obtained by 1) multi-parameter fracture mechanics approach based on three fracture mechanics criteria: maximum tangential stress (MTS), maximum tangential strain and strain energy density (SED); 2) atomistic modeling for the mixed-mode loading of the plane medium with the central crack. The temperature effects during fracture processes in MD simulations are considered and temperature field distributions for mixed-mode crack propagation are obtained.

中文翻译：

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混合模式裂纹行为的分子动力学计算研究和经典断裂力学的多参数裂纹场描述

摘要 本文的首要目标是通过分子动力学方法分析混合模式裂纹扩展方向角，并研究基于连续体的线弹性断裂力学裂纹扩展准则的有效性。为此，利用 LAMMPS（大规模原子/分子大规模并行模拟器）分子动力学 (MD) 软件中提供的嵌入原子势 (EAM) 来准确定位混合模式裂纹扩展。该研究的重点是应用不同的方法来确定初始裂纹扩展角。通过广泛的 MD 模拟研究了在复杂机械应力（模式 I 和模式 II 载荷）下具有中心裂纹的铜和铝板。对包含高阶项的裂纹尖端场使用威廉姆斯展开。模式 I 和模式 II 加载组合的裂纹扩展方向角通过 1) 基于三个断裂力学标准的多参数断裂力学方法获得：最大切向应力 (MTS)、最大切向应变和应变能密度 (SED)；2) 具有中心裂纹的平面介质混合模式加载的原子模型。考虑了 MD 模拟中断裂过程中的温度效应，并获得了混合模式裂纹扩展的温度场分布。2) 具有中心裂纹的平面介质混合模式加载的原子模型。考虑了 MD 模拟中断裂过程中的温度效应，并获得了混合模式裂纹扩展的温度场分布。2) 具有中心裂纹的平面介质混合模式加载的原子模型。考虑了 MD 模拟中断裂过程中的温度效应，并获得了混合模式裂纹扩展的温度场分布。