Mechanistic insight into the process of crack growth can be obtained through molecular dynamics (MD) simulations. In this investigation of fracture propagation, a slit crack was introduced into an atomistic amorphous silica model and mode I stress was applied through far-field loading until the crack propagates. Atomic displacements and forces and an Irving–Kirkwood method with a Lagrangian kernel estimator were used to calculate the J-integral of classical fracture mechanics around the crack tip. The resulting fracture toughness (K_IC), 0.76 ± 0.16 MPa√m, agrees with experimental values. In addition, the stress fields and dissipation energies around the slit crack indicate the development of an inelastic region ~30Å in diameter. This is one of the first reports of K_IC values obtained from up-scaled atomic-level energies and stresses through the J-integral. The application of the ReaxFF classical MD force field in this study provides the basis for future research into crack growth in multicomponent oxides in a variety of environmental conditions.

中文翻译：

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从反应经典分子动力学模拟到二氧化硅中的裂纹扩展

可以通过分子动力学（MD）模拟获得对裂纹扩展过程的机械洞察力。在此裂缝扩展研究中，将狭缝裂缝引入了原子无定形二氧化硅模型中，并通过远场载荷施加了模式I应力，直到裂缝扩展为止。原子位移和力以及带有拉格朗日核估计器的Irving-Kirkwood方法用于计算裂纹尖端周围经典断裂力学的J积分。所得的断裂韧性（K _IC）为0.76±0.16MPa√m，与实验值一致。另外，缝隙裂纹周围的应力场和耗散能表明出现了直径约为30Å的无弹性区域。这是K _IC的第一份报告之一通过J积分从按比例放大的原子能级和应力获得的B值。ReaxFF经典MD力场在本研究中的应用为将来在多种环境条件下研究多组分氧化物的裂纹扩展提供了基础。