The Capriccio method as a versatile tool for quantifying the fracture properties of glassy materials under complex loading conditions with chemical specificity

Molecular dynamics (MD) simulations are widely used to provide insights into fracture mechanisms while maintaining chemical specificity. However, particle-based techniques such as MD are limited in terms of accessible length scales and applicable boundary conditions, which restricts the investigation of fracture phenomena in typical engineering settings. In an attempt to overcome these limitations, we apply the partitioned-domain Capriccio method to couple atomistic MD samples representing silica glass with the finite element (FE) method. With this approach, we perform mode I (rectangular panel under tension, three-, and four-point bending), mode II as well as mode III (rectangular panel under in-plane or out-of-plane shear) simulations. Thereby, we investigate multiple criteria to identify the onset of crack propagation based on the virial stress, the number of pair interactions, the kinetic energy/temperature, the crack velocity, and the crack opening displacement. It becomes apparent that the maximum virial stress can actually serve as an objective and meaningful indicator for the start of crack growth, in contrast to, for example, the temperature evolution The approach presented provides quantitatively plausible results for the critical stress intensity factors K Ic , K IIc , and K IIIc . This contribution shows that the Capriccio method is a flexible means of performing fracture simulations that take into account boundary conditions typical of experimental test setups with atomistic specificity near the crack tip. While also pointing out the current limitations of the Capriccio method, we demonstrate its potential to integrate atomistic insights into FE models with significantly larger overall dimensions. • Chemically specific fracture simulations of silica glass under modes I, II and III. • Modeling brittle fracture by coupling molecular systems to a finite element domain. • Evaluation of the overall specimen size based on linear elastic fracture mechanics. • Intuitive protocol to derive K Ic , K IIc and K IIIc based on the virial stress. • Reasonable agreement of K Ic , K IIc and K IIIc with quantitative expectations.