Some Considerations on Stress Intensity Factor at Atomic Scale

Abstract

This work reviews recent molecular statistics (MS) numerical experiments of cracked samples, and discusses the crack-tip region stress field of ideal brittle materials. Continuum-based linear elastic fracture mechanics, indeed, breaks down at extremely small scale, where the discrete nature of atoms is considered. Surprisingly, recent results have shown that the concept of stress intensity factor (SIF) is still valid. In this work, by means of MS simulations on single-edge cracked samples of ideal brittle silicon, it is shown that the stress intensity factor derived from the virial stress may be useful to describe the fracture at extremely small dimensions and to quantify the breakdown of continuum-based linear elastic fracture mechanics. However, it is still debated whether a continuum-based concept such as the "stress" should be applied to a system made of atoms.

Nonlocal analysis of edge‐cracked nanobeams under Mode I and Mixed‐Mode (I + II) static loading

“…It is worth noticing that it was proved that in the cracked nanostructures, there is no stress singularity at the crack tip, 24,43–45 although stress still varies with a square root singularity in the region near the crack tip, 24,43–45 being this last trend similar to that occurring in the K‐dominance region according to LEFM. However, when the sizes of the material are scaled down to nanometers, the above region is limited to nanometers too.…”

“…In the context of cracked nanostructures under static loading, that is, the loading condition examined in the present research work, both atomistic modeling [19][20][21][22][23][24][25][26][27][28] and GCTs [29][30][31][32][33][34][35][36][37][38][39] are put forward into several studies to investigate their fracture behavior, being the experimental investigation still a challenge, due to technical difficulties connected with the nanoscale sizes involved.…”