FUNDAMENTAL OF FRACTURE MECHANICS BY ATOMISTIC SIMULATION

Recent fracture cleavage experiments of silicon crystal specimens indicate that atomistic scale effects at the crack front influence the macroscopic brittle cracks dynamical behavior, emphasizing the importance of atomistic work to the understanding of fracture mechanics. However, atomistic simulations have yet to provide an accurate representation of brittle fracture experiments as a boundary value problem (BVP) with appropriate boundary conditions (BC).

Molecular Dynamic simulations of static crack in the (110)[1-10] cleavage system of a silicon-like brittle crystal were performed. We first examined the applicability of the square root singularity and the Irwin K-G relationship using Psedo-2D atomistic models. We show that a square root singularity exists at the crack front, and a minimal model size, that is much larger than the existing models, is required to acquire this relationship.

We also employed a more realistic full 3D boundary value problem, instead of the commonly used Pseudo-2D computational setup, that allows the formation of a more realistic curved crack front. We show the stress intensity factor to not be of constant value along the crack font.