Massively parallel molecular dynamics simulations of crack-front dynamics and morphology in amorphous nanostructured silica

Abstract

Atomistic aspects of dynamic fracture in amorphous and nanostructured silica are herein studied via Molecular dynamics (MD) simulations, ranging from a million to 113 million atom system. The MD simulations were performed on massivelly parallel computers using highly efficient multi-resolution algorithms. Crack propagation in these systems is accompanied by nucleation and growth of nanometer scale cavities up to 20 nm ahead of the crack front. Cavities coalesce and merge with the advancing crack to cause mechanical failure. Recent AFM studies in silica glasses confirm this scenario of fracture [1]. The morphology of the fracture surfaces is studied by calculating the height-height correlation function. The MD simulation finds the first roughness exponent (æ=0.5). Simulations of amorphous nanostructured silica reveal pore nucleation ahead of the crack front, and the crack front meandering around the nanoparticles and merging with those pores.