Voxel based parallel post processor for void nucleation and growth analysis of atomistic simulations of material fracture

• Voronoi tesselation based void analysis is much slower than voxel based void analysis.
• Nucleation and growth (NAG) parameters obtained from voxel based void analysis conform with the NAG model.
• Three different parallel algorithms for voxel based void analysis are presented.
• Domain decomposition based parallel algorithm scales linearly with number of processes when incorporated into LAMMPS software.
• Proposed scheme is suitable for void analysis of multi-billion atom domains.

Molecular dynamics (MD) simulations are used in the study of void nucleation and growth in crystals that are subjected to tensile deformation. These simulations are run for typically several hundred thousand time steps depending on the problem. We output the atom positions at a required frequency for post processing to determine the void nucleation, growth and coalescence due to tensile deformation. The simulation volume is broken up into voxels of size equal to the unit cell size of crystal. In this paper, we present the algorithm to identify the empty unit cells (voids), their connections (void size) and dynamic changes (growth and coalescence of voids) for MD simulations of large atomic systems (multi-million atoms). We discuss the parallel algorithms that were implemented and discuss their relative applicability in terms of their speedup and scalability. We also present the results on scalability of our algorithm when it is incorporated into MD software LAMMPS.

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