Jeremy B. Lechman ^a, Joel T. Clemmer ^a, Joseph Monti ^a, Dan S. Bolintineanu ^a, Stewart A. Silling ^a.

^a Sandia National Laboratories

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Purpose. Design of particulate materials feedstocks and processing operations for optimal performance is challenging due to complex particle-scale properties and behaviors.  Several recent advances in the opensource code LAMMPS will be described, including a deformable particle modeling and simulation capability compatible with traditional discrete element methods for low-pressure particle dynamics that accurately predicts not only the bulk mechanical response of highly compacted powders, but also the resulting internal microstructure (density variations and particle interfaces).

Methods.  Recently implemented methods for handling large particle size distributions efficiently; an approach to model particle deformation, fracture and fragmentation based on discrete irregular lattice network; and additional meshless approaches for coupling fluids and solids will be highlighted.  The utility of these particle-scale approaches for understanding macroscale constitutive model forms will be highlighted. 

Results. Preliminarily, these methods provide good qualitative, phenomenological agreement to experimental data and are easily incorporated into LAMMPS (an opensource particle dynamics simulator).  Quantitative validation is on-going, but initial use is found in gaining physical insight into the complex particle-scale behavior not resolved in macroscale constitutive models.

Conclusions. Advances in experimental imaging and particle-scale modeling and simulation are allowing for the advancement of capabilities that elucidate the process-(meso)structure-property relationships in particulate materials potentially enabling powerful new design tools for optimizing the interplay of formulation, processing, and performance objectives.