The jamming of hard particles in the limit of zero pressure has been well studied in granular physics. However, many practical applications are far from this low-pressure limit. As the pressure increases, granular rearrangement is no longer the only mechanism for densification. Individual grains will deform and eventually fracture. This breakdown of granular matter, or comminution, produces irregular grain shapes and sizes and greatly changes macroscopic properties. We explore the compaction of brittle granular systems using large-scale discrete element simulations. Each grain is composed of many smaller, fundamental particles. These particles are interconnected within a grain by a network of bonds which break if stretched or bent beyond a critical value. This allows for grains to crack and fragment into smaller grains. During loading, we monitor both the evolution of macroscopic properties, such as the stress and porosity, as well as the evolution of distributions of grain size and shape. We characterize trends in behavior and explore how compaction depends on material properties and how it changes in the high rate limit. We also identify the pressure at which individual grains fracture and compare to theoretical models.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and 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-NA-0003525.