Three-dimensional compaction of soft granular packings

This paper analyzes the compaction behavior of assemblies composed of soft (elastic) spherical particles beyond the jammed state, using three-dimensional non-smooth contact dynamic simulations. The assemblies of particles are characterized using the evolution of the packing fraction, the coordination number, and the von Misses stress distribution within the particles as the confining stress increases. The packing fraction increases and tends toward a maximum value close to 1, and the mean coordination number increases as a square root of the packing fraction. As the confining stress increases, a transition is observed from a granular-like material with exponential tails of the shear stress distributions to a continuous-like material characterized by Gaussian-like distributions of the shear stresses. We develop an equation that describes the evolution of the packing fraction as a function of the applied pressure. This equation, based on the micromechanical expression of the granular stress tensor, the limit of the Hertz contact law for small deformation, and the power-law relation between the packing fraction and the coordination of the particles, provides good predictions from the jamming point up to very high densities without the need for tuning any parameters.

Automated summary

This study analyzes the compaction behavior of assemblies composed of soft spherical particles using three-dimensional non-smooth contact dynamic simulations. The evolution of packing fraction, coordination number, and von Misses stress distribution within the particles with increasing confining stress is characterized. A transition is observed from granular-like material to continuous-like material as the confining stress increases. An equation describing the evolution of packing fraction as a function of applied pressure is developed, providing accurate predictions up to very high densities without parameter tuning.