Compressibility of granular assemblies using MDR contact law

Modelling the compression behaviour of granular assemblies using homogenisation approaches presents limitations arising from the description of elastic, plastic and adhesive contact interactions between particles. In this work, a Method of Dimensionality Reduction (MDR) approach for normal sphere contact developed by Zunker and Kamrin (2024a,b) is employed to predict the compressibility of granular assemblies at high densities, assuming regular lattice arrangements of particles. A modification to the model is introduced to give improved estimates of contact force at high confinement. The simulations are validated against compaction experiments conducted using monosized aluminium spheres. The experimental results matched the predicted compressibility curves best when the most resistant lattice orientation relative to strain direction was selected. A micromechanical argument is developed to support the proposition that using a single lattice cell at minimum compliance orientation is suitable for capturing the compaction response of monosized spherical assemblies.