DEM simulation of the unconfined compaction of fine powders

Compaction of fine particles was studied by numerical simulation based on the discrete element method. The evolution of force structures during compaction was analysed in terms of the mean value, distribution and orientation of the normal contacted force. The large "backbone" forces were identified and the analysis of these forces was shown to be able to provide more insight into the force structure. Depending on the initial packing density prior to compaction, two or three transition regions could be observed in the relation between the packing density and the logarithm of pressure. Two critical packing densities were identified, which were related to the jamming states corresponding to the geometrically stable and mechanically stable packing structures.