Compaction bands

We study the formation and development of compaction bands by compact packing discrete element model.In the model, a discrete unit represents a collection of particles.The yield envelope of the element is defined by the aspect ratio of yield force and yield ellipse.When the stress state of connections of one unit exceeds its yield surface, the unit is compacted (shrunk).When the aspect ratio of yield ellipse increases from 0.5 to 2, the compression bands change from a straight shape to a wavy shape, which indicates that the shape of the compaction bands is affected by the shape of its yield surface.