Compression mechanics of granule beds: A combined finite/discrete element study

Compression of three-dimensional beds comprising 1000 plastically deforming initially spherical granules is investigated by using the combined finite/discrete element (FE/DE) method. The material model is formulated within the framework of multiplicative plasticity, and utilizes a density-dependent elliptic yield surface that allows porous particles to both deform and to densify plastically, whereas only volume-preserving plastic deformation is possible for nonporous ones. Granules with different characteristics (yield stress and initial porosity) are studied, and the relationship between the single-granule properties and the global compression behaviour of the granule bed is investigated. It is demonstrated that the FE/DE method may shed light on the deformation and densification behaviour of individual granules, since the size and shape of each granule are continually determined as an integral part of the solution procedure, and that the method thus provides a comprehensive picture of the processes occurring during confined compression of granular materials.