Modeling of high-density compaction of granular materials by the Discrete Element Method

Cold compaction of metal powders is now commonly studied at a microscopic scale, to further our understanding of contact mechanics between grains. The Discrete Element Method (DEM) is therefore, a good compromise between calculation time and precision. DEM simulations are in general limited to a relative density of about 0.8, because the existing contact laws do not reproduce all the physical phenomena involved in the densification of granular media. Local contact mechanics can be studied by finite element analyses on meshed distinct elements (MDEM, Meshed Distinct Element Method). However, this method is too time-consuming when in the presence of a large number of grains. In the following work, a new analytical contact law will be formulated with MDEM which will subsequently be used to validate the DEM model. Thus, it will be possible with DEM modeling to reproduce high-density compaction of random packings up to a relative density of about 0.95. By introducing a local relative density parameter in the force-displacement relationship, the incompressibility effects which rule high-density behaviors can be introduced in the modeling of powder compaction. (C) 2009 Elsevier Ltd. All rights reserved.