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

Abstract

a b s t r a c tCold 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.

An experimental evaluation of the accuracy to simulate granule bed compression using the discrete element method

“…Finally, Voronoi cells may be utilized to estimate particle volumes, resulting in a model similar to the one proposed by Harthong et al [13]. This would however increase the complexity of the DEM and particle number reduction might be necessary to maintain the computational cost within reasonable limits.…”

“…However, compression of plastically deforming granules has been investigated by the FE/DE method [12]. In order to save computational time when simulating contact forces, the extraction of a contact expression from the FE/DE method has proven successful in DEM simulations [13]. In order to simulate more realistic systems, corresponding to experimental compressions, the combined FE/DE method is impracticable.…”

“…At higher relative densities, the contact deformation is dependent on the influence of neighbouring particles [14], which is not considered in the contact model. However, simulations at relative densities exceeding 0.8 are feasible using a contact law derived from a combined discrete and continuum model in which Voronoi cells are used to estimate particle volumes [13].…”

A micro finite-element model for soil behaviour: numerical validation

“…Continuum deformable representation of ideal shapes using finite elements has been considered previously, particularly in powder technology (e.g. Harthong et al, 2009;Nezamabadi et al, 2015;Rathbone et al, 2015). The use of combined finite-discrete approaches to model systems of spheres is, however, not well established.…”

Micromechanical Analysis of Compaction and Drilling of Granular Media- A Review

“…Examples include: avalanches, segregation (which grains of different type separate under vibration), crystallization (when grains arrange into ordered configurations), pattern formation (when grains arrange into patterns, such as dunes or ripples) or jamming (when the flow of grains stops abruptly) [1]. Micromechanical analysis of compaction and particulate/granular materials has been of significance to academics and industrial communities, from beach sandcastles to chemical, pharmaceutical, food, mechanical, civil, mining and petroleum engineering as well as underground reservoir industry, and materials processing sectors [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Granular media are thermal, quite normal after all, usually with different particle-scale properties and inter-particle interactions, which are responsible for their complex behaviors at the low gravitational environment and macroscopic scale and difficult to assess experimentally [6,11,12,[16][17][18][19][20][21][22].…”