A strategy to determine DEM parameters for spherical and non-spherical particles

Abstract

In Discrete Element Method (DEM) simulations the choice of appropriate contact parameters is significant to obtain reasonable results. Particularly, for the determination of DEM parameters for non-spherical particles a general straightforward procedure is not available. Therefore, in a first step of the investigation here, methods to obtain the friction and restitution coefficients experimentally for single particles (Polyoxymethylene (POM) spheres and quartz gravel) will be introduced. In the following, these predetermined DEM coefficients are used as initial values for the adjustment of bulk simulations to respective experiments. In the DEM simulations, the quartz gravel particles are represented by non-spherical particles approximated by clustered spheres. The best fit approximation of the non-spherical particles is performed automatically by a genetic algorithm. In order to optimize the sliding and rolling friction coefficients for DEM simulations, the static and dynamic angle of repose are determined from granular piles obtained by slump tests and rotating drum experiments, respectively. Additionally, a vibrating plate is used to obtain the dynamic bed height which is mainly influenced by the coefficient of restitution. The adjustment of the results of the bulk simulations to the experiments is conducted automatically by an optimization tool based on a genetic algorithm. The obtained contact parameters are later used to perform batch-screening DEM simulations and lead to accurate results. This underlines the applicability of the in parts automated strategy to obtain DEM parameters for particulate processes like screening.

Separation Curves of Screening and Air Classifying Processes at Low Material Loadings

“…Durch diese positive Auswirkung wird die Notwendigkeit, die Partikelform exakter abzubilden, wie dies schon in kleinerem Maßstab in Elskamp et al [51] durchgeführt wurde, bestätigt. 6b).…”

“…Aufgrund dieser positiven Effekte wird bei zukünftigen Untersuchungen versucht, die komplexe Partikelform exakter abzubilden [51]. Dies ist in Abb.…”

Understanding granular media: from fundamentals and simulations to industrial application

“…This vital role of calibration as a part of the model setup/preparation can be observed as a running theme throughout the Topical Collection (e.g. [7,9,15]). …”

“…Optimisation algorithms are now becoming increasingly popular for this task [17,18]. From this perspective, Elskamp et al [9] presents a calibration procedure for spherical and nonspherical particles based on Genetic Algorithms.…”

“…• The multisphere/clustering/clump approach where defined shapes are constructed from conglomerations of several overlapping spheres [9], • Rounded polyhedral particles [10], and, • Particle shapes defined by generating functions such as superquadrics and spheroids [11].…”