Characterization of the microstructure of randomly-generated particle packs for DEM simulations of granular materials
Kamila R. Cassares1; Eduardo M. B. Campello2
1 University of São Paulo; 2 University of São Paulo
doi:10.20906/CPS/CILAMCE2015-0437
Resumo
In this work we generate packs of particles using the recently proposed particle-packing technique of [1] and perform assessment the microstructure of these packs. We compute each pack´s coordination number, fabric tensor, normal contact force tensor and tangential friction force tensor, such that the microstructure of the packs is fully characterized with respect to their granular fabric and principal contact directions (both normal and tangential). These quantities provide a good estimate to the degree of isotropy or anisotropy of the packs, and thus serve as indicators of "quality" of the packs and, ultimately, of the particle-packing technique. The average stress tensor of each pack, relating inter-particle contact forces and directions to the bulk stress response of the pack (and thereby providing an indirect relation between microscopic properties and macroscopic behaviour), is also computed. Statistical assessment of the attained results is performed by computing their mean value, standard deviation, variance and coefficients of variation. We show that the technique of [1], besides being able to generate packs at sufficiently high packing ratios (as demonstrated in [1]), is also able to generate packs that are very much repeatable with respect to their microstructure. This feature is extremely desirable if the packs are intended to serve as samples of granular materials on which DEM simulations are to be conducted, e.g. for material characterization purposes and/or determination of bulk material properties. This is indeed our interest in the next step of this research. We believe that simple, reliable techniques for generation of particle packs at sufficiently high packing ratios and with adequate microstructure are crucial tools for the DEM simulation of granular materials. REFERENCES [1] K. R. Cassares and E. M. B. Campello (submitted), "Rapid generation of particle packs at high packing ratios for DEM simulations of granular compacts", Lat Amer J Sol Struct.
Palavras-chave: Discrete Element Method; Particle packing; Microstructure