Computer simulation of model cohesive powders: influence of assembling procedure and contact laws on low consolidation states.Report as inadecuate




Computer simulation of model cohesive powders: influence of assembling procedure and contact laws on low consolidation states. - Download this document for free, or read online. Document in PDF available to download.

* Corresponding author 1 ? - Departamento de Electronica y Electromagnetismo Facultad de Fisica 2 LMSGC - Laboratoire des matériaux et structures du génie civil

Abstract : The structure and mechanical properties of a simple two-dimensional model of a cohesive powder are investigated by molecular dynamics simulations. Micromechanical ingredients involve elasticity, friction, a short range attraction and, possibly, rolling resistance RR in contacts. The microstructure of the cohesive packing varies according to the assembling procedure, from rather densely packed if isolated particles are directly compressed to much looser if the formation of large aggregates is allowed prior to compression. A crucial parameter is the ratio P*= Pa-F0 of applied pressure P, acting on grains of diameter $a$, to maximum tensile contact force F0. At low P* the final structure depends on the level of velocity fluctuations at the early stages of cluster aggregation. With RR the coordination number approaches 2 in the limit of low initial velocities or large rolling friction. The force network generally comprises small hyperstatic clusters with forces of the order of F0, joined by nearly unstressed, barely rigid arms. As P* grows, it quickly rearranges into force chain-like patterns. Density correlations witness a fractal structure, with dimension Df, up to some density-dependent blob size. WIth RR Df coincides with the ballistic aggregation result, despite a possibly different connectivity. Possible effects of some parameters on material strength are evoked.

keyword : granular materials cohesion ballistic aggregation fractal dimension





Author: Francisco Gilabert - Jean-Noël Roux - Antonio Castellanos -

Source: https://hal.archives-ouvertes.fr/



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