Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Granular matter II

DY 24.8: Vortrag

Donnerstag, 28. Februar 2008, 11:45–12:00, MA 004

Macroscopic stress and displacement response functions of static granular layers — •Pradip Roul and Klaus Kassner — Institute für Theoretische Physik,Otto-Von-Guericke-Universität,Magdeburg,Postfach-4120,D-39106,Magdeburg

We investigated numerically the averaged stress and displacement response functions to a local force perturbation of assemblies of grains that have been constructed by a layer-wise deposition of particles. We apply a load to a single grain of the top layer of the granular packing with a force small enough to not cause any rearrangement of the layer structure. This study has been done by use of a DEM numerical simulation generating granular packings with different packing order consisting of soft convex polygonal sand particles. The simulation was performed in two-dimensional systems. The shape of the vertical normal stress response function depends upon the packing order of the granular aggregate. Mono-disperse packings of round particles show double peak shapes underneath the point where the external force is applied, a behaviour predicted for hyperbolic continuum equations. For bidisperse packings, double peaks are also present, but much less pronounced, whereas there is only asingle peak present packings of pentagonal particles. Stress responses are compared qualitatively with experimental results by Junfei Geng et al. of photo elastic material. Our simulation results show good agreement with these experiments. Moreover, the calculation of the macroscopically averaged displacement response functions inside the granular aggregates will be presented.