Dresden 2003 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.84: Poster

Donnerstag, 27. März 2003, 15:30–18:00, P1

Anisotropy in granular media: classical elasticity and directed force chain network — •Matthias Otto¹, Jean-Philippe Bouchaud², Philippe Claudin³, and Joshua E.S. Socolar⁴ — ¹Institut für Theoretische Physik, Universität Göttingen,Bunsenstr. 9, D-37075 Göttingen, Germany — ²Service de Physique de l’Etat Condensé, CEA-Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France — ³Laboratoire des Milieux Désordonnés et Hétérogènes (UMR 7603), 4 place Jussieu – case 86, 75252 Paris Cedex 05, France — ⁴Department of Physics and Center for Nonlinear and Complex Systems, Duke University, Durham, NC 27708, USA

A general approach is presented for understanding the stress response function in anisotropic granular layers in two dimensions. The formalism accommodates both classical anisotropic elasticity theory and linear theories of anisotropic directed force chain networks. Perhaps surprisingly, two-peak response functions can occur even for classical, anisotropic elastic materials, such as triangular networks of springs with different stiffnesses. In such cases, the peak widths grow linearly with the height of the layer, contrary to the diffusive spreading found in ‘stress-only’ hyperbolic models. In principle, directed force chain networks can exhibit the two-peak, diffusively spreading response function of hyperbolic models, but all models in a particular class studied here are found to be in the elliptic regime.