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DY: Fachverband Dynamik und Statistische Physik

DY 4: Granular Matter / Contact Dynamics Part I

DY 4.10: Talk

Monday, March 16, 2015, 12:00–12:15, BH-N 128

nonaffine deformation and mechanical response of dense granular materials — •m reza shaebani¹ and jens boberski² — ¹Department of Theoretical Physics, Saarland University, Saarbrucken, Germany — ²Department of Physics, University of Duisburg-Essen, Duisburg, Germany

The mechanical response of granular materials considerably differs from that of an ordinary elastic solid. Understanding the behavior, besides the scientific interest, has important practical applications. The emerging nonlinear relation between stress and strain can be attributed e.g. to the presence of disorder, nonlinearity of the contact force law, and Coulomb friction threshold. However, even in the absence of these elements in the nature of the interactions and the environment, the nonlinear elastic response may still exist because of the unilateral interactions in dry granular systems. Opening of a contact terminates the local transmission of restoring or frictional forces, while formation of a contact provides new possibilities for it. We first show how taking the unilateral interparticle interactions into account would improve the analytical predictions for the mechanical response, and compare the results with simulations. We attribute the remaining discrepancy to the contribution of nonaffine motions during the deformation process, and discuss the possible ways to include these motions in the stochastic modeling of stress transmission in granular media. We also clarify how the evolution of the probability distributions of contact forces deviate from the affine assumption during isotropic compression or shear deformation processes.