Characterizing the shear and bulk moduli of an idealized granular materialV. Magnanimo1, L. La Ragione1, J. T. Jenkins2, P. Wang3 and H. A. Makse3
1 Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Bari - 70125 Bari, Italy
2 Department of Theoretical and Applied Mechanics, Cornell University - Ithaca, NY 14853, USA
3 Levich Institute and Physics Department, City College of New York - New York, NY 10031, USA
received 2 October 2007; accepted in final form 30 November 2007; published February 2008
published online 3 January 2008
Physical experiments on wave propagation on granular material control two macroscopic parameters that are assumed to characterize the response of a given assembly: the isotropic pressure p0 and the solid volume fraction . Here, by means of numerical simulation, we investigate the effect of the coordination number (the average number of contacts per particle) and the fluctuation of the number of contacts per particle . We adopt a numerical protocol to create several initial packings characterized by the same volume fraction and, for a given isotropic pressure, we are able to obtain different coordination numbers. That is, pressure and coordination number, for a given volume fraction, are independent. The result is that packings with fixed volume fraction and isotropic pressure exhibit a different elastic response. We attribute this behavior only to the coordination number as we find, surprisingly, that is linked to .
45.70.-n - Granular systems.
45.70.Cc - Static sandpiles; granular compaction.
46.40.-f - Vibrations and mechanical waves.
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