Volume 87, Number 3, August 2009
Article Number 34004
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 27 August 2009
EPL, 87 (2009) 34004
DOI: 10.1209/0295-5075/87/34004

Non-affine response: Jammed packings vs. spring networks

W. G. Ellenbroek1, 2, Z. Zeravcic2, W. van Saarloos2 and M. van Hecke3

1   Department of Physics and Astronomy, University of Pennsylvania - Philadelphia, PA 19104-6396, USA
2   Instituut-Lorentz, Universiteit Leiden - Postbus 9506, 2300 RA Leiden, The Netherlands
3   Kamerlingh Onnes Lab, Universiteit Leiden - Postbus 9504, 2300 RA Leiden, The Netherlands

received 12 May 2009; accepted in final form 27 July 2009; published August 2009
published online 27 August 2009

We compare the elastic response of spring networks whose contact geometry is derived from real packings of frictionless discs, to networks obtained by randomly cutting bonds in a highly connected network derived from a well-compressed packing. We find that the shear response of packing-derived networks, and both the shear and compression response of randomly cut networks, are all similar: the elastic moduli vanish linearly near jamming, and distributions characterizing the local geometry of the response scale with distance to jamming. Compression of packing-derived networks is exceptional: the elastic modulus remains constant and the geometrical distributions do not exhibit simple scaling. We conclude that the compression response of jammed packings is anomalous, rather than the shear response.

45.70.-n - Granular systems.
46.25.-y - Static elasticity. - Networks.

© EPLA 2009