Issue
EPL
Volume 82, Number 2, April 2008
Article Number 24004
Number of page(s) 5
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/82/24004
Published online 11 April 2008
EPL, 82 (2008) 24004
DOI: 10.1209/0295-5075/82/24004

Two kinds of dissipation in sheared granular materials

W.-J. Wang and Z.-G. Zhu

Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences P.O. Box 1129, Hefei, Anhui, 230031, PRC

wjwang@issp.ac.cn

received 3 October 2007; accepted in final form 5 March 2008; published April 2008
published online 11 April 2008

Abstract
Granular systems contain an internal force delay, which significantly influences their dynamical properties. Methods to estimate this delay in the presence of external disturbances are not systematically studied. Addressing this problem, we report the frequency response of a dense-fine-sand system to an external shear oscillator. With increasing frequency the mechanical spectrum measured shows four peaks of the energy dissipation, corresponding to four decreases of modulus. We discuss in detail the corresponding relationship between the loss peaks and the grain chains. The discussion indicates that the energy dissipation of the granular materials comes from two parts: the fragile dissipation and the rheological dissipation.

PACS
45.70.-n - Granular systems.
62.40.+i - Anelasticity, internal friction, stress relaxation, and mechanical resonances.
83.85.Vb - Small amplitude oscillatory shear (dynamic mechanical analysis).

© EPLA 2008