Logarithmic rate dependence of force networks in sheared granular materials

R. R. Hartley and R. P. Behringer ()
Additional contact information
R. R. Hartley: Duke University
R. P. Behringer: Duke University

Nature, 2003, vol. 421, issue 6926, 928-931

Abstract: Abstract Many models of slow, dense granular flows1,2,3,4,5 assume that the internal stresses are independent of the shearing rate. In contrast, logarithmic rate dependence is found in solid-on-solid friction6,7,8, geological settings9,10,11 and elsewhere12,13,14,15. Here we investigate the rate dependence of stress in a slowly sheared two-dimensional system of photoelastic disks, in which we are able to determine forces on the granular scale. We find that the mean (time-averaged) stress displays a logarithmic dependence on the shear rate for plastic (irreversible) deformations. However, there is no perceivable dependence on the driving rate for elastic (reversible) deformations, such as those that occur under moderate repetitive compression. Increasing the shearing rate leads to an increase in the strength of the force network and stress fluctuations. Qualitatively, this behaviour resembles the changes associated with an increase in density. Increases in the shearing rate also lead to qualitative changes in the distributions of stress build-up and relaxation events. If shearing is suddenly stopped, stress relaxations occur with a logarithmic functional form over long timescales. This slow collective relaxation of the stress network provides a mechanism for rate-dependent strengthening.

Date: 2003
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/nature01394 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:421:y:2003:i:6926:d:10.1038_nature01394

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/nature01394

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().