Logarithmic strengthening of granular materials with shear rate


Journal Article

Experiments on sheared granular materials show that the stresses grow as the first power of the log of the shear rate, γ. We suggest that this may be evidence of the stress ensemble recently proposed by Henkes, O'Hern, and Chakraborty. The picture that we propose is that under steady shearing, the local force network builds up over time, and then fails when the force on the network exceeds a characteristic value. In analogy to soft glassy rheology, we assume that this is an activated process, but now, with the Boltzmann factor replaced by the stress ensemble analogue. We assume that the probability that a local part of the network fails is proportional to exp[(σ- σm)/σo], where s is the local stress, sm is a failure threshold, and σo is related to the generalized temperature, α, of Henkes and Chakraborty. It is then possible to show that these assumptions lead to logarithmic increases in the stress as a function of γ. This contrasts with the SGR result that the stress grows as the square root of l og(γ). © 2009 American Institute of Physics.

Full Text

Cited Authors

  • Hartley, RR; Behringer, RP; Henkes, S; Bi, D; Chakraborty, B

Published Date

  • November 27, 2009

Published In

Volume / Issue

  • 1145 /

Start / End Page

  • 1089 - 1092

Electronic International Standard Serial Number (EISSN)

  • 1551-7616

International Standard Serial Number (ISSN)

  • 0094-243X

Digital Object Identifier (DOI)

  • 10.1063/1.3179834

Citation Source

  • Scopus