Recent studies on sliding friction in PRL

1: Sliding friction coefficient is not a material properties any more. It depends on the rupture history. It may shed some lights on DEM based modelling of particulate matter.
    Static Friction Coefficient Is Not a Material Constant

Oded Ben-David and Jay Fineberg The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Received 28 April 2011; published 20 June 2011

The static friction coefficient between two materials is considered to be a material constant. We present experiments demonstrating that the ratio of shear to normal force needed to move contacting bodies can, instead, vary systematically with controllable changes in the external loading configuration. Large variations in both the friction coefficient and consequent stress drop are tightly linked to changes in the rupture dynamics of the rough interface separating the two bodies.

© 2011 American Physical Society

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.106.254301

DOI:

10.1103/PhysRevLett.106.254301

PACS:

46.55.+d, 46.50.+a, 62.20.Qp, 81.40.Pq

2: A possible way to control friction

Sliding over a Phase Transition

A. Benassi^1,2, A. Vanossi^2,1, G. E. Santoro^2,3,1, and E. Tosatti^2,3,1 

¹CNR-IOM Democritos National Simulation Center, Via Bonomea 265, I-34136 Trieste, Italy
²International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
³International Centre for Theoretical Physics (ICTP), P.O. Box 586, I-34014 Trieste, Italy

Received 27 April 2011; published 22 June 2011

The effects of a displacive structural phase transition on sliding friction are in principle accessible to nanoscale tools such as atomic force microscopy, yet they are still surprisingly unexplored. We present model simulations demonstrating and clarifying the mechanism and potential impact of these effects. A structural order parameter inside the material will yield a contribution to stick-slip friction that is nonmonotonic as temperature crosses the phase transition, peaking at the critical T_c where critical fluctuations are strongest, and the sliding-induced order-parameter local flips from one value to another more numerous. Accordingly, the friction below T_c is larger when the order-parameter orientation is such that flips are more effectively triggered by the slider. The observability of these effects and their use for friction control are discussed, for future application to sliding on the surface of and ferro- or antiferrodistortive materials.

© 2011 American Physical Society

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.106.256102

DOI:

10.1103/PhysRevLett.106.256102

PACS:

68.35.Af, 07.79.Sp, 62.20.Qp, 63.70.+h