Part of the friction between two rough surfaces is due to the interlocking between asperities on opposite surfaces. In order for the surfaces to slide relative to each other, these interlocking asperities have to deform plastically. Here, we study the unit process of plastic ploughing of a single micrometer-scale asperity by means of two-dimensional dislocation dynamics simulations. Plastic deformation is described through the generation, motion, and annihilation of edge dislocations inside the asperity as well as in the subsurface. We find that the force required to plough an asperity at different ploughing depths follows a Gaussian distribution. For self-similar asperities, the friction stress is found to increase with the inverse of size. Comparison of the friction stress is made with other two contact models to show that interlocking asperities that are larger than ∼2 μm are easier to shear off plastically than asperities with a flat contact.

References

References
1.
Bowden
,
F. P.
, and
Tabor
,
D.
,
1950
,
The Friction and Lubrication of Solids, Part I
,
Clarendon
,
Oxford, UK
, Chap. 5.
2.
Greenwood
,
J. A.
, and
Williamson
,
J. B. P.
,
1966
, “
Contact of Nominally Flat Surfaces
,”
Proc. R. Soc. London, Ser. A
,
295
(
1442
), pp.
300
319
.10.1098/rspa.1966.0242
3.
Gao
,
Y. F.
, and
Bower
,
A. F.
,
2006
, “
Elastic-Plastic Contact of a Rough Surface With Weierstrass Profile
,”
Proc. R. Soc. London, Ser. A
,
462
(
2065
), pp.
319
348
.10.1098/rspa.2005.1563
4.
Pei
,
L.
,
Hyun
,
S.
,
Molinari
,
J. F.
, and
Robbins
,
M. O.
,
2005
, “
Finite Element Modeling of Elasto-Plastic Contact Between Rough Surfaces
,”
J. Mech. Phys. Solids
,
53
(
11
), pp.
2385
2409
.10.1016/j.jmps.2005.06.008
5.
Cha
,
P. R.
,
Srolovitz
,
D. J.
, and
Vanderlick
,
R. K.
,
2004
, “
Molecular Dynamics Simulations of Single Asperity Contact
,”
Acta Mater.
,
52
(
13
), pp.
3983
3996
.10.1016/j.actamat.2004.05.014
6.
Widjaja
,
A.
,
Van der Giessen
,
E.
,
Deshpande
,
V. S.
, and
Needleman
,
A.
,
2007
, “
Contact Area and Size Effects in Discrete Dislocation Modeling of Wedge Indentation
,”
J. Mater. Res.
,
22
(
03
), pp.
655
663
.10.1557/jmr.2007.0090
7.
Sun
,
F.
,
van der Giessen
,
E.
, and
Nicola
,
L.
,
2012
, “
Plastic Flattening of a Sinusoidal Metal Surface: A Discrete Dislocation Plasticity Study
,”
Wear
,
296
(
1–2
), pp.
672
680
.10.1016/j.wear.2012.08.007
8.
Deshpande
,
V. S.
,
Needleman
,
A.
,
Van der Giessen
,
E.
,
2004
, “
Discrete Dislocation Plasticity Analysis of Static Friction
,”
Acta Mater.
,
52
(
10
), pp.
3135
3149
.10.1016/j.actamat.2004.03.018
9.
Dikken
,
R. J.
,
Van der Giessen
,
E.
, and
Nicola
,
L.
, “
Plastic Shear Response of a Single Asperity: A Discrete Dislocation Plasticity Analysis
,” (submitted).
10.
Van der Giessen
,
E.
, and
Needleman
,
A.
,
1995
, “
Discrete Dislocation Plasticity: A Simple Planar Model
,”
Model. Simul. Mater. Sci. Eng.
,
3
, pp.
689
735
.10.1088/0965-0393/3/5/008
11.
Rice
,
J. R.
,
1987
, “
Tensile Crack Tip Fields in Elastic-Ideally Plastic Crystals
,”
Mech. Mater.
,
6
(4), pp.
317
335
.10.1016/0167-6636(87)90030-5
12.
Widjaja
,
A.
,
Needleman
,
A.
, and
Van der Giessen
,
E.
,
2007
, “
The Effect of Indenter Shape on Sub-Micron Indentation According to Discrete Dislocation Plasticity
,”
Model. Simul. Mater. Sci. Eng.
,
15
(
1
), pp.
121
131
.10.1088/0965-0393/15/1/S11
13.
Johnson
,
K. L.
,
1985
,
Contact Mechanics
,
Cambridge University
,
Cambridge, UK
, Chap. 2.
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