Experimental results are presented along the lines of the early work of Moore (1948) where a hard smooth roller is pressed into a softer rough surface to study the resulting real to apparent areas of contact and their associated local contact pressures. Results are presented for a hard steel roller deforming mild-steel and aluminum-alloy rough surface specimens. An analysis of the local contact mechanics is performed before and after indentation using a recently developed numerical elastic contact simulation method which allows local asperity contact pressures and areas to be studied in detail. The method is shown to reveal the level and distribution of pressures and asperity contact areas prevalent during the indentation process, and therefore allows the contribution of elastic and plastic load support to be quantified. The persistence of asperities during such indentation tests is discussed in terms of the pressures the asperities can support in relation to reported mechanisms of persistence. Results of subsequent sub-surface stresses are also presented and discussed in terms of how the method might be used to create an elastic-plasticdeformation model that can account for asperity persistence in future numerical contact simulation models.

1.
Archard, J. F., 1957, “Elastic Deformation and the Laws of Friction,” Proc. Roy. Soc., Series A243, pp. 190–205.
2.
Bailey, 1988, Private Communication, see Sayles (1995) for main results.
3.
Childs
T. H. C.
,
1973
, “
The Persistence of Asperities in Indentation Experiments
,”
Wear
, Vol.
25
, pp.
3
16
.
4.
Childs, T. H. C., 1977, “The Persistence of Roughness Between Surfaces in Static Contact,” Proc. Roy. Soc., Series A353, pp. 35–53.
5.
Chivers
T. C.
,
Mitchell
L. A.
, and
Rowe
M. D.
,
1974
, “
The Variation of Real Contact Area Between Surfaces With Contact Pressure and Material Hardness
,”
Wear
, Vol.
28
, pp.
171
185
.
6.
Greenwood, J. A., and Williamson, J. B. P., 1966, “The Contact of Nominally Flat Surfaces,” Proc. Roy. Soc., Series A295, pp. 300–319.
7.
Johnson
K. L.
,
1967
, “
The Correlation of Indentation Experiments
,”
Bull. Mech. Engng. Educ.
, Vol.
6
, pp.
245
250
.
8.
Johnson
K. L.
,
1970
, “
Contact Pressures: A Fundamental Experiment in Tribology
,”
J. Mech. Phys. Solids
, Vol.
18
, pp.
115
126
.
9.
Johnson, K. L., 1985, Contact Mechanics, Cambridge University Press.
10.
Moore, A. J. W., 1948, “The Deformation of Metals in Static and Sliding Contact,” Proc. Roy. Soc., Series A195, p. 231.
11.
Pullen and Williamson, J. P. B., 1972, “On the Plastic Contact of Rough Surfaces,” Proc. Roy. Soc., Series A327, pp. 159–173.
12.
Sayles
R. S.
, and
Thomas
T. R.
,
1979
, “
Measurements of the Statistical Microgeometry of Engineering Surfaces
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
101
, pp.
409
418
.
13.
Sayles
R. S.
,
1995
, “
Debris and Roughness in Machine Element Contacts: Some Current and Future Engineering Implications
,”
Proc. Instn. Mech. Engrs., Part J: Journal of Engineering Technology
, Vol.
209
, pp.
149
172
.
14.
Webster
M. N.
, and
Sayles
R. S.
, “
A Numerical Model for the Elastic Frictionless Contact of Real Rough Surfaces
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
108
, pp.
314
420
.
15.
West, M. A., and Sayles, R. S., 1987, “A 3-Dimensional Method of Studying 3-Body Contact Geometry and Stress on Real Rough Surfaces,” Proc. 14th Leeds-Lyon Symposium on Tribology.
16.
Williamson, J. P. B., and Hunt, R. T., 1972, Asperity Persistence and the Real Area of Contact Between Rough Surfaces, Proc. Roy. Soc., Series A327, p. 147.
This content is only available via PDF.
You do not currently have access to this content.