In many tribological applications, some geometrical parameters defined
in Euclidean space such as the developed area, surface bearing, void
and material volume are very difficult to measure independently of the
unit of measurement. The values of these parameters increase when the
scale of measurement is decreased. Fractal geometry can be used as an
adapted space for rough morphology in which roughness can be consider
ed as a continuous but nondifferentiable function and dimension D of t
his space is an intrinsic parameter to characterize the surface topogr
aphy. In the first part of this work, the fractal theory is used as a
mathematical model for random surface topography, which can be used as
input data in contact mechanics modeling. The result shows that the f
ractal model is realistic and the fractal dimension can be used as an
indicator of the real values of different scale-dependent parameters s
uch as length, surfaces, and volume of roughness. In the second part,
we have analyzed through experiments, the contact between fractal rand
om surfaces and a smooth plane, the experimental results show that the
fractal dimension can be used as an invariant parameter to analyse th
e distribution law of the contact points area. (C) 1998 Elsevier Scien
ce Ltd. All rights reserved.