Contact of rough surfaces - A comparison of experimental and numerical results

Measurements of rough surfaces show that the roughness topography can be described as a fractal over several length scales. A suitable description is then given by a discrete structure function. For a large class of typical surfaces measured structure functions can be approximated by a three-parameter function, employing the rms-value of the roughness, a transition length between fractal behaviour at high wavenumbers and stationary behaviour at low wavenumbers, and the fractal dimension in the fractal region, respectively, as intrinsic parameters to describe an isotropic rough surface.

To study the normal contact behaviour of such fractal surfaces numerically, the first author presented in a numerical model which allows to describe the elasto-plastic normal contact of isotropic fractal surfaces. This model is now tested against experimental data which are obtained from contact tests of several aluminum specimens.

The paper gives a short review of the numerical model and describes than the experimental set-up for the contact tests. Numerical and experimental data for several aluminum specimens with different surface properties are shown and compared.