Levels of topography in mechanics of precision joints

Abstract

Characterizing even very smooth surfaces it is necessary to take into account multilevel structure of topography. By methods of stylus profilometry and atomic force microscopy (AFM) roughness of hard magnetic disk substrates textured under different regimes was measured. It is shown that the methods reflect various levels of roughness with overlapping ranges of wave lengths. Quantitative parameters for each roughness level suitable for the subsequent modeling of an actual contact zone were determined. To reduce influence of the roughness' long-wave components on the relief parameters at a small-scale level, computer processing of the AFM-images was performed. For the description of the actual contact area hybrid two-level model was offered. The Greenwood-Williamson scheme using the profilometry data and complemented by the account of superficial forces influence was used at a microlevel. Computer simulation of a contact on a database of AFM-image of a surface was used at submicrolevel. Influence of the contact area discreteization at a microlevel on a degree of submicroasperities deformation was taken into account. Visualization of the real contact area was performed. Distinctions in the operational characteristics of surfaces depending on their texturing modes was shown.