Comparing surface topography parameters of rough surfaces obtained with spectral moments and deterministic methods

• Surface topography parameters depend significantly on the calculation method.
• The definition of an asperity is stricter in the deterministic compared to the statistical approach.
• Statistical analysis does not distinguish between asperity-peaks and asperity-shoulders.

Understanding contact between rough surfaces is of critical importance to the design of many engineering applications. Contact models rely on material properties and surface topography of the contacting surfaces as input parameters. Hence, the relevance of the contact models is dependent on their inherent assumptions and the accuracy with which the input parameters are determined. We have evaluated the difference between the surface topography parameters calculated with a statistical and deterministic approach for actual engineering surfaces. We have found topography values that change up to 300% depending on the method used, and attribute this to the stringent definition of an asperity-peak in the case of deterministic analysis as opposed to statistical analysis, which not only considers asperity-peaks but also asperity-shoulders.