Multiscale Prediction of the Surface Separation Between Rough Surfaces

Abstract

The current work considers the multiscale nature of surface roughness in a new model that predicts the real area of contact and surface separation, both as functions of load. By summing the distance between the two surfaces at all scales, a model of surface separation as a function of dimensionless load is also obtained. A previous rough surface multiscale contact model was based on stacked elastic-plastic spheres. This work uses stacked 3-D sinusoids to represent the asperities in contact at each scale of the surface. The results are also compared to several other existing rough surface contact models and experimental results. It appears that the statistical and multiscale models make different assumptions when considering surface separation. The statistical model does not consider the effect of deformation on the mean surface height, but the multiscale model does (the location of the mean height will change as the surface deforms). When deformation is included and the surface separation becomes zero, the surfaces must also come into complete contact.