Sampling effect on contact and transport properties between fractal surfaces

Christophe Vallet (1) , Didier Lasseux (2) , H. Zahouani (3) , Philippe Sainsot (4)

1 EDF - EDF
2 TREFLE - Transferts, écoulements, fluides, énergétique
3 LTDS - Laboratoire de Tribologie et Dynamique des Systèmes
4 LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]

In this work, we are interested in the contact between a self-affine fractal surface pressed against a smooth and perfectly rigid plane. The purpose is to analyse the influence of both sampling interval delta and sampling length L, on the determination of surface roughness parameters, contact areas and viscous and diffusive flow through the aperture field resulting from the contact under load. To accomplish this analysis, fractal surfaces used in this work are obtained from numerical simulations. Models for synthesizing a fractal surface, computing mechanical deformation of asperities as well as determining viscous and diffusive flow are briefly presented. At the macroscopic scale, viscous and diffusive flow are fully characterized by the transmissivity K and effective diffusivity D tensors respectively. Results show that fractal dimension Df and arithmetic roughness Ra are almost insensitive to delta and L under conditions that are discussed. Contact areas are invariant whatever L and become increasingly sensitive to delta while decreasing the arithmetic roughness Ra. The impact of L and delta in the determination of transport properties also increases when K and D decrease, i.e. for small Ra and large average contact pressure Pca.

Mots clés: Self-affine fractal surfaces; Rough contact; Transport properties; Sampling parameters

Domaines: Mécanique [physics.med-ph]

Christophe Vallet, Didier Lasseux, H. Zahouani, Philippe Sainsot. Sampling effect on contact and transport properties between fractal surfaces. Tribology International, 2009, 42, pp.1132-1145. ⟨10.1016/j.triboint.2009.02.013⟩. ⟨hal-00413318⟩