title: Elastic contact mechanics: percolation of the contact area and fluid squeeze-out.
abstract: The dynamics of fluid flow at the interface between elastic solids with rough surfaces depends sensitively on the area of real contact, in particular close to the percolation threshold, where an irregular network of narrow flow channels prevails. In this paper, numerical simulation and experimental results for the contact between elastic solids with isotropic and anisotropic surface roughness are compared with the predictions of a theory based on the Persson contact mechanics theory and the Bruggeman effective medium theory. The theory predictions are in good agreement with the experimental and numerical simulation results and the (small) deviation can be understood as a finite-size effect. The fluid squeeze-out at the interface between elastic solids with randomly rough surfaces is studied. We present results for such high contact pressures that the area of real contact percolates, giving rise to sealed-off domains with pressurized fluid at the interface. The theoretical predictions are compared to experimental data for a simple model system (a rubber block squeezed against a flat glass plate), and for prefilled syringes, where the rubber plunger stopper is lubricated by a high-viscosity silicon oil to ensure functionality of the delivery device. For the latter system we compare the breakloose (or static) friction, as a function of the time of stationary contact, to the theory prediction.
authors.affiliation: IFF, FZ Jülich, D-52425 Jülich, Germany. b.persson@fz-juelich.de
authors.forename: B N J
authors.initials: BN
authors.lastname: Persson
authors.forename: N
authors.initials: N
authors.lastname: Prodanov
authors.forename: B A
authors.initials: BA
authors.lastname: Krick
authors.forename: N
authors.initials: N
authors.lastname: Rodriguez
authors.forename: N
authors.initials: N
authors.lastname: Mulakaluri
authors.forename: W G
authors.initials: WG
authors.lastname: Sawyer
authors.forename: P
authors.initials: P
authors.lastname: Mangiagalli
mesh_terms: D016880:Anisotropy; D003198:Computer Simulation; D004548:Elasticity; D019563:Mechanics; D008956:Models, Chemical; D011312:Pressure; D012408:Rubber / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D014783:Viscosity
chemical_list: D012996:Solutions; D012408:Rubber