Volume 109, Number 4, February 2015
|Number of page(s)||6|
|Section||Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics|
|Published online||06 March 2015|
Contact mechanics of and Reynolds flow through saddle points
On the coalescence of contact patches and the leakage rate through near-critical constrictions
1 Supercomputing Centre Jülich, Institute for Advanced Simulation, FZ Jülich - 52425 Jülich, Germany
2 Lehrstuhl für Materialsimulation, Universität des Saarlandes - 66123 Saarbrücken, Germany
Received: 19 December 2014
Accepted: 14 February 2015
We study numerically local models for the mechanical contact between two solids with rough surfaces. When the solids softly touch either through adhesion or by a small normal load L, contact only forms at isolated patches and fluids can pass through the interface. When the load surpasses a threshold value, , adjacent patches coalesce at a critical constriction, i.e., near points where the interfacial separation between the undeformed surfaces forms a saddle point. This process is continuous without adhesion and the interfacial separation near percolation is fully defined by scaling factors and the sign of . The scaling leads to a Reynolds flow resistance which diverges as with . Contact merging and destruction near saddle points become discontinuous when either short-range adhesion or specific short-range repulsion are added to the hard-wall repulsion. These results imply that coalescence and break-up of contact patches can contribute to Coulomb friction and contact aging.
PACS: 46.55.+d – Tribology and mechanical contacts / 68.35.-p – Solid surfaces and solid-solid interfaces: structure and energetics
© EPLA, 2015
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