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Boundary lubrication of heterogeneous surfaces and the onset of cavitation in frictional contacts

: Savio, D.; Pastewka, L.; Gumbsch, P.

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Science advances 2 (2016), Nr.3, Art. e1501585, 6 S.
ISSN: 2375-2548
Deutsche Forschungsgemeinschaft DFG
PA 2023/2
Deutsche Forschungsgemeinschaft DFG
GU 367/30
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IWM ()
boundary lubrication; confined fluid; wall slip; surface heterogeneity; cavitation; reynolds equation; Molecular dynamics; tribology

Surfaces can be slippery or sticky depending on surface chemistry and roughness. We demonstrate in atomistic simulations that regular and random slip patterns on a surface lead to pressure excursions within a lubricated contact that increase quadratically with decreasing contact separation. This is captured well by a simple hydrodynamic model including wall slip. We predict with this model that pressure changes for larger length scales and realistic frictional conditions can easily reach cavitation thresholds and significantly change the load-bearing capacity of a contact. Cavitation may therefore be the norm, not the exception, under boundary lubrication conditions.