Affiliation:
1. Department of Chemical and Biomolecular Engineering Lehigh University Bethlehem PA 18015 USA
2. Department of Mechanical and Aerospace Engineering Cornell University Ithaca NY 14853 USA
3. Michelin Americas Research Center Michelin North America Inc. Greenville SC 29605 USA
4. Department of Bioengineering Lehigh University Bethlehem PA 18015 USA
Abstract
AbstractLubricated contacts in soft materials are common in various engineering and natural settings, such as tires, haptic applications, contact lenses, and the fabrication of soft electronic devices. Two major regimes are elasto‐hydrodynamic lubrication (EHL), in which solid surfaces are fully separated by a fluid film, and mixed lubrication (ML), in which there is partial solid‐to‐solid contact. The transition between these regimes governs the minimum sliding friction achievable and is thus very important. Generally, the transition from EHL to ML regimes is believed to occur when the thickness of the lubricant layer is comparable with the amplitude of surface roughness. Here, it is reported that in lubricated sliding experiments on smooth, soft, poly(dimethylsiloxane) substrates, the transition can occur when the thickness of the liquid layer is much larger than the height of the asperities. Direct visualization of the “contact” region shows that the transition corresponds to the formation of wave‐like surface wrinkles at the leading contact edge and associated instabilities at the trailing contact edge, which are believed to trigger the transition to the mixed regime. These results change the understanding of what governs the important EHL–ML transition in the lubricated sliding of soft solids.
Funder
National Science Foundation
Subject
Mechanical Engineering,Mechanics of Materials,General Materials Science
Cited by
2 articles.
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