Abstract
An experimental investigation of the lubricated steady-sliding contact for elastically soft solids is reported. We show that the anisotropic character of the surface roughness has a strong influence in determining the transition from boundary lubrication, where the normal load is fully supported by the asperity–asperity interactions, to the hydrodynamic regime, where a thin fluid layer completely separates solid surfaces from direct contact. In particular, tests have been carried out using a ball-on-flat test configuration to measure the friction coefficient at the contact between a smooth steel ball and a rough PDMS as a function of the sliding speed. The most noteworthy result is that the presence of roughness anisotropy strongly modifies the classical shape of the Stribeck curve as a consequence of local micro-EHL conditions which occur at the contact interface.
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Acknowledgments
MS and GC acknowledge Regione Apulia for having supported the research activity through the constitution of the Trasforma Laboratory Network code 28. MS acknowledges the Tribology Group for the kind hospitality received during his visit to the Department of Mechanical Engineering at Imperial College London, where part of this study has been performed. MS also acknowledges Dr. C. Myant and Dr. M. Fowell for discussions and help in setting up the experimental setup. GC acknowledges the support of the European Science Foundation EUROCORES-FANAS Programme-EC Sixth Framework Programme under contract no. ERASCT-2003-980409.
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Scaraggi, M., Carbone, G. & Dini, D. Experimental Evidence of Micro-EHL Lubrication in Rough Soft Contacts. Tribol Lett 43, 169–174 (2011). https://doi.org/10.1007/s11249-011-9794-6
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DOI: https://doi.org/10.1007/s11249-011-9794-6