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Oil pockets and surface topography: Mechanisms of friction reduction
Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.ORCID iD: 0000-0001-8058-1252
Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.
Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.
Chalmers University of Technology, Gothenburg, Sweden.
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2004 (English)Conference paper, Poster (Other academic)
Abstract [en]

Oil pockets reduce friction in two ways: by providing lift themselves by a cavitation mechanism, and also by acting as a reservoir of lubricant which will leak out around their boundaries to minimise direct metallic contact in the surrounding region. The relative importance of these mechanisms is estimated in particular tribological environments. The general cavitation conditions for oil pockets are defined and the cavitation models of Etsion and Kato are compared. Both these models require knowledge of the size and distribution of oil pockets, and an attempt is made to relate these to measurable surface topography parameters. Mechanisms for leakage of lubricant from oil pockets are also discussed. Advantages and disadvantages of the Wihiborg-Crafoord index are presented. The effect of oil pockets on the contact regime in gears is assessed, and in particular the likely effect of oil-pocket-induced cavitation on gear noise, and its relation to existing work on gear roughness, is discussed. Problems of oil pocket measurement on reaÌ surfaces are outlined and the advantages of 3D measurement are identified.

Place, publisher, year, edition, pages
2004.
National Category
Manufacturing, Surface and Joining Technology
Identifiers
URN: urn:nbn:se:hh:diva-30572OAI: oai:DiVA.org:hh-30572DiVA: diva2:914075
Conference
The XI. International Colloquium on Surfaces, February 2-3, 2004, Chemnitz, Germany
Available from: 2016-03-23 Created: 2016-03-23 Last updated: 2016-06-08Bibliographically approved
In thesis
1. Adaptive Finite Element Methods for the Reynolds Thin Film Model with Cavitation
Open this publication in new window or tab >>Adaptive Finite Element Methods for the Reynolds Thin Film Model with Cavitation
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The main purpose of this thesis is to use modern goal-oriented adaptive finite element techniques in order to improve the numerical simulation of tribology. Two novel adaptive finite element methods for the Reynolds thin film model including cavitation are presented and their different strategies are compared. The algorithms are inspired by an analogy with the obstacle problem and the cavitation problem that we consider is written as a variational inequality considering in the formulation the fact that the lubricant can not stand negative stresses induced by sub-atmospheric pressure. A posteriori, error estimates and adaptive algorithms are derived, and numerical examples illustrating the theory are supplied. The cavitation problem and calculations is introduced and put into historical and modern perspective. Modern thoughts and techniques around the oil-pocket idea in sheet metal forming are presented. The influence of oil pockets on the contact regime is assessed, and in particular the likely effect of oil-pocket-induced cavitation in order to produce lift, is discussed. The ultimate goal with the numerical simulation is to be able to optimize the surface structure so as to take advantage of cavitation effects in the lubricant.

Place, publisher, year, edition, pages
Göteborg: Chalmers University of Technology, 2005. 21 p.
Series
Technical report, ISSN 1652-8565 ; 2005:6
Keyword
tribology, Reynolds equation, cavitation, FEM, adaptivity, variational inequality, penalty formulation, error estimation, residual, duality
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hh:diva-1359 (URN)2082/1738 (Local ID)2082/1738 (Archive number)2082/1738 (OAI)
Presentation
(English)
Available from: 2008-04-25 Created: 2008-04-25 Last updated: 2016-05-18Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
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