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  • Journal article
    Cann P, 2009,

    Grease degradation in rolling element bearings - Development of a simulation tests

    , World Tribology Congress 2009 - Proceedings

    Improvements in rolling element bearing design, manufacturing standards and materials have resulted in significant increase in bearing life and performance. Thus, bearing life is often limited by lubrication failure of the grease. A study was carried out to examine grease degradation under controlled operating conditions simulating those experienced in rolling element bearings. The critical bearing factors determining grease lubrication failure wee considered to be the short replenishment time between over-rolling, thin lubricant films in the raceway, and the presence of metal wear debris. This is an abstract of a paper presented at the 2009 World Tribology Congress (Kyoto, Japan 9/6-11/2009).
  • Journal article
    Arora H, Cann P, 2009,

    Lubrication properties of alkyl imidazolium tetrafluoroborate and hexafluorophosphate ionic liquids under mixed sliding-rolling conditions

    , World Tribology Congress 2009 - Proceedings

    The ionic liquids (IL) lubrication properties in mixed rolling-sliding and rolling EHL conditions were studied. The tribological performance of four neat IL was compared with an additized mineral oil (MO). RITL friction coefficients were less than the MO for all speed and slide-roll conditions studied. The film thickness results showed that three of the fluids demonstrated classical EHL behavior with log film vs. log speed gradients in the range 0.56-0.66. However, the 1-butyl-3-methyl imidazolium tetrafluoroborate fluid gave anomalously thick, time-dependent film results at low speeds. This behavior was associated with the shorter, alkyl chain cations (l-butyl-3-methyl) rather than the anion. Film formation was not due to RTIL decomposition and subsequent anion reaction with the wear surface. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/2009).
  • Journal article
    Reddyhoff T, Spikes HA, Olver AV, 2009,

    Improved infrared temperature mapping of elastohydrodynamic contacts

    , Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Vol: 223, Pages: 1165-1177, ISSN: 1350-6501

    An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction
  • Conference paper
    Zografos A, Dini D, Olver AV, 2009,

    Fretting fatigue and wear in bolted connections: A multi-level formulation for the computation of local contact stresses

    , 35th Leeds-Lyon Symposium on Tribology, Publisher: ELSEVIER SCI LTD, Pages: 1663-1675, ISSN: 0301-679X
  • Journal article
    Banerjee N, Hills DA, Dini D, 2009,

    The derivation and application of a semi-infinite flat and rounded asymptotic frictionless contact

    , INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 51, Pages: 662-666, ISSN: 0020-7403
  • Journal article
    Miklozic KT, Forbus TR, Spikes HA, 2009,

    Performance of Friction Modifiers on ZDDP-Generated Surfaces

    , TRIBOLOGY & LUBRICATION TECHNOLOGY, Vol: 65, Pages: 40-+, ISSN: 1545-858X
  • Journal article
    Olver AV, 2009,

    The Effect of Configuration in the Design of Geared Transmission Systems

    , JOURNAL OF MECHANICAL DESIGN, Vol: 131, ISSN: 1050-0472
  • Journal article
    Qiu H, Hills DA, Dini D, 2009,

    An investigation of convection effects in complete and almost complete contact problems

    , EUR J MECH A-SOLID, Vol: 28, Pages: 680-687, ISSN: 0997-7538

    The problem of a rigid, square-ended and an almost square-ended rigid punch sliding with both plane and anti-plane velocity components is studied. It is shown that, for a truly complete contact, if the contacting body is incompressible, convection effects are absent. Introducing either: (a) local rounding or (b) finite compressibility of the contacting body into the problem introduces convection, and hence an inconsistency into the bulk/pointwise application of the orthogonal friction law. (c) 2008 Published by Elsevier Masson SAS.
  • Journal article
    Sinnett-Jones PE, Browne M, Moffat AJ, Jeffers JRT, Saffari N, Buffiere J-Y, Sinclair Iet al., 2009,

    Crack initiation processes in acrylic bone cement

    , JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, Vol: 89A, Pages: 1088-1097, ISSN: 1549-3296
  • Journal article
    Joyce TJ, Langton D, Jameson SS, Nargol AVF, Medley JB, Masen M, Mathia TG, Blunt Let al., 2009,

    TRIBOLOGICAL ANALYSIS OF FAILED RESURFACING HIP PROSTHESES AND COMPARISON WITH CLINICAL DATA

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 223, Pages: 605-606, ISSN: 1350-6501
  • Journal article
    Mavraki A, Cann PM, 2009,

    Friction and lubricant film thickness measurements on simulated synovial fluids

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 223, Pages: 325-335, ISSN: 1350-6501
  • Journal article
    Mavraki A, Cann PM, Mischler S, Boedo S, Booker JF, Bayada G, van Leeuwen H, van Ostayen RAJ, Bayada G, Meurisse M-H, Renondeau H, Papke BL, Pozebanchuk M, Parthasarathy PP, Davies L, Nilsson D, Isaksson P, Prakash B, Bansal Det al., 2009,

    FRICTION AND LUBRICANT FILM THICKNESS MEASUREMENTS ON SIMULATED SYNOVIAL FLUID

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 223, Pages: 606-607, ISSN: 1350-6501
  • Journal article
    Dini D, Hills DA, 2009,

    Frictional Energy Dissipation in a Rough Hertzian Contact

    , J TRIBOL-T ASME, Vol: 131, ISSN: 0742-4787

    The interfacial contact pressure and shear traction distributions are found for a sphere pressed onto an elastically similar half-space whose surface is populated by a uniform array of spherical asperities, when the normal load is constant and an oscillatory shear, less than that needed to cause sliding, is imposed. Details of the load history suffered by asperities in an outer sliding annulus and an inner disk, where they experience partial slip, are found, together with the effects of the roughness on the overall tangential compliance and the frictional energy losses. It is shown that for the example combination of parameters chosen, under light shear loads, the rough contact absorbs less energy than a smooth one subject to the same loading history, but that for larger shearing forces the reverse is true.
  • Conference paper
    Dini D, 2007,

    Between continuum and atomistic contact mechanics: could we bridge the gap?

    , IJTC2007, STLE/ASME International Joint Tribology Conference
  • Journal article
    Nikas GK, Sayles RS, 2009,

    Surface coatings and finite-element analysis of layered fretting contacts

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 223, Pages: 159-181, ISSN: 1350-6501
  • Journal article
    Dini D, Song X, Zhang SY, Korsunsky AMet al., 2009,

    Residual strain analysis in polycrystalline aggregates using diffraction measurement and finite element modelling

    , J STRAIN ANAL ENG, Vol: 44, Pages: 55-70, ISSN: 0309-3247

    This paper reviews some of the modelling and experimental techniques recently employed by the authors for the analysis of the macro- and mesoscopic behaviour of polycrystalline aggregates. A joined-up approach is used for assessing the deformation behaviour of polycrystalline materials at the macroscopic and grain levels, based on combining modelling using the crystal plasticity finite element (CPFE) method with experimental characterization by in situ loading and continuous lattice strain measurement by diffraction. The complementarity of the two methodologies is emphasized, as it helps to improve understanding of the physics underlying inelastic deformation, damage mechanisms, and fatigue crack initiation. The proposed approach is part of the attempt to develop a general framework that will enable reliable and accurate determination of the inhomogeneous fields of plastic strain, the regions of localized plasticity, and intergranular residual stresses. Examples are given of microscopically calibrated CPFE simulations being used to match the experimentally observed evolution of lattice stresses and strains in advanced structural alloys of industrial interest.
  • Conference paper
    Mavraki A, Cann PM, 2009,

    Lubricating Film Thickness Measurements on Bovine Serum

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 123-125
  • Conference paper
    Fowell MT, Olver A, Spikes HA, Pegg IGet al., 2009,

    MODELLING OF MICRO TEXTURED BEARINGS WITH MASS-CONSERVING CAVITATION: A TWO DIMENSIONAL PROBLEM

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 343-+
  • Journal article
    Benedet J, Green JH, Lamb GD, Spikes HAet al., 2009,

    Spurious Mild Wear Measurement Using White Light Interference Microscopy in the Presence of Antiwear Films

    , TRIBOLOGY TRANSACTIONS, Vol: 52, Pages: 841-846, ISSN: 1040-2004
  • Conference paper
    Hili J, Olver AV, Edwards S, Jacobs Let al., 2009,

    EXPERIMENTAL INVESTIGATION OF FILM THICKNESS BEHAVIOUR AT VERY HIGH SPEEDS

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 291-+
  • Conference paper
    Medina S, Dini D, Olver AV, Hills DAet al., 2009,

    FAST COMPUTATION OF FRICTIONAL ENERGY DISSIPATION IN ROUGH CONTACTS UNDER PARTIAL SLIP

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 573-575
  • Conference paper
    Accardi MA, Dini D, 2009,

    MODELLING OF THE MECHANICAL BEHAVIOUR OF HUMAN JOINTS CARTILAGE

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 147-149
  • Journal article
    Reddyhoff T, Spikes HA, Olver AV, 2009,

    Compression heating and cooling in elastohydrodynamic contacts

    , Tribology Letters, Vol: 36, Pages: 69-80, ISSN: 1023-8883

    In this study, the infrared temperature mapping technique, originally developed by Sanborn and Winer (Trans ASME J Tribol 93:262-271, 1971) and extended by Spikes et al. (Tribol Lett 17(3):593-605, 2004), has been made more sensitive and used to study the temperature rise of elastohydrodynamic contacts in pure rolling. Under such conditions lubricant shear heating within the contact is considered negligible and this allows temperature changes due to lubricant compression to be investigated. Pure rolling surface temperature distributions have been obtained for contacts lubricated with a range of lubricants, included a group I, and group II mineral oil, a polyalphaolefin (group IV), the traction fluid Santotrac 50 and 5P4E, a five-ring polyphenyl-ether. Resulting maps show the temperature rise in the contact increases in the inlet due to compression heating and then decreases and in most cases becomes negative in the exit region due to the effect of decompression. Temperature changes increase with entrainment speed but in the current tests are always very small, and less than 1 C. Contact temperature rises from compression were compared to those from sliding contacts (where a slide-roll ratio of 0.5 was applied). Here the contribution to the contact temperature from compression is shown to decrease dramatically with entrainment speed. The lubricant 5P4E is found to behave differently from other lubricants tested in that it showed a peak in temperature at the outlet. This effect becomes more pronounced with increasing speed, and has tentatively been attributed to a phase change in the exit region. Using moving heat source theory, the measured temperature distributions have been converted to maps showing rate of heat input into each surface and the latter compared with theory. Qualitative agreement between theory and experiment is found, and a more accurate theoretical comparison is the subject of ongoing study. 2009 Springer Science+Business Media, LLC.
  • Conference paper
    Reddyhoff T, Spikes HA, Olver AV, 2009,

    Improved temperature mapping of ehl contacts

    , Miami, FL, United states, 2008 STLE/ASME International Joint Tribology Conference, IJTC 2008, October 20, 2008 - October 22, 2008, Publisher: ASME, Pages: 265-267

    An effective means of studying lubricant film rheology within EHL contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. This provides a way of directly measuring the rheology of lubricant films under true EHL conditions. Furthermore, temperature measurement itself provides a very effective means of testing and validating computer simulations. In the current work, the experimental approach initially developed by Sanborn and Winer [11 and then by Spikes and co-workers [2], has been advanced to include a high specification infrared (IR) camera and microscope. This is a similar approach to that taken by Yagi and Kyogoku [3]. As well as the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions; namely lower loads, speeds and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. One additional advantage of instantaneous full field measurements is that the weak infrared optical interference caused by the film can be observed and can used to exactly locate the centre of the contact in the resulting temperature maps. These new possibilities have been used to investigate and compare the rheological properties and compression cooling effects exhibited by a PAO, a group II mineral oil, and a traction fluid. Copyright 2008 by ASME.
  • Conference paper
    Reina S, Dini D, 2009,

    INCIPIENT SLIP AND FRICTIONAL CREEP OF TYRED SYSTEMS

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 613-615
  • Conference paper
    Balcombe R, Fowell MT, Dini D, 2009,

    Modelling rolling contact fatigue cracks in the hydrodynamic lubrication regime: a coupled approach

    , Mesomechanics 2009 Conference, Publisher: ELSEVIER SCIENCE BV, Pages: 245-248, ISSN: 1877-7058
  • Conference paper
    Zografos A, Dini D, 2009,

    A combined BEM/Contact Asymptotics (BEM-CA) semi-analytical formulation for the assessment of fretting damage in bolted joints

    , Mesomechanics 2009 Conference, Publisher: ELSEVIER SCIENCE BV, Pages: 201-204, ISSN: 1877-7058
  • Conference paper
    Reina S, Dini D, Hills DA, 2009,

    On the accurate prediction of interfacial micro-slip in frictional joints using distributed dislocations and quadratic programming techniques

    , Mesomechanics 2009 Conference, Publisher: ELSEVIER SCIENCE BV, Pages: 181-184, ISSN: 1877-7058
  • Conference paper
    Sih GC, Korsunsky AM, Dini D, 2009,

    Mesomechanics 2009 Foreword: Dissipation and damage across multiple scales in physical and mechanical systems

    , Mesomechanics 2009 Conference, Publisher: ELSEVIER SCIENCE BV, Pages: 1-3, ISSN: 1877-7058
  • Journal article
    Laine E, Olver AV, Lekstrom MF, Shollock BA, Beveridge TA, Hua DYet al., 2009,

    The Effect of a Friction Modifier Additive on Micropitting

    , TRIBOLOGY TRANSACTIONS, Vol: 52, Pages: 526-533, ISSN: 1040-2004
  • Conference paper
    Korsunsky AM, Song X, Belnoue J, Jun T, Hofmann F, De Matos PFP, Nowell D, Dini D, Aparicio-Blanco O, Walsh MJet al., 2009,

    Crack tip deformation fields and fatigue crack growth rates in Ti–6Al–4V☆

    , Pages: 1771-1779, ISSN: 0142-1123

    In this paper we present an overview of experimental and modelling studies of fatigue crack growth rates in aerospace titanium alloy Ti-6Al-4V. We review work done on the subject since the 1980s to the present day, identifying test programmes and procedures and their results, as well as predictive approaches developed over this period. We then present the results of some of our recent experiments and simulations. Fatigue crack growth rates (FCGRs) under constant applied load were evaluated as a function of crack length, and the effect of overload (retardation) was considered. Crack opening was measured during cycling using digital image correlation, and residual stress intensity factor was determined using synchrotron X-ray diffraction mapping. Modelling techniques used for the prediction of FCGRs are then reviewed, and an approach based on the analysis of energy dissipation at the crack tip is proposed. Finally, directions for further research are identified.
  • Conference paper
    Ku ISY, Reddyhoff T, Choo JH, Holmes AS, Spikes HAet al., 2009,

    Lubrication performance of liquids of different viscosities in MEMS devices

    , Lake Buena Vista, FL, United states, Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2009, May 17, 2009 - May 21, 2009, Publisher: Society of Tribologists and Lubrication Engineers, Pages: 178-180
  • Journal article
    Dickinson A, Browne M, Jeffers J, Taylor Aet al., 2009,

    Pre-clinical analysis of an acetabular cup with improved in vivo stability and integrity

    , Key Engineering Materials, Vol: 396-398, Pages: 31-34
  • Journal article
    Jeffers JRT, Roques A, Taylor A, Tuke MAet al., 2009,

    The problem with large diameter metal-on-metal acetabular cup inclination.

    , Bull NYU Hosp Jt Dis, Vol: 67, Pages: 189-192, ISSN: 1936-9719

    Large diameter metal-on-metal hip bearings have proven to be clinically successful in active patients, but, in a small number, they are associated with elevated wear and high metal ion levels when cup inclination angles are too steep and the version is too extreme, or either alone. Based on the geometry of six different commercially available large diameter metal-on-metal acetabular components, this study demonstrated that the critical bearing surface operates at an angle up to 16 masculine greater than the cup face inclination. Due to geometry alone, measured cup inclination is not the angle that most surgeons perceive it to be. We strongly recommend when employing large diameter metal-on-metal bearings that lower inclination and version angles are targeted to prevent excessive wear.
  • Conference paper
    Nyqvist J, Kadiric A, Sayles R, Ioannides Set al., 2009,

    ROUGHNESS EFFECTS IN THERMO-MECHANICALLY LOADED CONTACTS

    , STLE/ASME 2008 International Joint Tribology Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 637-639
  • Journal article
    Cann PM, 2008,

    In-contact molecular spectroscopy of liquid lubricant films

    , MRS Bulletin, Vol: 33, Pages: 1151-1158, ISSN: 0883-7694
  • Journal article
    Dini D, Hills DA, 2008,

    Characteristics of asymptotic solutions for slightly rounded contacts

    , Tribology - Materials, Surfaces and Interfaces, Vol: 2, Pages: 121-127, ISSN: 1751-5831

    The characteristics of a semi-infinite flat and rounded contact, subject to constant normal load and oscillating shear, are found. These include the slip displacement and frictional energy expenditure, together with the process of frictional shakedown. The set of solutions is applied to the problem of a D shaped punch having a very small radius at the notionally sharp corner. The possible application of the methodology outlined in this paper to a range of fretting fatigueproblems is also discussed. © 2008 W. S. Maney & Son Ltd.
  • Journal article
    Qiu H, Dini D, Hills DA, 2008,

    Torsional contact of an elastic flat-ended cylinder

    , JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 56, Pages: 3352-3362, ISSN: 0022-5096
  • Journal article
    Banerjee N, Dini D, Hills DA, 2008,

    Frictional complete contacts subject to shear and bulk tension

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 222, Pages: 2301-2309, ISSN: 0954-4062
  • Journal article
    Topolovec-Miklozic K, Lockwood F, Spikes H, 2008,

    Behaviour of boundary lubricating additives on DLC coatings

    , WEAR, Vol: 265, Pages: 1893-1901, ISSN: 0043-1648
  • Journal article
    Dini D, Sackfield A, Hills DA, 2008,

    An axi-symmetric Hertzian Contact subject to cyclic shear and severe wear

    , WEAR, Vol: 265, Pages: 1918-1922, ISSN: 0043-1648
  • Conference paper
    Spikes H, 2008,

    Low saps antiwear additives

    Modern engine lubricant specifications impose limits on permissible sulfur and phosphorus and ash levels. This necessitates a reduction in the concentration of the additive ZDDP which, in future, may require the latter's partial or complete replacement by other chemistries which have less or zero phosphorus, sulfur, and/or ash. The main types of low SAPS additive that have been suggested to have antiwear performance includes MDDP, thiophosphates and thiophosphonates, metal dialkylphosphates phosphates, metal dithiocarbamates, and organosulfides. These classes of additives were presented. This is an abstract of a paper presented at the 16th International Colloquium Tribology Lubricants Materials and Lubrication Engineering (Stuttgart/Ostfildern, Germany 1/15-17/2008).
  • Journal article
    Nikas GK, Sayles RS, 2008,

    Finite-element analysis of layered rolling contacts

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 222, Pages: 865-886, ISSN: 1350-6501
  • Conference paper
    Laine E, Olver AV, Beveridge TA, 2008,

    Effect of lubricants on micropitting and wear

    , 34th Leeds-Lyon Symposium on Tribology, Publisher: ELSEVIER SCI LTD, Pages: 1049-1055, ISSN: 0301-679X
  • Conference paper
    Song X, Zhang SY, Dini D, Korsunsky AMet al., 2008,

    Finite element modelling and diffraction measurement of elastic strains during tensile deformation of HCP polycrystals

    , Symposium on Frontiers in Computational Materials Science, Publisher: ELSEVIER SCIENCE BV, Pages: 131-137, ISSN: 0927-0256
  • Journal article
    Hartinger M, Dumont M-L, Ioannides S, Gosman D, Spikes Het al., 2008,

    CFD modeling of a thermal and shear-thinning elastohydrodynamic line contact

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 130, ISSN: 0742-4787
  • Journal article
    Dini D, Barber JR, Churchman CM, Sackfield A, Hills DAet al., 2008,

    The application of asymptotic solutions to contact problems characterised by logarithmic singularities

    , EUR J MECH A-SOLID, Vol: 27, Pages: 847-858, ISSN: 0997-7538

    We give the contact pressure distribution near a contacting wedge having a slightly rounded form adjacent to a discontinuity in surface profile. It is shown that, well away from the rounding the pressure is logarithmic in form, just as it is near the apex of a sharp wedge. This pair of solutions may then be used to 'patch in' a roundness correction relevant to any punch having a discontinuous gradient. Further, it is noted that the multiplier on the logarithm term is pre-determined by the change in gradient. This process is applied to a finite, slightly blunt wedge, where the exact answer is known, and to a wheel having a worn flat. The agreement with the exact solution in the former case is seen to be very good. (c) 2007 Elsevier Masson SAS. All rights reserved.
  • Journal article
    Nikas GK, Sayles RS, 2008,

    A study of lubrication mechanisms using two-phase fluids with porous bearing materials

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 222, Pages: 771-783, ISSN: 1350-6501
  • Journal article
    Qiu H, Hills DA, Dini D, 2008,

    Further consideration of closure at the root of a sharp notch

    , JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 43, Pages: 405-409, ISSN: 0309-3247
  • Conference paper
    Smeeth M, Hamer C, Spikes HA, 2008,

    A study of antiwear additive film build up using the MTM (mini-traction machine)

    , Pages: 101-103

    The measurement of lubricant film thickness under elastohydrodynamic (EHL) contact conditions is well established and a variety of experimental techniques have been used, the most accurate and widely used of which is optical interferometry. This lends itself particularly well to the study of the all-important mixed and boundary regimes, since the films are of the same order of magnitude as the wavelength of light. The vast majority of these studies have been made under pure rolling conditions, since the necessary optical coatings preclude the use of high sliding speeds within the critical thin fluid film regime. These conditions are however precisely those required to activate ZDDPs and other antiwear additives, making accurate 'in situ' optical studies of additive film build-up difficult. A modification to the existing MTM (mini-traction machine) has allowed steel on steel contacts to be run under high sliding speed conditions, thereby allowing antiwear additive reactions to occur. By optically measuring the film thickness of these reaction films as they form, in tandem with friction measurements, a full picture of both friction and reaction film build-up can be made. Using a novel LED (light emitting diode) light source and accurate calibration procedures, the film thickness of the whole contact area can be measured down to a few nanometres. This paper presents a study of the behaviour of standard additive combinations under realistic operating conditions and describes the rig in detail. Copyright © 2007 by ASME.

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