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  • Conference paper
    Glovnea RP, Spikes HA, 2005,

    EHD contacts in low-amplitude oscilatory motion

    , Pages: 455-456

    In some practical applications such as spline couplings or constant velocity joints, the machine components are subjected to a low amplitude lateral motion, very often oscillatory, so that conditions for a full elastohydrodynamic film to form are not completely realized. The questions that arise are what mechanism of lubricating takes place in such contacts and what is the influence of working parameters and lubricant properties on such mechanism? In the present study, a EHD contact formed between a flat and a ball is subjected to oscillatory-motion of amplitude ranging between one half to one contact diameter. High speed ultra-thin film interferometry is used to monitor the gap between the two solid surfaces. The influence of parameters such as load, frequency and amplitude of motion are investigated. Copyright © 2005 by ASME.
  • Conference paper
    Olver AV, Glovnea R, Choo JW, Spikes HAet al., 2005,

    Elastohydrodynamic lubrication of multiple periodic ridges

    , Pages: 519-520

    The lubrication of rolling contacts in which one surface has a roughness consisting of periodic transverse or longitudinal ridges has been widely investigated, both theoretically and experimentally. Results of these investigations now permit a substantially complete picture to emerge in which it is possible to characterize the state of lubrication by evaluating and comparing the (minimum) film thickness near the crests of the roughness to the corresponding thickness in the valleys. Crest and valley film thickness were studied over a wide range of non-dimensional speed. Two lubricants were used, both Group I mineral oils with viscosities of 22 and 453 cp and alpha values of 19.8 and 20.4/GPa. The elastostatic and asperity values agreed well with the corresponding measurements but both crest and valley measured film thicknesses exceeded the predictions of equation 4 for higher speeds. This is an abstract of a paper presented at the World Tribology Congress III (Washington, DC 9/12-16/2005).
  • Conference paper
    Hartinger M, Gosman D, Ioannides S, Spikes Het al., 2005,

    CFD modelling of elastohydrodynamic lubrication

    , Pages: 531-532

    The finite volume method was evaluated to model fluid behavior in rolling-element bearing systems. The effect of cavitation was modeled with a barotropic cavitation model. Two cases with a cylinder on a flat plate, one under rolling and one under sliding conditions, were studied. These solutions were compared to the Reynolds-EHL approach. Towards higher loads, stability problems were encountered and strategies for dealing with these were presented. This is an abstract of a paper presented at the World Tribology Congress III (Washington, DC 9/12-16/2005).
  • Journal article
    de Vicente J, Stokes JR, Spikes HA, 2005,

    The frictional properties of newtonian fluids in rolling-sliding soft-EHL contact

    , TRIBOLOGY LETTERS, Vol: 20, Pages: 273-286, ISSN: 1023-8883
  • Journal article
    Reddyhoff T, Kasolang S, Dwyer-Joyce RS, Drinkwater BWet al., 2005,

    The phase shift of an ultrasonic pulse at an oil layer and determination of film thickness

    , Proceedings of the Institution of Mechanical Engineers, Part J (Journal of Engineering Tribology), Vol: 219, Pages: 387-400, ISSN: 1350-6501

    An ultrasonic pulse incident on a lubricating oil film in a machine element is partially reflected and partially transmitted. The proportion of the wave amplitude reflected, termed the reflection coefficient, depends on the film thickness and the acoustic properties of the oil. When the appropriate ultrasonic frequency is used, the magnitude of the reflection coefficient can be used to determine the oil film thickness. However, the reflected wave has both a real component and an imaginary component, and both the amplitude and the phase are functions of the film thickness. The phase of the reflected wave is shifted from that of the incident wave when it is reflected. In the present study, this phase shift is explored as the film changes and is evaluated as an alternative means to measure oil film thickness. A quasi-static theoretical model of the reflection response from an oil film has been, developed. This model relates the phase shift to the wave frequency and the film properties. Measurements of reflection coefficient from a static model oil film and also from a rotating journal bearing have been recorded. These have been used to determine the oil film thickness using both amplitude and phase shift methods. In both cases, the results agree closely with independent assessments of the oil film thickness. The model of ultrasonic reflection is further extended to incorporate mass and damping terms. Experiments show that both the mass and the internal damping of the oil films tested in this work have a negligible effect on ultrasonic reflection. A potentially very useful application for the simultaneous measurement of reflection coefficient amplitude and phase is that the data can be used to negate the need for a reference. The theoretical relationship between phase and amplitude is fitted to the data. An extrapolation is performed to determine the values of amplitude and phase for an infinitely thick layer. This is equivalent to the reference signal determined by mea
  • Journal article
    Ciavarella M, Dini D, 2005,

    A refined CLNA model in fretting fatigue using asymptotic characterization of the contact stress fields

    , FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES, Vol: 28, Pages: 1099-1112, ISSN: 8756-758X
  • Journal article
    Sackfield A, Dini D, Hills DA, 2005,

    The tilted shallow wedge problem

    , EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, Vol: 24, Pages: 919-928, ISSN: 0997-7538
  • Journal article
    Fujita H, Spikes HA, 2005,

    Study of zinc dialkyldithiophosphate antiwear film formation and removal processes, part II: Kinetic model

    , TRIBOLOGY TRANSACTIONS, Vol: 48, Pages: 567-575, ISSN: 1040-2004
  • Journal article
    Fujita H, Glovnea RP, Spikes HA, 2005,

    Study of zinc dialkydithiophosphate antiwear film formation and removal processes, part I: Experimental

    , TRIBOLOGY TRANSACTIONS, Vol: 48, Pages: 558-566, ISSN: 1040-2004
  • Journal article
    Cann PM, Spikes HA, 2005,

    Measurement of pressure distribution in EHL - Development of method and application to dry static contacts

    , TRIBOLOGY TRANSACTIONS, Vol: 48, Pages: 474-483, ISSN: 1040-2004
  • Journal article
    Braidic-Mitidieri P, Gosman AD, Ioannides E, Spikes HAet al., 2005,

    CFD analysis of a low friction pocketed pad bearing

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 127, Pages: 803-812, ISSN: 0742-4787
  • Journal article
    Dini D, Nowell D, Korsunsky AM, 2005,

    Size and scale effects in fretting fatigue thresholds

    , INTERNATIONAL JOURNAL OF FRACTURE, Vol: 135, Pages: L11-L18, ISSN: 0376-9429
  • Journal article
    Jeffers JRT, Browne M, Taylor M, 2005,

    Damage accumulation, fatigue and creep behaviour of vacuum mixed bone cement

    , BIOMATERIALS, Vol: 26, Pages: 5532-5541, ISSN: 0142-9612
  • Journal article
    Sackfield A, Dini D, Hills DA, 2005,

    The finite and semi-infinite tilted, flat but rounded punch

    , INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 42, Pages: 4988-5009, ISSN: 0020-7683
  • Conference paper
    Mueller MA, Stoehr T, Eisenberg B, Bollinger JM, Spikes HA, Topolovec-Miklozic Ket al., 2005,

    Synthesis and characterization of polyalkylmethacrylate block copolymers and their application in high performance lubricants

    , 230th National Meeting of the American-Chemical-Society, Publisher: AMER CHEMICAL SOC, Pages: U4316-U4316, ISSN: 0065-7727
  • Journal article
    Jeffers JRT, Browne M, Roques A, Taylor Met al., 2005,

    On the importance of considering porosity when simulating the fatigue of bone cement

    , JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 127, Pages: 563-570, ISSN: 0148-0731
  • Journal article
    Cann PM, Spikes HA, 2005,

    In-contact IR spectroscopy of hydrocarbon lubricants

    , TRIBOLOGY LETTERS, Vol: 19, Pages: 289-297, ISSN: 1023-8883
  • Journal article
    Dardin A, Hedrich K, Müller M, Topolovec-Miklozic K, Spikes Het al., 2005,

    Influence of polyalkylmethacrylate viscosity index improvers on boundary film formation and efficiency of lubricants

    , Tribologia, Vol: 24, Pages: 3-14, ISSN: 0780-2285

    The efficiency of lubricated machine elements such as transmissions, crankcase engines, and hydraulic pumps depends strongly on the friction properties of the lubricant employed. For the design of modern, highly efficient lubricants it is thus essential to understand the influence of the components of the lubricating fluid in terms of boundary film formation and friction. PAMAs are well-known as viscosity index improve rs and dispersant boosters. This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces, to produce thick, viscous boundary films. These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction in friction in engine and transmission lubrication. A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry. A range of dispersant and non-dispersant polymethacrylates has been synthesised having different functionalities, molecular weights and architectures. The influence of each of these factors on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting. From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties. Bench tests which more closely simulate the proposed application of the lubricants have been used to measure their torque transmitting efficiency (FZG gear test). First results from these tests demonstrate that the identified structure-property relations can be transferred into real gear and ATF oils.
  • Journal article
    Glovnea RP, Olver AV, Spikes HA, 2005,

    Experimental investigation of the effect of speed and load on film thickness in elastohydrodynamic contact

    , TRIBOLOGY TRANSACTIONS, Vol: 48, Pages: 328-333, ISSN: 1040-2004
  • Conference paper
    Golshan M, Liu J, Kim K, Laundy D, Dini D, Korsunsky AMet al., 2005,

    Analysis of plastic deformation and residual elastic strain in a titanium alloy using synchrotron x-ray diffraction

    , 7th Biennial Conference on High Resolution X-Ray Diffraction and Imaging, Publisher: IOP PUBLISHING LTD, Pages: A195-A199, ISSN: 0022-3727
  • Journal article
    de Vicente J, Stokes JR, Spikes HA, 2005,

    Lubrication properties of non-adsorbing polymer solutions in soft elastohydrodynamic (EHD) contacts

    , TRIBOLOGY INTERNATIONAL, Vol: 38, Pages: 515-526, ISSN: 0301-679X
  • Journal article
    Miklozic KT, Spikes HA, 2005,

    Application of atomic force microscopy to the study of lubricant additive films

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 127, Pages: 405-415, ISSN: 0742-4787
  • Journal article
    Dini D, Sackfield A, Hills DA, 2005,

    Comprehensive bounded asymptotic solutions for incomplete contacts in partial slip

    , JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 53, Pages: 437-454, ISSN: 0022-5096
  • Journal article
    Hills DA, Churchman CM, Dini D, 2005,

    Asymptotic methods applied to the correlation of fretting fatigue lives

    , Proceedings of the World Tribology Congress III - 2005, Pages: 387-388

    Local or asymptotic states of stress relevant to the characterization of the state of stress adjacent to the edges of incomplete contacts are discussed. It is shown that the multipliers for the asymptotic solutions effectively characterize the nucleation propensity of the geometries. This idea is tested by applying the approach to reliable fretting fatigue data in the literature, and re-examining it in this light. Copyright © 2005 by ASME.
  • Conference paper
    Fan JY, Spikes HA, 2005,

    New bench test to study mild lubricated wear

    , Pages: 961-962

    This extended abstract describes a new bench test for measuring and studying mild, lubricated wear. The method combines MTM, which is able to produce contra-rotation so as to obtain high sliding speed while retaining low entrainment speed and thus boundary lubrication conditions, with ICP which is employed to analyze trace levels of iron in lubricants so as to monitor mild wear throughout a test. Copyright © 2005 by ASME.
  • Conference paper
    Choo JH, Spikes HA, Ratoi M, Glovnea RP, Forrest Aet al., 2005,

    A technique for the detection of liquid slip at a load-bearing, high shear contact

    , Pages: 835-836

    This research aims to exploit the physical phenomenon of simple liquids slipping against very smooth solid surfaces, to create a new type of bearing where the lubricant slips against one surface but not the other. To demonstrate the feasibility of this idea, a special test rig capable of measuring milli-Newton forces has been employed to measure friction in high-speed, sliding contacts between a steel roller and sapphire window, lubricated by hexadecane. Sapphire was made either lyophobic by coating with a self-assembled silane monolayer, or lyophilic by O2-plasma cleaning. The roller was made lyophilic. A significant reduction in friction was achieved with lyophobic sapphire but not with lyophilic sapphire. This reduced friction is believed to result from lubricant slip against the lyophobic surface. One possible application of such a bearing will be in microsystems and devices. Copyright © 2005 by ASME.
  • Conference paper
    Cann PM, Spikes HA, 2005,

    A micro-IRRAS study of lubricant degradation under thin film conditions

    , Pages: 569-570

    This paper studies lubricant degradation in a rubbing contact under thin film conditions. Friction tests have been carried out in an MTM test device using a steel ball/steel disc configuration. The tests were run with a small amount of lubricant present. At the end of the test the disc was retained for analysis. Micro-reflection FTIR spectroscopy was used to analyse the lubricant chemistry within and close to the rubbed track. The technique offers a more direct method for studying lubricant degradation products during rubbing. The results are compared to those from more conventional experimental methods. Copyright © 2005 by ASME.
  • Journal article
    Morales-Espejel GE, Dumont ML, Lugt PM, Olver AVet al., 2005,

    A limiting solution for the dependence of film thickness on velocity in EHL contacts with very thin films

    , TRIBOLOGY TRANSACTIONS, Vol: 48, Pages: 317-324, ISSN: 1040-2004
  • Journal article
    De Vicente J, Spikes HA, Stokes JR, 2005,

    Soft EHL lubrication of complex multiphase fluids

    , Proceedings of the World Tribology Congress III - 2005, Pages: 589-590

    The lubrication properties of a series of multiphase water-based fluids of complex rheology and microstructure, including o/w emulsions, have been studied in a rolling-sliding steel ball-on-elastomer flat contact. The results show that friction curves of Newtonian fluids made over a wide range of entrainment speeds and viscosity can be used to identify the prevailing mechanisms of lubrication for more complex fluids and, for emulsions, to show the predominant film-forming phase. Copyright © 2005 by ASME.
  • Journal article
    Briscoe BB, Cann PM, Delfino A, Maitland Get al., 2005,

    Lubrication with water-based clay suspensions

    , Proceedings of the World Tribology Congress III - 2005, Pages: 529-530

    The lubricating behaviour of a water-based rock drilling fluid (bentonite clay suspension) has been studied in a simple tribometer. Friction measurements were carried out with a model contact formed between a rotating shaft and a loaded planar counterface. The experiments were designed to investigate the tribology of the contact between the drillstring and the metal wall of an oilwell. Friction measurements were made for a range of loads and contact velocities and clay concentrations. The results are presented in the form of classical Stribeck-Hersey curves in order to identify the lubrication regime and to illustrate the combined effects of load and speed on the friction coefficient. Optical interferometry experiments were also carried out, using a ball-on-disc apparatus, in order to visualise the flow of the suspension through the contact. In a separate series of tests the interfacial shear stress of the mud formulations was measured for different contact metallurgies and operating conditions. Two basic lubrication regimes are identified: at high loads a regime characterised by the deposition of layers of solid clay onto the contacting surfaces and at low loads, a regime in which the main lubricating action is provided by the base fluid. In the transition between the two regimes, an intermediate region is characterised by changes in the fluid composition and rheology within the contact. The general trend of the Stribeck curve is obtained and a peculiar scattering of the data is evident in the region between the boundary lubrication regime and the mixed lubrication regime. The intrinsic nature and the complex rheology of the fluid appear to be the parameters that may control this effect and in part define the lubrication regime. Copyright © 2005 by ASME.
  • Journal article
    Masen MA, de Rooij MB, Schipper DJ, 2005,

    Micro-contact based modelling of abrasive wear

    , WEAR, Vol: 258, Pages: 339-348, ISSN: 0043-1648
  • Journal article
    Glovnea RP, Olver AV, Spikes HA, 2005,

    Lubrication of rough surfaces by a boundary film-forming viscosity modifier additive

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 127, Pages: 223-229, ISSN: 0742-4787
  • Journal article
    Reddyhoff T, Kasolang S, Dwyer-Joyce RS, Drinkwater BWet al., 2005,

    The phase shift of an ultrasonic pulse at an oil layer and determination of film thickness

    , Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Vol: 219, Pages: 387-400, ISSN: 1350-6501

    An ultrasonic pulse incident on a lubricating oil film in a machine element will be partially reflected and partially transmitted. The proportion of the wave amplitude reflected, termed the reflection coefficient, depends on the film thickness and the acoustic properties of the oil. When the appropriate ultrasonic frequency is used, the magnitude of the reflection coefficient can be used to determine the oil film thickness. However, the reflected wave has both a real component and an imaginary component, and both the amplitude and the phase are functions of the film thickness. The phase of the reflected wave will be shifted from that of the incident wave when it is reflected. In the present study, this phase shift is explored as the film changes and is evaluated as an alternative means to measure oil film thickness. A quas i-static theoretical model of the reflection response from an oil film has been, developed. This model relates the phase shift to the wave frequency and the film properties. Measurements of reflection coefficient from a static model oil film and also from a rotating journal bearing have been recorded. These have been used to determine the oil film thickness using both amplitude and phase shift methods. In both cases, the results agree closely with independent assessments of the oil film thickness. The model of ultrasonic reflection is further extended to incorporate mass and damping terms. Experiments show that both the mass and the internal damping of the oil films tested in this work have a negligible effect on ultrasonic reflection. A potentially v ery useful application for the simultaneous measurement of reflection coefficient amplitude and phase is that the data can be used to negate the need for a reference. The theoretical relationship between phase and amplitude is fitted to the data. An extrapolation is performed to determine the values of amplitude and phase for an infinitely thick layer. This is equivalent to the reference signal deter
  • Conference paper
    Dwyer-Joyce RS, Reddyhoff T, Drinkwater B, 2005,

    Ultrasonic phase and amplitude and the measurement of oil film thickness

    , Washington, D.C., United states, 2005 World Tribology Congress III, September 12, 2005 - September 16, 2005, Publisher: American Society of Mechanical Engineers, Pages: 515-516

    The reflection of ultrasound at an oil film can be used to determine the film thickness. A thin oil film reflects less ultrasound than a thick film. When the film is thin there is a simple relationship between oil film thickness and the proportion of the wave amplitude reflected. The reflection coefficient is in fact a complex quantity with both magnitude and phase. A model for how both the phase and amplitude vary with oil film thickness (and the properties of the bearing materials) has been developed. It has been shown that both can be used to determine film thickness. Tests have been performed to determine the oil film thickness and explore the relationship between reflection amplitude and phase. Experiments are performed both on a static oil film between flat plates, and on an operating journal bearing. Both methods provide a simple accurate method for the measurement of oil film thickness. Copyright 2005 by ASME.
  • Conference paper
    Dini D, Nowell D, Korsunsky AM, 2005,

    Size and scale effects in fretting fatigue thresholds

    , 11th International Conference on Fracture, 20 - 25 March, Turin, Italy, Publisher: CCI Centro Congressi Internazionale, Pages: 1-6
  • Conference paper
    Dini D, Nowell D, Dyson IN, Hills DAet al., 2005,

    Fretting fatigue of Ti/6Al/4V: experiments and analysis

    , NATO RTO High Cycle Fatigue Symposium, Publisher: NATO
  • Conference paper
    Hills DA, Churchman CM, Dini D, 2005,

    Asymptotic methods applied to the correlation of fretting fatigue lives (Article no.WTC2005-63995)

    , Proceedings of the World Tribology Congress III, 12 - 16 September 2005, Washington, D.C., USA, Publisher: ASME
  • Journal article
    Olver AV, 2005,

    The mechanism of rolling contact fatigue: an update

    , Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, Vol: 219, Pages: 313-330, ISSN: 1350-6501
  • Conference paper
    Glovnea RP, Olver AV, Spikes A V, 2005,

    Effectiveness of boundary lubricant additives on some coated surfaces

    , London, Life Cycle Tribology, Proceedings of 31st Leeds-Lyon Symposium, Leeds 2004, Publisher: Elsevier, Pages: 135-143
  • Journal article
    Dini D, Hills DA, 2004,

    Bounded asymptotic solutions for incomplete contacts in partial slip

    , INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 41, Pages: 7049-7062, ISSN: 0020-7683
  • Journal article
    Dini D, Hills DA, 2004,

    Asymptotic characterisation of nearly-sharp notch root stress fields

    , INTERNATIONAL JOURNAL OF FRACTURE, Vol: 130, Pages: 651-666, ISSN: 0376-9429
  • Journal article
    Dini D, Nowell D, 2004,

    Flat and rounded fretting contact problems incorporating elastic layers

    , INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 46, Pages: 1635-1657, ISSN: 0020-7403
  • Journal article
    Hills DA, Dini D, Magadu A, Korsunsky AMet al., 2004,

    A review of asymptotic procedures in stress analysis: known solutions and their applications

    , JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 39, Pages: 553-568, ISSN: 0309-3247
  • Journal article
    Spikes H, 2004,

    The history and mechanisms of ZDDP

    , TRIBOLOGY LETTERS, Vol: 17, Pages: 469-489, ISSN: 1023-8883
  • Journal article
    Spikes HA, Anghel V, Glovnea R, 2004,

    Measurement of the rheology of lubricant films within elastohydrodynamic contacts

    , TRIBOLOGY LETTERS, Vol: 17, Pages: 593-605, ISSN: 1023-8883
  • Journal article
    Cann PME, Damiens B, Lubrecht AA, 2004,

    The transition between fully flooded and starved regimes in EHL

    , TRIBOLOGY INTERNATIONAL, Vol: 37, Pages: 859-864, ISSN: 0301-679X
  • Journal article
    Hills DA, Dini D, 2004,

    What level of friction guarantees adhesion in a complete contact?

    , JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 39, Pages: 549-551, ISSN: 0309-3247
  • Journal article
    Fujita H, Spikes HA, 2004,

    The formation of zinc dithiophosphate antiwear films

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 218, Pages: 265-277, ISSN: 1350-6501
  • Journal article
    Nikas GK, Sayles RS, 2004,

    Nonlinear elasticity of rectangular elastomeric seals and its effect on elastohydrodynamic numerical analysis

    , TRIBOLOGY INTERNATIONAL, Vol: 37, Pages: 651-660, ISSN: 0301-679X
  • Journal article
    Dini D, Hills DA, 2004,

    The effect of a crack-tip radius on the validity of the singular solution

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 218, Pages: 693-701, ISSN: 0954-4062

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