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  • Journal article
    Chevalier F, Lubrecht AA, Cann PME, Colin F, Dalmaz Get al., 1995,

    Starved Film Thickness: A Qualitative Explanation

    , Tribology Series, Vol: 30, Pages: 249-257, ISSN: 0167-8922

    Numerically calculated film thickness can accurately predict measured film thicknesses under fully flooded conditions. However, as more detailed information concerning real life applications becomes available, the validity of the “fully flooded” assumption becomes less tenable. Starved films are much thinner than those formed under fully flooded conditions and it is of great practical importance therefore to be able to predict the ensuing lubrication level. Previous researchers have investigated the relation between the position of the inlet meniscus and starved film thickness. This paper combines a hydrodynamic lubrication approach with a physical boundary condition: the oil inlet film thickness distribution on the surface. Three different cases are investigated; a constant and a harmonic oil inlet film thickness distribution, and the effect of repeated passes. The results are compared qualitatively with experimental observations of starved EHL. © 1995 Elsevier Science B.V.

  • Journal article
    Enthoven JC, Spikes HA, 1995,

    Visual Observation of the Process of Scuffing

    , Tribology Series, Vol: 30, Pages: 487-494, ISSN: 0167-8922

    A visual study has been made of the process of scuffing between a lubricated steel ball and a sapphire flat. This has shown that the onset of scuffing is always preceded by the build-up of fine particles of wear debris in the contact inlet which result in starvation and consequently scuffing. Based upon these observations a new mechanism of scuffing is proposed: that scuffing is caused by a critical rate of production of wear debris and its accumulation in the inlet of the lubricated contact. © 1995 Elsevier Science B.V.

  • Journal article
    POON CY, SAYLES RS, 1994,

    CONTACT ANALYSIS OF A SMOOTH BALL ON AN ANISOTROPIC ROUGH-SURFACE

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 116, Pages: 850-859, ISSN: 0742-4787
  • Journal article
    CANN PM, SPIKES HA, 1994,

    THE BEHAVIOR OF POLYMER-SOLUTIONS IN CONCENTRATED CONTACTS - IMMOBILE SURFACE-LAYER FORMATION

    , TRIBOLOGY TRANSACTIONS, Vol: 37, Pages: 580-586, ISSN: 0569-8197
  • Journal article
    CANN P, IOANNIDES E, JACOBSON B, LUBRECHT AAet al., 1994,

    THE LAMBDA RATIO - A CRITICAL REEXAMINATION

    , WEAR, Vol: 175, Pages: 177-188, ISSN: 0043-1648
  • Journal article
    DWYERJOYCE RS, SAYLES RS, IOANNIDES E, 1994,

    AN INVESTIGATION INTO THE MECHANISMS OF CLOSED 3-BODY ABRASIVE WEAR

    , WEAR, Vol: 175, Pages: 133-142, ISSN: 0043-1648
  • Journal article
    POON CY, SAYLES RS, 1994,

    NUMERICAL CONTACT MODEL OF A SMOOTH BALL ON AN ANISOTROPIC ROUGH-SURFACE

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 116, Pages: 194-201, ISSN: 0742-4787
  • Journal article
    Spikes HA, 1994,

    The Behaviour of Lubricants in Contacts: Current Understanding and Future Possibilities

    , Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Vol: 208, Pages: 3-15, ISSN: 1350-6501
  • Journal article
    Cann PM, Spikes HA, 1994,

    The Influence of Base Oil Rheology on the Behaviour of VI Polymers in Concentrated Contacts

    , Tribology Series, Vol: 27, Pages: 65-72, ISSN: 0167-8922

    Whereas elastohydrodynamic (EHD) film thicknesses for simple base stocks can be predicted with some confidence from their bulk properties this is not so for polymer-containing fluids. The behaviour of such fluids in an EHD contact is extremely complex and can include elements of shear thinning, viscoelasticity and boundary properties. In this paper polymer solution behaviour in a concentrated contact has been investigated through detailed EHD film thickness measurements. A series of model polymers; polyisoprenes in the molecular weight range 27-86,000, have been studied in two different basestocks, the intention being to examine the effect of base stock rheology and solvation properties on polymer behaviour. © 1994, Elsevier Science B.V.

  • Journal article
    Zhu YY, Kelsall GH, Spikes HA, 1994,

    The Influence of Electrochemical Potentials on the Friction and Wear of Iron and Iron Oxides in Aqueous Systems

    , Tribology Transactions, Vol: 37, Pages: 811-819, ISSN: 1040-2004
  • Journal article
    Aderi ME, Johnsto GJ, Spikes HA, Balson TG, Emery MGet al., 1993,

    The film-forming properties of polyalkylene glycols

    , Journal of Synthetic Lubrication, Vol: 10, Pages: 23-45, ISSN: 0265-6582
  • Journal article
    KELSALL GH, ZHU YY, SPIKES HA, 1993,

    ELECTROCHEMICAL EFFECTS ON FRICTION BETWEEN METAL-OXIDE SURFACES IN AQUEOUS-SOLUTIONS

    , JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, Vol: 89, Pages: 267-272, ISSN: 0956-5000
  • Conference paper
    SPIKES HA, 1993,

    BOUNDARY LUBRICATION AND BOUNDARY FILMS

    , 19th Leeds-Lyon Symposium on Tribology: Thin Films in Tribology, Publisher: ELSEVIER SCIENCE PUBL B V, Pages: 331-346
  • Conference paper
    OLVER AV, COLE SJ, SAYLES RS, 1993,

    CONTACT STRESSES IN NITRIDED STEELS

    , 19th Leeds-Lyon Symposium on Tribology: Thin Films in Tribology, Publisher: ELSEVIER SCIENCE PUBL B V, Pages: 71-80
  • Journal article
    Chang HS, Wayte R, Spikes HA, 1993,

    Measurement of Piston Ring and Land Temperatures in a Firing Engine Using Infrared

    , Tribology Transactions, Vol: 36, Pages: 104-112, ISSN: 1040-2004
  • Journal article
    Barker DC, Johnston GJ, Spikes HA, Bünemann TFet al., 1993,

    EHD Film Formation and Starvation of Oil-in-Water Emulsions

    , Tribology Transactions, Vol: 36, Pages: 565-572, ISSN: 1040-2004
  • Journal article
    Enthoven JC, Cann PM, Spikes HA, 1993,

    Temperature and Scuffing

    , Tribology Transactions, Vol: 36, Pages: 258-266, ISSN: 1040-2004
  • Journal article
    Gunsel S, Spikes HA, Aderin M, 1993,

    In-Situ Measurement of ZDDP Films in Concentrated Contacts

    , Tribology Transactions, Vol: 36, Pages: 276-282, ISSN: 1040-2004
  • Journal article
    POON CY, SAYLES RS, JONES TA, 1992,

    SURFACE MEASUREMENT AND FRACTAL CHARACTERIZATION OF NATURALLY FRACTURED ROCKS

    , JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 25, Pages: 1269-1275, ISSN: 0022-3727
  • Journal article
    ADERIN M, JOHNSTON GJ, SPIKES HA, CAPORICCIO Get al., 1992,

    THE ELASTOHYDRODYNAMIC PROPERTIES OF SOME ADVANCED NONHYDROCARBON-BASED LUBRICANTS

    , LUBRICATION ENGINEERING, Vol: 48, Pages: 633-638, ISSN: 0024-7154
  • Journal article
    Chang H-S, Spikes HA, Bunemann TF, 1992,

    The shear stress properties of ester lubricants in elastohydrodynamic contacts

    , Journal of Synthetic Lubrication, Vol: 9, Pages: 91-114, ISSN: 0265-6582
  • Journal article
    CANN PM, SPIKES HA, 1992,

    FOURIER-TRANSFORM INFRARED STUDY OF THE BEHAVIOR OF GREASE IN LUBRICATED CONTACTS

    , LUBRICATION ENGINEERING, Vol: 48, Pages: 335-343, ISSN: 0024-7154
  • Conference paper
    COLE SJ, SAYLES RS, 1992,

    A NUMERICAL-MODEL FOR THE CONTACT OF LAYERED ELASTIC BODIES WITH REAL ROUGH SURFACES

    , Publisher: ASME, Pages: 334-340, ISSN: 0742-4787
  • Journal article
    Guangteng G, Cann PM, Spikes HA, 1992,

    A study of parched lubrication

    , Wear, Vol: 153, Pages: 91-105, ISSN: 0043-1648
  • Conference paper
    POON CY, SAYLES RS, 1992,

    THE CLASSIFICATION OF ROUGH-SURFACE CONTACTS IN RELATION TO TRIBOLOGY

    , Publisher: IOP PUBLISHING LTD, Pages: A249-A256, ISSN: 0022-3727
  • Conference paper
    CANN PM, WILLIAMSON BP, COY RC, SPIKES HAet al., 1992,

    THE BEHAVIOR OF GREASES IN ELASTOHYDRODYNAMIC CONTACTS

    , INTERNATIONAL CONF ON FRONTIERS OF TRIBOLOGY, CELEBRATING THE 10TH ANNIVERSARY OF THE TRIBOLOGY GROUP OF THE INST OF PHYSICS, Publisher: IOP PUBLISHING LTD, Pages: A124-A132, ISSN: 0022-3727
  • Journal article
    Cann PM, Williamson BP, Coy RC, Spikes HAet al., 1992,

    The behaviour of greases in elastohydrodynamic contacts

    , Journal of Physics D: Applied Physics, Vol: 25, Pages: A124-A132, ISSN: 0022-3727

    The ability of grease to generate elastohydrodynamic (ehd) films has been studied and interpreted in terms of the response of grease structure to contact conditions. For most liquid lubricants, ehd film thickness depends upon the rheological properties of the fluid in the contact inlet. This mechanism is reasonably well understood for fluids that are Newtonian in behaviour. However, greases have complex bulk structures, the scale of which is larger than the dimensions of a contact inlet. The ehd performance of grease must therefore depend upon the response of grease structure to the high-shear inlet conditions. In this study, ehd film thickness has been measured for a range ol greases using optical interierometry. In parallel work, grease structural changes have been monitored directly in the inlet of ehd contacts using reflection-absorption infrared speciruswjpy. By using these two approaches in combination, changes in composition and loss of bulk grease structure have been observed and correlated with the ability of greases to form films under EHD conditions. © 1992 IOP Publishing Ltd.

  • Journal article
    BAILEY DM, SAYLES RS, 1991,

    EFFECT OF ROUGHNESS AND SLIDING FRICTION ON CONTACT STRESSES

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 113, Pages: 729-738, ISSN: 0742-4787
  • Journal article
    HAMER JC, SAYLES RS, IOANNIDES E, 1991,

    THE COLLAPSE OF SLIDING MICRO-EHL FILMS BY PLASTIC EXTRUSION

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 113, Pages: 805-810, ISSN: 0742-4787
  • Journal article
    Gunsel S, Wayte R, Spikes HA, 1991,

    Measurement of the viscosity of thin films of lubricants on solid surfaces

    , SAE Technical Papers, ISSN: 0148-7191

    This paper describes the development of a thin film rheometer able to measure the viscosity of lubricant films of the order of 200 μm thickness on flat, solid surfaces. The rheometer consists of a small cylinder mounted on a piezo bimorph which is divided electrically into two halves. When an AC voltage is applied to the one half of the piezo it causes the flat surface of the cylinder to oscillate in its own plane with an amplitude of a few microns. This motion produces an AC output from the other half of the piezo. The flat face of the cylinder is held parallel to an oily test surface and the latter is supported on a micrometer stage so that the gap between the two surfaces can be adjusted. As the gap is narrowed the oil film dampens the sinusoidal motion of the cylinder and the extent of this damping can be used to determine the viscosity of the oil film between the surfaces. Copyright © 1991 Society of Automotive Engineers, Inc.

  • Journal article
    HAMER JC, SAYLES RS, IOANNIDES E, 1991,

    AN EXPERIMENTAL INVESTIGATION INTO THE BOUNDARIES OF SMEARING FAILURE IN ROLLER-BEARINGS

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 113, Pages: 102-109, ISSN: 0742-4787
  • Journal article
    Johnston GJ, Wayte R, Spikes HA, 1991,

    The Measurement and Study of Very Thin Lubricant Films in Concentrated Contacts

    , Tribology Transactions, Vol: 34, Pages: 187-194, ISSN: 1040-2004
  • Journal article
    Cann PM, Spikes HA, 1991,

    In Lubro Studies of Lubricants in EHD Contacts Using FTIR Absorption Spectroscopy

    , Tribology Transactions, Vol: 34, Pages: 248-256, ISSN: 1040-2004
  • Journal article
    Olver A V, 1991,

    Testing transmission lubricants: the importance of thermal response

    , Proceedings Institution of Mechanical Engineers London Part G Journal of Aerospace Engineering, Vol: 205G, Pages: 35-44, ISSN: 0954-4100
  • Journal article
    Wardle RWM, Coy RC, Cann PM, Spikes HAet al., 1990,

    An ‘in lubro’ study of viscosity index improvers in end contacts

    , Lubrication Science, Vol: 3, Pages: 45-62, ISSN: 0954-0075

    Polymeric viscosity index (VI) improver solutions in oils suffer from both temporary and permanent viscosity losses in high shear hydrodynamic and elastohydrodynamic (EHD) contacts. In some cases in EHD contacts, these losses can be so severe that the additive makes negligible contribution to oil film thickness. This paper describes the use of a combination of optical interferometry and FTIR micro‐reflectance spectroscopy to measure the effectiveness, and to observe directly the behaviour, of conventional VI improver solutions within rolling and sliding EHD contacts. The study shows the extent to which polymers enter EHD contacts and charts the degradation that they suffer therein. Copyright © 1990 John Wiley & Sons, Ltd

  • Journal article
    Black CM, Clark RP, Darton K, Goff MR, Norman TD, Spikes HAet al., 1990,

    A pyroelectric thermal imaging system for use in medical diagnosis

    , Journal of Biomedical Engineering, Vol: 12, Pages: 281-286, ISSN: 0141-5425

    The value of infra-red thermography in a number of pathologies, notably rheumatology and vascular diseases, is becoming well established. However, the high cost of thermal scanners and the associated image processing computers has been a limitation to the widespread availability of this technique to the clinical community. This paper describes a relatively inexpensive thermographic system based on a pyroelectric vidicon scanner and a microcomputer. Sofware has been written with particular reference to the use of thermography in rheumatoid arthritis and vasospastic conditions such as Raynaud's phenomenon. © 1990.

  • Journal article
    Spikes HA, Cann PM, 1990,

    The Influence of Sliding Speed and Lubricant Shear Stress on EHD Contact Temperatures

    , Tribology Transactions, Vol: 33, Pages: 355-362, ISSN: 1040-2004
  • Journal article
    Spikes HA, 1990,

    A Thermodynamic Approach to Viscosity

    , Tribology Transactions, Vol: 33, Pages: 140-148, ISSN: 1040-2004
  • Journal article
    KIMURA Y, OKADA K, 1989,

    LUBRICATING PROPERTIES OF OIL-IN-WATER EMULSIONS

    , TRIBOLOGY TRANSACTIONS, Vol: 32, Pages: 524-532, ISSN: 0569-8197
  • Journal article
    Spikes HA, 1989,

    Additive-additive and additive-surface interactions in lubrication

    , Lubrication Science, Vol: 2, Pages: 3-23, ISSN: 0954-0075
  • Journal article
    HAMER JC, SAYLES RS, IOANNIDES E, 1989,

    PARTICLE DEFORMATION AND COUNTERFACE DAMAGE WHEN RELATIVELY SOFT PARTICLES ARE SQUASHED BETWEEN HARD ANVILS

    , TRIBOLOGY TRANSACTIONS, Vol: 32, Pages: 281-288, ISSN: 1040-2004
  • Journal article
    Cann PM, Spikes HA, 1989,

    Determination of the Shear Stresses of Lubricants in Elastohydrodynamic Contacts

    , Tribology Transactions, Vol: 32, Pages: 414-422, ISSN: 1040-2004
  • Journal article
    SAYLES RS, IOANNIDES E, 1988,

    DEBRIS DAMAGE IN ROLLING BEARINGS AND ITS EFFECTS ON FATIGUE LIFE

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 110, Pages: 26-31, ISSN: 0742-4787
  • Journal article
    Wan GTY, Spikes HA, 1988,

    The behavior of suspended solid particles in rolling and sliding elastohydrodynamic contacts

    , Tribology Transactions, Vol: 31, Pages: 12-21, ISSN: 1040-2004

    Tiny, dispersed, solid particles are often present in oils, either having been added deliberately as solid lubricants or having been formed during wear. It has been shown that such solids may be beneficial or deleterious, depending upon the nature of the particles and the operating conditions employed. This paper describes a study of the behavior of a range of solid particle suspensions in elastohydrodynamic (EHD) lubrication. The main aim of the work was to gain some insights into the reasons for the varying effects on performance of solid suspended particles in the EHD and mixed EHD-boundary regimes. © 1988 Taylor & Francis Group, LLC.

  • Conference paper
    Cann PME, Johnston GJ, Spikes HA, 1987,

    FORMATION OF THICK FILMS BY PHOSPHORUS-BASED ANTI-WEAR ADDITIVES.

    , Pages: 543-554, ISSN: 0144-0799

    Phosphorus-containing esters are widely used as additives in lubricating oils to reduce wear of rubbing steel surfaces. Recent work has suggested that these additives function by forming a protective layer on the rubbing surfaces, of the order of the surface roughness in thickness. This layer can be a rigid polymeric solid but in some cases appears to be material weakly bonded to the metal surfaces and easily rubbed off. The enhanced viscosity of this material relative to that of bulk oil appears to ensure surface separation by elastohydrodynamic means even at high temperatures where the viscosity of the bulk oil is very low. This paper provides experimental support for the existence of thick anti-wear films for a range of phosphorous esters and discusses their structure, mechanism of formation and practical implications.

  • Journal article
    HUTCHINSON JM, SAYLES RS, 1987,

    THE APPLICATION OF ULTRASONIC STANDING WAVES TO PARTICLE FILTRATION

    , ULTRASONICS, Vol: 25, Pages: 351-351, ISSN: 0041-624X
  • Journal article
    BLACK CM, CLARK RP, DARTON K, GOFF MR, NORMAN TD, SPIKES HAet al., 1987,

    A PYROELECTRIC VIDICON THERMOGRAPHIC SYSTEM FOR PHYSIOLOGICAL AND CLINICAL USE

    , JOURNAL OF PHYSIOLOGY-LONDON, Vol: 384, Pages: P6-P6, ISSN: 0022-3751
  • Journal article
    Cann PM, Spikes HA, 1987,

    The influence of lubricant on temperature generated in elasto-hydrodynamic contacts.

    , Tribology Series, Vol: 12, Pages: 183-192, ISSN: 0167-8922

    Direct measurement of temperatures generated in concentrated contacts by infra-red (IR) radiometry can be used to explore the rheological properties of lubricants under elastohydrodynamic (EHD) conditions. This paper describes the influence of lubricant composition on thermal effects in EHD and attempts to relate rheological characteristics of the fluids to the temperature produced. The lubricants have been chosen to provide a range of rheological and chemical properties. They include synthetic hydrocarbons, polyglycols, perfluorethers, and a traction fluid. An emission technique similar to that employed by Winer and coworkers (1976) has been used to measure the surface temperature distribution within an EHD contact. Significant differences have been found between the surface temperature response of these fluids. The role of lubricant rheology in determining temperature with EHD contacts is discussed together with the implications of such measurement in the study of the traction response of lubricants.

  • Journal article
    Spikes HA, 1987,

    Wear and fatigue problems in connection with water‐based hydraulic fluids

    , Journal of Synthetic Lubrication, Vol: 4, Pages: 115-135, ISSN: 0265-6582

    Water‐containing fluids are widely used in hydraulic applications where there is a significant risk of fire, as in underground mining and metal working applications. Although primarily intended as power transmitting media, hydraulic fluids need to possess a modicum of lubricating ability to limit wear, seizure and contact fatigue of pumps and other rubbing parts. Unfortunately water‐based hydraulic fluids generally show significantly poorer wear and rolling‐contact fatigue performance than mineral or synthetic oil‐based fluids of similar viscosity and this means that pumping equipment usually has to be derated when used with water‐based fluids. This paper examines the poor wear and fatigue performance of water‐based fluids and discusses, in some detail, the origins of this poor performance and the ways it can be mitigated. Copyright © 1987 John Wiley & Sons, Ltd

  • Conference paper
    Spikes HA, 1986,

    HELICOPTER LUBRICATION.

    , Pages: 59-74

    Helicopter systems, and in particular helicopter transmissions, pose severe problems of lubrication and these are reflected in shorter overhaul periods and lower reliability than other, comparable systems in fixed wing aircraft. Many of these problems may be met by the introduction of new materials, such as ceramic engine bearings, flexible rotor parts, new gear steels and synthetic transmission oils. One stumbling block should, however be recognised. Helicopters, though important and irreplaceable for some applications, are not produced in large numbers and the cost of applying new technology can be prohibitive if a significant amount of development work needs to be done. Even the validation of a new material is enormously expensive, involving as it must, helicopter flying time. It is these costs, rather than the merits or availability of new materials and technologies that may be the main barrier to improvements in helicopter lubrication.

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