Many Tribology Group publications are Open Access thanks to funding from the EPSRC.

Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Journal article
    Bovington C, Caprotti R, Meyer K, Spikes HAet al., 1995,

    Development of laboratory tests to predict the lubricity properties of diesel fuels and their application to the development of highly refined diesel fuels

    , Tribotest, Vol: 2, Pages: 93-112, ISSN: 1354-4063

    In the last few years there has been an increasing requirement for the provision of environmentally benign diesel fuels. However, the introduction of such fuels into service has been associated with high levels of field failure of rotary distribution fuel pumps due to wear. This is because the refining processes necessary to produce ecologically acceptable fuels result in greatly reduced levels of sulphur compounds, aromatics, and polar material, many of which are potential lubricity agents. This paper describes the development of bench test methods to evaluate diesel fuel lubricity and thus enable the identification of appropriate ‘solutions’. It has been found that the key to obtaining good correlation between field experience and bench tests is (1) to reproduce the thermal conditions present in operating pump contacts and (2) to ensure that the same mechanisms of wear operate in the bench test as in the pump environment. The physical and chemical processes involved in the lubrication of fuel pumps and the influence of temperature on these processes are outlined. As a result of the work described in this paper, effective additive solutions have been discovered for controlling the failure of diesel fuel pumps in the field and a provisional ISO (ISO/TC 22 / SC 7 M595: ‘Diesel engines ‐ diesel fuel ‐ performance requirement and test method for assessing fuel lubricity’) and CEC test method for assessing diesel fuel lubricity has also been developed. Copyright © 1995 John Wiley & Sons, Ltd

  • Conference paper
    Smeeth M, Spikes H, Gunsel S, 1995,

    Boundary film formation by viscosity index improvers

    , STLE/ASME 1995 Tribology Conference, Publisher: SOC TRIBOLOGISTS & LUBRICATION ENGINEERS, Pages: 121-129
  • Journal article
    Cann PM, Spikes HA, 1995,

    Visualisation of starved grease and fluid lubricant films

    , Tribology Series, Vol: 30, Pages: 161-166, ISSN: 0167-8922

    Most grease lubricated applications operate under starved conditions as there is usually no mechanism to continually resupply the contact with bulk grease. Consequently the grease is rapidly pushed to the side of the track where it is thought to act as a reservoir supplying oil to the contact (3). Recent work (5) has shown that grease lubricant films measured under such conditions in a rolling contact have two Theologically distinct components; a solid surface film of deposited thickener particles, which is augmented by a hydrodynamically generated film from base oil either in the track or supplied from the grease reservoir. The resulting film thickness represents a balance between increasing bulk starvation, deposition of shear degraded grease thickener within the track and oil replenishment from the grease reservoir. All these effects are time, speed and temperature dependent. It is impossible therefore to predict film thickness from simple rheological properties or from classical elastohydrodynamic theory using the base oil viscosity. These effects have been studied in a series of papers in which grease film thickness has been measured with time and rolling speed for the fully starved condition in a model rolling contact (4)(5)(6). The current paper provides visual evidence for some of the proposed mechanisms by direct observation of the changes in the grease track using spacer layer imaging. © 1995 Elsevier Science B.V.

  • Journal article
    Glovnea RP, Spikes HA, 1995,

    Mapping shear stress in elastohydrodynamic contacts

    , Tribology Transactions, Vol: 38, Pages: 932-940, ISSN: 1040-2004

    A new method has been, devised for investigating the rheological properties of lubricant films in two-dimensional EHD contacts. A lubricated, sliding contact is produced between a sapphire flat and a steel ball. Thermal infrared, emission microscopy is then employed to obtain 2-D maps of the variation of temperature rise due to friction across the contact. These maps are then used in conjunction with moving heal source theory to produce maps of energy dissipation and thus shear strength of the lubricant, film across the contact. A series of mixtures of two lubricants, one giving high traction and one with low traction, have been studied using this technique to investigate the influence of lubricant, blending on shear stress and traction. © 1995 Taylor & Francis Group, LLC.

  • Journal article
    Smeeth M, Cann PM, Spikes HA, 1995,

    Measurement of Elastohydrodynamic Film Formation in Rolling Contacts at Very High Pressures

    , Tribology Series, Vol: 30, Pages: 497-502, ISSN: 0167-8922

    A modified optical interferometry technique was used to measure the EHD central film thickness of two oils up to pressures of 3.6 GPa. In order to generate such pressures a tungsten carbide ball was loaded against a hardened steel disc with a sapphire window insert. The results showed that the film thickness generated was slightly lower than that predicted by the Dowson-Hamrock equation and the load exponent lay between that predicted by Dowson-Hamrock and recent high pressure computed solutions. © 1995 Elsevier Science B.V.

  • Journal article
    Guangteng G, Spikes HA, 1995,

    Behaviour of lubricants in the mixed elastohydrodynamic regime

    , Tribology Series, Vol: 30, Pages: 479-485, ISSN: 0167-8922

    A range of lubricant base fluids have been chosen and their film-forming properties measured in the mixed elastohydrodynamic regime in pure rolling conditions. The Dowson-Hamrock elastohydrodynamic film thickness equation was found to remain valid over a large film thickness range for the tested base fluids. For hexadecane, the film thickness equation remains valid down to a film thickness of about 0.5 nm, a size equivalent to a molecular monolayer on each solid surface. However thicker films than predicted by elastohydrodynamic theory were found for all the other tested fluids at low speeds in the very thin film regime. This effect can be interpreted as boundary film formation by the fluids. The origins of these boundary films are still being explored but may be due to adsorption of molecules of the fluid on the solid surfaces and/or enhancement of viscosity due to the presence of a solid surface. This study has shown that full film lubrication is still possible for smooth surfaces in pure rolling in the very thin film regime where the film thickness is far smaller than the composite surface roughness. © 1995 Elsevier Science B.V.

  • 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.

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=391&limit=50&page=20&respub-action=search.html Current Millis: 1597206737331 Current Time: Wed Aug 12 05:32:17 BST 2020