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  • Journal article
    Myant CWI, Cann PME, 2013,

    In contact observation of model synovial fluid lubricating mechanisms

    , Tribology International, Vol: 63, Pages: 97-104, ISSN: 0301-679X

    This paper examines the fundamental mechanisms of synovial fluid lubrication in artificial joints. Film thickness measurements were made for bovine serum solutions in a model test device. In contact imaging was also carried out to aid interpretation of these results. The results indicated that two types of film are formed; a boundary layer of adsorbed protein molecules, which are augmented by a high-viscosity fluid film generated by hydrodynamic effects. The high-viscosity film is due to inlet aggregation of protein molecules forming a gel which is entrained into the contact preferentially at low speeds. As the speed increases this gel appears to shear thin, giving much lower lubricant film thickness. Results suggest that protein-containing fluids do not obey classical Newtonian EHL models. © 2012 Elsevier Ltd. All rights reserved.
  • Journal article
    Hills DA, Flicek RC, Dini D, 2013,

    Sharp contact corners, fretting and cracks

    , Frattura Ed Integrita Strutturale, Vol: 7, Pages: 27-35

    Contacts with sharp edges subject to oscillatory loading are likely to nucleate cracks from the corners, if the loading is sufficiently severe. To a first approximation, the corners behave like notches, where the local elastic behaviour is relieved by plasticity, and which in turn causes irreversibilities that give rise to crack nucleation, but also by frictional slip. One question we aim to answer here is; when is the frictional slip enveloped by plastic slip, so that the corner is effectively a notch in a monolithic material? We do this by employing the classical Williams asymptotic solution to model the contact corner, and, in doing so, we render the solution completely general in the sense that it is independent of the overall geometry of the components. We then re-define the independent parameters describing the properties of the Williams solution by using the inherent length scale, a procedure that was described at the first IJFatigue and FFEMS joint workshop [1]. By proceeding in this way, we can provide a self-contained solution that can be 'pasted in' to any complete contact problem, and hence the likelihood of crack nucleation, and the circumstances under which it might occur, can be classified. Further, this reformulation of Williams' solution provides a clear means of obtaining the strength (defined by crack nucleation conditions) of a material pair with a particular contact angle. This means that the results from a test carried out using a laboratory specimen may easily be carried over to any complicated contact problem found in engineering practice, and a mechanical test of the prototypical geometry, which may often be quite difficult, is avoided.
  • Conference paper
    Nyqvist JT, Kadiric A, Sayles RS, Ioannides Eet al., 2013,

    Three-dimensional analysis of multilayered rough surface contacts

    , Pages: 181-183
  • Conference paper
    Fowell MT, Kadiric A, Morales-Espejel G, Stacke LE, Ioannides Set al., 2013,

    Smearing damage in rolling element bearings

    , Pages: 1135-1137
  • Conference paper
    Guégan J, Kadiric A, Reddyhoff T, Morales-Espejel G, Spikes Het al., 2013,

    Friction and lubrication of textured surfaces in elasto-hydrodynamic contacts

    , Pages: 1659-1661
  • Conference paper
    Myant C, Cann P, 2013,

    Lubrication of artificial articular joints

    , Pages: 132-134
  • Conference paper
    Medina S, Dini D, 2013,

    Aspects of modelling adhesion with surface topography

    , Pages: 184-187
  • Conference paper
    Gattinoni C, Lorenz C, Heyes DM, Dini Det al., 2013,

    NEMD simulations of confined liquids under pressure and shear

    , Pages: 912-915
  • Conference paper
    Giacopini M, Bertocchi L, Baldini A, Dini Det al., 2013,

    A complementarity formulation for the EHL analysis of a connecting rod big end bearing

    , Pages: 3499-3502
  • Journal article
    Underwood RJ, Fowell M, Sayles R, Kurtz SM, Cann Pet al., 2013,

    The development of a standard method for assessing wear of explanted metal-on-metal hip joints

    , ASTM Special Technical Publication, Vol: 1560 STP, Pages: 130-145, ISSN: 0066-0558

    The concerns surrounding the current generation of metal-on- metal (MoM) hips and the regulatory requirements regarding the reporting of revised MoM components highlight the need for a standardised method for measuring the wear of explanted MoM hip components. This paper reviews the published measurement and analysis protocols used in studies of explanted MoM hips. Because of differences in the measurement and analysis techniques, it is not reliable to directly compare measurements between studies. This paper considers the requirements for a standardised measurement protocol and forms the rationale for a proposed international standard. Copyright © 2013 by ASTM International.
  • Journal article
    Underwood RJ, Kocagoz SB, Smith R, Sayles RS, Siskey R, Kurtz SM, Cann PMet al., 2013,

    A protocol to assess the wear of head/neck taper junctions in large head metal-on-metal (LHMoM) hips

    , ASTM Special Technical Publication, Vol: 1560 STP, Pages: 209-234, ISSN: 0066-0558

    Researchers have hypothesized that the increased revision rate of LHMoM (Large Head Metal-on-Metal) hips compared to MoM hip resurfacings may be attributed to corrosion and wear at the head neck taper junction. Studies have reported visual evidence of fretting and corrosion at the taper junction, but no method has been described in the literature to quantify the amount of material lost from the taper junction. This paper describes a measurement protocol using a Taylor Hobson Talyrond Roundness instrument that allows the simultaneous measurement of surface form (wear) and surface topography (roughness). The methodology allows the measurement of the taper angle, geometry of worn region (depth, length), 3D surface maps and surface topography of the head conical taper. The accurate quantification of the taper geometry, wear and topography is essential to the understanding of the in vivo wear and corrosion mechanisms of taper junctions in LHMoM hips. Copyright © 2013 by ASTM International.
  • Journal article
    Ingram M, Underwood R, Denyer P, Cann Pet al., 2013,

    The development of a laboratory screening method to optimize lubrication maintenance of high voltage equipment

    , NLGI Spokesman, Vol: 76, Pages: 9-21, ISSN: 0027-6782

    Imperial College and National Grid Electricity Transmission carried out a study to evaluate lubrication maintenance of electrical switchgear used throughout the network. A discussion on this project covers the switchgear components and lubrication requirements; identification of lubricant degradation mechanisms; development of pertinent screening tests; survey of current lubricants used; and recommendations for the future.
  • Journal article
    Imai Y, Sayles RS, Kadiric A, 2013,

    A study of the tribological benefits offered by various surface features and roughness conditions within grease-lubricated interfaces

    , Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2013, Pages: 134-140

    The use of lubricant in machine elements requires a fundamental understanding of the lubrication mechanisms, particularly in components such as bearings and sliding parts. Various kinds of greases which have different concentration of thickener agent are studied as to whether there is an effect on the plastic deformation of surface roughness. On smooth surfaces, the fluid load support of all greases was the same or lower than the base oil because the entrapped base oil was not allowed to escape from the inside of the pre-indent. On rough surfaces, the fluid load support of all greases was higher than the base oil because the base oil was allowed to escape easily from pre-indent through the valleys of surface roughness, thus the base oil is not compressed enough and cannot support the load. On much rougher surfaces, the fluid load support of all greases decreased and there was no difference. Benefits are optimized by linking together the surface finish and the grease formulation. This is an abstract of paper presented at the 2013 STLE Annual Meeting and Exhibition (Detroit, MI 5/5-9/13).
  • Conference paper
    Hajishafiee A, Dini D, Kadiric A, Ioannides Set al., 2013,

    A fully-coupled finite volume solver for elasto-hydrodynamic lubrication problems with particular application to rolling element bearings

    , Pages: 1105-1108
  • Conference paper
    Medina S, Dini D, Fowell M, Olver Aet al., 2013,

    Performance of transient surface texture in hydrodynamic bearings

    , Pages: 1662-1665
  • Conference paper
    Putignano C, Reddyhoff T, Dini D, Carbone Get al., 2013,

    Viscoelastic contact mechanics: Numerical simulations with experimental validation

    , Pages: 1511-1514
  • Conference paper
    Xu Y, Balint DS, Dini D, 2013,

    Multi-scale modeling of indentation and contact fatigue: A coupled CPFE/DD approach

    , Pages: 3416-3419
  • Conference paper
    Strozzi A, Giacopini M, Bertocchi E, Dini Det al., 2013,

    A complementarity formulation of the tangential velocity slip problem in lubricant films

    , Pages: 3503-3506
  • Conference paper
    Balcombe R, Fowell MT, Kadiric A, Dini D, Olver AVet al., 2013,

    Modeling the propagation of Rolling Contact Fatigue (RCF) cracks in the presence of lubricant

    , Pages: 3577-3579
  • Journal article
    Veijgen NK, Masen MA, van der Heide E, 2013,

    Relating Friction on the Human Skin to the Hydration and Temperature of the Skin

    , TRIBOLOGY LETTERS, Vol: 49, Pages: 251-262, ISSN: 1023-8883
  • Journal article
    Flicek R, Hills DA, Dini D, 2013,

    Progress in the application of notch asymptotics to the understanding of complete contacts subject to fretting fatigue

    , FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES, Vol: 36, Pages: 56-64, ISSN: 8756-758X
  • Journal article
    Leong JY, Reddyhoff T, Sinha SK, Holmes AS, Spikes HAet al., 2013,

    Hydrodynamic Friction Reduction in a MAC-Hexadecane Lubricated MEMS Contact

    , TRIBOLOGY LETTERS, Vol: 49, Pages: 217-225, ISSN: 1023-8883
  • Journal article
    Medina S, Nowell D, Dini D, 2013,

    Analytical and Numerical Models for Tangential Stiffness of Rough Elastic Contacts

    , TRIBOLOGY LETTERS, Vol: 49, Pages: 103-115, ISSN: 1023-8883
  • Journal article
    Putignano D, 2013,

    Experimental investigation of viscoelastic rolling contacts: A comparison with theory

    , Tribology Letters, Vol: 51, Pages: 105-113
  • Journal article
    Botta F, Marx N, Schwingshackl C, Cerri G, Dini Det al., 2013,

    A WIRELESS VIBRATION CONTROL TECHNIQUE FOR GAS TURBINE BLADES USING PIEZOELECTRIC PLATES AND CONTACTLESS ENERGY TRANSFER

    , PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2013, VOL 7A
  • Journal article
    Bertocchi L, Giacopini M, Dini D, 2013,

    ANALYSIS OF THE LUBRICATION REGIMES AT THE SMALL END AND BIG END OF A CONNECTING ROD OF A HIGH PERFORMANCE MOTORBIKE ENGINE

    , PROCEEDINGS OF THE ASME/STLE INTERNATIONAL JOINT TRIBOLOGY CONFERENCE, IJTC 2012, Pages: 229-231
  • Journal article
    Zhang J, Yamaguchi E, Spikes H, 2013,

    Comparison of three laboratory tests to quantify mild wear rate

    , Tribology Transactions, Vol: 56, Pages: 919-928, ISSN: 1040-2004

    Because the viscosities of engine and transmission lubricants are lowered in order to reduce hydrodynamic friction and thus energy consumption, it is important to ensure that wear rates do not increase and thus machine durability is not impaired. In practical terms this means that we require reliable methods for measuring the mild wear rates present in most lubricated machine components.This article compares three mild wear reciprocating laboratory tests, one based on the high-frequency reciprocating rig (HFRR) and two on the mini-traction machine (MTM), in order to explore the extent to which wear rate is determined by the test configuration. The results show that some additive-containing lubricants including blends of antiwear additive and dispersant give quite consistent wear rates, independent of whether the surface is in continuous or intermittent contact, whereas others such as two friction modifiers do not. Possible reasons for these differences are discussed. The importance of accounting for wear during running-in and the need to remove any thick tribofilms present before quantifying wear volume are also confirmed.
  • Conference paper
    Arana C, Evangelou SA, Dini D, 2012,

    Pitch Angle Reduction for Cars under Ac- celeration and Braking by Active Variable Geometry Suspension

    , 51st Conference on Decision and Control; CDC2012
  • Journal article
    Woldman M, Van der Heide E, Tinga T, Masen MAet al., 2012,

    The influence of abrasive body dimensions on single asperity wear

    , WEAR, Vol: 301, Pages: 76-81, ISSN: 0043-1648
  • Journal article
    Oldfield M, Dini D, Rodriguez y Baena F, 2012,

    Predicting failure in soft tissue phantoms via modeling of non-predetermined tear progression.

    , Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, Pages: 6305-6308, ISSN: 1557-170X

    The advantageous, curved trajectory of bevel-tipped devices in soft tissue is a function of the interplay between material deformation, contact interactions and material failure. Highly detailed modeling of tool-tissue interactions is therefore vital in optimising performance and design. At high resolution, discontinuous failure of soft tissue phantoms has not been demonstrated. An iterative procedure, making incremental additions to the failure path in an otherwise continuous finite element mesh, is presented to achieve this goal. The procedure's efficacy was demonstrated in two materials including a soft tissue phantom. Failure path is shown to respond well to different and evolving shear and normal stress states. The iterative procedure would thus be ideal for analysing and optimising complex tool-tissue interactions, for instance in needle steering systems, where the path taken by the needle also depends on the progression of a tear which develops ahead of the tip during the insertion process. With the method presented here, this behaviour could be modeled and analysed at an unprecedented resolution.
  • Journal article
    Holtzinger J, Green J, Lamb G, Atkinson D, Spikes Het al., 2012,

    New Method of Measuring Permanent Viscosity Loss of Polymer-Containing Lubricants

    , TRIBOLOGY & LUBRICATION TECHNOLOGY, Vol: 68, Pages: 66-+, ISSN: 1545-858X
  • Journal article
    Campen S, Green J, Lamb G, Atkinson D, Spikes Het al., 2012,

    On the Increase in Boundary Friction with Sliding Speed

    , TRIBOLOGY LETTERS, Vol: 48, Pages: 237-248, ISSN: 1023-8883
  • Journal article
    Timm K, Myant C, Nuguid H, Spikes HA, Grunze Met al., 2012,

    Investigation of friction and perceived skin feel after application of suspensions of various cosmetic powders

    , INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol: 34, Pages: 458-465, ISSN: 0142-5463
  • Journal article
    Veijgen NK, Masen MA, van der Heide E, 2012,

    A novel approach to measuring the frictional behaviour of human skin in vivo

    , TRIBOLOGY INTERNATIONAL, Vol: 54, Pages: 38-41, ISSN: 0301-679X
  • Journal article
    Vengudusamy B, Green JH, Lamb GD, Spikes HAet al., 2012,

    Behaviour of MoDTC in DLC/DLC and DLC/steel contacts

    , TRIBOLOGY INTERNATIONAL, Vol: 54, Pages: 68-76, ISSN: 0301-679X
  • Journal article
    Hills DA, Thaitirarot A, Barber JR, Dini Det al., 2012,

    Correlation of fretting fatigue experimental results using an asymptotic approach

    , INTERNATIONAL JOURNAL OF FATIGUE, Vol: 43, Pages: 62-75, ISSN: 0142-1123
  • Journal article
    Fowell MT, Medina S, Olver AV, Spikes HA, Pegg IGet al., 2012,

    Parametric study of texturing in convergent bearings

    , TRIBOLOGY INTERNATIONAL, Vol: 52, Pages: 7-16, ISSN: 0301-679X
  • Journal article
    Woldman M, van der Heide E, Schipper DJ, Tinga T, Masen MAet al., 2012,

    Investigating the influence of sand particle properties on abrasive wear behaviour

    , Wear, Vol: 294-295, Pages: 419-426, ISSN: 0043-1648
  • Journal article
    Jeffers JRT, Walter WL, 2012,

    Ceramic-on-ceramic bearings in hip arthroplasty STATE OF THE ART AND THE FUTURE

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 94B, Pages: 735-745, ISSN: 0301-620X
    • Cite
    • Citations: 72
  • Journal article
    Smith ER, Heyes DM, Dini D, Zaki TAet al., 2012,

    Control-volume representation of molecular dynamics

    , Physical Review E, Vol: 85, Pages: 056705-056705, ISSN: 1539-3755

    A molecular dynamics (MD) parallel to the control volume (CV) formulation of fluid mechanics is developedby integrating the formulas of Irving and Kirkwood [J. Chem. Phys.18, 817 (1950)] over a finite cubic volumeof molecular dimensions. The Lagrangian molecular system is expressed in terms of an Eulerian CV, whichyields an equivalent to Reynolds’ transport theorem for the discrete system. This approach casts the dynamics ofthe molecular system into a form that can be readily compared to the continuum equations. The MD equationsof motion are reinterpreted in terms of a Lagrangian-to-control-volume (LCV) conversion functionθifor eachmoleculei.TheLCVfunction and its spatial derivatives are used to express fluxes and relevant forces across thecontrol surfaces. The relationship between the local pressures computed using the volume average [Lutsko,J.Appl. Phys.64, 1152 (1988)] techniques and the method of planes [Toddet al.,Phys.Rev.E52, 1627 (1995)]emerges naturally from the treatment. Numerical experiments using the MD CV method are reported forequilibrium and nonequilibrium (start-up Couette flow) model liquids, which demonstrate the advantages ofthe formulation. The CV formulation of the MD is shown to be exactly conservative and is, therefore, ideallysuited to obtain macroscopic properties from a discrete system.
  • Journal article
    Quinchia LA, Delgado MA, Franco JM, Spikes HA, Gallegos Cet al., 2012,

    Low-temperature flow behaviour of vegetable oil-based lubricants

    , INDUSTRIAL CROPS AND PRODUCTS, Vol: 37, Pages: 383-388, ISSN: 0926-6690
  • Journal article
    van Kuilenburg J, Masen MA, Groenendijk MNW, Bana V, van der Heide Eet al., 2012,

    An experimental study on the relation between surface texture and tactile friction

    , TRIBOLOGY INTERNATIONAL, Vol: 48, Pages: 15-21, ISSN: 0301-679X
  • Patent
    Evangelou SA, Dini D, De Meerschman O, Tocatlian A, Kneip C, Palas Cet al., 2012,

    Variable-geometry suspension apparatus and vehicle comprising such apparatus
  • Journal article
    Myant CW, Fan T, Underwood R, cann Pet al., 2012,

    Synovial Fluid Lubrication of Artificial Joints: Protein Film Formation and Composition

    , Faraday Discussions, ISSN: 1364-5498
  • Conference paper
    Coleman I, Dini D, Smith R, 2012,

    Wheel-rail contact detection and stress analysis at railway switches and crossings

    , Pages: 652-654

    Many authors have investigated the phenomenon of wheel-rail contact and from a variety of perspectives. In recent years there has been a research push towards using rolling contact stresses for modeling subsequent material degradation at the wheel-rail interface. This extended abstract describes the development of an integrated tool for advanced wheel-rail contact detection and detailed, non-Hertzian normal and tangential contact stress analysis for use within subsequent material degradation models at the railway switch and crossing interface.
  • Conference paper
    Hajishafiee A, Dini D, Zaki T, Kadiric A, Ioannides Set al., 2012,

    MODELLING ELASTO-HYDRODYNAMIC LUBRICATION USING CFD

    , 15th International Conference on Experimental Mechanics (ICEM), Publisher: INEGI-INST ENGENHARIA MECANICA E GESTAO INDUSTRIAL
  • Conference paper
    Rycerz P, Kadiric A, Pasaribu R, Espejel GM, Olver AVet al., 2012,

    EFFECT OF ADDITIVES ON SURFACE PERFORMANCE

    , 15th International Conference on Experimental Mechanics (ICEM), Publisher: INEGI-INST ENGENHARIA MECANICA E GESTAO INDUSTRIAL
  • Journal article
    Hills DA, Paynter RJH, Dini D, 2012,

    An overview of the quantification of fretting fatigue lives of complete contacts

    , ENGINEERING FRACTURE MECHANICS, Vol: 80, Pages: 3-12, ISSN: 0013-7944
  • Journal article
    Ku ISY, Reddyhoff T, Wayte R, Choo JH, Holmes AS, Spikes HAet al., 2012,

    Lubrication of microelectromechanical devices using liquids of different viscosities

    , Journal of Tribology, Vol: 134, ISSN: 0742-4787

    Lubrication of contacting and sliding surfaces in MEMS (microelectromechanical systems) is particularly challenging because of the predominance of surface forces at the microscale. The current paper explores the possibility of using liquid lubrication in this application. Measurements of friction and lubricant film thickness have been made for liquid lubricants of different viscosities, including low viscosity silicone oil, hexadecane, squalane, and water. Testing was carried out using a newly developed MEMS tribometer in which a rotating silicon disk is loaded against a stationary silicon disk. Two different test setups were used: one where both disks are flat, and the other where the stationary disk is structured as in a thrust pad bearing. In all tests the disks were fully submerged in the lubricant. With the flat-on-patterned disk combination, the variation of friction with rotation speed was found to follow classical Stribeck curves for all the lubricants tested. The friction at high speeds also decreased with increasing normal load, in accordance with hydrodynamic lubrication theory. For the least viscous lubricants, it was found that the hydrodynamic friction coefficients remained relatively low even at higher speeds. In particular, for water the friction coefficient for water was around 0.1 at 10,000 rpm. However, boundary friction was found to be unacceptably high at low speeds where there was insufficient lubricant entrainment. The experimental results have been compared with a finite difference solution of Reynolds equation and reasonable agreement is seen between theory and experiment. The results indicate that liquid lubrication is potentially an effective means of lubricating MEMS components with high levels of sliding.
  • Journal article
    Medina S, Olver AV, Dini D, 2012,

    The Influence of Surface Topography on Energy Dissipation and Compliance in Tangentially Loaded Elastic Contacts

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 134, ISSN: 0742-4787

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