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  • 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
    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
    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
    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
    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

    Recent research has shown that hydrodynamic lubrication is an effective means of reducing friction in high sliding micro-electromechanical systems (MEMS). At high speeds, however, such lubrication can lead to increased friction due to viscous drag. This article describes a series of hydrodynamic tests on a silicon MEMS contact lubricated with a blend of hexadecane and a multiplyalkylated cyclopentane (MAC). Results show that the presence of the MAC reduces hydrodynamic friction compared with neat hexadecane. Such behaviour is contrary to conventional hydrodynamic theory, since the viscosity of the MAC - a mixture of di and tri(2 octyldodecyl)cyclopentane - is significantly higher than that of neat hexadecane. This effect increases with MAC concentration up to an optimum value of 3 wt%, where the hydrodynamic friction coefficient at 15,000 rpm is reduced from 0.5 to 0.3. Above this concentration, friction begins to rise due to the overriding effect of increasing viscosity. The viscosity of the blended lubricant increased monotonically with MAC concentration, when measured using both a Stabinger and an ultrahigh shear viscometer. In addition to this, no reduction in friction was observed when a squalane-hexadecane blend of equal viscosity was tested. This suggests that some property of the MAC-hexadecane lubricant, other than its viscosity, is influencing hydrodynamic lubrication. A tentative explanation for this behaviour is that the MAC induces the liquid to slip, rather than shear, close to the silicon surfaces. This hypothesis is supported by the fact that the friction reducing ability of the MAC blend was inhibited by the inclusion of octade-cylamine - a substance known to form films on silicon surfaces. Furthermore, the MAC reduces friction in the mixed regime, in a manner suggesting that the formation of a viscous boundary layer. This unusual behaviour may have useful implications for reducing hydrodynamic friction in liquidlubricated MEMS devices. © Sprin

  • 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
    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
    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
    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
    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
    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
  • 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
  • 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
    Medina S, Dini D, 2013,

    Aspects of modelling adhesion with surface topography

    , Pages: 184-187
  • Conference paper
    Myant C, Cann P, 2013,

    Lubrication of artificial articular joints

    , Pages: 132-134
  • 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
    Fowell MT, Kadiric A, Morales-Espejel G, Stacke LE, Ioannides Set al., 2013,

    Smearing damage in rolling element bearings

    , Pages: 1135-1137
  • Conference paper
    Nyqvist JT, Kadiric A, Sayles RS, Ioannides Eet al., 2013,

    Three-dimensional analysis of multilayered rough surface contacts

    , Pages: 181-183
  • Journal article
    Putignano D, 2013,

    Experimental investigation of viscoelastic rolling contacts: A comparison with theory

    , Tribology Letters, Vol: 51, Pages: 105-113
  • 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
    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
    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
    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
    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
    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
    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
    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
    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
  • 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
    Oldfield M, Dini D, Rodriguez y Baena F, 2012,

    Predicting Failure in Soft Tissue Phantoms via Modeling of Non-Predetermined Tear Progression

    , 34th Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS), Publisher: IEEE, Pages: 6305-6308, ISSN: 1557-170X
  • Journal article
    Jeffers JRT, 2012,

    The role of biomechanics and engineering in total hip replacement. Why surgeons need technical help

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, Vol: 226, Pages: 947-954, ISSN: 0954-4119
  • 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 TRANSACTIONS, Vol: 55, Pages: 631-639, ISSN: 1040-2004
  • Journal article
    Fan J, Myant C, Underwood R, Cann Pet al., 2012,

    Synovial fluid lubrication of artificial joints: protein film formation and composition

    , FARADAY DISCUSSIONS, Vol: 156, Pages: 69-85, ISSN: 1359-6640
  • 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
  • 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
    Underwood RJ, Zografos A, Sayles RS, Hart A, Cann Pet al., 2012,

    Edge loading in metal-on-metal hips: low clearance is a new risk factor

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, Vol: 226, Pages: 217-226, ISSN: 0954-4119
  • 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.

  • Journal article
    Flicek R, Dini D, Hills DA, 2012,

    THE INFLUENCE OF INITIAL RESIDUAL STRESS STATE ON THE STEADY STATE BEHAVIOUR OF CYCLICALLY LOADED COUPLED

    , PROCEEDINGS OF THE ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE 2011, VOL 1, PTS A AND B, Pages: 1319-1328

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