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

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  • Journal article
    Campen S, Green JH, Lamb GD, Spikes HAet al., 2015,

    In situ study of model organic friction modifiers using liquid cell AFM; saturated and mono-unsaturated carboxylic acids

    , Tribology Letters, Vol: 57, Pages: 1-20, ISSN: 1023-8883

    Fatty acids and their derivatives have been used as model organic friction modifiers for almost a century, but there is still debate as to the nature of the boundary films that they form on rubbed surfaces. In this study, in situ liquid cell atomic force microscopy (AFM) is used to monitor the self-assembly of boundary films from solutions of fatty acids in alkanes on to mica surfaces. Because the mica surfaces are wholly immersed in solution, it is possible to study directly changes in the morphology and friction of these films over time and during heating and cooling. It has been found that stearic acid and elaidic acid, which are able to adopt linear molecular configurations, form irregular islands on mica that are tens to hundreds of microns in diameter and typically 1.6 nm thick, corresponding to domains of tilted single monolayers. At a relatively high concentration of 0.01 M, stearic acid in hexadecane forms an almost complete monolayer, but at lower concentrations, in dodecane solution and for elaidic acid solutions, these films remain incomplete after prolonged immersion of more than a day. The films formed by fatty acids on mica are displaced by repeated scanning in contact mode AFM but can be imaged without damage using tapping mode AFM. Rubbed quartz surfaces from a sliding ball-on-disc test were also scanned ex situ using AFM, and these showed that stearic acid forms similar monolayer island films on quartz in macro-scale friction experiments as are found on mica. Oleic acid solutions behave quite differently from stearic acid and elaidic acid, forming irregular globular films on both mica and rubbed quartz surfaces. This is believed to be because its cis-double bond geometry means that, unlike its trans-isomer elaidic acid or saturated stearic acid, it is unable to adopt a linear molecular configuration and so is less able to form close-packed monolayers.
  • Journal article
    Arana C, Evangelou SA, Dini D, 2015,

    Series Active Variable Geometry Suspension for Road Vehicles

    , IEEE-ASME TRANSACTIONS ON MECHATRONICS, Vol: 20, Pages: 361-372, ISSN: 1083-4435
  • Journal article
    Vladescu S-C, Olver AV, Pegg IG, Reddyhoff Tet al., 2015,

    The effects of surface texture in reciprocating contacts - An experimental study

    , TRIBOLOGY INTERNATIONAL, Vol: 82, Pages: 28-42, ISSN: 0301-679X
  • Journal article
    Nyqvist J, Kadiric A, Ioannides S, Sayles Ret al., 2015,

    Semi-analytical model for rough multilayered contacts

    , Tribology International, Vol: 87, Pages: 98-112, ISSN: 1879-2464

    This paper presents a new model for analysis of non-conformal rough surface contacts where one or both of the contacting bodies are coated with a multilayered coating. The model considers elastic contact of arbitrary geometry with real measured roughnesses and both normal and tangential surface loads. It predicts contact pressure distribution, surface deformations and full subsurface stress field. As such, the model offers an optimisation tool for analysis and development of multilayered coatings. Influence coefficients approach is utilised to obtain contact pressures and subsurface stresses while the contact solver is based on a standard conjugate gradient method. To improve model efficiency, a semi-analytical approach is devised, where the influence coefficients for displacements and stresses are expressed explicitly by solving the fundamental equations in the frequency domain. Fast Fourier Transforms in conjunction with discrete convolution are then utilised to provide the solution in spatial domain. Selected results are presented to first validate the model and then illustrate the potential improvements that can be achieved in the design of multilayered coatings through application of the model.
  • Conference paper
    Dini D, Giacopini M, Giuseppe MA, Bertocchi Eet al., 2015,

    The influence of textured surfaces on the tribological behaviour of hip replacements employng a mass conserving complementarity algorithm

    , Pages: 4-6
  • Conference paper
    Mastrandrea LN, Giacopini M, Dini D, Bertocchi Eet al., 2015,

    Elastohydrodynamic analysis of the conrod small-end of a high performance motorbike engine via a mass conserving cavitation algorithm

    In this contribution a complementarity formulation for the solution of EHL problem in presence of cavitation is employed in order to investigate the tribological behavior of the conrod small-end of a high performance motorbike engine. The influence of different physical and geometrical parameters is discussed. In particular, the clearance between the conrod small-end and the piston pin, the lubricant physical properties, the surface roughness and the stiffness of the piston pin are investigated, thus providing preliminary guidelines for the correct design of the coupling. Due to the negligible influence of the transversal forces acting on the conrod small-end and of the relative sliding speed between the mating surfaces, a two symmetrical model of the assembly is prepared and results are compared with those obtained adopting a simply symmetrical model.
  • Conference paper
    Profito FJ, Dini D, Zachariadis DC, 2015,

    A general finite volume method solution for the reynolds lubrication equation with Mass-Conserving cavitation model

    , Pages: 303-305
  • Journal article
    Flicek RC, Hills DA, Barber JR, Dini Det al., 2015,

    Determination of the shakedown limit for large, discrete frictional systems

    , EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, Vol: 49, Pages: 242-250, ISSN: 0997-7538
  • Journal article
    Spikes H, 2015,

    Basics of EHL for practical application

    , LUBRICATION SCIENCE, Vol: 27, Pages: 45-67, ISSN: 0954-0075
  • Journal article
    Wong JSP, Hu M, Shi D, Li RKY, Wong JSSet al., 2014,

    In-situ Monitoring on Dynamics of Solute Transport in Polymer Films

    , Polymer, Vol: 58, Pages: 67-75, ISSN: 0032-3861

    A new and non-invasive technique based on confocal laser scanning microscopy (CLSM) that allows the visualization of penetrant diffusion in-situ has been developed and was applied to quantify local solute dynamics in polymeric films. The effectiveness of the proposed technique was demonstrated using a model penetrant, rhodamine-6G (Rh-6G), and a system of polyvinyl alcohol (PVA) films with different degree of cross-linking, and different content of montmorillonite (MMT) clay. The penetrant's transport across PVA films were monitored by measuring the time evolutions of through thickness fluorescence intensity profiles. These profiles were then converted to concentration profiles, which allow local diffusion coefficients of the model solute (i.e. Rh-6G) to be determined. The developed methodology was applied to both single layer and bilayers films and local diffusion heterogeneity was detected. Hence the technique developed can be applied to multi-layer films, and can be beneficial to film developments for packaging and filtration technology.
  • Journal article
    Tavasci A, Arizzi F, Dini D, Rizzi Eet al., 2014,

    Heat flux evaluation in high temperature ring-on-ring contacts

    , Wear, Vol: 330-331, Pages: 320-326, ISSN: 1873-2577

    A comprehensive methodology to investigate heat flux in a ring-on-ring tribometer is presented. Thermal fluxes under high contact pressures and temperature differences were evaluated through an experimental campaign and by a numerical procedure of inverse analysis applied to surface temperature measurements. An approximation of a two-dimensional time-dependent analytical solution for the temperature distribution was first developed and subsequently adapted to mimic the specific testing configuration characteristics; the problem was finally simplified to enable further inverse analysis. Experiments were performed using an innovative high temperature ring-on-ring tribometer. The evaluated contact heat-transfer rates were reported as a function of normal load and temperature difference between the discs under steady-state conditions; the results reported here show that, in the present test configuration, the temperature difference has stronger influence than the applied load in terms of heat transfer induced by contact.
  • Journal article
    Parkes M, Myant C, Dini D, Cann Pet al., 2014,

    Tribology-optimised silk protein hydrogels for articular cartilage repair

    , Tribology International, Pages: ---, ISSN: 0301-679X
  • Journal article
    Myant CW, Fowell M, Spikes H, Kadiric Aet al., 2014,

    A study of lubricant film thickness in compliant contacts of elastomeric seal materials using a laser induced fluorescence technique

    , Tribology International, Vol: 80, Pages: 76-89, ISSN: 0301-679X

    A laser induced fluorescence technique was used to investigate the build-up of lubricant films in compliant contacts operating in the isoviscous elasto-hydrodynamic regime (I-EHL). The described technique utilises an optimised optical set-up with a relatively high signal-to-noise ratio and was shown to be able to produce film thickness maps of the complete contact area and measure a very wide span of thicknesses, from 50 nm to 100 μm. Maps of film thickness were obtained over a range of entrainment speeds and loads for three different contact configurations and two elastomer materials, polydimethylsiloxane (PDMS) and a fluorocarbon rubber (FKM) which is typically used in rotary seal applications. In a model contact of a nominally smooth PDMS ball sliding on a glass flat, a crescent shaped area of reduced film thickness was observed towards the contact exit. In contrast to typical elasto-hydrodynamic contacts, no side-lobes of reduced film thickness were recorded, while the central film region exhibited a converging wedge shape. The elliptical contact of an FKM O-ring rolling on a flat glass showed a central region of flat film while areas of minimum film thickness were located near the contact edges either side of the centre. The highly conformal contact of relatively rough FKM O-ring sliding against a concave glass lens, a geometry more representative of that found in elastomeric seals, showed discrete regions of reduced film, corresponding to surface roughness asperities. With rising entrainment speed, some lift-off was observed, with surface roughness asperities appearing to be increasingly compressed. Measured films thicknesses were compared to existing theoretical predictions for I-EHL contacts and the level of agreement was found to be highly dependent on contact geometry and applied conditions.
  • Journal article
    Puthumanapully PK, Harris SJ, Leong A, Cobb JP, Amis AA, Jeffers Jet al., 2014,

    A morphometric study of normal and varus knees

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 22, Pages: 2891-2899, ISSN: 0942-2056
  • Book chapter
    Gurrutxaga Lerma B, Balint DS, Dini D, Eakins DE, Sutton APet al., 2014,

    Dynamic Discrete Dislocation Plasticity

    , Advances in Applied Mechanics, Publisher: Elsevier, Pages: 93-224, ISBN: 978-0-12-800130-1

    This chapter concerns with dynamic discrete dislocation plasticity (D3P), a two- dimensional method of discrete dislocation dynamics aimed at the study of plastic relaxation processes in crystalline materials subjected to weak shock loading. Traditionally, the study of plasticity under weak shock loading and high strain rate has been based on direct experimental measurement of the macroscopic response of the material. Using these data, well-known macroscopic constitutive laws and equations of state have been formulated. However, direct simulation of dislocations as the dynamic agents of plastic relaxation in those circumstances remains a challenge. In discrete dislocation dynamics (DDD) methods, in particular the two-dimensional discrete dislocation plasticity (DDP), the dislocations are modeled as discrete discontinuities in an elastic continuum. However, current DDP and DDD methods are unable to adequately simulate plastic relaxation because they treat dislocation motion quasi- statically, thus neglecting the time-dependent nature of the elastic fields and assuming that they instantaneously acquire the shape and magnitude predicted by elastostatics. This chapter reproduces the findings by Gurrutxaga-Lerma, Balint, Dini, Eakins, and Sutton (2013), who proved that under shock loading, this assumption leads to models that invariably break causality, introducing numerous artifacts that invalidate quasi- static simulation techniques. This chapter posits that these limitations can only be overcome with a fully time-dependent formulation of the elastic fields of dislocations. In this chapter, following the works of Markenscoff and Clifton (1981) and Gurrutxaga- Lerma et al. (2013), a truly dynamic formulation for the creation, annihilation, and nonuniform motion of straight edge dislocations is derived. These solutions extend the DDP framework to a fully elastodynamic formulation that has been called dynamic discrete dislocation plasticity (D3P). This chapter describes t
  • Journal article
    Costa HL, Spikes H, 2015,

    Effects of Ethanol Contamination on Friction and Elastohydrodynamic Film Thickness of Engine Oils

    , TRIBOLOGY TRANSACTIONS, Vol: 58, Pages: 158-168, ISSN: 1040-2004
  • Journal article
    Gurrutxaga-Lerma B, Balint DS, Dini D, Eakins DE, Sutton Aet al., 2014,

    Dynamic Discrete Dislocation Plasticity

    , Advances in Applied Mechanics, Vol: 47, ISSN: 0065-2156

    This chapter concerns with dynamic discrete dislocation plasticity (D3P), a two- dimensional method of discrete dislocation dynamics aimed at the study of plastic relaxation processes in crystalline materials subjected to weak shock loading. Traditionally, the study of plasticity under weak shock loading and high strain rate has been based on direct experimental measurement of the macroscopic response of the material. Using these data, well-known macroscopic constitutive laws and equations of state have been formulated. However, direct simulation of dislocations as the dynamic agents of plastic relaxation in those circumstances remains a challenge. In discrete dislocation dynamics (DDD) methods, in particular the two-dimensional discrete dislocation plasticity (DDP), the dislocations are modeled as discrete discontinuities in an elastic continuum. However, current DDP and DDD methods are unable to adequately simulate plastic relaxation because they treat dislocation motion quasi- statically, thus neglecting the time-dependent nature of the elastic elds and assuming that they instantaneously acquire the shape and magnitude predicted by elastostatics. This chapter reproduces the ndings by Gurrutxaga-Lerma, Balint, Dini, Eakins, and Sutton (2013), who proved that under shock loading, this assumption leads to models that invariably break causality, introducing numerous artifacts that invalidate quasi- static simulation techniques. This chapter posits that these limitations can only be overcome with a fully time-dependent formulation of the elastic elds of dislocations. In this chapter, following the works of Markensco and Clifton (1981) and Gurrutxaga- Lerma et al. (2013), a truly dynamic formulation for the creation, annihilation, and nonuniform motion of straight edge dislocations is derived. These solutions extend the DDP framework to a fully elastodynamic formulation that has been called dynamic discrete dislocation plasticity (D3P). This chapter describes the s
  • Conference paper
    Forte AE, Dini D, 2014,

    Modelling and Characterisation of Soft Tissue Deformation and Indentation with Particular Application to Articular Cartilage and Brain

    , STLE Frontiers 2014
  • Journal article
    Gattinoni C, Mackowiak S, Heyes DM, Branka AC, Dini Det al., 2014,

    Boundary-controlled barostats for slab geometries in molecular dynamics simulations

    , PHYSICAL REVIEW E, Vol: 90, ISSN: 1539-3755
  • Journal article
    Borges PDN, Forte AE, Vincent TL, Dini D, Marenzana Met al., 2014,

    Rapid, automated imaging of mouse articular cartilage by microCT for early detection of osteoarthritis and finite element modelling of joint mechanics

    , Osteoarthritis and Cartilage, Vol: 22, Pages: 1419-1428, ISSN: 1063-4584

    ObjectiveMouse articular cartilage (AC) is mostly assessed by histopathology and its mechanics is poorly characterised. In this study: (1) we developed non-destructive imaging for quantitative assessment of AC morphology and (2) evaluated the mechanical implications of AC structural changes.MethodsKnee joints obtained from naïve mice and from mice with osteoarthritis (OA) induced by destabilization of medial meniscus (DMM) for 4 and 12 weeks, were imaged by phosphotungstic acid (PTA) contrast enhanced micro-computed tomography (PTA-CT) and scored by conventional histopathology. Our software (Matlab) automatically segmented tibial AC, drew two regions centred on each tibial condyle and evaluated the volumes included. A finite element (FE) model of the whole mouse joint was implemented to evaluate AC mechanics.ResultsOur method achieved rapid, automated analysis of mouse AC (structural parameters in <10 h from knee dissection) and was able to localise AC loss in the central region of the medial tibial condyle. AC thickness decreased by 15% at 4 weeks and 25% at 12 weeks post DMM surgery, whereas histopathology scores were significantly increased only at 12 weeks. FE simulations estimated that AC thinning at early-stages in the DMM model (4 weeks) increases contact pressures (+39%) and Tresca stresses (+43%) in AC.ConclusionPTA-CT imaging is a fast and simple method to assess OA in murine models. Once applied more extensively to confirm its robustness, our approach will be useful for rapidly phenotyping genetically modified mice used for OA research and to improve the current understanding of mouse cartilage mechanics.
  • Journal article
    Liu X, Spikes H, Wong JSS, 2014,

    In-situ pH responsive fluorescent probing of localized iron corrosion

    , Corrosion Science, ISSN: 0010-938X
  • Journal article
    Strozzi A, Giacopini M, Bertocchi E, Dini Det al., 2014,

    Formulation of the tangential velocity slip problem in terms of variational inequalities

    , Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Vol: 228, Pages: 1122-1135, ISSN: 2041-305X
  • Journal article
    Putignano C, Le Rouzic J, Reddyhoff T, Carbone G, Dini Det al., 2014,

    A theoretical and experimental study of viscoelastic rolling contacts incorporating thermal effects

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 228, Pages: 1112-1121, ISSN: 1350-6501
  • Journal article
    Spikes H, Jie Z, 2014,

    History, Origins and Prediction of Elastohydrodynamic Friction

    , TRIBOLOGY LETTERS, Vol: 56, Pages: 1-25, ISSN: 1023-8883
  • Conference paper
    Geraldes D, Hansen U, Jeffers J, Amis Aet al., 2014,

    A framework for parametric analysis of glenoid implant design

    , International Society for Technology in Arthroplasty 2014
  • Conference paper
    Forte AE, galvan S, manieri F, Dini Det al., 2014,

    A Novel Composite Phantom for Brain Tissue

    , EMBC 2014
  • Journal article
    Bodnarchuk MS, Dini D, Heyes DM, Chahine S, Edwards Set al., 2014,

    Self-assembly of calcium carbonate nanoparticles in water and hydrophobic solvents

    , Journal of Physical Chemistry C, Vol: 118, Pages: 21092-21103, ISSN: 1932-7455

    The self-assembly of Ca2+ and CO32– ions into nanoparticles in water and hydrophobic solvents is investigated using molecular dynamics (MD) computer simulation. A new three-stage particle assembly procedure is used which relaxes the structure of the nanoparticle toward a lower energy state. In hydrophobic solvent the bare particle is essentially spherical whereas in water it is ellipsoidally shaped. With surfactant stabilizer the nanoparticles typically exhibit nonspherical cores in model hydrophobic solvents. Binary surfactant systems exhibit synergistic effects where for example a salicylate-sulfonate combination forms a cage which promotes a compact core. Synergistic effects on the shape of the particle were also observed in a hydrophobic solvent for surfactant-stabilized systems with trace water as a third component. The simulations show that rather than being a rigid structure the carbonate core shape and stabilizing shell coverage are sensitive to solvent, surfactant, and small polar molecules which act as cosurfactants.
  • Journal article
    Le Rouzic J, Reddyhoff T, 2014,

    Spatially Resolved Triboemission Measurements

    , Tribology Letters, Vol: 55, Pages: 245-252, ISSN: 1573-2711
  • Journal article
    Flicek RC, Hills DA, Dini D, 2014,

    Refinements in the characterisation of mode-mixity and small scale yielding at sharp notch roots

    , ENGINEERING FRACTURE MECHANICS, Vol: 126, Pages: 73-86, ISSN: 0013-7944
  • Conference paper
    Cattilino M, Secoli R, Galvan S, Forte AE, Dini D, rodriguez y Baena Fet al., 2014,

    Development of a Dynamic Soft Tissue Phantom for Cooperative Control Testing in Robotic Surgery

    , Hamlyn Symposium
  • Conference paper
    Rasin I, Pekar Z, Sadowsky O, Forte AE, Galvan S, Dini D, Shoham M, Joskowicz Let al., 2014,

    Real-Time Modelling of Intra-operative Brain Shift Based on Video Tracking

    , The Hamlyn Symposium on Medical Robotics 2014
  • Journal article
    Medina S, Dini D, 2014,

    A numerical model for the deterministic analysis of adhesive rough contacts down to the nano-scale

    , INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 51, Pages: 2620-2632, ISSN: 0020-7683
  • Journal article
    Myant C, Cann P, 2014,

    On the matter of synovial fluid lubrication: implications for Metal-on-Metal hip tribology

    , Journal of The Mechanical Behavior of Biomedical Materials, Vol: 34, Pages: 338-348, ISSN: 1751-6161

    Artificial articular joints present an interesting, and difficult, tribological problem. These bearing contacts undergo complex transient loading and multi axes kinematic cycles, over extremely long periods of time (>10 years). Despite extensive research, wear of the bearing surfaces, particularly metal–metal hips, remains a major problem. Comparatively little is known about the prevailing lubrication mechanism in artificial joints which is a serious gap in our knowledge as this determines film formation and hence wear. In this paper we review the accepted lubrication models for artificial hips and present a new concept to explain film formation with synovial fluid. This model, recently proposed by the authors, suggests that interfacial film formation is determined by rheological changes local to the contact and is driven by aggregation of synovial fluid proteins. The implications of this new mechanism for the tribological performance of new implant designs and the effect of patient synovial fluid properties are discussed.
  • Journal article
    Myant CW, Cann P, 2014,

    The effect of transient conditions on synovial fluid protein aggregation lubrication

    , Journal of The Mechanical Behavior of Biomedical Materials, Vol: 34, Pages: 349-357, ISSN: 1751-6161

    Little is known about the prevailing lubrication mechanisms in artificial articular joints and the way in which these mechanisms determine implant performance. The authors propose that interfacial film formation is determined by rheological changes local to the contact and is driven by aggregation of synovial fluid proteins within the contact inlet region. A direct relationship between contact film thickness and size of the protein aggregation within the inlet region has been observed.In this paper the latest experimental observations of the protein aggregation mechanism are presented for conditions which more closely mimic joint kinematics and loading. Lubricant films were measured for a series of bovine calf serum solutions for CoCrMo femoral component sliding against a glass disc. An optical interferometric apparatus was employed to study the effects of transient motion on lubricant film formation. Central film thickness was measured as a function of time for a series of transient entrainment conditions; start-up motion, steady-state and non-steady-state uni-directional sliding, and bi-directional sliding. The size of the inlet aggregations was found to be dependent upon the type of transient condition. Thick protective protein films were observed to build up within the main contact region for all uni-directional tests. In contrast the inlet aggregation was not observed for bi-directional tests. Contact film thickness and wear was found to be directly proportional to the presence of the inlet protein phase. The inlet phase and contact films were found to be fragile when disrupted by surface scratches or subjected to reversal of the sliding direction.
  • Journal article
    Bodnarchuk MS, Heyes DM, Dini D, Chahine S, Edwards Set al., 2014,

    Role of Deprotonation Free Energies in p<i>K</i><sub>a</sub> Prediction and Molecule Ranking

    , JOURNAL OF CHEMICAL THEORY AND COMPUTATION, Vol: 10, Pages: 2537-2545, ISSN: 1549-9618
  • Journal article
    Zhang J, Yamaguchi E, Spikes H, 2014,

    The Antagonism between Succinimide Dispersants and a Secondary Zinc Dialkyl Dithiophosphate

    , TRIBOLOGY & LUBRICATION TECHNOLOGY, Vol: 70, Pages: 60-+, ISSN: 1545-858X
  • Journal article
    Hernandez Battez A, Viesca JL, Gonzalez R, Garcia A, Reddyhoff T, Higuera-Garrido Aet al., 2014,

    Effect of Shear Rate, Temperature, and Particle Concentration on the Rheological Properties of ZnO and ZrO<sub>2</sub> Nanofluids

    , TRIBOLOGY TRANSACTIONS, Vol: 57, Pages: 489-495, ISSN: 1040-2004
  • Journal article
    Fowell M, Ioannides S, Kadiric A, 2014,

    An Experimental Investigation into the Onset of Smearing Damage in Nonconformal Contacts with Application to Roller Bearings

    , Tribology Transactions, Vol: 57, Pages: 472-488, ISSN: 1547-397X

    The onset of smearing damage was studied under controlled conditions in a custom test rig that simulates the passage of a rolling element through loaded and unloaded zones of a rolling bearing. The setup includes a spherical roller that is intermittently loaded between two bearing raceways driven at a prescribed speed. The roller is free to accelerate during the loading phase. Contact load, roller speed and acceleration, and electrical contact resistance are recorded during the test. Contact shear stress, friction coefficient, frictional power intensity, and elastohydrodynamic film thickness are calculated from the recorded kinematics data. Results suggest that the first onset of smearing occurs early in the loading phase where the roller is near stationary and the frictional power intensity is high. The raceway speed at the onset of damage decreases with increasing load and increasing lubricant supply temperature. The maximum frictional power intensity is found to be relatively constant at all contact conditions that led to smearing. An existing thermomechanical contact model is used to estimate the contact temperature distribution under smearing conditions and the potential for elastohydrodynamic lubrication (EHL) film thickness reduction due to forward heat conduction.
  • Journal article
    Steele JAM, McCullen SD, Callanan A, Autefage H, Accardi MA, Dini D, Stevens MMet al., 2014,

    Combinatorial scaffold morphologies for zonal articular cartilage engineering

    , ACTA BIOMATERIALIA, Vol: 10, Pages: 2065-2075, ISSN: 1742-7061
  • Journal article
    Parkes M, Myant C, Cann PM, Wong JSSet al., 2014,

    The effect of buffer solution choice on protein adsorption and lubrication

    , Tribology International, Vol: 72, Pages: 108-117, ISSN: 0301-679X
  • Journal article
    Kolekar AS, Olver AV, Sworski AE, Lockwood FEet al., 2014,

    Windage and Churning Effects in Dipped Lubrication

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 136, ISSN: 0742-4787
  • Journal article
    Hills DA, Dini D, 2014,

    Common edge contacts: Effect of interface line orientation

    , INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 81, Pages: 73-76, ISSN: 0020-7403
  • Journal article
    Ponjavic A, di Mare L, Wong J, 2014,

    Effect of pressure on the flow behavior of polybutene

    , Journal of Polymer Science Part B: Polymer Physics, Vol: 52, Pages: 708-715, ISSN: 0887-6266

    The rheology of submicron thick polymer melt is examined under high normal pressure conditions by a recently developed photobleached‐fluorescence imaging velocimetry technique. In particular, the validity and limitation of Reynold equation solution, which suggests a linear through‐thickness velocity profile, is investigated. Polybutene (PB) is sheared between two surfaces in a point contact. The results presented in this work suggest the existence of a critical pressure below which the through‐thickness velocity profile is close to linear. At higher pressures however, the profile assumes a sigmoidal shape resembling partial plug flow. The departure of the sigmoidal profile from the linear profile increases with pressure, which is indicative of a second‐order phase/glass transition. The nature of the transition is confirmed independently by examining the pressure‐dependent dynamics of PB squeeze films. The critical pressure for flow profile transition varies with molecular weight, which is consistent with the pressure‐induced glass transition of polymer melt.
  • Conference paper
    Christodoulias AI, Olver AV, Kadiric A, Sworski AE, Kolekar A, Lockwood FEet al., 2014,

    The efficiency of a simple spur gearbox - A thermally coupled lubrication model

    , Pages: 81-98

    A thermally coupled efficiency model for a simple dip-lubricated gearbox is presented. The model includes elastohydrodynamic (EHL) friction losses in gear teeth contacts as well as bearing, seal and churning losses. An iterative numerical scheme is used to fully account for the effects of contact temperature, pressure and shear rates on EHL friction. The model is used to predict gearbox efficiency with selected transmission oils whose properties were first obtained experimentally through rolling-sliding tribometer tests under representative contact conditions. Although the gearbox was designed using standard methods against a fixed rating, the model was used to study efficiency over a much wider range of conditions. Results are presented to illustrate the relative contribution of different sources of energy loss and the effect of lubricant properties on the overall gearbox efficiency under varying operating conditions.
  • Journal article
    Hills DA, Flicek RC, Dini D, 2014,

    A discussion of: Development of a complete contact fretting test device by J Juoksukangas et al.

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 228, Pages: 123-126, ISSN: 1350-6501
  • Conference paper
    Maćkowiak S, Gattinoni C, Heyes DM, Brańka AC, Dini Det al., 2014,

    Boundary-controlled barostats for slab geometries in molecular dynamics simulations

    , Pages: 2712-2715
  • Conference paper
    Thaitirarot A, Hills D, Dini D, 2014,

    Contact mechanics of frictional lap joint

    , Pages: 2228-2231
  • Conference paper
    Dini D, Mastrandrea LN, Giacopini M, Bertocchi Eet al., 2014,

    Numerical investigation of the cavitation damage in a high performance engine conrod big end bearing via a mass-conserving complementarity algorithm

    , Pages: 586-589
  • Conference paper
    Arana C, Evangelou SA, Dini D, 2014,

    Car attitude control by series mechatronic suspension

    , 19th World Congress of the International-Federation-of-Automatic-Control (IFAC), Publisher: ELSEVIER SCIENCE BV, Pages: 10688-10693, ISSN: 2405-8963
  • Journal article
    Quinchia LA, Delgado MA, Reddyhoff T, Gallegos C, Spikes HAet al., 2014,

    Tribological studies of potential vegetable oil-based lubricants containing environmentally friendly viscosity modifiers

    , TRIBOLOGY INTERNATIONAL, Vol: 69, Pages: 110-117, ISSN: 0301-679X

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