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Conference paperKorsunsky AM, Song X, Belnoue J, et al., 2007,
Modeling crack initiation and propagation in nickel base superalloys
, 6th International Conference on Fracture and Damage Mechanics, Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 53-+, ISSN: 1013-9826 -
Journal articleJeffers JRT, Browne M, Lennon AB, et al., 2007,
Cement mantle fatigue failure in total hip replacement: Experimental and computational testing
, JOURNAL OF BIOMECHANICS, Vol: 40, Pages: 1525-1533, ISSN: 0021-9290- Author Web Link
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- Citations: 57
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Journal articleSackfield A, Dini D, Hills DA, 2006,
The contact problem for a wheel having a 'flat'
, WEAR, Vol: 261, Pages: 1265-1270, ISSN: 0043-1648- Author Web Link
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- Citations: 18
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Conference paperCann PM, 2006,
Grease degradation in a bearing simulation device
, 32nd Leeds-Lyon Symposium on Tribology, Publisher: ELSEVIER SCI LTD, Pages: 1698-1706, ISSN: 0301-679X- Author Web Link
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- Citations: 49
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Journal articleCann PM, 2006,
The "leaves on the line" problem - a study of leaf residue film formation and lubricity under laboratory test conditions
, TRIBOLOGY LETTERS, Vol: 24, Pages: 151-158, ISSN: 1023-8883- Author Web Link
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- Citations: 45
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Journal articleSpikes HA, 2006,
Sixty years of EHL
, Lubrication Science, Vol: 18, Pages: 265-291, ISSN: 0954-0075It is now 60 years since Ertel produced the first solution to the elastohydrodynamic lubrication (EHL) problem. There has been enormous progress since then, both in numerical modelling and in experimental research on EHL. The moving, rough surface EHL problem can now be solved on laptop-level computers, while maps of film thickness, pressure and temperature can be obtained experimentally from within rolling/sliding contacts. However, there remain some important questions that have not been fully resolved. One of the most contentious is how to describe the Rheological properties of lubricants under the very severe conditions present in thin film EHL contacts. A second is how to model mixed lubricated contact, where the fluid film can break down at asperity conjunctions. But perhaps the greatest challenge to researchers in EHL is to produce useful design equations for predicting the performance of machine components operating in EHL and thereby ensure that EHL theory becomes an integral part of the design process. Copyright © 2006 John Wiley & Sons, Ltd.
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Journal articlede Vicente J, Spikes HA, Stokes JR, 2006,
Viscosity ratio effect in the emulsion lubrication of soft EHL contact
, JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 128, Pages: 795-800, ISSN: 0742-4787- Author Web Link
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- Citations: 57
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Conference paperHills DA, Dini D, 2006,
A new method for the quantification of nucleation of fretting fatigue cracks using asymptotic contact solutions
, 4th International Symposium on Fretting Fatique, Publisher: ELSEVIER SCI LTD, Pages: 1114-1122, ISSN: 0301-679X- Author Web Link
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- Citations: 19
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Journal articleChurchman CM, Dini D, Hills DA, 2006,
Closure at the root of a sharp notch
, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 48, Pages: 1063-1071, ISSN: 0020-7403- Author Web Link
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- Citations: 11
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Journal articleNikas GK, Sayles RS, 2006,
Study of leakage and friction of flexible seals for steady motion via a numerical approximation method
, TRIBOLOGY INTERNATIONAL, Vol: 39, Pages: 921-936, ISSN: 0301-679X- Author Web Link
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- Citations: 47
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Journal articleKorsunsky AM, Liu J, Golshan M, et al., 2006,
Measurement of residual elastic strains in a titanium alloy using high energy synchrotron X-ray diffraction
, EXPERIMENTAL MECHANICS, Vol: 46, Pages: 519-529, ISSN: 0014-4851- Author Web Link
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- Citations: 14
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Conference paperDini D, Regino GM, Dunne FPE, et al., 2006,
Polycrystal Deformation: Modelling And Diffraction Measurements For The Development Of Microscopic Energy-Based Fatigue Prediction Criteria
, Mesomechanics 2006 (8th Mesomechanics Conference) -
Journal articleSpikes H, 2006,
Origins of the friction and wear properties of antiwear additives
, Lubrication Science, Vol: 18, Pages: 223-230, ISSN: 0954-0075Experimental techniques have been developed to measure the friction, antiwear film-forming and wear properties of lubricants in rolling-sliding contact. Friction measurements show that zinc dialkyldithiophosphates (ZDDPs) and also some other phosphorus-based additives increase friction in mixed lubrication. Film thickness measurements show that this increase in friction correlates with the thickness of antiwear film. They also reveal some of the drivers of antiwear film formation and removal. A novel wear tester is described which enables the mild wear resulting from ZDDP-containing oils to be monitored. Copyright © 2006 John Wiley & Sons, Ltd.
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Journal articleNikas GK, Sayles RS, 2006,
Computational model of tandem rectangular elastomeric seals for reciprocating motion
, TRIBOLOGY INTERNATIONAL, Vol: 39, Pages: 622-634, ISSN: 0301-679X- Author Web Link
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- Citations: 21
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Conference paperHills DA, Churchman CM, Dini D, 2006,
Fretting fatigue: The equivalence of critical plane and critical asymptotic solutions
, 15th U.S. National Congress on Theoretical and Applied Mechanics -
Journal articleNikas GK, Sayles RS, 2006,
Modelling and optimization of composite rectangular reciprocating seals
, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 220, Pages: 395-412, ISSN: 1350-6501- Author Web Link
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- Citations: 28
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Journal articlede Vicente J, Stokes JR, Spikes HA, 2006,
Soft lubrication of model hydrocolloids
, FOOD HYDROCOLLOIDS, Vol: 20, Pages: 483-491, ISSN: 0268-005X- Author Web Link
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- Citations: 142
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Conference paperMiklozic KT, Forbus R, Spikes HA, 2006,
Friction performance of combined antiwear and friction modifier systems
A study on the friction and tribo-film properties when molybdenum dithiocarbamate (MoDTC) solution lubricates surfaces covered with previously-formed zinc dithiophosphate (ZDDP) film was carried out. For the MoDTC oil solution, a remarkable friction reduction of coefficient of friction was observed in the boundary lubrication regime. Some alteration of the previously-formed ZDDP film could be seen. This is an abstract of a paper presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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Conference paperFan JY, Muller M, Spikes H, 2006,
Reduction of wear using functionalised PAMA viscosity modifiers
The wear performance of dispersant polyalkylmethacrylates (d-PAMA) was studied under pure sliding and mixed sliding/rolling conditions. Reference base oil and blends of functionalized PAMA and non-functionalized PAMA were tested using Bi-direction Mini Traction Machine and Inductively Coupled Plasma Atomic Emission Spectroscopy. Significant reductions in wear could be produced by appropriate concentrations of some functionalized PAMA. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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Conference paperDe Vicente J, Stokes J, Spikes H, 2006,
Soft-EHL - The tribology of tyres and tongues
Thick hydrodynamic lubricant films can be formed in soft-EHL contacts, even by low viscosity lubricants such as aqueous solutions, and this has practical relevance in both engineering and biological applications. Work to measure the friction of simple Newtonian liquids in soft-EHL contacts over a wide range of entrainment speeds and viscosities is presented. A new technique is described for separating the rolling and sliding components of friction. To study the boundary lubrication regime, solutions of a surfactant Tween 80 (ethoxylated-60-sorbitan monostearate) are examined. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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Conference paperSpikes HA, 2006,
Sixty years of EHL
The birth of EHL took place in 1945 and is graphically described by Cameron. Sixty years have elapsed since then, during which period EHL has progressed from infancy to maturity. A discussion presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006), covers the development of EHL research; numerical solutions of the line contact EHL problem; and optical interference image from point contact.
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Conference paperFujita H, Spikes HA, 2006,
The study of antiwear film formation kinetics
Despite the demand for a progressive decrease in phosphorus concentration in engine oils to reduce impact on the de-NOx catalyst and diesel particulate filter, ZnDTP have not yet been replaced completely by other antiwear additives. A study on the influence of ZnDTP type and concentration of dispersant on the antiwear film formation process was carried out. ZnDTP type strongly affected the formation process. Dispersant inhibited the antiwear film from being generated on rubbed surface and this effect increased with dispersant concentration. Film formation models and formula were discussed, which stimulate the film formation process. This is an abstract of a paper presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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Conference paperVan Beek A, Van Ostayen RAJ, Spikes HA, 2006,
Viscoelastic behavior of soft layered EHL curved slider bearings
The design of a water lubricated shaftless propeller bearing arrangement is presented. Because the bearing arrangement has to function in an aqueous environment, a polymer layer is applied at one of the bearing surfaces to obtain good start-stop conditions in the boundary lubrication regime and to obtain EHL at higher surface velocities. To properly design the bearing arrangement, consisting of multiple curved bearing pads sliding on the soft polymer layer, it is essential to be able to predict the effect of the viscoelastic material behavior on the formation of the thin lubricant film. The numerical model applied covers the hydrodynamic pressure distribution in a thin lubricant film and the elastic deformation of one of the slide surfaces. Both problems are coupled by the pressure distribution over the thin film. The pressure distribution depends on the film thickness profile and thus on deformation. The elastic deformation depends on the pressure. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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Conference paperNowell D, Dini D, 2006,
Explaining the size effect in fretting fatigue: short crack arrest and bounded asymptotic approaches
, Fatigue 2006 -
Conference paperHills DA, Churchman CM, Dini D, 2006,
The application of asymptotic solutions to Nucleation Prediction in Fretting Fatigue
, Fatigue 2006 -
Journal articleKorsunsky AM, Vorster WJJ, Zhang SY, et al., 2006,
The principle of strain reconstruction tomography: Determination of quench strain distribution from diffraction measurements
, ACTA MATERIALIA, Vol: 54, Pages: 2101-2108, ISSN: 1359-6454- Author Web Link
- Open Access Link
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- Citations: 33
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Journal articleMedina S, Olver AV, Shollock BA, 2006,
Rolling contact damage accumulation in two contrasting copper alloys
, WEAR, Vol: 260, Pages: 794-802, ISSN: 0043-1648- Author Web Link
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- Citations: 1
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Journal articlede Vicente J, Stokes JR, Spikes HA, 2006,
Rolling and sliding friction in compliant, lubricated contact
, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol: 220, Pages: 55-63, ISSN: 1350-6501- Author Web Link
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- Citations: 39
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Journal articleCambiella A, Benito JM, Pazos C, et al., 2006,
The effect of emulsifier concentration on the lubricating properties of oil-in-water emulsions
, TRIBOLOGY LETTERS, Vol: 22, Pages: 53-65, ISSN: 1023-8883- Author Web Link
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- Citations: 76
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Conference paperSpikes HA, Fan J, 2006,
Design of polymeric lubricant additives to reduce friction and wear
, 231st National Meeting of the American-Chemical-Society, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727 -
Journal articleDini V, Romanelli M, Piaggesi A, et al., 2006,
Cutaneous tissue engineering and lower extremity wounds (part 2).
, Int J Low Extrem Wounds, Vol: 5, Pages: 27-34, ISSN: 1534-7346In a previous article, this group described the principles involved in the development of bioengineered skin equivalents that held out much promise. This article has examined some of the uses of such products in treating venous ulcers, diabetic foot ulcers, and skin diseases leaving skin wounds. Data encouraging the use of such products in certain indications are available. The costs of using such products are also appreciated.
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Journal articleChoo JW, Olver AV, Spikes HA, et al., 2006,
The influence of longitudinal roughness in thin-film, mixed elastohydrodynamic lubrication
, TRIBOLOGY TRANSACTIONS, Vol: 49, Pages: 248-259, ISSN: 1040-2004- Author Web Link
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- Citations: 22
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Journal articleKadiric A, Sayles RS, Ioannides E, 2006,
Thermo-mechanical effects in layered rough surface contacts
, Proceedings of STLE/ASME International Joint Tribology Conference, IJTC 2006, Vol: 2006A recently developed thermo-mechanical model was used to study the temperature distribution in a sliding contact of a cylinder and a coated real rough surface. The model conducts a full thermo-mechanical analysis of the contact including the interactions between the thermal and elastic displacements and full heat division. Following a brief description of the numerical model, results are presented to illustrate the thermo-mechanical effects of various contact parameters, coating properties and surface roughness structure Copyright © 2006 by ASME.
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Conference paperFowell MT, Olver AV, Pegg IG, et al., 2006,
Two mechanisms of hydrodynamic lubrication in textured bearings
There is currently great interest in the use of textured bearings, where many tiny micropockets are incorporated in one of the bearing surfaces. Such texturing has been found to enhance load support and to reduce hydrodynamic friction in low load conditions, when the two surfaces have very low or zero convergence ratio, i.e. are essentially parallel. It is not immediately clear from hydrodynamic lubrication theory how a bearing with parallel surfaces and internal pockets can entrain any lubricant to form a hydrodynamic film and thus support load. However in a recent technical note the authors have shown that the occurrence of cavitation within micropockets results in suction of lubricant into the bearing, because the pressure inside the pockets is less than the surrounding, atmospheric pressure [1]. For parallel or very low convergence ratio bearings, this supply process replaces fluid entrainment as the main mechanism by which lubricant is drawn into the contact. In previous work this suction mechanism was demonstrated using a simple analytical approach for a 1D parallel bearing having a single pocket. The current paper extends this analytical method to convergent bearings having a single pocket and then applies a numerical solution of the first order Reynolds equation to solve for flow in multi-pocketed bearings. This enables the contribution of fluid suction on the load support of low convergence ratio bearings to be investigated. Copyright © 2006 by ASME.
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Journal articleCann PM, 2006,
The "leaves on the line" problem - A study of film formation and lubricity under simulated railtrack conditions
, Proceedings of STLE/ASME International Joint Tribology Conference, IJTC 2006, Vol: 2006The problem of leaf residue and loss of adhesion in the wheel/rail track contact has been studied in ball-on-disc test device. The friction properties of sycamore leaf samples were measured for a range of speeds and imposed slip at a maximum contact pressure of 1.0 GPa. At the end of the test the leaf lubricant films were examined under a low-power microscope and the organic content analysed by Infra-Red (IR) Reflection-Absorption Microspectroscopy. The test samples included water-saturated leaves and the supernatant soaking water to measure the effect of water-soluble leaf components. The results were compared to pure water. During the initial film formation the leaf samples rapidly formed a slurry composed of small black particles, this dried to a thick adherent black film as the test proceeded. This suggested that the black film was due to a chemical reaction between the water-soluble leaf component and steel rather than as the result of charring of the organic material. Friction coefficients of the leaf slurry were in the range μ=0.03-0.06 (50% slip) compared to values of μ=0.15-0.2 for pure water. Friction was also reduced in tests with the leaf-soaking water, suggesting that water-soluble leaf components (identified as pectin) play a role in the low adhesion mechanism. IR analysis showed that the black residue films contained pectin (pectate) and cellulose derived from the leaf samples. Pectin appears to play an important role in the lubrication process. In the presence of metal ions pectin will gel and thus could form a thin but highly viscous layer on the track surface. This gel will also flocculate cellulose to create the black biomass, which provides the lubricating film. Copyright © 2006 by ASME.
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Conference paperDini D, Hills DA, 2006,
On the nature of singularities and asymptotic fields in contact mechanics
, IJTC2006, STLE/ASME International Joint Tribology Conference -
Journal articleMüller M, Topolovec-Miklozic K, Dardin A, et al., 2006,
The design of boundary film-forming PMA viscosity modifiers
, TRIBOLOGY TRANSACTIONS, Vol: 49, Pages: 225-232, ISSN: 1040-2004- Author Web Link
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- Citations: 61
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Journal articleDini D, Hills DA, 2006,
When does a notch behave like a crack?
, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 220, Pages: 27-43, ISSN: 0954-4062- Author Web Link
- Open Access Link
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- Citations: 11
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Conference paperNowell D, Dini D, Hills DA, 2006,
Recent developments in the understanding of fretting fatigue
, 15th European Conference on Fracture, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 207-222, ISSN: 0013-7944- Author Web Link
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- Citations: 182
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Journal articleKondo S, Sayles RS, Lowe MJS, 2006,
A combined optical-ultrasonic method of establishing the compressibility of high-pressure oil and grease films entrapped in a ball on flat contact
, JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 128, Pages: 155-167, ISSN: 0742-4787- Author Web Link
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- Citations: 6
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Journal articleBaly H, Poll G, Cann PM, et al., 2006,
Correlation between model test devices and full bearing tests under grease lubricated conditions
, IUTAM SYMPOSIUM ON ELASTOHYDRODYNAMICS AND MICRO-ELASTOHYDRODYNAMICS, Vol: 134, Pages: 229-+, ISSN: 0925-0042- Author Web Link
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- Citations: 18
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Journal articleLee-Prudhoe I, Venner CH, Cann PM, et al., 2006,
Experimental and theoretical approaches to thin film lubrication problems
, IUTAM SYMPOSIUM ON ELASTOHYDRODYNAMICS AND MICRO-ELASTOHYDRODYNAMICS, Vol: 134, Pages: 241-+, ISSN: 0925-0042- Author Web Link
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- Citations: 3
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Conference paperDini D, Korsunsky AM, Dunne FPE, 2006,
Diffraction post-processor for polycrystalline plasticity modelling
, 7th European Conference on Residual Stresses (ECRS 7), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 427-432, ISSN: 0255-5476- Author Web Link
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- Citations: 2
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Journal articleOlver AV, Fowell MT, Spikes HA, et al., 2006,
'Inlet suction', a load support mechanism in non-convergent, pocketed, hydrodynamic bearings
, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, Vol: 220, Pages: 105-108, ISSN: 1350-6501 -
Journal articleReddyhoff T, Dwyer-Joyce R, Harper P, 2006,
Ultrasonic measurement of film thickness in mechanical seals
, Sealing Technology, Pages: 7-11, ISSN: 1350-4789Measurement of the interface film thickness of mechanical seals has been of interest to researchers and industry for many years. This feature describes work to measure the liquid film using a novel ultrasonic approach with a view to developing a condition monitoring tool. Initial tests were based on a laboratory simulation, to compare the method with optical interference and capacitance measurements. Tests were then carried out on a seal test rig. Film thickness was successfully recorded as speed and load was varied. 2006 Elsevier Ltd. All rights reserved.
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Conference paperKorsunsky AM, Zhang SY, Dini D, et al., 2006,
Oxford HEXameter: Laboratory high energy X-ray diffractometer for bulk residual stress analysis
, 7th European Conference on Residual Stresses (ERCS 7), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 743-748, ISSN: 0255-5476- Author Web Link
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- Citations: 4
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Conference paperDini D, Kim K, Nowell D, et al., 2006,
Multi-layer coatings for the enhancement of fretting fatigue performance
, 16th AeroMat Advanced Aerospace Materials & Processes Conference and Exposition, AeroMat 2005, Orlando, Florida, 6 - 9 June 2005, USA, Publisher: ASM -
Conference paperDwyer-Joyce RS, Reddyhoff T, 2006,
Ultrasonic measurement of EHL oil films in a mixed regime contact
, San Antonio, TX, United states, STLE/ASME International Joint Tribology Conference, IJTC 2006, October 23, 2006 - October 25, 2006, Publisher: American Society of Mechanical EngineersIn applications, such as gears and rolling bearings, where concentrated contact occurs, extreme loading can result in damaging asperity contact. To study this, an adapted elastohydrodynamic rig was used to measure the film using the reflection of an ultrasonic pulse. Ultrasonic reflection depends on the stiffness of the contact interface. The stiffness of an oil film depends on its thickness. A single contact was operated dry, full film lubricated, and in the mixed regime, by changing the sliding speed. The reflection then depends on the stiffness of both the liquid contact (oil film) and the solid (asperity) contact, acting as two springs in series. When dry, the solid stiffness dominates. As an oil film starts to form, a high stiffness thin liquid film forms. As the speed is increased the stiffness of this layer reduces, as its thickness increases, until it becomes thicker than the roughness and the stiffness then originates from liquid contact alone. By comparing dry, wet and sliding conditions the contributions of solid and liquid stiffness can be separated. Copyright 2006 by ASME.
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Journal articleDini D, Nowell D, Korsunsky AM, 2005,
Size and scale effects in fretting fatigue thresholds
, 11th International Conference on Fracture 2005, ICF11, Vol: 4, Pages: 2522-2527Components subject to fretting experience a peculiar combination of loading conditions, where contact and classical fatigue interact intricately to produce failure. As a consequence, the prediction of fretting fatigue limit curves poses a challenge, in part due to the large number of parameters governing the phenomenon. This poses an obstacle to formulating efficient predictive approaches. We demonstrate that these difficulties can be overcome successfully by means of a combination of experimental and computational approaches. Our analysis relies on various experimental data from Hertzian and 'flat and rounded' contact pad specimens and different calculation procedures developed previously, which resulted in fretting threshold curves for specific loading conditions. The derivation of such thresholds is however rather lengthy, so that for the purposes of formulating design rules a more efficient 'master curve' approach is proposed. This paper presents comprehensive results on the application of an efficient and concise functional description of the fretting fatigue threshold curves based on the use of a 'multi-scaling power law'. The predictions encompass all of the results obtained for different loading conditions by the stress-based approach and by short crack arrest methodology.
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Journal articleCann PM, Lubrecht AA, 2005,
Bearing performance limits with grease lubrication
, Proceedings of the World Tribology Congress III - WTC 2005, Pages: 35-36The effect of bearing design and operating in controlling lubricant supply to the contact zone was studied. Grease lubricated contacts are liable to starvation and as a result the film thickness is reduced, this can result in surface damage or premanufacture bearing failure. A starvation parameter capable of predicting the operating limits for a particular bearing/grease system was developed. Increasing bearing size, line contract geometries, and high load resulted in reduced lubricant replenishment of the contact. A limited amount of lubricant was available to the contact and efficient replenishment mechanisms were required to maintain an adequate film thickness level. Efficient relubrication was the key to higher speed operation and extended bearing life. This is an abstract presented at the World Tribology Congress III (Washington, DC 9/12-16/2005).
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