284 results found
Ewen JP, Heyes DM, Dini D, 2018, Advances in nonequilibrium molecular dynamics simulations of lubricants and additives, Friction, ISSN: 2223-7690
Ewen JP, Kannam S, Todd B, et al., 2018, Slip of hexadecane on organic friction modifier monolayers, APS March Meeting 2018, Publisher: American Physical Society, ISSN: 0003-0503
Ewen JP, Kannam SK, Todd BD, et al., 2018, Slip of Alkanes Confined between Surfactant Monolayers Adsorbed on Solid Surfaces, LANGMUIR, Vol: 34, Pages: 3864-3873, ISSN: 0743-7463
Ferretti A, Giacopini M, Mastrandrea L, et al., 2018, Investigation of the Influence of Different Asperity Contact Models on the Elastohydrodynamic Analysis of a Conrod Small-End/Piston Pin Coupling, WCX World Congress Experience
© 2018 SAE International. All Rights Reserved. Bearings represent one of the main responsible of friction losses in internal combustion engines and their lubrication performance has a crucial influence on the operating condition of the engine. In particular, the conrod small-end bearing is one of the most critical engine parts from a tribological point of view since limited contact surfaces have to sustain high inertial and combustion forces. In this contribution an analysis is performed of the tribological behaviour of the lubricated contact between the piston pin and the conrod small-end of a high performance motorbike engine. An algorithm is employed based on a complementarity formulation of the cavitation problem. A comparison between two different approaches to simulate the asperity contact problem is performed, the former based on the standard Greenwood-Tripp theory and the latter based on a complementarity formulation of the asperity contact problem. A model validation is performed by comparing the results with those obtained adopting the commercial software AVL Excite Power Unit. Similar results are obtained from both the approaches, if a proper calibration of the model input data is performed. However, a remarkable sensitivity is highlighted of the results obtained using the Greenwood/Tripp model to the adjustment parameters. The realistic (engineering) difficulty in defining and identifying the roughness data and their purely statistical nature returns results that may be afflicted by a dose of uncertainty. Considering that results of such simulations usually offer guidelines for a correct design of the coupling, further investigations are suggested to identify a relationship between simply available roughness data and model input, starting from a direct experimental measurements of real roughness profiles.
Forte AE, Galvan S, Dini D, 2018, Models and tissue mimics for brain shift simulations, BIOMECHANICS AND MODELING IN MECHANOBIOLOGY, Vol: 17, Pages: 249-261, ISSN: 1617-7959
Heyes DM, Dini D, Smith ER, 2018, Incremental viscosity by non-equilibrium molecular dynamics and the Eyring model, JOURNAL OF CHEMICAL PHYSICS, Vol: 148, ISSN: 0021-9606
Kanca Y, Milner P, Dini D, et al., 2018, Tribological properties of PVA/PVP blend hydrogels against articular cartilage, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 78, Pages: 36-45, ISSN: 1751-6161
Kanca Y, Milner P, Dini D, et al., 2018, Tribological evaluation of biomedical polycarbonate urethanes against articular cartilage, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 82, Pages: 394-402, ISSN: 1751-6161
Lu J, Reddyhoff T, Dini D, 2018, 3D Measurements of Lubricant and Surface Temperatures Within an Elastohydrodynamic Contact, TRIBOLOGY LETTERS, Vol: 66, ISSN: 1023-8883
Menga N, Carbone G, Dini D, 2018, Do uniform tangential interfacial stresses enhance adhesion?, Journal of the Mechanics and Physics of Solids, Vol: 112, Pages: 145-156, ISSN: 0022-5096
© 2017 Elsevier Ltd We present theoretical arguments, based on linear elasticity and thermodynamics, to show that interfacial tangential stresses in sliding adhesive soft contacts may lead to a significant increase of the effective energy of adhesion. A sizable expansion of the contact area is predicted in conditions corresponding to such scenario. These results are easily explained and are valid under the assumptions that: (i) sliding at the interface does not lead to any loss of adhesive interaction and (ii) spatial fluctuations of frictional stresses can be considered negligible. Our results are seemingly supported by existing experiments, and show that frictional stresses may lead to an increase of the effective energy of adhesion depending on which conditions are established at the interface of contacting bodies in the presence of adhesive forces.
Experiments over the last 50 years have suggested a tentative correlation between the surface (shear) viscosity and the stability of a foam or emulsion. We examine this link theoretically using small-amplitude capillary waves in the presence of a surfactant solution of dilute concentrations where the associated Marangoni and surface viscosity effects are modelled via the Boussinesq-Scriven formulation. The resulting integro-differential initial value problem is solved analyticallyand surface viscosity is found to contribute an overall damping effect on the amplitude of the capillary wave with varying degrees depending on the lengthscale of the system.Numerically, we find the critical damping wavelength to increase for increasing surface concentration but the rate of increase remains different for both the surface viscosity and the Marangoni effect.
Tajabadi-Ebrahimi M, Dini D, Balint DS, et al., 2018, Discrete crack dynamics: a planar model of crack propagation and crack-inclusion interactions in brittle materials, International Journal of Solids and Structures, ISSN: 0020-7683
The Multipole Method (MPM) is used to simulate the many-body self-consistentproblem of interacting elliptical micro-cracks and inclusions in single crystals. Acriterion is employed to determine the crack propagation path based on the stressdistribution; the evolution of individual micro-cracks and their interactions withexisting cracks and inclusions is then predicted using what we coin the DiscreteCrack Dynamics (DCD) method. DCD is fast (semi-analytical) and particularlysuitable for the simulation of evolving low-speed crack networks in brittle orquasi-brittle materials. The method is validated against finite element analysispredictions and previously published experimental data.
Vakis AI, Yastrebov VA, Scheibert J, et al., 2018, Modeling and simulation in tribology across scales: An overview, TRIBOLOGY INTERNATIONAL, Vol: 125, Pages: 169-199, ISSN: 0301-679X
Arana C, Evangelou SA, Dini D, 2017, Series Active Variable Geometry Suspension application to comfort enhancement, CONTROL ENGINEERING PRACTICE, Vol: 59, Pages: 111-126, ISSN: 0967-0661
Bodnarchuk MS, Dini D, Heyes DM, et al., 2017, Molecular Dynamics Studies of Overbased Detergents on a Water Surface, LANGMUIR, Vol: 33, Pages: 7263-7270, ISSN: 0743-7463
Bodnarchuk MS, Doncom KEB, Wright DB, et al., 2017, Polyelectrolyte pK(a) from experiment and molecular dynamics simulation, RSC ADVANCES, Vol: 7, Pages: 20007-20014, ISSN: 2046-2069
Ewen J, Gattinoni C, Spikes H, et al., 2017, Nonequilibrium molecular dynamics simulations of organic friction modifiers, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Ewen JP, Gattinoni C, Zhang J, et al., 2017, On the effect of confined fluid molecular structure on nonequilibrium phase behaviour and friction, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 17883-17894, ISSN: 1463-9076
Ewen JP, Restrepo SE, Morgan N, et al., 2017, Nonequilibrium molecular dynamics simulations of stearic acid adsorbed on iron surfaces with nanoscale roughness, TRIBOLOGY INTERNATIONAL, Vol: 107, Pages: 264-273, ISSN: 0301-679X
Forte AE, Gentleman SM, Dini D, 2017, On the characterization of the heterogeneous mechanical response of human brain tissue, BIOMECHANICS AND MODELING IN MECHANOBIOLOGY, Vol: 16, Pages: 907-920, ISSN: 1617-7959
Gurrutxaga-Lerma B, Balint DS, Dini D, et al., 2017, A Dynamic Discrete Dislocation Plasticity study of elastodynamic shielding of stationary cracks, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 98, Pages: 1-11, ISSN: 0022-5096
Gurrutxaga-Lerma B, Shehadeh MA, Balint DS, et al., 2017, The effect of temperature on the elastic precursor decay in shock loaded FCC aluminium and BCC iron, INTERNATIONAL JOURNAL OF PLASTICITY, Vol: 96, Pages: 135-155, ISSN: 0749-6419
Hajishafiee A, Kadiric A, Ioannides S, et al., 2017, A coupled finite-volume CFD solver for two-dimensional elasto-hydrodynamic lubrication problems with particular application to rolling element bearings, TRIBOLOGY INTERNATIONAL, Vol: 109, Pages: 258-273, ISSN: 0301-679X
Heyes DM, Dini D, Smith ER, et al., 2017, Nanowire Stretching by Non-Equilibrium Molecular Dynamics, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, Vol: 254, ISSN: 0370-1972
Hu H, Wen J, Bao L, et al., 2017, Significant and stable drag reduction with air rings confined by alternated superhydrophobic and hydrophilic strips, SCIENCE ADVANCES, Vol: 3, ISSN: 2375-2548
Knight C, Abdol Azis MH, O'Sullivan C, et al., 2017, Sensitivity analysis of Immersed Boundary Method simulations of fluid flow in dense polydisperse random grain packings, ISSN: 2101-6275
© The Authors, published by EDP Sciences, 2017. Polydisperse granular materials are ubiquitous in nature and industry. Despite this, knowledge of the momentum coupling between the fluid and solid phases in dense saturated grain packings comes almost exclusively from empirical correlations [2-4, 8] with monosized media. The Immersed Boundary Method (IBM) is a Computational Fluid Dynamics (CFD) modelling technique capable of resolving pore scale fluid flow and fluid-particle interaction forces in polydisperse media at the grain scale. Validation of the IBM in the low Reynolds number, high concentration limit was performed by comparing simulations of flow through ordered arrays of spheres with the boundary integral results of Zick and Homsy . Random grain packings were studied with linearly graded particle size distributions with a range of coefficient of uniformity values (Cu= 1.01, 1.50, and 2.00) at a range of concentrations (Φ ∈ [0.396; 0.681]) in order to investigate the influence of polydispersity on drag and permeability. The sensitivity of the IBM results to the choice of radius retraction parameter  was investigated and a comparison was made between the predicted forces and the widely used Ergun correlation .
Ma S, Scaraggi M, Lin P, et al., 2017, Nanohydrogel Brushes for Switchable Underwater Adhesion, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 121, Pages: 8452-8463, ISSN: 1932-7447
Mackowiak S, Heyes DM, Pieprzyk S, et al., 2017, Non-Equilibrium Phase Behavior of Confined Molecular Films at Low Shear Rates, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, Vol: 254, ISSN: 0370-1972
McCarron R, Stewart D, Shipway P, et al., 2017, Sliding wear analysis of cobalt based alloys in nuclear reactor conditions, WEAR, Vol: 376, Pages: 1489-1501, ISSN: 0043-1648
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