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Journal articles on the topic 'Hydrodynamic lubrication mode'
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1
Албагачиев, Али, Ali Albagachiev, Владимир Данилов, and Vladimir Danilov. "MAGNETIC LIQUID IN HYDRODYNAMIC LUBRICATION MODE OF SPHERICAL SURFACES." Bulletin of Bryansk state technical university 2016, no. 3 (2016): 90–93. http://dx.doi.org/10.12737/22017.
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From the position of the hydrodynamic lubrication theory are considered the peculiarities of magnetoliquid lubrication in a point contact determined with a complicated character of the interaction of hydrodynamic and magnetic forces in a lubrication layer. The pressure distribution in a lubrication layer of magnetic liquid is considered as a superposition of the augend and addend pr and pm induced with hydrodynamic and magnetic forces. The contribution of the constituent pr is described by Reynolds equation in accordance with the classic hydrodynamic theory. At the saturation of magnetic liquid the constituent pm is presented as a function of the magnetic field strength, saturation magnetization of magnetic liquid and its viscosity and also velocity of rolling. As a result of the solution of a hydrodynamic problem through a numerical method there are defined conditions under which a lubrication layer loses its stability that is followed with the loss of carrying capacity in areas with negative pressure. The dependences of resistance to rolling forces, and sliding ones in a contact of spherical surfaces.
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Mikosianchyk, O., O. Yakobchuk, R. Mnatsakanov, and A. Khimko. "Evaluation of operational properties of aviation oils by tribological parameters." Problems of tribology 99, no. 1 (2021): 43–50. http://dx.doi.org/10.31891/2079-1372-2021-99-1-43-50.
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The quality of aviation oils was evaluated online on the basis of their lubricating, antifriction, rheological and antiwear properties in the friction contact. The use of the software and hardware complex for evaluation of operational characteristics of triboelements is offered. Approbation of the proposed methodology was performed on aviation oils SM-9. The increase in antifriction properties of the “Bora B” SM-9 oil was established to be due to the formation of limiting adsorption layers of lubricant on friction-activated contact surfaces, which are characterized by low shear stresses of the lubricant, and their structuring provides high effective viscosity in the contact at a level of 5142 Pa.s. It was revealed that at start-up the lubricant temperature is 20 0С and the mixed lubrication mode prevails, but with increasing the lubricant temperature to 100 0С the elastic-hydrodynamic (contact-hydrodynamic) lubrication mode dominates, then at maximum rotation speed of friction pairs the hydrodynamic lubrication mode dominates, regardless of oil temperature, which indicates the effective separation of the contact surfaces due to the formation of a lubricating layer between them. Analysis of the specific work of friction in the friction contact showed that the instability of this parameter evidences to intensification of destructive processes in the near-surface layers of metal and reduction in its wear resistance. The decrease in wear resistance of the lagging surface in the conditions of rolling with sliding for all types of investigated oils is due to the different directions of the friction force vector in the contact. In the course of operation of friction pairs in nonstationary conditions, the softening of the surface metal layers occurs, which has a positive effect on the tribological processes in the contact. The practical significance of the work consists in developing a methodology of analysis of lubricants, which makes it possible to more accurately evaluate their performance and provide recommendations for the choice of lubricant for specific friction units.
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AKHVERDIEV, K. S., E. A. BOLGOVA, E. O. LAGUNOVA, and S. V. KUMANIN. "HYDRODYNAMIC CALCULATION OF A WEDGE-SHAPED SYSTEM «SLIDER – GUIDE» OPERATING ON A COMPRESSIBLE LUBRICANT IN THE PRESENCE OF MELT ON THE SURFACE OF THE GUIDE." Fundamental and Applied Problems of Engineering and Technology 2 (2021): 109–17. http://dx.doi.org/10.33979/2073-7408-2021-346-2-109-117.
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Recently, various methods have been used to ensure the hydrodynamic mode of lubrication, one of the methods is devoted to this scientific article. In the article, on the basis of the equation of motion of a compressible, truly viscous liquid for a "thin layer", the equations of state, the continuity equation, as well as the equations describing the profile of the molten contour of the surface of the support ring, an asymptotic and self-similar solution is found for the zero (without taking into account the melt) and the first (taking into account the melt) approximation, for determining the velocity field and pressure in the lubricating layer. For the profile of the molten contour and the pressure, the solution is found by the method of sequential approximation, for the extreme and non-extreme case. As a result, a refined mathematical calculation model of a wedge-shaped sliding support with a low-melting metal coating on the movable contact surface is developed, which compensates for the emergency lack of lubricant and provides a stable hydrodynamic lubrication mode, which allows determining the bearing capacity and friction force. As a result of numerical analysis, the obtained refined mathematical calculation model of a wedge-shaped sliding support with a low-melting metal coating on the surface of the support ring, taking into account the compressibility of the liquid lubricant and the coating melt, and experimental research, the effectiveness of the obtained complex of refined models that allow performing both pre-design evaluation and design engineering calculations, in a wide range of operational load-speed modes, as well as the mechanism and stages of transition to lubrication with metal sprays is established, providing an increase in the level of the main tribotechnical parameters and the resource of tribosystems.
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Milanenko, O., and A. Bobro. "Multifactorial criterion evaluation of lubrication efficiency and wear resistance of friction units operating under extreme operating conditions." Problems of Tribology 30, no. 2/116 (2025): 6–13. https://doi.org/10.31891/2079-1372-2025-116-2-6-13.
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A new multifactor criterial approach to modifying lubricants by rheological properties and chemical composition is proposed in order to increase the lubricating ability of modified layers and wear resistance of friction units from the position of mixed lubrication conditions. Prevention of micro-EНD lubricating layer is achieved by a set of measures: implementation of stable micro-EHD lubrication by the criterion of lubrication mode; optimal viscosity class with an increase in the fraction of hydrodynamic pressure of modified layers relative to the contact pressure from micro-unevenness of rough surfaces by the pressure criterion; optimal type of lubricant by the rheological criterion; assessment of the appearance of a plastically deformed state by the criterion of plasticity; selection of the qualitative and quantitative chemical composition of active components in the lubricant to create durable modified layers with high structural adaptability and thermomechanical stability by the temperature criterion. A new concept for increasing lubricity and wear resistance for friction units operating in extreme operating conditions, using an appropriate criteria approach, takes into account: non-stationary friction conditions, the shape of local contact and friction kinematics, rheological properties of lubricating layers, contact temperature, and the composition of components in the lubricant
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Kaneko, Satoru, Hiroyuki Takabatake, and Kanya Ito. "Numerical Analysis of Static Characteristics at Start of Operation in Porous Journal Bearings With Sealed Ends." Journal of Tribology 121, no. 1 (1999): 62–68. http://dx.doi.org/10.1115/1.2833812.
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Static characteristics at the start of the operation are theoretically investigated in a porous journal bearing with sealed ends lubricated only by the oil initially provided within its pores. This is a preliminary study for estimating the variation of these characteristics with running time. A simple analytical model of the mixed lubrication regime is proposed on the basis of the assumption that the external forces acting on the journal, i.e., the applied static load, the oil-film force and the force at the boundary friction part, are balanced. Numerical results show that air penetrates into the porous matrix at the oil-film rupture zone due to negative pressure in the porous matrix; this causes the reduction of oil content within the porous matrix and contributes to formation of the oil film in the bearing clearance. The oil leakage from the porous matrix induced by the air penetration suggests that, even if hydrodynamic lubrication conditions are possible at the start of operation, the lubrication mode will become mixed or boundary lubrication conditions with running time. The numerical data on the static characteristics are presented in graphical form, illustrating the effects of the Sommerfeld number in the hydrodynamic and mixed lubrication regimes.
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Tichy, J. "Rheological Behavior of Confined Fluids in Thin Lubricated Contacts." Journal of Applied Mechanics 68, no. 2 (1999): 278–83. http://dx.doi.org/10.1115/1.1354204.
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Continuum based methods are traditionally thought to be of little value in describing boundary lubrication, or the mode of lubrication in molecular scale films that may occur at asperity interactions during the sliding of nominally flat surfaces. There is considerable experimental evidence, which suggests that the classical theory may be valid with modification to films as thin as several nanometers. In addition, lubricants, which exhibit viscous liquid properties in bulk, may form attached solid-like elastic layers when confined between solid surfaces. In the present paper, the simple “elastic foundation” concept is used to model the elastic layers, in contact with a viscous fluid film. Several typical bearing contact flow problems are solved, giving hope that boundary lubrication may eventually be modeled in the same manner as hydrodynamic lubrication in thicker films.
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Леванов, Игорь, Igor Levanov, Елена Задорожная, Elena Zadorozhnaya, Артём Дудников, and Artem Dudnikov. "METHODOLOGY IN DEFINITION OF CONROD BEARINGS LIFE OF HEAT-ENGINE." Bulletin of Bryansk state technical university 2016, no. 3 (2016): 46–57. http://dx.doi.org/10.12737/22168.
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The paper reports the sequence of the definition of bearings resource in a crank gear of heatengines. A brief description is given regarding the procedure for the computation of bearing hydromechanical properties in terms of hydrodynamic theory of lubrication and that of the procedure for the definition of an area of contact interaction. The input equations for the computation of dynamics and lubrication are: the equation for the field of hydrodynamic pressures in a lubrication layer separating random loaded surfaces (Reynolds equation); the equations set of plane motion of a shaft journal center; the heatbalance equation manifesting the equality of heat values mean in a cycle of load disseminated in a lubrication layer of a bearing and heat removed by lubricant flowing out in its faces. The procedure for the determination of an area of a contact interaction is developed in accordance with a molecular-mechanical theory of friction and a fatigue theory of wear according to I.V. Kragelsky. The extension of the area of a contact interaction (an area of the violation of a hydrodynamic mode of lubrication) in a slider bearing was defined in terms of the computation of the de-pendence of a minimum thickness in a lubrication layer of a bearing of a connecting rod upper head upon a rotation angle of a crankshaft. At the same time there were taken into account: the non-Newton’s properties of a lubricant; the presence of oil feeding sources on friction surfaces; possible deviations of friction surfaces from a regular form. The procedures presented at the given stage can be used for a comparative assessment of tribocouplings life in heatengines at an initial stage of designing.
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Korchagina, M. V., V. N. Stepanov, S. O. Kireev, and A. R. Lebedev. "Investigation of Parameters Influencing the Establishment of Hydrostatic Mode in the Crosshead-Guide Assembly of High-Pressure Plunger Pump." Advanced Engineering Research (Rostov-on-Don) 24, no. 4 (2024): 316–27. https://doi.org/10.23947/2687-1653-2024-24-4-316-327.
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Introduction. When applying hydraulic fracturing technology to increase the efficiency of formation fluids, high-pressure pumps with a crosshead drive assembly are used. The major problem in the operation of these pumps is the wear of the crosshead guides. The crosshead is a flat sliding friction pair, leading to wear of the plunger seals and a decrease in the basic pump performance indicators. To solve this problem, it was previously proposed to use new materials and antifriction coatings, original designs of friction units, etc. However, a detailed description and solution to the problem under consideration has not been found in the literature at present. The objective of this study is to determine, under maximum load, the influence of the unit design, process temperature and pressure in the lubrication system on the values of the parameters that provide for the hydrostatic mode for a flat thrust bearing in a crosshead-guide unit of a high-pressure plunger pump.Materials and Methods. The parameters were determined by the simulation technique using modal analysis applicable in the case of high dynamic loads acting on the studied unit. The calculation of the hydrodynamic parameters of the lubricating layer was based on the combination of the Reynolds model and the Stokes model in numerical modeling. The study was conducted using a calculation model representing a section of a plunger pump, considered as “flexible bodies” model, in the field of gravity forces. The mathematical dependences of the parameters under consideration were presented in the form of regression equations obtained from the results of a numerical experiment.Results. The maximum load on the lower crosshead guide was determined, for which further hydrodynamic studies were conducted. Factors influencing the process were studied — gaps filled with lubricant (depending on the design of the unit), temperature, and pressure in the lubrication system. Mathematical dependences of the influence of the considered factors on the values of the parameters determining the establishment of the hydrostatic mode were obtained.Discussion and Conclusion. The obtained mathematical models show the degree and influence of the factors under consideration on the studied parameters of the hydrostatic lubrication mode of the unit — the force acting on the crosshead from the lubricating layer, and the mass flow rate of the lubricant at the outlet of the system. It is found that the greatest influence is exerted by the change in the volume of gaps filled with lubricant, the mass flow rate of lubricant at the entrance to the system, which simulates the increase in pressure in the lubrication system of the friction unit. The results obtained do not contradict the conclusions reached in works on similar topics, and can be used in further research.
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Wang, Yan Qing, Hai Feng Yang, Qing Gong Han, Liang Fang, and Shi Rong Ge. "Tribological and Lubrication Properties of Sandblast-Textured Surfaces with Varied Roughness." Advanced Materials Research 154-155 (October 2010): 1019–22. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1019.
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Surface roughening, with certain roughness topography, is thought to be as an effective tribological method of decreasing friction coefficient of kinematic pairs. Friction and wear of AISI1045 steel surface roughened by convenient and economical way of sandblasting was investigated under lubrication conditions. Roughened and polished samples run against Φ4mm GCr15 pin lubricated by engine oil were tested in reciprocating mode with different load and speed on UMT- testing machine. It is found that there exists the optima surface roughness (Ra is about 3.92μm) roughened by sandblasting in which the least wettability contact angle between engine oil and textured steel surface is obtained, hence the lowest friction coefficient and wear rate is due to the optima hydrodynamic sliding property, although the sliding surface was not in hydrodynamic lubrication state.
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Oh, Kong Ping. "The Formulation of the Mixed Lubrication Problem as a Generalized Nonlinear Complementarity Problem." Journal of Tribology 108, no. 4 (1986): 598–603. http://dx.doi.org/10.1115/1.3261274.
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The mixed-lubrication problem is formulated as a nonlinear generalized complementarity problem in which the pressure acting on the load-bearing surface is taken as the unknown, and the lubricant flow and the gap between the surfaces are taken as its complements. An iterative method was developed to find the solution, which satisfies the complementarity condition that at each point on the load-bearing surface, the pressure or at least one of its complements, is zero at all times. Moreover, the pressure and its complements satisfy non-negativity constraints. The solution intrinsically decomposes the load-bearing surface into three distinct subregions: solid-to-solid contact, hydrodynamically lubricated contact, and no contact (or cavitation). It is shown that the mixed-lubrication formulation degenerates into the special cases of hydrodynamic or solid-to-solid contacts under appropriate load and speed conditions. A journal bearing with elastic support is analyzed to illustrate the method of solution. The transition of the lubrication mode from pure hydrodynamic contact to mixed contact is demonstrated.
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Ilina, O. A., O. O. Mikosianchyk, O. P. Yashchuk, R. H. Mnatsakanov, and N. M. Berezivskyi. "Tribomonitoring of the quality of aviation hydraulic oils according to lubricity and rheological indicators." Problems of Tribology 28, no. 1/107 (2023): 34–40. http://dx.doi.org/10.31891/2079-1372-2023-107-1-34-40.
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The study proposes a diagnostic control method for assessing the quality of commercial batches of hydraulic oils based on the kinetics of changes in the thickness of lubricating layers, shear stresses of the lubricating material, and effective viscosity in tribotechnical contact. Timely and high-quality tribomonitoring of lubricants provides a perspective on their rational use and reduced wear of equipment parts. The developed methodology simulates the operation of gears in rolling conditions with a slip of 30% using a roller analogy. Samples of AMG-10 oil from two manufacturers were analyzed. For "Bora B" AMG-10 oil (sample 1) with gradients of the sliding speed of the lubricating layer in contact from 5.63·103 to 5.73·105 с-1, the effective viscosity is set at the level of 4249 and 5039 Pa·s at a bulk oil temperature of 20 and 100 oС, respectively, which indicates the resistance of oil components to destruction under conditions of increasing shear rate gradient. For AMG-10 oil (sample 2), the effective contact viscosity decreases by 1.53 times both at an oil temperature of 20 oС and at 100 oС and is 2764 Pa·s (at 20 oС) and 3309 Pa·s (at 100 oС), which indicates the destruction of the components of the lubricant. For "Bora B" AMG-10 oil, effective lubricating properties have been established both during the start-up period and at maximum revolutions in conditions of rolling with slipping. It was shown that at start-up, regardless of the temperature of the lubricant, the mixed lubrication mode dominates. At the maximum revolutions of the tested samples, the hydrodynamic lubrication mode dominates, which indicates the effective lubricating properties of the Bora B AMG-10 oil. According to the kinetics of changes in the rheological parameters of oils, it was established that the resistance of the lubricant's components to mechano-thermal destruction under non-stationary lubrication conditions contributes to the effective formation of a lubricating layer in contact with a high bearing capacity
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Hou, Ya Li, and Chang He Li. "Numerical Simulation of Hydrodynamic Fluid Pressure in Grinding Zone with Resin-Bonded Diamond Grinding Wheel." Key Engineering Materials 426-427 (January 2010): 668–73. http://dx.doi.org/10.4028/www.scientific.net/kem.426-427.668.
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In the grinding process, grinding fluid is delivered for the purposes of chip flushing, cooling, lubrication and chemical protection of work surface. Lubrication and cooling are the most important roles provided by a grinding fluid. Hence, the conventional method of flood delivering coolant fluid by a nozzle in order to achieve high process performance purposivelly. However, hydrodynamic fluid pressure can be generated ahead of the grinding zone due to the wedge effect between wheel peripheral surface and part surface. In the paper, a theoretical hydrodynamic pressure modeling is presented for flow of coolant fluid through the grinding zone in flood delivery mode in the surface grinding using resin-bonded diamond grinding wheel, which based on Navier-Stokes equation and continuous formulae. The numerical simulation results showed that the hydrodynamic pressure was proportion to grinding wheel velocity, and inverse proportion to the minimum gap between wheel and workpiece and the maximum pressure was generated just in the minimum clearance region in which higher fluid pressure gradient occur. It can also be concluded the pressure distribution was uniform in the direction of width of wheel except at the edge of wheel because of the side-leakage.
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Chen, Juan, Jie Zhou, Binbin Ji, Liangcai Zeng, Yang Mao, and Jun Wei. "Experimental Investigation of Lubrication Performance of Rhombic-Textured TiN-Coated Surfaces Under Lubricated Conditions." Coatings 15, no. 5 (2025): 594. https://doi.org/10.3390/coatings15050594.
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Surface texture and titanium nitride (TiN) coating have been established as effective methods for enhancing the tribological properties of mechanical friction pairs. This work aims to investigate the lubrication performance of rhombic-textured TiN-coated surfaces under oil-lubricated conditions using a pin-on-disk test mode. A total of 17 sets of samples were designed, including a control sample (with no rhombic texture and no TiN coating), a TiN-coated sample and rhombic-textured TiN-coated samples. The rhombic surface texture was fabricated using the end surface of a brass bar. TiN coating deposited TiN on the textured surface. This study focuses on measuring and comparatively analyzing the lubrication load capacity, friction coefficient (COF) and binding force of TiN coatings/substrates in the pin-on-disk friction test mode. Compared with the bare control sample, a rhombic texture can enhance lubrication load-carrying capacity by generating hydrodynamic lubrication effects, thereby reducing friction. Additionally, a rhombic texture enables the mitigation of third-body wear due to wear debris. This research provides valuable insights into the design and fabrication of mechanical friction pairs with high wear resistance under oil-lubricated conditions. For lubrication property enhancement, the influence of groove depth was larger than that of the length of the rhombic side.
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Ouyang, Wu, Bin Wang, and Jian Huang. "Regional Characteristics and Control Method of the Mixing Flow Pattern for Water-Lubricated Tilting Pad Thrust Bearings." Applied Sciences 12, no. 14 (2022): 6999. http://dx.doi.org/10.3390/app12146999.
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The water-lubricated tilting pad thrust bearings (WTTBs) of the reactor coolant main pump and high-power RDT operate at a large linear velocity, heavy load, and low viscosity. On the basis of the performance prediction of WTTBs in the mixing flow pattern, a hypothesis of the regional flow pattern is proposed. To compare the lubrication performance under four kinds of flow pattern modes, a thermo-elasto-hydrodynamic lubrication model of the WTTB considering the flow pattern is established, and a partition iteration algorithm for the mixing flow pattern is provided. Moreover, a method for controlling the flow pattern by changing the pad surface morphology is proposed. A simulation is used to indicate that the bearing performance under the mixing flow pattern calculated by the regional flow pattern mode is between that of the laminar and turbulent flows. The regional mixing flow pattern mode can automatically retrogress to the single flow pattern mode by changing the operation conditions. Both the circumferential bulge and radial concave pad surfaces are beneficial for increasing the turbulent area and thereby improving the load-carrying capacity of the WTTB.
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Yin, Bifeng, Bo Xu, Hekun Jia, Huiqin Zhou, Yonghong Fu, and Xijun Hua. "Effects of the array modes of laser-textured micro-dimples on the tribological performance of cylinder liner–piston ring." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, no. 7 (2017): 871–81. http://dx.doi.org/10.1177/1350650117732718.
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A mixed lubrication model of textured cylinder liner–piston ring was built to investigate the effects of four array modes namely, square array, stagger array, stretching, and shortening along liner axis array of micro-dimples on the tribological properties of cylinder liner–piston ring pair. The simulation results indicate that micro-dimples can enhance the hydrodynamic effects of lube oil, improving the film bearing capability. However, the effects differ significantly under the four dimple array modes: for square array, the cylinder liner–piston ring pair is well lubricated due to the synergistic effects of uniformly spaced micro-dimples that form homogeneous bearing film even around the fired top dead center where the lubrication condition is harsh; while the film of stagger array is the thinnest among the four schemes, which means its lubrication is also the worst. From square array mode, to shortening and stretching along liner axis array, then to stagger array mode, the total friction force of cylinder liner–piston ring shows an upward trend. By utilizing laser surface texturing method, square array, stretching along liner axis array, and stagger array of micro-dimples were textured on the gasoline engine cylinder bores, followed by a set of engine bench tests. The experimental results demonstrate that the engine motored torque of the three array modes increases in turns, which validates that the anti-friction effect of square array is optimal whereas that of stagger array is the most inefficient.
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Yu, Zhaosheng, Yutian Yang, and Jianzhong Lin. "Lubrication Force Saturation Matters for the Critical Separation Size of the Non-Colloidal Spherical Particle in the Deterministic Lateral Displacement Device." Applied Sciences 12, no. 5 (2022): 2733. http://dx.doi.org/10.3390/app12052733.
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Deterministic lateral displacement (DLD) is a popular technique for separating micro-scale and nano-scale particles continuously. In this paper, an efficient three-dimensional fictitious domain method is developed for the direct numerical simulation of the motion of a non-colloidal spherical particle in the DLD device (i.e., cylinder array), based on substantial modification of our previous FD method. A combination of the fast Fourier transformation (FFT) and a tri-diagonal solver is developed to efficiently solve the pressure Poisson equation for a DLD unit with a shifted periodic boundary condition in the streamwise direction. The lubrication force correction is adopted in the fictitious domain method to correct the unresolved hydrodynamic force when the particle is close to the cylinder with the gap distance below one mesh, and the lubrication force is assumed to saturate at a smaller critical gap distance as a result of the surface roughness effect. The proposed method is then employed to investigate the effect of the critical gap distance of the lubrication force saturation on the motion mode (i.e., separation size) of the particle in the DLD device. Our results indicate that the lubrication force saturation is important to the particle critical separation size, and a smaller saturation distance generally makes the particle more prone to the zigzag mode.
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Chen, Zhi Lan, and Jun Zhu. "Comparison with Thermo Hydrodynamic Lubrication between 2D and 3D Model in Thrust Bearing by Computing Simulation." Advanced Materials Research 129-131 (August 2010): 1336–40. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.1336.
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As the interface problem of discontinuity boundary condition between the oil film and the pad in thrust bearing, a conjugated solution method by using the temperature continuity and the heat flux continue is proposed. The three-dimensional calculated model of thrust bearing is constructed and solved by using finite difference method. Comparing with 2D model, the characteristics of the lubrication performance of 3D model are more different. The results show that the three-dimensional calculated model not only revealed the relation of temperature variation between the oil film layer and the pad in axial direction, but also exactly reflected real temperature distribution in the pad surface. In the same oil feed temperature condition, the minimum film thickness is 63.8μm and the maximum temperature on the pad surface reached 55°C for 3D mode, 72.6μm and 60°C for 2D mode.
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Qin, Zhaoju, Chenheng Yuan, Yanpeng Yuan, and Yuanyuan Huang. "Tribological characteristics of piston rings in a single-piston hydraulic free-piston engine." Industrial Lubrication and Tribology 69, no. 2 (2017): 131–41. http://dx.doi.org/10.1108/ilt-01-2015-0011.
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Purpose A free-piston engine (FPE) is an unconventional engine that abandons the crank system. This paper aims to focus on a numerical simulation for the lubricating characteristics of piston rings in a single-piston hydraulic free-piston engine (HFPE). Design/methodology/approach A time-based numerical simulation program was built using Matlab to define the piston motion of the new engine. And a lubrication mode of piston rings was built which is based on the gas flow equation, hydrodynamic lubrication equation and the asperity contact equation. The piston motion and the lubrication model are coupled, and then the finite difference method is used to obtain the piston rings lubrication performances of the FPE. Meanwhile, the lubrication characteristics of the new engine were compared with those of a corresponding conventional crankshaft-driven engine. Findings The study results indicate that compared with the traditional engine, the expansion stroke of the HFPE is longer, and the compression stroke is shorter. Lubrication oil film of the new engine is thicker than the traditional engine during the initial stage of compression stroke and the final stage of the power stroke. The average friction force and power of the hydraulic free piston engine are slightly lower than those of the traditional engine, but the peak friction power of the FPE is significantly greater than that of the traditional engine. With an increase in load, the friction loss power and friction loss efficiency decrease, and with a decrease in equivalence ratio, the friction power loss reduces, but the friction loss efficiency decreases first and then increases. Research limitations/implications In this paper, only qualitative analysis was performed on the tribological difference between conventional crankshaft engine and HFPE, instead of a quantitative one. Practical implications This paper contributes to the tribological design method of HFPE. Social implications No social implications are available now, as the HFPE is under the development phase. However, the authors are positive that their work will be commercialized in the near future. Originality/value The main originality of the paper can be introduced as follows: the lubrication and friction characteristics of the new engine (HFPE) were investigated and revealed, which have not been studied before; the effect of the HFPE’s special piston motion on the tribological characteristics was considered in the lubrication simulation. The results show that compared with the traditional crankshaft engine, the new engine shows a different lubrication performance because of its free piston motion.
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EROKHIN, MIKHAIL N. "USE OF THE SELECTIVE TRANSFER MECHANISM IN MOVABLE COUPLINGS USED IN POWER TRANSMISSIONS OF AGRICULTURAL MACHINES." Agricultural engineering, no. 2 (2022): 52–58. http://dx.doi.org/10.26897/2687-1149-2022-2-52-58.
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Searching for new effective ways of increasing the wear resistance of power transmissions and improving their durability, the authors propose a device for enriching the lubrication system of power transmissions with copper-alloying elements. The tribochemical processes have been studied and the components of the lubricating composition have been selected to provide for the self-organized selective transfer in the “steel-steel” friction couples accompanied by the formation of a servovit film. The authors developed a utility model for enriching the lubricating system oil with copper-alloying elements for power transmission. For testing the effectiveness of the proposed additive and the method of forming the servovit film during operation, a roller test bench was used. It provided for synchronous measurement of the wear rate and the friction force moment during the whole experiment without disconnecting the friction zone. The friction zone (test contact) was formed by the cyclic surfaces of a roller with a diameter of 70.0 ± 0.1 mm made of steel 45 (HRs 50) and a homogenized pad with a radius of 35.0 ± 0.1 mm and dimensions (plan view) of 2.01 mm (along the sliding line) and 7.27 mm (across the sliding line). The friction area was 0.1461 cm2. A set of normal forces: 730; 925; and 1130 N – was experimentally determined to ensure that there was no seizure. The shaft speed of 100 min-1 (a linear velocity of 0.37 m) was experimentally chosen under the condition of guaranteed absence of the hydrodynamic lubrication mode. The presented method of cladding additive production is easily implemented in the transmission units and also prevents the sedimentary instability of the lubricating composition. The device for enriching the lubricating system oil with copper alloying elements in the process of operation provides for a stable and self-organized mode of selective transfer. The results of tribological studies have shown the high efficiency of the cladding additive – the wear rate in the range of the normal force of 720 to 1130 N has reduced in 2.8…7 times.
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EROKHIN, MIKHAIL N. "USE OF THE SELECTIVE TRANSFER MECHANISM IN MOVABLE COUPLINGS USED IN POWER TRANSMISSIONS OF AGRICULTURAL MACHINES." Agricultural engineering, no. 2 (2022): 52–58. http://dx.doi.org/10.26897/2687-1149-2022-2-52-58.
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Searching for new effective ways of increasing the wear resistance of power transmissions and improving their durability, the authors propose a device for enriching the lubrication system of power transmissions with copper-alloying elements. The tribochemical processes have been studied and the components of the lubricating composition have been selected to provide for the self-organized selective transfer in the “steel-steel” friction couples accompanied by the formation of a servovit film. The authors developed a utility model for enriching the lubricating system oil with copper-alloying elements for power transmission. For testing the effectiveness of the proposed additive and the method of forming the servovit film during operation, a roller test bench was used. It provided for synchronous measurement of the wear rate and the friction force moment during the whole experiment without disconnecting the friction zone. The friction zone (test contact) was formed by the cyclic surfaces of a roller with a diameter of 70.0 ± 0.1 mm made of steel 45 (HRs 50) and a homogenized pad with a radius of 35.0 ± 0.1 mm and dimensions (plan view) of 2.01 mm (along the sliding line) and 7.27 mm (across the sliding line). The friction area was 0.1461 cm2. A set of normal forces: 730; 925; and 1130 N – was experimentally determined to ensure that there was no seizure. The shaft speed of 100 min-1 (a linear velocity of 0.37 m) was experimentally chosen under the condition of guaranteed absence of the hydrodynamic lubrication mode. The presented method of cladding additive production is easily implemented in the transmission units and also prevents the sedimentary instability of the lubricating composition. The device for enriching the lubricating system oil with copper alloying elements in the process of operation provides for a stable and self-organized mode of selective transfer. The results of tribological studies have shown the high efficiency of the cladding additive – the wear rate in the range of the normal force of 720 to 1130 N has reduced in 2.8…7 times.
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Wei, Lidui, Haijun Wei, Shulin Duan, and Yu Zhang. "An EHD-mixed lubrication analysis of main bearings for diesel engine based on coupling between flexible whole engine block and crankshaft." Industrial Lubrication and Tribology 67, no. 2 (2015): 150–58. http://dx.doi.org/10.1108/ilt-08-2013-0088.
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Purpose – The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life. Design/methodology/approach – Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method. Findings – Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously. Originality/value – Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.
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Задорожная, Елена, Elena Zadorozhnaya, Игорь Мухортов, Igor Mukhortov, Ксения Почкайло, and Kseniya Pochkaylo. "Anti-wear additives influence upon hydrodynamic friction mode parameters in bearings of internal-combustion engines." Bulletin of Bryansk state technical university 2016, no. 3 (2016): 29–36. http://dx.doi.org/10.12737/22007.
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An essential condition to ensure an engine life having 300,000 – 1 000,000 km according to race consists in assurance of a minimum wear rate of crankshaft bearings. For such units as connectingrod bearings a maximum allowable value of bearing brass wear makes 100 mkm which corresponds to an integral linear wear intensity of 10-14 …10-13 that is possible only at a hydrodynamic mode of friction actually at all modes of engines operations. Ensuring liquid friction in all range of contact pressures is achieved both through design methods, and technological ones. To the latter belongs first of all the application of lubricants with high wearresistant properties. In this connection arises a problem to reveal a mechanism and degree of the effect of lubricant components upon a range of contact pressure where liquid friction is realized. This paper reports the experimental evidences of the increase of contact pressures at which is achieved a minimum value of a constant of friction at the introduction in lubricant a standard wear-resistant additive – dialkyldithiophosphate of zinc (ZDDP). So, at the introduction in coal oil without additives I-20A (viscosity type ISO 32) 1.25 and 2.5% ZGGP maxi-mum contact pressure at which is realized a hydrody-namic mode of friction increases by 1.8 and 2 times accordingly. Because of impossibility to explain experimental data by a chemical interaction of ZDDP with surface material of tribo-coupling there is offered and substantiated a mechanism of ZDDP influence upon rheological parameters of lubricant in a separation layer. A rheological model allowing the computation of the wearresistant additives influence upon a value of hydrodynamic pressures in a lubrication layer is of-fered. The idea of the initiation by a wearresistant additive of multimolecular adsorption of lubricant on the surface of tribocoupling may be used for the optimization of ZDDP structure and also for the prognostication of changes in pressure coefficient of viscosity in a lubrication layer.
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Chanchikov, Vasiliy Aleksandrovich, Ivan Nikolaevich Guzhvenko, Nina Vladimirovna Pryamuhina, Mariya Sergeevna Pryamukhina, Elena Prokofievna Karlina, and Vladimir Grigorievich Bukin. "The research of a tribotechnical efficiency of modified lubricants in crankshaft sliding bearings of a marine diesel engine." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2024, no. 4 (2024): 65–74. https://doi.org/10.24143/2073-1574-2024-4-65-74.
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The conditions of friction and lubrication of sliding bearings in a marine diesel engine are considered. In conditions of transient conditions, heavy loads or contamination of the lubricant used in bearings of marine diesel engines, the lubricating film becomes quite thin with a thickness in the range of 0.25-2.5 microns, and the local pressure is large enough – about 15-20 MPa. At the same time, for the operation of sliding bearings in hydrodynamic mode, the minimum pressure in the lubrication system is P = 0.05 MPa, otherwise, a zone of boundary friction is formed between the neck of the crankshaft and the liner through the hydrodynamic wedge. A method is proposed to improve the tribotechnical properties of lubricants in sliding friction pairs by using a patented anti-wear additive based on molybdenum diselenide MoSe2 and fatty acids. An assessment of the tribotechnical characteristics of modified lubricants using the anti-wear additive Nanotex-12 was carried out under conditions simulating the operation of a real crankshaft bearing of a marine diesel engine 6ChNSP 18/22 on a friction machine 2070 SMT-1. The variables of the wear conditions of the parts of the simulated sliding bearing were the pressure at the contact of the rubbing surfaces and the concentration of the anti-wear additive (by volume) in the lubricating oil M-16G2CS. As a result of computational and experimental studies, graphical dependences of wear, wear intensity and wear resistance of the simulated friction unit on the volume concentration Ci of the anti-wear additive in the lubricating oil and the contact pressure Pi were obtained. It has been confirmed that the use of additives in M-16G2CS lubricating oil significantly improves its tribotechnical characteristics, since the wear of the friction pair decreases by 5-15%, the wear intensity decreases by 7-17%, and the wear resistance increases by 6-18%, depending on the concentration of the additive in the lubricant. Reducing wear on the sliding bearing in the case of using an anti-wear additive (compared with non-shrink lubricating oil) creates grounds for its successful use in marine oils, but increasing the concentration of the additive in oil over 2.0% by volume is impractical due to the deterioration of tribotechnical characteristics and a decrease in the economic efficiency of such lubricating compositions.
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Akhverdiev, K. S., E. A. Bolgovа, E. O. Lagunova, and S. V. Kumanin. "Hydrodynamic calculation of wedge-shaped system «slider-guide» operating on compressible lubricant in presence of melt on surface of guide." Omsk Scientific Bulletin, no. 176 (2021): 10–14. http://dx.doi.org/10.25206/1813-8225-2021-176-10-14.
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In the article on the basis of the equation of motion of the compressible lubricant for the «thin layer», continuity, state, and the equation describing the profile of the molten contour taking into account the formula of mechanical energy dissipation the asymptotic and self-similar solution is found for the extreme (when the speed tends to infinity) and non-extreme case. As a result of solving the problem, a refined mathematical calculation model of a wedgeshaped sliding support with a low-melting metal coating on a movable contact surface is obtained, which compensates for an emergency lack of lubricant and provides a stable hydrodynamic lubrication mode
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Kirishchieva, Victoria, and Murman Mukutadze. "INCREASING THE WEAR RESISTANCE OF RADIAL BEARINGS WITH NON-CIRCULAR PROFILE AND COMPOSITE FLUOROPLASTIC POLYMER COATING." Transport engineering 2022, no. 11 (2022): 10–17. http://dx.doi.org/10.30987/2782-5957-2022-11-10-17.
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The study objective is to find out the regularities of a stable hydrodynamic regime.
 The paper is devoted to the analysis of a model of a radial sliding bearing with a profile adapted to friction conditions, which also has a polymer coating with a groove on the support.
 Research methods: there are proposed new models describing the movement of the lubricant in the approximation of a "thin layer", the continuity equation taking into account the dependence of viscosity on pressure.
 The novelty of the work is in the development of a methodology for engineering calculations of the bearing structure with a polymer coating, a groove and an adapted profile.
 As a result of the study, a significant expansion of the possibilities is achieved to apply in practice the calculation models of a radial sliding bearing with a polymer coating and operating in a hydrodynamic lubrication mode.
 Conclusions: the design of a radial bearing with a polymer coating and a groove 3 mm wide, as well as adapted to the loading conditions of the support surface with a profile provide a stable shaft lift-up on a hydrodynamic wedge.
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Putintsev, Sergey V., Sergey A. Anikin, Sofia P. Demenkova, and Sofya S. Strelnikova. "Calculation of the required minimum of a motor oil level on cylinder-piston group moving surfaces of the automotive diesel." Traktory i sel hozmashiny 89, no. 1 (2022): 53–65. http://dx.doi.org/10.17816/0321-4443-100063.
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BACKGROUND: Theme of this article is actual because issues of the reliable and cost-effective opera-tion of augmented automotive piston engines are still not solved. An important aspect of solving the problem is rational oil supply of the cylinder-piston group.
 AIMS: The purpose of this work is the required minimum motor oil level estimation for the hydrodynamic lubrication of the cylinder-piston skirt pair. There were set and solved the tasks of determining the volume of motor oil capable of filling: 1) cavities of the flat-topped surface of the cylinder; 2) a raised surface of the piston skirt and 3) the piston skirt clearance. The object of study is an automotive diesel.
 METHODS: Three types of analytical determination of the total volume of the cavities of the rough surface and the piston skirt clearance were used as methods for estimation of a motor oil level.
 RESULTS: It was found, that the estimation with the well known formula for oil volume (a method 1) gives the overevaluated result of oil level estimation, in comparison with methods 2 and 3, which taking into account the real geometry of cavities and roughness parameters. The advantage of method 3 was determened by criteria of generalization and of simplicity to apply. Using the method 3, the estimated volume of motor oil ensured the hydrodynamic lubrication mode of the cylinder piston skirt pair of the object of study was obtained.
 CONCLUSION: The analytical expressions obtained by method 3 can be recommended to optimize the piston engine lubrication systems for reducing the friction and wear losses as well as to minimize a risk of oil starvation and increased oil consumption through burning.
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Vasilenko, V. V., V. I. Kirishchieva, M. A. Mukutadze, and V. E. Shvedova. "Investigation of the Wear Resistance of a Journal Bearing with Polymer-Coated Grooved Support Ring." Advanced Engineering Research 22, no. 4 (2023): 365–72. http://dx.doi.org/10.23947/2687-1653-2022-22-4-365-372.
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Introduction. In modern heavy-loaded friction units, metallopolymer coated bearings operating in the boundary friction mode are widely used. Their successful application is provided by the viscoelastic deformation of these coatings under load. To pass from boundary friction to liquid friction, it is required to create a bearing hydrodynamic wedge. Currently, the use of journal bearings with polymer-coated grooved support ring is hindered by the lack of a methodology for their calculation. This work analyzes a model of movement of a micropolar lubricant in the operating clearance of a journalbearing with a nonstandard support profile having a PTFE composite coating with a groove on the bearing surface. The study aims at establishing the dependence of the stable hydrodynamic regime on the width of the groove on the surface of the bearing profile. Materials and Methods. Tribological tests of journal bearings with a nonstandard bearing profile having a polymer coating with a groove on the surface were carried out on samples in the form of partial bushes (blocks). Using the equation of movement of a lubricant with micropolar rheological properties, as well as the continuity equation, new mathematical models were obtained that took into account the width of the groove, polymer coating, and nonstandard bearing profile. Results. A significant expansion of the applicability of design models of journal bearings with structural changes has been achieved. Polymer-coated bearings with a groove provided a hydrodynamic lubrication mode. The results obtained allowed us to evaluate the operational characteristics of the bearing: hydrodynamic pressure value, load capacity, and coefficient of friction. Discussion and Conclusions. The design of polymer coated journal bearing and a groove 3 mm wide on the surface of the liner provided a stable ascent of the shaft on the hydrodynamic wedge, which was validated experimentally. The experiments were carried out for journal bearings with a diameter of 40 mm with a groove 1–8 mm wide, at a sliding speed of 0.3–3 m/s and a load of 4.8–24 MPa.
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Andreeva, O. B., V. I. Kirishcheva, and M. A. Mukutadze. "Increasing the Wear Resistance of a Polymer-Coated Radial Bearing Running on a Micropolar Lubricant." Vestnik IzhGTU imeni M.T. Kalashnikova 25, no. 3 (2022): 23–31. http://dx.doi.org/10.22213/2413-1172-2022-3-23-31.
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The article is devoted to the analysis of a mathematical model of a lubricant mootion in the working gap of a radial sliding bearing with a support profile having a fluoroplast-containing composite polymer coating with a groove on the support surface, which has micro-polar properties. New mathematical models describing the motion of the bearing material in the working gap of a radial bearing with a support profile having a polymer coating with a groove, which has micropolar rheological properties in the laminar mode of motion, in the approximation for a “thin layer”, are proposed. A comparative analysis of the obtained results of a theoretical experimental study of a radial sliding bearing with a support profile having a polymer coating with a groove, without a groove, and the existing ones, confirming the approximation of the obtained model to real practice, is performed. The novelty of the work lies in the development of a methodology for engineering calculations of the design of a radial sliding bearing with a polymer coating in the presence of a groove that allows determining the value of the main tribotechnical parameters: hydrodynamic pressure, load capacity, friction force, friction coefficient. As a result of the study, a significant expansion of the possibilities of applying in practice the obtained mathematical models of a sliding bearing with a support profile having a polymer coating with a groove, operating in the mode of hydrodynamic lubrication with a material having non-Newtonian rheological properties in the laminar flow mode, allowing assessment of the operational characteristics of the bearing - the amount of hydrodynamic pressure, load capacity and coefficient of friction was achieved. The design of a radial bearing with a fluoroplastic-containing anti-friction composite polymer coating and a groove with a width of 2 mm ensured stable ascent of the shaft on a hydrodynamic wedge, which experimentally confirmed the correctness of the results of theoretical studies of sliding bearings with a diameter of 40 mm with a support profile having a polymer coating with a groove 1…8 mm wide, at a speed of sliding 1…3 m/s, load 4.2…45.5 MPa.
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Pradeep, Shravan, Alan Wessel, and Lilian C. Hsiao. "Hydrodynamic origin for the suspension viscoelasticity of rough colloids." Journal of Rheology 66, no. 5 (2022): 895–906. http://dx.doi.org/10.1122/8.0000424.
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We report the linear rheology for dense suspensions of sterically stabilized smooth and mesoscopically rough colloids interacting as hard particles. Small amplitude oscillatory measurements reveal that rough colloids at high volume fractions exhibit storage and loss moduli that are orders of magnitude greater than smooth colloids. Frequency-concentration superposition is used to collapse the viscoelasticity data onto a master curve, where shift factors suggest a more elastic microstructure and reduced cage volume for rough particles. A combination of the mode-coupling theory, hydrodynamic modeling, and the activated hopping theory shows that these rough particles with significantly reduced localization lengths tend to become trapped in their glassy cages for extended periods of time. High-frequency data show that rough colloids, but not smooth colloids, display a transition from a free-draining to a fully lubricated state above the crossover volume fraction and, furthermore, exhibit solidlike behavior. Scaling analyses support the idea that lubrication forces between interlocking asperities are enhanced, leading to rotational constraints and stress-bearing structures that significantly elevate the viscoelasticity of dense suspensions. The results provide a framework for how particle surface topology affects the linear rheology in applications such as coatings, cement, consumer products, and shock-absorbing materials.
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Yamashita, Minoru, Toshio Hattori, and Koji Kuwahara. "Circular Cup Drawing of Magnesium Alloy Sheet under Cold Condition Using Rubber Tool and Improvement of Surface Appearance." Materials Science Forum 773-774 (November 2013): 646–52. http://dx.doi.org/10.4028/www.scientific.net/msf.773-774.646.
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In order to accomplish the circular cup drawing of the sheet material whose ductility is extremely poor under the cold forming condition, the Maslennikov's technique was applied. A deformable rubber ring was used instead of the hard punch. Test material was magnesium alloy AZ31-O sheet. Small die profile radius was applied, which was twice or 4 times of the sheet thickness. A semisolid lubricant was used for the lubrication of the blank - die interface, on the other hand, the rubber - blank interface was degreased to increase friction. The limiting drawing ratio of 1.31 was attained. A peculiar fracture mode arises, where the material suddenly fractured with crack evolution emanating from the flange periphery. The fracture strain is found approximately equal to the work hardening exponent n-value in plastic property. Another kind of crack arose in the circumferential direction of the cup during unbending process with smaller die profile radius. To decrease the scratched lines of the cup surface caused by very high sliding contact pressure to the die, high-speed drawing was tested using a drop-weight. The surface was improved, because the material - tool contact was successfully prevented by the hydrodynamic lubrication film.
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Kireev, Sergey, Valentin Stepanov, and Marina Korchagina. "Study of crosshead-guided lubrication systems for hydraulic fracturing plunger pumps." E3S Web of Conferences 592 (2024): 05010. http://dx.doi.org/10.1051/e3sconf/202459205010.
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Efficient extraction of hard-to-recover hydrocarbon reserves requires impressive expenditures on the use of advanced technologies and energy-intensive equipment. Hydraulic fracturing technologies require the use of high-pressure pumps (105 and 138 MPa), and this determines the use of plunger pumps in these conditions. To relieve the radial load on the plunger seals, a crosshead layout of the drive part is used. The goal is to investigate crosshead (guide) load distribution throughout the crankcase and also the oil distribution in the crosshead-guide gap to find the most efficient design. The methods of simulation modeling of the kinematics of the crosshead and connecting rod group with the use of modal analysis were applied for the study. The analysis was performed taking into account the elastic properties of the crosshead, seal and connecting rod. The Reynolds-Stokes-Halerkin finite element method (R-SGFEM) with sliding boundary conditions was used to model and study hydrodynamic lubrication. A study was conducted for three types of oil channels on the crosshead: one longitudinal channel at the apex, one longitudinal channel and two transverse channels, one longitudinal channel and three transverse channels. Load distribution graphs were obtained for the contact area with respect to the oil-feeding hole in the guide. The obtained data make it possible to understand the nature of the crosshead sliding on the guide and evaluate the possibility of providing the hydrostatic mode in the friction knot at different types of the lubricant supply into the contact zone. The study showed one of the causes of increased wear of the bottom guide of the crosshead, which consists in insufficient non-drying ability of the lubricating layer and allowed to determine the parameters for further research and optimization of the node design.
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Liang, Wen Hong, Kai Liu, Xiao Lin Liu, and Ya Hui Cui. "Research on Influence of Intertooth Space Confriction to Transmission Efficiency under EHL." Advanced Materials Research 605-607 (December 2012): 1158–63. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1158.
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Engagement between gear teeth with confriction has been analyzed aim at low speed and heavy transmission mode of spur gear in aerogenerator gearbox. Nonlinear relation between parameters such as confriction, normal pressure, number of teeth, ratio of transmission, and thickness of fluid film has been deduced by using the theory of elasto-hydrodynamic lubrication (EHL) and gear mesh. Numerical calculation of these equations has been made progress by using MATLAB software under the premise of no analytical solution. The efficiency of each point on line of action has been received. And then the influence of confriction in intertooth space to transmission efficiency under EHL has been analyzed. The results can be provided as argument and numerical value reference for optimization of the gearbox lectotype in areogenerator to make the efficiency maximized, and for further research on transmission efficiency of planet gear train.
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Tian, Dong, Yanjun Feng, Hongbo Su, et al. "Research on the Accumulative Damage of Flywheels Due to In-Space Charging Effects." Aerospace 12, no. 2 (2025): 98. https://doi.org/10.3390/aerospace12020098.
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High-speed rotating flywheel bearings, designed for space applications, generate a high-resistance hydrodynamic lubrication film, which isolates the rotor, transforming it into a conductor. This phenomenon introduces a novel failure mode—flywheel bearing electrical damage caused by space charging effects. This paper first reviews the sources of common shaft voltages in flywheels and the mechanisms of electrical damage and improves the principle of deep charge causing shaft voltages in flywheel bearings, proposing that surface charge is another source of shaft voltages. The quantified analysis model of flywheel bearing electrical damage in relation to rotational speed and high-energy electron flux is derived, indicating that the damage caused by space charge–discharge to the bearing is of small magnitude and only becomes apparent after long-term accumulation, thus being easily overlooked. Based on the causal chain of electrical damage, a correlation analysis model consistent with physical principles is constructed, and the correlation between on-orbit anomalies of the flywheel and high-energy electron flux is confirmed through the use of big data. Preliminary experiments are conducted to validate all of the research results. Finally, suggestions are given for the reliable design, application, and testing of flywheels.
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Nicoletti, Rodrigo, and Ilmar Ferreira Santos. "Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System." Journal of Engineering for Gas Turbines and Power 127, no. 3 (2005): 638–45. http://dx.doi.org/10.1115/1.1850940.
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In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted into the model by using two different approaches: (a) linearized active oil film forces and the assumption that the hydrodynamic forces and the active hydraulic forces can be decoupled, and (b) equivalent dynamic coefficients of the active oil film and the solution of the modified Reynolds equation for the active lubrication. The second approach, based on the equivalent dynamic coefficients, leads to more accurate results because it includes the frequency dependence of the active hydraulic forces. Theoretical and experimental results reveal the feasibility of reducing resonance peaks by using the active lubricated tilting-pad bearing. By applying a simple proportional controller, it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility of increasing their operational range by attenuating resonance peaks and reducing vibration problems.
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Wang, Xiaolei, Koji Kato, Koshi Adachi, and Kohji Aizawa. "The effect of laser texturing of SiC surface on the critical load for the transition of water lubrication mode from hydrodynamic to mixed." Tribology International 34, no. 10 (2001): 703–11. http://dx.doi.org/10.1016/s0301-679x(01)00063-9.
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Stelmakh, Oleksandr, Hongyu Fu, Yiqiao Guo, Xinbo Wang, Hao Zhang, and Oleksandr Dykha. "Adhesion-Deformation-Hydrodynamic model of friction and wear." Problems of Tribology 27, no. 3/105 (2022): 49–54. http://dx.doi.org/10.31891/2079-1372-2022-105-3-49-54.
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The proposed Adhesion-Deformation-Hydrodynamic model of friction and wear is based on the relationship of elastic-deformation processes in the surfaces of curvilinear contacts with hydrodynamic regular processes of extrusion and rarefaction in lubricating layers in tribocontacts, as well as with the processes of primary adhesion of friction surfaces and subsequent acts of adhesive wear. The proposed Adhesion-Deformation-Hydrodynamic model of friction and wear and its main provisions on the relationship between extrusion, rarefaction in lubricating layers and primary adhesion of friction surfaces of curvilinear contacts cover the entire load-speed range and all modes of lubrication of friction surfaces
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Czaban, Adam, and Andrzej Miszczak. "Influence of Pressure Changes on the Viscosity of Lubricating Oil in CFD Simulations of Conical Bearing Hydrodynamic Lubrication." Journal of KONBiN 52, no. 3 (2022): 259–78. http://dx.doi.org/10.2478/jok-2022-0036.
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Abstract The aim of this study is to consider the effect of pressure on the viscosity of lubricating oil in the adopted model of hydrodynamic lubrication and on the calculated flow parameters and operating parameters of a conical slide bearing. The numerical analysis consisted in solving the Reynolds type equation for the process of stationary hydrodynamic lubrication.
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Bolgova, E. A., M. A. Mukutadze, and V. M. Prihod'ko. "Modified Radial Bearing Wear Resistance Assessment with Respect to Compressibility." Vestnik IzhGTU imeni M.T. Kalashnikova 27, no. 4 (2024): 14–21. https://doi.org/10.22213/2413-1172-2024-4-14-21.
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Polymer composite materials in the form of antifriction coatings arewidely used nowadays in heavily loaded low-speed tribosystems of various machines, providing significant resources for friction units. The use of liquid lubricants makes it possible to expand the speed range of their applicability since it provides a transition from self-lubrication boundary friction to liquid friction under hydrodynamic conditions. Then, coatings will be active during starts and runouts, and lubricant will work during stationary mode. Liquid lubricant moving in the working gap inevitably contains atmospheric gases, that significantly affect the performance characteristics of a lubricant, and primarily, its compressibility. Therefore, the introduction of the compressibility parameter into the model allows a more accurate prediction oflubricant behavior and lubrication efficiency in various bearing operating modes. This study includes the development and analysis of a mathematical model of a micropolar lubricant for a polymer-coated bearing on the bearing sleeve support surface. The modified bearing design provides for a polymer coating with a groove, which improves the distribution of lubricant and increases the durability of the system. The novelty of the work lies in the methodology development for design engineering analysis of thepolymer coating journal bearingwith a groove, taking into account compressibility, allowing to determine the value of the main tribotechnical parameters. The aim of the work is to assess wear resistance of the modified design of journal bearing, taking into account the compressibility of the micropolar lubricant. Based on the motion equation of the liquid lubricant under study, the continuity equation and the equation of state, new mathematical models were obtained taking into account the compressibility of the lubricant. The results of the study showed that the modified design of the bearing with a polymer coating and groove significantly improved its performance. A decrease in the friction coefficient value and an increase in the bearing capacity of the bearing in comparison with conventional designs were noticed. The modified design of the journal bearing allowed clarification of friction coefficient by 8-11% within the range of the studied modes, taking into account an additional parameter - the lubricant compressibility.
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Ilina, O. A., O. O. Mikosianchyk, R. H. Mnatsakanov, R. E. Kostyunik, O. P. Yashchuk, and M. A. Shteinyk. "Mechanisms of formation of wear-resistant dissipative structures in non-stationary lubrication conditions." Problems of Tribology 28, no. 3/109 (2023): 49–55. http://dx.doi.org/10.31891/2079-1372-2023-109-3-49-55.
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The work aimed to determine the influence of the processes of supramolecular self-organization in the lubricating layer on the patterns of wear of friction pairs. The mechanisms of structural adaptability of tribocoupler elements were analyzed, and the regularities of the manifestation of a large-scale and energy jump, which characterizes the transition of the tribosystem to a metastable state, were determined. An evaluation of the tribotechnical characteristics of commercial transmission oils was carried out on a software-hardware complex that, using a roller analogy, simulates the operation of gears in conditions of rolling with slipping. It was established that the activation of contact surfaces in the mode of frequent starts and stops leads to active interaction of the lubricant's components and the metal's surface layers with the gradual formation of boundary adsorption layers. For transmission oil 'Bora B' T-Shyp, an increase in anti-friction properties has been established due to the effective lubricating ability of the oil when forming the hydro- and non-hydrodynamic components of the lubricating layer thickness. The effect of the chemical activity of the zinc dialkyl dithiophosphate antiwear additive and the hydrocarbon components of the base of transmission oils on the effectiveness of the formation of boundary films is considered. It was determined that the formation of stable boundary films of the lubricant is the leading process in manifesting their damping properties concerning the localization of elastic-plastic deformation along the depth of the metal. When boundary films are formed on 90-95% of the contact area, the change in the microstructure of the near-surface layers is fixed at a depth of up to 20 microns; when boundary films are formed on 20...50% of the surface area, the spread of elastic-plastic deformation reaches a depth of up to 50 microns. The kinetics of the formation of boundary films by the lubricant and the indicators of the specific work of friction in contact are correlated with the intensity of wear of the contact surfaces
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Burstein, Leonid. "Surfaces with pores: hydrodynamic lubrication." Industrial Lubrication and Tribology 69, no. 4 (2017): 471–83. http://dx.doi.org/10.1108/ilt-05-2016-0108.
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Purpose This paper aims to assess the hydrodynamic lubrication of two opposing surfaces with identical pores having a semicircular profile. The surfaces are treated with more than one pore that allows clarification of whether there exists interaction between the pores. Design/methodology/approach A transient, spatial, one-dimensional model of surfaces with regular pores was developed and applied in the context of fluid lubrication. MATLAB software has been used. Findings Calculations show that a lubricating film between two surfaces with pores provides better hydrodynamic conditions in comparison to that on one surface with pores. It was also shown that the pores of one surface act as separate objects and can take into account only the interaction between the pores of the opposite surfaces. In addition, it was found that there are optimum values of the pore radii, gap and pore cell dimensions at which the bearing capacity of the film is maximal. Practical implications The computer program used for the pore parameter calculations provided the optimal lubrication. Originality/value This is the first study of the lubricating film hydrodynamic behavior of two opposite surfaces with pores having a semicircular profile.
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Pasco, Corentin, Muhammad Khan, Jaipal Gupta, and Kenneth Kendall. "Experimental investigation on interply friction properties of thermoset prepreg systems." Journal of Composite Materials 53, no. 2 (2018): 227–43. http://dx.doi.org/10.1177/0021998318781706.
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A comprehensive novel investigation into the characterisation of interply friction behaviour of thermoset prepregs for high-volume manufacturing was conducted. High interply slipping rate and normal pressure typically used for high-volume manufacturing present challenges when preforming carbon fibre reinforced plastics. The study involved multiple reinforcement architectures (woven and unidirectional with the same rapid-cure resin system) which were characterised using a bespoke interply friction test rig used to simulate processing conditions representative to press forming and double diaphragm forming. Under prescribed conditions, woven and unidirectional prepregs exhibit significantly different frictional behaviour. Results demonstrated the unidirectional material obeys a hydrodynamic lubrication mode. For the woven material, a rate-dependent friction behaviour was found at low normal pressure. At higher normal pressure however, the woven material exhibited a friction behaviour similar to that of a dry reinforcement and significant tow displacement was observed. Post-characterisation analysis of test-specimens showed significant resin migration towards the outer edges of the plies, leaving a relatively resin-starved contact interface. The findings generate new knowledge on interply friction properties of thermoset prepreg for high-volume manufacturing applications, yet reveal a lack of understanding of the influence of tow tensions as well as the pre-impregnation level for a range of processing conditions.
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Xiang, Chang Zheng, Yu Juan Wang, and Yun Fei Chen. "Hydrodynamic Lubrication in a Nanoscale Bearing." Advanced Materials Research 60-61 (January 2009): 1–5. http://dx.doi.org/10.4028/www.scientific.net/amr.60-61.1.
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Nonequilibrium molecular dynamics simulation is used to simulate the hydrodynamics lubrication in the nanoscale bearing. A physical model of the nanascale bearing that the thin liquid water film confined between two solid walls has been set up. The simulation results indicate that the hydrodynamic pressure profiles as the macroscopic state are formed in nanoscale bearings. The hydrodynamic pressure increases with increasing shear velocity, and corresponding load capacity also increases with increasing sliding velocity of the upper driven wall. These results are in accordance with classical Reynolds’ theory about hydrodynamic lubrication. On the other hand, the shear thinning behavior of the liquid water film appears, so that effective viscosity decreases under high shear velocity. Although effective viscosity of water film decreases under high shear velocity, this phenomenon doesn’t affect the hydrodynamic lubrication of the nanoscale bearing.
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Engao, Peng, Xiong Zhihong, Luo Zhenkun, Zhang Yongyang, and Yin Zhansong. "Analysis on Lubrication Performance of Piston Ring-Cylinder Liner based on Numerical Simulation." Journal of Physics: Conference Series 2510, no. 1 (2023): 012017. http://dx.doi.org/10.1088/1742-6596/2510/1/012017.
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Abstract This paper mainly studies the tribological performance of friction pairs and poor lubrication during piston movement. Based on the average Reynolds equation and comprehensively considering the variable viscosity and variable density characteristics of lubricating oil, a transient hydrodynamic lubrication model of the piston ring-cylinder liner friction pair is established. By solving the established lubrication model, the lubricating oil film thickness value, friction value and other parameters that can characterize the lubrication performance of the friction pair throughout the cycle are obtained, whilst revealing the surface roughness, lubricating oil viscosity and piston ring barrel surface height. And the influence mechanism of the friction performance of the friction pair is presented on the basis of the previous analysis. The research shows that improving the surface roughness of the piston ring will help to improve the lubrication, increasing the viscosity of lubricating oil will help to improve the lubricating performance of friction pairs and reduce the peak friction at the top dead centre of piston rings and improving the surface texture of the piston rings can reduce the oil film thickness and reduce the friction caused by fluid shear effect in the high-speed region.
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Dykha, O., O. Babak, O. Makovkin, and S. Posonskiy. "Tribological properties of anode-spark coatings on aluminum alloys." Problems of Tribology 27, no. 2/104 (2022): 28–34. http://dx.doi.org/10.31891/2079-1372-2022-104-2-28-34.
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It is established that at present the technology of anode-spark coatings in general is well studied. However, the lack of recommendations for the choice of modes of technological processes and tribological characteristics in different operating conditions limit the widespread introduction of this technology. The task of this work was to analyze the processes of anode-spark coatings, improve technology and study the wear resistance of samples processed by this and traditional anode technology. The development of technology for the application of protective coatings on valve metals in the conditions of spark discharge included the choice of electrolyte and mode of operation of the bath: voltage, current density, hydrodynamic conditions and other parameters. Wear resistance tests were performed on a special installation. Structurally, the installation is made in two positions, which allows you to test two samples with different load conditions at a constant sliding speed. The design of the installation implements the friction scheme of the liner shaft. The study of anode-spark coatings in the mode of limiting lubrication was studied in the environment of industrial oil. The wear criterion was the weight wear of the samples according to the results of weight measurements before and after wear. It is established that prolonged electrolysis in the conditions of sparking leads to the formation of anode coatings that exceed in their properties the films obtained by non-sparking oxidation. Comparative studies of the wear resistance of anode-spark coatings and galvanic anode coatings under the same test conditions showed that the wear of anode-spark coatings is almost twice lower for the entire load range. The considered technology is recommended for increase of wear resistance of elements of devices from the aluminum alloys working in the conditions of corrosion and mechanical wear
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Meyer,, Donna M., and John A. Tichy,. "3-D Model of a Total Hip Replacement In Vivo Providing Hydrodynamic Pressure and Film Thickness for Walking and Bicycling." Journal of Biomechanical Engineering 125, no. 6 (2003): 777–84. http://dx.doi.org/10.1115/1.1631585.
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Formulation of a 3-D lubrication simulation of a total hip replacement in vivo is presented using a finite difference approach. The goal is to determine if hydrodynamic lubrication is taking place, how thick the joint fluid film is and over what percentage of two gait cycles, (walking and bicycling), the hydrodynamic lubricating action is occurring, if at all. The assumption of rigid surfaces is made, which is conservative in the sense that pure hydrodynamic lubrication is well known to predict thinner films than elastohydrodynamic lubrication (EHL) for the same loading. The simulation method includes addressing the angular velocity direction changes and accurate geometry configuration for the acetabular cup and femoral head components and provides a range of results for material combinations of CoCrMo-on-UHMWPE, CoCrMo-on-CoCrMo, and alumina-on-alumina components. Results are in the form of the joint fluid film pressure distributions, load components and film thicknesses of the joint fluid, for the gait cycles of walking and bicycling. Results show hydrodynamic action occurs in only about 10% of a walking gait cycle and throughout nearly 90% of a bicycling gait. During the 10% of the walking cycle that develops hydrodynamic lubrication, the minimum fluid film thicknesses are determined to be between 0.05 μm and 1.1 μm, while the range of film thicknesses for bicycling is between 0.1 μm and 1.4 μm, and occurs over 90% of the bicycling gait. Pressure distributions for these same periods are in the range of 2 MPa to 870 MPa for walking and 1 MPa to 24 MPa for bicycling.
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Meng, Guang Yao, Ji Wen Tan, and Yi Cui. "Grinding Fluid Flow Field Modeling and Multi-Parameter Numerical Analysis Based on Smooth Model." Advanced Materials Research 156-157 (October 2010): 948–55. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.948.
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Relative motion between grinding wheel and workpiece makes the lubricant film pressure formed by grinding fluid in the grinding area increase, consequently, dynamic pressure lubrication forms. The grinding fluid flow field mathematical model in smooth grinding area is established based on lubrication theory. The dynamic pressure of grinding fluid field, flow velocity and carrying capacity of lubricating film are calculated by the numerical analysis method. An analysis of effect of grinding fluid hydrodynamic on the total lifting force is performed, and the results are obtained.
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Czaban, Adam, and Andrzej Miszczak. "Simulations of the Influence of the Heat Flux at the Shaft Surface of the Conical Slide Bearing on Its Hydrodynamic Lubrication and Operating Parameters." Journal of KONES 26, no. 4 (2019): 29–37. http://dx.doi.org/10.2478/kones-2019-0086.
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AbstractThe aim of this work is to investigate, how in the adopted model of hydrodynamic lubrication of a conical slide bearing, the change of the heat flux value at the bearing shaft, affects bearing operating parameters. In this research, the authors use, the known from the literature, Reynolds type equation, describing the stationary hydrodynamic lubrication process of a conical slide bearing. The analytical, solutions, that determine the components of the lubricating oil velocity vector and the equation (analytical solution of energy equation) determining the three-dimensional temperature distribution in the lubrication gap, was also adopted from previous works. In order to obtain numerical solutions, the Newton’s method was used, and the derivatives in the Reynolds type equation were approximated by the finite differences. An application of the method of subsequent approximations allowed considering the influence of temperature, pressure and shearing rate on the viscosity of lubricating oil. The considerations were performed by adopting the Reynolds condition of the hydrodynamic oil film. It was tested, how the assumed value of the heat flux on the bearing shaft surface affects the values of the obtained operating parameters, i.e. the transverse and longitudinal component of the load carrying capacity, friction force and coefficient of friction.
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Wang, Leizhen, Wen Wang, Shangjun Chen, and Yujian Bai. "Study on Lubricating Performance of Soft Slider Bearing in Conformal Contact." Journal of Physics: Conference Series 2355, no. 1 (2022): 012074. http://dx.doi.org/10.1088/1742-6596/2355/1/012074.
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ABSTRACT In this paper, the lubricating performance of soft slider bearing in conformal contact is analyzed. Compared with the hard slider, the soft slider will have greater elastic deformation under low pressure. Three kinds of sliders with different elastic modulus are used for comparative study in this paper. The materials of the three sliders are: steel, glass and PMMA. A hydrodynamic lubrication model of conformal contact considering elastic deformation is established according to the theory of fluid lubrication. A program for calculating dynamic pressure lubrication performance of conformal contact considering elastic deformation is developed by using Matlab and Comsol. The influence of different inclination, different speed and different load on hydrodynamic lubrication performance was studied respectively. The results show that under the same conditions, the elastic deformation on the surface of the slider is more conducive to the formation of oil film, and more conducive to the conditions of high load.
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Li, Kaiyue, Guoding Chen, and Deng Liu. "Study of the influence of lubrication parameters on gear lubrication properties and efficiency." Industrial Lubrication and Tribology 68, no. 6 (2016): 647–57. http://dx.doi.org/10.1108/ilt-06-2015-0089.
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Purpose The analysis of lubricating properties and efficiency is important for aviation high-speed gear. So far, the project of lubricating properties and efficiency are processing under the condition of a given lubricating state, which is still depending on practical experience. This paper aims to mostly focus on the analysis of given lubricating state but lost sight of the relevance of lubrication parameters and lubricating state, which not only makes the analysis of aviation high-speed gear transmission and efficiency fail to trace to practical situation but also has an adverse effect on the reliance and validity of the project. Design/methodology/approach Based on this, the numerical model of spraying oil and oil film spreading is established, and the quantitative relationship between spray lubrication parameters and spreading characteristics of oil film is studied. According to the geometric and mechanical conditions of meshing points and taking the influence of rich-oil/starved-oil lubrication and roughness of teeth surface into consideration, corrected film thickness under condition of elasto-hydrodynamic lubrication and lubricating state of mesh points are analyzed. On this basis, power consumption and efficiency of gear transmission are also calculated by figuring out the solid friction and oil friction separately. Findings Through the research of this thesis, the effect of friction power consumption and efficiency with lubrication parameters is discussed. The effect of lubrication parameters on friction power consumption and efficiency of gear is complex. With the increase of spreading film thickness and film length, the frictional power consumption is less and the efficiency is higher. Originality/value This work provides a systematic technological approach to lubrication design and efficiency calculation of aviation high-speed gear transmission, which has remarkable engineering significance for the accurate lubrication design of the aviation mechanical parts.
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Gulwadi, S. D. "A Mixed Lubrication and Oil Transport Model for Piston Rings Using a Mass-Conserving Algorithm." Journal of Engineering for Gas Turbines and Power 120, no. 1 (1998): 199–208. http://dx.doi.org/10.1115/1.2818076.
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A numerical study of the interactions between hydrodynamic/boundary lubrication, oil transport, and radial dynamics of a piston ring using a mass-conserving (cavitation) algorithm is presented. The scheme outlined in this investigation facilitates the calculation of the volume of oil accumulating at the leading and trailing edges of the piston ring as it scrapes against the line. The calculation of this oil accumulation is important in the estimation of lubricating oil consumption in engines. The numerical procedure employed in this study is capable of depicting the transition between the various modes of piston ring lubrication (hydrodynamic, mixed, and boundary) over an engine cycle, including the detachment of oil film from the ring and its subsequent re-attachment. Additionally, the effects of (a) liner lubricant availability and (b) ring face profiles on the oil accumulation are also discussed.