Letteratura scientifica selezionata sul tema "TEHL - Thermal-Elastohydrodynamic lubrication"
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Articoli di riviste sul tema "TEHL - Thermal-Elastohydrodynamic lubrication"
1
Yang, Fuqin, Xiaojie Han e Mingqing Si. "Thermal elastohydrodynamic lubrication characteristics and optimisation of the ball-type tripod universal joint". Industrial Lubrication and Tribology 73, n. 10 (12 novembre 2021): 1310–18. http://dx.doi.org/10.1108/ilt-07-2021-0273.
Testo completoAbstract (sommario):
Purpose This paper aims to study the influence of three-column groove shell radius, ball radius, lubricating oil viscosity and elastic modulus on the thermal elastohydrodynamic lubrication (TEHL) characteristics and optimisation of the ball-type tripod universal joint. Design/methodology/approach The point contact TEHL model of the joint was developed, and the multi-grid method was used to solve it. The influence of three-column groove shell radius, ball radius, lubricating oil viscosity and elastic modulus on the lubrication characteristics was analysed. Further, the optimisation of the joint TEHL performance was carried out by the Kriging approximation model combined with the multi-objective particle swarm optimisation (MOPSO) algorithm. Findings The research results show that increasing groove shell radius and ball radius can effectively increase the oil film thickness, and decrease the oil film pressure, as well as the temperature rise. Decreasing elastic modulus can reduce the oil film temperature rise and pressure, and increasing viscosity can effectively increase the oil film thickness. The optimised minimum oil film thickness increases by 33.23% and the optimised maximum oil film pressure and maximum temperature rise decrease by 11.92% and 28.87%, respectively. Furthermore, the relative error of each response output is less than 10%. Originality/value This study applies TEHL theory to the tribological research of the ball-type tripod universal joint, and the joint’s lubrication performance is improved greatly by the Kriging model and MOPSO algorithm, which provides an effective measure to raise the joint’s working efficiency.
2
Zhou, Ye, Degong Chang e Songmei Li. "Grease thermal elastohydrodynamic lubrication properties of tripod sliding universal couplings". Industrial Lubrication and Tribology 70, n. 1 (8 gennaio 2018): 133–39. http://dx.doi.org/10.1108/ilt-11-2016-0277.
Testo completoAbstract (sommario):
Purpose This paper aims to improve the grease thermal elastohydrodynamic lubrication (TEHL) properties of the tripod sliding universal coupling (TSUC) under automotive practical conditions. For this purpose, the effect of effective radius was theoretically investigated. Design/methodology/approach Based on the simplified geometric model, the effect of effective radius on the pressure distribution, film thickness and temperature distribution of the TSUC was theoretically investigated using the multigrid and stepping methods. The TEHL properties were compared with the results obtained using the isothermal calculation method. Findings The results show that the thermal effect has a great impact on the film thickness and the pressure distribution of grease lubrication properties. Moreover, larger effective radius results in a wider but lower pressure distribution, a wider and thicker lubricating film and a lower temperature distribution. Originality/value The TSUC can be widely used in the front drive automotive transmission because it can transmit larger torque than before. The effect of effective radius on the thermal grease lubrication properties under automotive practical conditions provides a new direction for designing it.
3
Lohner, Thomas, Andreas Ziegltrum, Johann-Paul Stemplinger e Karsten Stahl. "Engineering Software Solution for Thermal Elastohydrodynamic Lubrication Using Multiphysics Software". Advances in Tribology 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/6507203.
Testo completoAbstract (sommario):
The complexity of thermal elastohydrodynamic lubrication (TEHL) problems has led to a variety of specialised numerical approaches ranging from finite difference based direct and inverse iterative methods such as Multilevel Multi-Integration solvers, via differential deflection methods, to finite element based full-system approaches. Hence, not only knowledge of the physical and technical relationships but also knowledge of the numerical procedures and solvers is necessary to perform TEHL simulations. Considering the state of the art of multiphysics software, the authors note the absence of a commercial software package for solving TEHL problems embedded in larger multiphysics software. By providing guidelines on how to implement a TEHL simulation model in commercial multiphysics software, the authors want to stimulate the research in computational tribology, so that, hopefully, the research focus can be shifted even more on physical modelling instead of numerical modelling. Validations, as well as result examples of the suggested TEHL model by means of simulated coefficients of friction, coated surfaces, and nonsmooth surfaces, highlight the flexibility and simplicity of the presented approach.
4
Yan, Xiaoliang, Yuyan Zhang, Guoxin Xie, Fen Qin e Xuewen Zhang. "Effects of spinning on the mixed thermal elastohydrodynamic lubrication and fatigue life in point contacts". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, n. 12 (2 maggio 2019): 1820–32. http://dx.doi.org/10.1177/1350650119847404.
Testo completoAbstract (sommario):
This paper presents a numerical study on the fatigue life for the non-Newtonian mixed thermal elastohydrodynamic lubrication (TEHL) of elliptical contacts with spinning. Sinusoidal surface is used to consider the effect of surface roughness, and the influences of spinning on the mixed TEHL characteristics and fatigue life are investigated. The results show that the temperature, friction coefficient and power loss increase monotonously with the increase of spinning. The spinning motion with moderate velocity is beneficial for improve the lubrication characteristics and fatigue life. However, the fatigue life can be reduced significantly by spinning under severe mixed lubrication conditions. The effects of spinning become weak or even negligible in the full-film lubrication state.
5
Meng, Fan-Ming, Sheng Yang, Zhi-Tao Cheng, Yong Zheng e Bin Wang. "Effect of fluid inertia force on thermal elastohydrodynamic lubrication of elliptic contact". Mechanics & Industry 22 (2021): 13. http://dx.doi.org/10.1051/meca/2021010.
Testo completoAbstract (sommario):
A non-Newtonian thermal elastohydrodynamic lubrication (TEHL) model for the elliptic contact is established, into which the inertia forces of the lubricant is incorporated. In doing so, the film pressure and film temperature are solved using the associated equations. Meanwhile, the elastic deformation is calculated with the discrete convolution and fast Fourier transform (DC-FFT) method. A film thickness experiment is conducted to validate the TEHL model considering the inertia forces. Further, effects of the inertia forces on the TEHL performances are studied at different operation conditions. The results show that when the inertia forces are considered, the central and minimum film thicknesses increase and film temperature near the inlet increases obviously. Moreover, the inertial solution of the central film thickness is closer to the experimental result compared with its inertialess value.
6
Hu, Xiaozhou, Jie Chen, Minggui Wu e Jianing Wang. "Thermal Analysis of Herringbone Gears Based on Thermal Elastohydrodynamic Lubrication Considering Surface Roughness". Energies 14, n. 24 (19 dicembre 2021): 8564. http://dx.doi.org/10.3390/en14248564.
Testo completoAbstract (sommario):
To predict the temperature distribution of the tooth surface of a herringbone gear pair, a numerical method for the determination of frictional heat generation was proposed by establishing a thermal elastohydrodynamic lubrication (TEHL) model in the meshing zone taking surface roughness into account. According to the real micro topography of the tooth surface measured by a non-contact optical system and loaded tooth contact analysis, the friction coefficient was obtained by a TEHL analysis and then the heat generation in the contact zone was determined. With the combination of heat generation and heat dissipation analysis, the single tooth model of the herringbone gear pair due to the finite element method (FEM) was proposed and the steady-state temperature distribution of the tooth surfaces was predicted by FEM simulations. The simulation and the experimental results demonstrated good agreement, which verified the feasibility of the present numerical method.
7
Li, Jinkuan, Yujie Wen e Zaixin Liu. "Thermal Elastohydronamic Lubrication Characteristics of Inclined Double-roller Enveloping Hourglass Worm Drive". Journal of Physics: Conference Series 2510, n. 1 (1 giugno 2023): 012016. http://dx.doi.org/10.1088/1742-6596/2510/1/012016.
Testo completoAbstract (sommario):
Abstract To grasp thermal elastohydrodynamic lubrication (TEHL) characteristics of the conjugating tooth-pairs of inclined double-roller enveloping hourglass worm drive in transmission process. The numerical solutions of line contact thermal EHL were obtained based on meshing theory of this worm drive and the theory of EHL. The TEHL line contact numerical solution of this worm drive is solved by using the multigrid method, and the TEHL film pressure and thickness are got at the same time. The effects of roller radius, offset distance, orifice coefficient and inclined angler on the TEHL characteristics and temperature rise are analysed and compared. The results show that with the increase of roller radius, offset distance and inclined angler, the secondary pressure peak decreases and moves to the outlet region, and the oil film thickness decreases accordingly, with increase in orifice coefficient the second pressure peak rises and move toward the inlet, the film thickness increases. The maximum temperature rises of film, worm and worm gear contact surface reduce as the roller radius, orifice coefficient and inclined angler increase, rose as the offset distance increases. It can reduce temperature rise and improve the oil film thickness thought the optimization calculation in the design.
8
Zhao, Jia-Jia, Ming-Xing Lin, Xian-Chun Song e Nan Wei. "Coupling analysis of the fatigue life and the TEHL contact behavior of ball screw under the multidirectional load". Industrial Lubrication and Tribology 72, n. 10 (4 luglio 2020): 1285–93. http://dx.doi.org/10.1108/ilt-03-2020-0097.
Testo completoAbstract (sommario):
Purpose This paper aims to provide thermal elastohydrodynamic lubrication (TEHL) contact model to study all balls’ lubrication performance of the ball screw when the multidirectional load is applied. Design/methodology/approach A new TEHL contact model combining the multidirectional load and the roughness surface texture is established to describe fatigue life of the ball screw. Meanwhile, the authors use the Reynolds equation to study the lubrication performance of the ball screw. Findings When the multidirectional load is applied, contact load, slide-roll ratio and entrainment velocity of all balls have a periodic shape. The TEHL performance values at the ball-screw contact points including contact stress, shear stress, minimum film thickness and temperature rise are higher than that at the ball-nut contact points. The TEHL performance values increase with the increase of root mean square (RMS) except for the film thickness. In addition, the radial load of the ball screw has a significant effect on the fatigue life. Originality/value The results of the studies demonstrate the new TEHL contact model that provides the instructive significance to analyze the fatigue life of the ball screw under the multidirectional load. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0097/
9
Yang, P., S. Qu, M. Kaneta e H. Nishikawa. "Formation of Steady Dimples in Point TEHL Contacts". Journal of Tribology 123, n. 1 (10 ottobre 2000): 42–49. http://dx.doi.org/10.1115/1.1332399.
Testo completoAbstract (sommario):
Experimental results of steady dimples measured in elliptical glass-steel contact under pure sliding conditions are presented. It is found that two dimples connected with a shallower furrow are generated, each near an end of the major radius of the contact ellipse. The complete solution of the corresponding thermal elastohydrodynamic lubrication (TEHL) problem is calculated numerically. Good agreement is obtained between the experimental and theoretical results. This agreement can be explained by the temperature-viscosity wedge mechanism. Correctness of this mechanism is demonstrated using additional experiments with ceramic balls in contact with glass and sapphire disks.
10
Wang, Shun, Qingchang Tan e Zunquan Kou. "Thermal elastohydrodynamic lubrication analysis of large scale composite thrust bearing with sector pad faced by PTFE". Industrial Lubrication and Tribology 68, n. 1 (8 febbraio 2016): 67–75. http://dx.doi.org/10.1108/ilt-03-2015-0031.
Testo completoAbstract (sommario):
Purpose – The purpose of this paper was to construct lubrication model closer to the fact of thrust bearings and to calculate the bearings characteristics of lubrication for understanding how structures influence bearings performances and, importantly, what can be the most beneficial. Large-scale composite thrust bearings with Polytetrafluoroethylene (PTFE)-faced sector pad backed by steel base are used increasingly in equipment. But there are plenty of puzzled problems in design and application. Design/methodology/approach – The authors established a 3D thermal elastohydrodynamic lubrication (TEHL) model. Oil film was formulated by Reynolds equation for pressure, and by energy equation for temperature varying through oil film thickness. Meanwhile, pad temperature was formulated by solid heat transfer equation. Elastic and thermal deformations of pad surface were calculated. Viscosity and density of oil were valued separately under different pressure and temperature. Load balance was considered as well as overturning moment balance. Finite difference method was applied to discrete these equations. Findings – PTFE layer and steel base have either helpful or detrimental impact on contact strength and full film lubrication of thrust bearing depending on their relationship in thickness. Temperature lag between middle layer of steel base and pad surface depends on PTFE layer, but not on the steel base. PTFE layer thickness should be considered when alarming threshold value of the bearings temperature is chosen. Originality/value – Three-dimensional TEHL model of large-scale composite thrust bearings was established, which included more factors close to the actual. Conclusions were drawn. These proposals are helpful to design the bearings.
Tesi sul tema "TEHL - Thermal-Elastohydrodynamic lubrication"
1
Decote, Maxence. "Numerical modelling of an EHL contact undergoing multiple overrollings". Electronic Thesis or Diss., Lyon, INSA, 2024. http://www.theses.fr/2024ISAL0096.
Testo completoAbstract (sommario):
Les roulements à billes sont des éléments cruciaux pour une boîte de vitesse d’hélicoptère, car ils lui permettent de voler. En effet, une défaillance de ces éléments peut entraîner une fin dramatique de l’hélicoptère, comme un crash. Ce travail a pour but de mieux comprendre le fonctionnement d’un roulement à billes dans des conditions de défaillance de lubrification. Afin de réaliser cela, ce travail ne va pas considérer un roulement entier (trop compliqué). Il va se focaliser sur un contact entre un élément roulant et une bande de roulement. Il constitue une première étape dans la compréhension du fonctionnement d’un roulement à billes en présence d’une panne de lubrification. L’extrapolation des résultats obtenus sur un contact à l’ensemble du roulement serait la prochaine étape. Des travaux présentent deux comportements différents : la présence de grippage ou un fonctionnement stable. Un modèle numérique permettant de prendre en compte la sous-alimentation dans un contact ElastoHydroDynamique (EHD) (et Thermo-ElastoHydrodynamique (TEHD)) a été développé dans le but de reproduire ces travaux expérimentaux. La sous-alimentation est introduite par le biais d’une méthode innovante faisant appel au maillage mobile. Ce modèle numérique a été confronté avec succès à une référence provenant de la littérature. Par la suite, il a été comparé à des résultats expérimentaux en condition de perte de lubrifiant. Des situations stables dans lesquelles le contact fonctionne durant de nombreuses heures sans ajout de lubrifiant ont été obtenuesRolling element bearings (REB) in helicopter gearboxes are essential components that enable the helicopter to fly. A failure of these components can result in severe consequences, such as the crash of the helicopter or ditching while undertaking offshore operations. In excess of 1000 incidents have been attributed to issues with the lubrication system. In the current era, helicopters are required to demonstrate a 30-minutes autorotation capability when confronted with an oil shortage. The objective of this work is to gain a deeper comprehension of the operational capabilities of a REB in the presence of an oil shortage. The ultimate goal is to enhance the run-dry requirement time in the future. In order to achieve this, this work does not consider a full REB, as this would be computationally intractable. Instead, the investigation is focused on a single contact between a rolling element and a raceway. This work represents the initial stage in the process of developing an understanding of the behaviour of a REB when it is subjected to an oil shortage. The next step would be to extrapolate the behaviour of one contact to the entire REB. Experimental studies on Loss of Lubricant (LoL) applications (i.e. oil shortages) have yielded two distinct outcomes: the stabilisation and non-stabilisation of the friction coefficient during multiple overrollings. A numerical model enabling the starvation of a Thermo-ElastoHydrodynamic Lubricated (TEHL) contact has been developed with the objective of reproducing the experimental results. An innovative method based on Moving Mesh (MM) is employed to introduce starvation. The numerical model has been validated against existing literature. A comparison with experimental works on oil shortage revealed successful replication of scenarios in which the contact operates for an extended duration without replenishment
2
Doki-Thonon, Thomas. "Thermal effects in elastohydrodynamic spinning circular contacts". Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00749882.
Testo completoAbstract (sommario):
This thesis is devoted to the study of spinning contacts located in bearing between the roller-end and the ring flange. The main direction of the lubricant flow may change when the contact is subjected to skew. This complex kinematics influences the contact behaviour. A dual experimental-numerical approach is proposed to study this problem. The Tribogyr test-rig allows the experimentation of the contact at the 1:1 scale. A film thickness measurement method, based on white light interferometry, was developed on Tribogyr. This method allows the measurement of film thickness between 0 and 800 nm with an accuracy of a few nanometres. The measurement of forces in the main flow direction shows similarities with classical rolling-sliding contacts. However, the friction coefficient is globally lower as soon as spin is involved. Transverse forces are of the same order of magnitude as the longitudinal forces. This is due to transverse shearing caused by the spin. A numerical model has been developed for the simulation of these spinning contacts. The finite element model, which is based on a fully-coupled solving strategy, takes into account the temperature calculation and the lubricant non-Newtonian rheology. Its validation with Tribogyr experimental results in terms of film thickness and friction has been conducted. Spin and skew effects induce high shear-thinning and thermal-thinning of the lubricant that lead to a decrease of the film thickness. Under high spinning condition, the lubricant exiting the contact may be re-injected to the contact inlet. Consequently, the heat transfers between the lubricant and the solids in contact are modified. In contact subjected to high skew, a local increase (dimple) of the film thickness may occur. Important skew may also lead to starvation conditions. Many experimental campaigns, coupled with an intensive use of the numerical model, allowed to understand the physical phenomena involved as well as to predict the efficiency, in terms of power losses, of the spinning contacts.
Atti di convegni sul tema "TEHL - Thermal-Elastohydrodynamic lubrication"
1
Liu, Yuchuan, Q. Jang Wang, Dong Zhu e Fanghui Shi. "A Generalized Thermal EHL Model for Point Contact Problems". In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71120.
Testo completoAbstract (sommario):
A generalized thermal elastohydrodynamic lubrication (TEHL) model for point contact problems is developed based on an isothermal generalized Newtonian elastohydrodynamic (EHL) model recently developed. The thermal model couples FDM for lubricant energy equation and the DC-FFT method for surface temperature integration. A generalized Reynolds equation is derived considering the change of viscosity with respect to temperature, pressure and shear in three dimensions. Numerical cases are conducted to verify the model.
2
Dhar, Sujan, Andrea Vacca e Antonio Lettini. "A Novel Fluid–Structure–Thermal Interaction Model for the Analysis of the Lateral Lubricating Gap Flow in External Gear Machines". In ASME/BATH 2013 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fpmc2013-4482.
Testo completoAbstract (sommario):
A novel Fluid-Structure-Thermal Interaction (FSTI) model for modeling of the lateral lubricating gaps between gears and lateral bushes in External Gear Machines (EGM) is presented in this study. Pressure compensated lateral bushes are key design elements for efficient operation of EGMs for high pressure hydraulic applications. The axial balance of these elements determines their actual position during operation, with significant implications on the effective sealing capabilities of the displacement chambers and on the losses from viscous friction. The FSTI model presented in this paper is the first model of the lateral lubricating interface in EGMs capable of considering the heat transfer, thermal effects in the fluid film and solid components as well as thermo-elastic deformation of the solids. These capabilities, alongside a fluid flow solver and a stress/deformation solver for solid components due to pressure loads, enable prediction of the film thickness in the lateral gaps in EGMs considering thermo-elastohydrodynamic lubrication (TEHD) for the first time. In the present study the formulation of the novel FSTI model and detailed results are discussed with a particular focus on understanding the implications of thermal and TEHD effects.
3
Mongkolwongrojn, Mongkol, e Kasame Thammakosol. "Theoretical Investigation in Thermoelastohydrodynamic Lubrication With Non-Newtonian Lubricants Under Heavy Load Change". In ASME/STLE 2004 International Joint Tribology Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/trib2004-64123.
Testo completoAbstract (sommario):
The time-dependent thermal compressible elastohydrodynamic (EHD) lubrication of sliding line contact has been developed to investigate the effect of a sudden load change. The time-dependent modified Reynolds equation with non-Newtonian fluids has been formulated using power law’s model. In this study, the non-Newtonian dilatant fluids for liquids-solid lubricants have been purposed experimentally using the common solid particles namely, Molybdenum disulfide (MoS2) and Polytetrafluoroethylene (PTFE). The simultaneous systems of modified Reynolds and elasticity and energy equations with initial conditions were solved numerically using multigrid multilevel technique. The performance characteristics of the thermoelastohydrodynamic under line contact were presented with varying time for the pressure distribution, temperature distribution and oil film thickness. The transient response of the line contact between two surfaces was simulated under a heavy step load function. The coefficients of friction were also presented in this work at steady state condition with varying particle concentration. This simulation showed a significant effect of liquid-solid on thermoelastohydrodynamic (TEHD) lubrication under heavy load conditions.