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Yongbin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • analytical solution to a mode of mixed elastohydrodynamic lubrication with mixed contact regimes part ii considering the contact adhering layer effect in the inlet zone
    Journal of Molecular Liquids, 2007
    Co-Authors: Yongbin Zhang
    Abstract:

    Abstract The present paper presents the researches succeeding the first part of the paper [Y.B. Zhang, Analytical Solution to A Mode of Mixed elastohydrodynamic lubrication with Mixed Contact Regimes: Part I—Without Consideration of Contact Adhering Layer in the Inlet Zone. Journal of Molecular Liquids, 2006, Vol.117, (10.1016/j.molliq.2006.04.006)], which analyzed one mode of mixed elastohydrodynamic lubrication with mixed contact regimes for the relatively heavy load and low rolling speed which make the conventional hydrodynamic lubrication occur in the inlet zone while make the physical adsorbed layer boundary lubrication occur in the Hertzian zone, based on the Newtonian fluid model. The present paper presents analysis to other two modes of mixed EHL with mixed contact regimes for relatively heavy loads, low rolling speeds and Newtonian fluids, where the conventional hydrodynamic lubrication, physical adsorbed layer boundary lubrication and oxidized chemical layer boundary lubrication can simultaneously occur in the inlet zone while the oxidized chemical layer boundary lubrication or the fresh metal-oxidized chemical boundary layer dry contact occur in the Hertzian zone, considering the contact adhering layer effect in the inlet zone. The present analysis is also extended to the first mode of mixed EHL with mixed contact regimes as analyzed in Part I [Y.B. Zhang, Analytical Solution to A Mode of Mixed elastohydrodynamic lubrication with Mixed Contact Regimes: Part I—Without Consideration of Contact Adhering Layer in the Inlet Zone. Journal of Molecular Liquids, 2006, Vol.117, (10.1016/j.molliq.2006.04.006)] when the contact adhering layer effect in the inlet zone is considered. Results of contact pressures, film thicknesses, load partitions in the contact and characteristic rolling speeds for approaching to zero averaged hydrodynamic film thickness in the Hertzian zone are obtained from this analysis respectively as functions of the contact adhering layer thickness in the inlet zone. The results show that the contact adhering layer effect in the inlet zone in the present EHL is reduced with the increase of load; At large loads, this effect may be negligible; At small loads, it may be very significant. The results also show that at low rolling speeds, when the contact adhering layer effect in the inlet zone is considered, the load-carrying capacity of the present EHL contact is increased especially for small loads. This means that at low rolling speeds the contact adhering layer effect in the inlet zone may reduce the elastohydrodynamic lubrication deviation from classical EHL theory predictions especially for small loads.

  • analytical solution to a mode of mixed elastohydrodynamic lubrication with mixed contact regimes part i without consideration of contact adhering layer in the inlet zone
    Journal of Molecular Liquids, 2007
    Co-Authors: Yongbin Zhang
    Abstract:

    In 2005, Zhang presented a Grubin-like inlet zone analysis to the isothermal line contact elastohydrodynamic lubrication under relatively heavy loads when the hydrodynamic film thickness in the Hertzian zone approaches zero and the EHL fluid is Newtonian [Zhang, Y.B. A justification of the load-carrying capacity of elastohydrodynamic lubrication film based on the Newtonian fluid model. Industrial Lubrication and Tribology, 2005, Vol. 57, pp. 224–232]. His results showed that in this EHL, when the rolling speed is lower than the characteristic rolling speed (Uch =) 0.0372W1.50/G, the Hertzian zone is in physical adsorbed layer boundary lubrication while the inlet zone is in conventional hydrodynamic lubrication. This mode of EHL represents a mode of mixed EHL with mixed contact regimes, where hydrodynamic films with different rheological behaviors occur in different areas of the contact. The present paper presents an analysis to this mode of mixed EHL by using the Grubin type method when the contact adhering layer in the inlet zone is neglected. Pressures, film thicknesses and load partition in the contact are obtained from this analysis. It is also found that the formula for the characteristic rolling speed Uch = 0.0372W1.50/G obtained by Zhang [Zhang, Y.B. A justification of the load-carrying capacity of elastohydrodynamic lubrication film based on the Newtonian fluid model. Industrial Lubrication and Tribology, 2005, Vol. 57, pp. 224–232] may be valid for the dimensionless load W > 1.0E−7, while it may be invalid for the dimensionless load W < 1.0E−8. In part II [Zhang, Y.B. Analytical solution to a mode of mixed elastohydrodynamic lubrication with mixed contact regimes: Part II. Considering the contact adhering layer effect in the inlet zone. Journal of Molecular Liquids, 2006, Vol. 117. (doi:10.1016/j.molliq.2006.04.007)] will be presented an analysis to other two modes of mixed EHL with mixed contact regimes for relatively heavy loads, low rolling speeds and Newtonian fluids, where the conventional hydrodynamic lubrication, physical adsorbed layer boundary lubrication and oxidized chemical layer boundary lubrication can simultaneously occur in the inlet zone while the oxidized chemical layer boundary lubrication or the fresh metal-oxidized chemical boundary layer dry contact occur in the Hertzian zone, considering the contact adhering layer effect in the inlet zone.

Jiawei Xiang - One of the best experts on this subject based on the ideXlab platform.

  • study on the load carrying capacity of surface textured slipper bearing of axial piston pump
    Applied Mathematical Modelling, 2020
    Co-Authors: Shaogan Ye, Hesheng Tang, Jiawei Xiang
    Abstract:

    Abstract To introduce the elastohydrodynamic lubrication effect caused by the pressure distribution under a surface-textured slipper, the slipper's load-carrying capacity is studied. An elastohydrodynamic model was established to analyse the load-carrying capacity at different rotational speeds and load pressures. The comprehensive effects of tilting angle, area density, dimple depth to diameter ratio, and operating conditions are investigated. The results indicate that the optimum film thickness with the maximum stiffness coefficient can be obtained by adjusting the rotational speed, but the load-carrying capacity is slightly lower than that of a rigid surface considering the textured-surface deformation. The load-carrying capacity enhancement of a textured-surface slipper bearing is obvious at the optimum tilting angle, but the maximal load-carrying capacity becomes lower at a higher tilting angle. A textured slipper with an area density and a dimple depth to diameter ratio of 24% and 0.3, respectively, can generate a high load-carrying capacity under an elastohydrodynamic lubrication condition.

  • a novel model for predicting thermoelastohydrodynamic lubrication characteristics of slipper pair in axial piston pump
    International Journal of Mechanical Sciences, 2017
    Co-Authors: Hesheng Tang, Jiawei Xiang
    Abstract:

    Abstract A novel thermoelastohydrodynamic (TEHD) lubrication model has been developed for slipper pair in axial piston pump. The model considers the interaction between elastohydrodynamic behavior and viscosity temperature effect. Deformation of the slipper is discussed as well as the distribution of oil film thickness, pressure and temperature. Effects of working conditions and slipper structure parameters on TEHD lubrication performance, such as film thickness, pressure, temperature, and leakage flow rate are investigated. The predicted temperature and film thickness show good agreement with measurements, while the pressure shows a reasonable distribution comparing with previous studies. The influence of load pressure and shaft rotational speed on the TEHD lubrication characteristics are illustrated which shows the elastohydrodynamic pressure should be balanced against the oil film temperature and pressure in optimized design of slipper structure parameters. Finally, the structure parameters of slipper, such as the slipper radius ratio and orifice length-diameter ratio, were optimized to improve the TEHD lubrication performance of slipper pair.

Shaogan Ye - One of the best experts on this subject based on the ideXlab platform.

  • study on the load carrying capacity of surface textured slipper bearing of axial piston pump
    Applied Mathematical Modelling, 2020
    Co-Authors: Shaogan Ye, Hesheng Tang, Jiawei Xiang
    Abstract:

    Abstract To introduce the elastohydrodynamic lubrication effect caused by the pressure distribution under a surface-textured slipper, the slipper's load-carrying capacity is studied. An elastohydrodynamic model was established to analyse the load-carrying capacity at different rotational speeds and load pressures. The comprehensive effects of tilting angle, area density, dimple depth to diameter ratio, and operating conditions are investigated. The results indicate that the optimum film thickness with the maximum stiffness coefficient can be obtained by adjusting the rotational speed, but the load-carrying capacity is slightly lower than that of a rigid surface considering the textured-surface deformation. The load-carrying capacity enhancement of a textured-surface slipper bearing is obvious at the optimum tilting angle, but the maximal load-carrying capacity becomes lower at a higher tilting angle. A textured slipper with an area density and a dimple depth to diameter ratio of 24% and 0.3, respectively, can generate a high load-carrying capacity under an elastohydrodynamic lubrication condition.

Hesheng Tang - One of the best experts on this subject based on the ideXlab platform.

  • study on the load carrying capacity of surface textured slipper bearing of axial piston pump
    Applied Mathematical Modelling, 2020
    Co-Authors: Shaogan Ye, Hesheng Tang, Jiawei Xiang
    Abstract:

    Abstract To introduce the elastohydrodynamic lubrication effect caused by the pressure distribution under a surface-textured slipper, the slipper's load-carrying capacity is studied. An elastohydrodynamic model was established to analyse the load-carrying capacity at different rotational speeds and load pressures. The comprehensive effects of tilting angle, area density, dimple depth to diameter ratio, and operating conditions are investigated. The results indicate that the optimum film thickness with the maximum stiffness coefficient can be obtained by adjusting the rotational speed, but the load-carrying capacity is slightly lower than that of a rigid surface considering the textured-surface deformation. The load-carrying capacity enhancement of a textured-surface slipper bearing is obvious at the optimum tilting angle, but the maximal load-carrying capacity becomes lower at a higher tilting angle. A textured slipper with an area density and a dimple depth to diameter ratio of 24% and 0.3, respectively, can generate a high load-carrying capacity under an elastohydrodynamic lubrication condition.

  • a novel model for predicting thermoelastohydrodynamic lubrication characteristics of slipper pair in axial piston pump
    International Journal of Mechanical Sciences, 2017
    Co-Authors: Hesheng Tang, Jiawei Xiang
    Abstract:

    Abstract A novel thermoelastohydrodynamic (TEHD) lubrication model has been developed for slipper pair in axial piston pump. The model considers the interaction between elastohydrodynamic behavior and viscosity temperature effect. Deformation of the slipper is discussed as well as the distribution of oil film thickness, pressure and temperature. Effects of working conditions and slipper structure parameters on TEHD lubrication performance, such as film thickness, pressure, temperature, and leakage flow rate are investigated. The predicted temperature and film thickness show good agreement with measurements, while the pressure shows a reasonable distribution comparing with previous studies. The influence of load pressure and shaft rotational speed on the TEHD lubrication characteristics are illustrated which shows the elastohydrodynamic pressure should be balanced against the oil film temperature and pressure in optimized design of slipper structure parameters. Finally, the structure parameters of slipper, such as the slipper radius ratio and orifice length-diameter ratio, were optimized to improve the TEHD lubrication performance of slipper pair.

Homer Rahnejat - One of the best experts on this subject based on the ideXlab platform.

  • Transient mixed non-Newtonian thermo-Elastohydrodynamics of vehicle differential hypoid gears with starved partial counter-flow inlet boundary
    Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2014
    Co-Authors: Mohammadpour, Stephanos Theodossiades, Homer Rahnejat
    Abstract:

    The paper presents solutions for transient mixed thermo-Elastohydrodynamics of meshing differential hypoid gears of a vehicle under low speed urban driving and high speed cruising. Realistic gear meshing conditions, such as contact load including inertial effects are used, in line with engine power torque and wheel traction. This constitutes simultaneous solution of gear pair dynamics, non-Newtonian Elastohydrodynamics as well as vehicle longitudinal inertial dynamics, an approach not hitherto reported in the literature. The important link between contact tribology and vehicle gearing dynamics is highlighted. It is also shown that gear teeth pairs are subjected to a starved inlet boundary condition, represented by realistic inlet flow analysis. These conditions lead to the formation of a thin lubricant film with non-Newtonian shear and with modest boundary interactions.

  • Special Issue Article
    2014
    Co-Authors: Mahdi Mohammadpour, Stephanos Theodossiades, Homer Rahnejat
    Abstract:

    Transient mixed non-Newtonian thermo-Elastohydrodynamics of vehicle differential hypoid gears with starved partial counter-flow inlet boundar

  • XML Template (2014) [30.5.2014–9:48am] [1–15] //blrnas3/cenpro/ApplicationFiles/Journals/SAGE/3B2/PIJJ/Vol00000/140061/APPFile/SG-PIJJ140061.3d (PIJ) [PREPRINTER stage] Original Article
    2014
    Co-Authors: Mahdi Mohammadpour, Stephanos Theodossiades, Homer Rahnejat
    Abstract:

    Transient mixed non-Newtonian thermo-Elastohydrodynamics of vehicle differential hypoid gears with starved partial counter-flow inlet boundar

  • Elastohydrodynamic lubrication of hypoid gear pairs at high loads
    Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2012
    Co-Authors: Mehrdad Mohammadpour, Stephanos Theodossiades, Homer Rahnejat
    Abstract:

    Differential hypoid gear pairs have been the mechanism of choice for high-torque capacity final drives in all forms of vehicles, at least since mid-19th century. Transmission efficiency as well noise and vibration concerns requires combined elastohydrodynamic and tooth contact analysis of hypoid gear teeth pairs through mesh. Although such analyses have been reported for general cases of elliptical point contact conjunctions with angled flow entrainment, they do not comply with the prevailing load and kinematic conditions in differential gears. In particular, teeth pair contacts are subject to significant loads of order of several kilo Newtons requiring solution to the elastohydrodynamic lubrication problem at such high loads. The current analysis reports solutions for rolling and sliding Elastohydrodynamics of hypoid gear teeth pairs at realistic drive torques, not hitherto reported in literature.

  • Elastohydrodynamic lubrication of hypoid gear pairs at high loads
    2012
    Co-Authors: Mahdi Mohammadpour, Stephanos Theodossiades, Homer Rahnejat
    Abstract:

    Differential hypoid gear pairs have been the mechanism of choice for high torque capacity final drives in all forms of vehicles, at least since mid 19th century. Transmission efficiency as well noise and vibration concerns require combined elastohydrodynamic and tooth contact analysis of hypoid gear teeth pairs through mesh. Although such analyses have been reported for general cases of elliptical point contact conjunctions with angled flow entrainment, they do not comply with the prevailing load and kinematic conditions in differential gears. In particular, teeth pair contacts are subject to significant loads of order of several kN requiring solution to the EHL problem at such high loads. The current analysis reports solutions for rolling and sliding Elastohydrodynamics of hypoid gear teeth pairs at realistic drive torques, not hitherto reported in literature