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Jane Q Wang - One of the best experts on this subject based on the ideXlab platform.

  • modeling thermal visco Elastohydrodynamic Lubrication tvehl interfaces of polymer based materials
    Tribology International, 2021
    Co-Authors: Jane Q Wang, Xin Zhang, Yuchuan Liu, Hun June Kim, Seongchan Pack
    Abstract:

    Abstract This paper reports a novel thermal-visco-elasohydrodynamic Lubrication (TVEHL) model for analyzing the Lubrication behavior of the interface formed by an elastic sphere and a polymer half-space. The temperature-dependent viscoelastic displacement of the polymer surface is calculated through the elastic-viscoelastic correspondence theory and frequency-temperature superposition. The discrete convolution and fast Fourier transform (DC-FFT) algorithm is used for efficient solution computation. The model is verified by comparing results from its degenerated forms with those from thermal-viscoelastic (TVE) contact and thermal-Elastohydrodynamic Lubrication (TEHL) theories. The results from the current model with and without considering temperature effect are also compared. The new TVEHL model is explored to study the viscoelastic material property, entraining speed, sliding-to-rolling ratio, and the coupled thermal-viscoelasticity effects.

  • visco Elastohydrodynamic Lubrication of layered materials with imperfect layer substrate interfaces
    International Journal of Mechanical Sciences, 2021
    Co-Authors: Jane Q Wang, Xin Zhang, Yuchuan Liu, Hun June Kim, Seongchan Pack
    Abstract:

    Abstract This paper reports a novel visco-Elastohydrodynamic Lubrication (VEHL) model for the Lubrication interface formed by a rigid sphere and a viscoelastic layer imperfectly coated on an elastic half-space, aiming to study the effects of layer viscoelasticity and imperfect layer-substrate interface on the Lubrication behavior. The surface viscoelastic deformation is calculated based on a linear viscoelastic model and the correspondence principle. The contact solution is formulated with the discrete convolution and fast Fourier transform (DC-FFT) algorithm by using the influence coefficients (ICs) converted from frequency response functions (FRFs). The model is validated by using the results from its degenerated versions through comparisons with available published data. The new VEHL model is implemented to explore the effects of surface speed, layer thickness, and layer-substrate elastic modulus ratio, as well as the degree of displacement discontinuity or stiffness defect at the layer-substrate interface.

  • mixed Elastohydrodynamic Lubrication model for finite roller coated half space interfaces
    Tribology International, 2019
    Co-Authors: Dong Zhu, Jane Q Wang
    Abstract:

    Abstract This paper presents a mixed Elastohydrodynamic Lubrication (EHL) model for finite roller-coated half space interfaces. The model is built with the unified mixed Lubrication approach and the influence coefficients (ICs) relating the pressure on a contact surface to surface deformations and subsurface stresses, converted from the frequency response functions (FRFs). The elastic deformation is solved with the discrete convolution and fast Fourier transform (DC-FFT) algorithm. This model is used to explore the EHL performance of rollers subjected to a wide range of operating conditions. A parameters study is conducted to reveal the effects of coatings, macro geometry, and surface roughness on the Lubrication of rollers.

  • Elastohydrodynamic Lubrication a gateway to interfacial mechanics review and prospect
    Journal of Tribology-transactions of The Asme, 2011
    Co-Authors: Dong Zhu, Jane Q Wang
    Abstract:

    Elastohydrodynamic Lubrication (EHL) is commonly known as a mode of fluid-film Lubrication in which the mechanism of hydrodynamic film formation is enhanced by surface elastic deformation and lubricant viscosity increase due to high pressure. It has been an active and challenging field of research since the 1950s. Significant breakthroughs achieved in the last 10–15 years are largely in the area of mixed EHL, in which surface asperity contact and hydrodynamic lubricant film coexist. Mixed EHL is of the utmost importance not only because most power-transmitting components operate in this regime, but also due to its theoretical universality that dry contact and full-film Lubrication are in fact its special cases under extreme conditions. In principle, mixed EHL has included the basic physical elements for modeling contact, or hydrodynamic Lubrication, or both together. The unified mixed Lubrication models that have recently been developed are now capable of simulating the entire transition of interfacial status from full-film and mixed Lubrication down to dry contact with an integrated mathematic formulation and numerical approach. This has indeed bridged the two branches of engineering science, contact mechanics, and hydrodynamic Lubrication theory, which have been traditionally separate since the 1880s mainly due to the lack of powerful analytical and numerical tools. The recent advancement in mixed EHL begins to bring contact and Lubrication together, and thus an evolving concept of “Interfacial Mechanics” can be proposed in order to describe interfacial phenomena more precisely and collaborate with research in other related fields, such as interfacial physics and chemistry, more closely. This review paper briefly presents snapshots of the history of EHL research, and also expresses the authors’ opinions about its further development as a gateway to interfacial mechanics. [DOI: 10.1115/1.4004457]

  • plasto Elastohydrodynamic Lubrication pehl in point contacts
    Journal of Tribology-transactions of The Asme, 2010
    Co-Authors: Ning Ren, Dong Zhu, Wayne W Chen, Jane Q Wang
    Abstract:

    Elastohydrodynamic Lubrication (EHL) is an important branch of the Lubrication theory, describing Lubrication mechanisms in nonconformal contacts widely found in many mechanical components such as various gears, rolling bearings, cams and followers, metal-rolling tools, traction drives, and continuous variable transmissions. These components. often transmit substantial power under heavy loading conditions. Also, the roughness of machined surfaces is usually of the same order of magnitude as, or greater than, the estimated average EHL film thickness. Consequently, most components operate in mixed Lubrication regime with significant asperity contacts. Due to very high pressure concentrated in small areas, resulted from either heavy external loading or severe asperity contacts, or often a combination of both, subsurface stresses may exceed the material yield limit, causing considerable plastic deformation, which may not only permanently change the surface profiles and contact geometry but also alter material properties through work hardening as well. In the present study, a three-dimensional plasto-Elastohydrodynamic Lubrication (PEHL) model has been developed by taking into account plastic deformation and material work-hardening. The effects of surface/subsurface plastic deformation on lubricant film thickness, surface pressure distribution, and subsurface stress field have been investigated. This paper briefly describes the newly developed PEHL model and presents preliminary results and observed basic behavior of the PEHL in smooth-surface point contacts, in comparison with those from corresponding EHL solutions under the same conditions. The results indicate that plastic deformation may greatly affect contact and Lubrication characteristics, resulting in significant reductions in lubricant film thickness, peak surface pressure and maximum subsurface stresses.

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.

  • an analysis of Elastohydrodynamic Lubrication with limiting shear stress part i theory and solutions
    Tribology Transactions, 2002
    Co-Authors: Yongbin Zhang, Shizhu Wen
    Abstract:

    This paper investigates line contact Elastohydrodynamic Lubrication assuming a limiting shear stress of the fluid-contact interfaces. The film pressures and film thickness distributions are obtained for the slide-roll ratios between a cylinder and a plane. The results show that the interfacial limiting shear stress effect can directly cause a drastic film thickness reduction.

Zhongmin Jin - One of the best experts on this subject based on the ideXlab platform.

  • finite element analysis of Elastohydrodynamic Lubrication in an artificial hip joint under squeeze film motion using fluid structure interaction method
    Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2017
    Co-Authors: Hessam Nooridokht, Hanieh Niroomandoscuii, Davood Jalalivahid, Zhongmin Jin
    Abstract:

    Classical approach for Elastohydrodynamic Lubrication problems contains solution of Reynolds and elasticity equations simultaneously, where elasticity equation was derived based on semi-infinite solid assumption. Fluid–structure interaction method which uses finite element formulation is another alternative approach for Elastohydrodynamic Lubrication problems. Present study contains two sections: first finite element method was used to evaluate accuracy of semi-infinite assumption for deformation in an artificial joint cup for a verity of material and geometrical properties. Then fluid–structure interaction method was used to simulate an artificial hip joint Lubrication under squeeze film motion and efficiency and accuracy of this method was speculated by comparing the results to a previously done work. In the first section, deformation of a cup under Hertzian contact was calculated by finite element software ADINA. Various combinations of cup thickness, material properties, and dimensions of contact elli...

  • transient Elastohydrodynamic Lubrication of hip joint implants
    Journal of Tribology-transactions of The Asme, 2008
    Co-Authors: Fengcai Wang, Zhongmin Jin
    Abstract:

    A general transient Elastohydrodynamic Lubrication model was developed for artificial hip joint implants, particularly in which the three-dimensional time-dependent physiological load and motion components experienced during walking conditions were considered in the theoretical formulation, although only a predominantly vertical load combined with a flexion-extension motion was actually solved. A nominal ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup in both simplified and anatomical positions. An appropriate spherical coordinate system and the corresponding mesh grids were used in the general transient Lubrication model. Additionally, an equivalent discrete spherical convolution model and the corresponding spherical fast Fourier transform technique were employed to facilitate the evaluation of elastic deformation of spherical bearing surfaces in hip joint implants. The general Lubrication model was subsequently applied to investigate the transient Lubrication performance of a typical metal-on-metal hip joint implant. The effects of both cup inclination angles in either anatomical or horizontally simplified positions and different lubricant viscosities on the transient Elastohydrodynamic Lubrication were analyzed under the predominant components of vertically dynamic loading and flexion-extension motion. It was found that the general Lubrication model and the numerical methodology were efficient for the transient Elastohydrodynamic Lubrication analysis during walking condition in hip joint implants. Furthermore, the significant effect of squeeze-film action on maintaining and enhancing the total thin film thickness formation was discussed for the transient Lubrication study of the typical hip joint implant.

  • importance of head diameter clearance and cup wall thickness in Elastohydrodynamic Lubrication analysis of metal on metal hip resurfacing prostheses
    Proceedings of the Institution of Mechanical Engineers Part H: Journal of Engineering in Medicine, 2006
    Co-Authors: Feng Liu, Zhongmin Jin, P Roberts, P Grigoris
    Abstract:

    AbstractThe main design features of metal-on-metal (MOM) hip resurfacing prostheses in promoting Elastohydrodynamic Lubrication were investigated in the present study, including the femoral head diameter, the clearance, and the cup wall thickness. Simplified conceptual models were developed, based on equivalent uniform wall thicknesses for both the cup and the head as well as the support materials representing bone and cement, and subsequently used for Elastohydrodynamic Lubrication analysis. Both typical first- and second-generation MOM hip resurfacing prostheses with different clearances and cup wall thicknesses were considered with a fixed large bearing diameter of 50 mm, as well as a 28 mm diameter MOM total hip replacement bearing for the purpose of comparison. The importance of the head diameter and the clearance in promoting Elastohydrodynamic Lubrication was confirmed. Furthermore, it was also predicted that a relatively thin acetabular cup in the more recently introduced second-generation MOM hip...

  • Elastohydrodynamic Lubrication analysis of metal on metal hip resurfacing prostheses
    Journal of Biomechanics, 2003
    Co-Authors: I J Udofia, Zhongmin Jin
    Abstract:

    The Elastohydrodynamic Lubrication analysis was carried out in this study for a typical metal-on-metal hip-resurfacing prosthesis under a simple steady-state rotation. Both the Reynolds equation and the elasticity equation were coupled and solved numerically by the finite difference method. The finite element method was used to determine the elastic deformation of both the femoral and the acetabular components required for the Lubrication analysis. The effect of the radial clearance between the femoral head and the acetabular cup on the predicted film thickness and pressure distribution was investigated. The predicted minimum lubricating film thickness was found to compare favourably with the prediction using the Hamrock and Dowson [J. Lubrication Technol. 100 (1978) 236] formula based on the assumption of ball-on-plane semi-infinite solids. This implies that the non-metallic materials such as bone and cement underlying the metallic components have a small effect on the predicted Lubrication performance for the particular metal-on-metal hip-resurfacing prosthesis considered in this study. Under realistic physiological walking conditions, a decrease in the radial clearance from 150 to 50 μm resulted in a 137% increase in the predicted minimum film thickness from 19 to 45 nm. Consequently, given a surface roughness of 0.01 μm for both the metallic femoral and acetabular bearing surfaces, the predicted mixed Lubrication regime for the larger clearance was changed to a full fluid film Lubrication regime for the smaller clearance. This clearly highlighted the importance of the design and manufacturing parameters on the tribological performance of these hard-on-hard hip prostheses.

Zeliang Xiao - One of the best experts on this subject based on the ideXlab platform.

  • stiffness and damping models for the oil film in line contact Elastohydrodynamic Lubrication and applications in the gear drive
    Applied Mathematical Modelling, 2018
    Co-Authors: Changjiang Zhou, Zeliang Xiao
    Abstract:

    Abstract Innovative stiffness and damping models for oil films are developed to account for the impacts in both normal and tangential directions. Given that these models are applied to a gear drive in line contact Elastohydrodynamic Lubrication (EHL), the combined stiffness is derived from the stiffness of both the oil film and gear tooth while the combined damping is established from the damping of these parts. The effects of three fundamental parameters (contact force, rotation speed, and tooth numbers) of the gear drive in line contact EHL on the combined stiffness and damping are then investigated. The results reveal that the small normal and tangential stiffness of the lubricant can alleviate meshing impact and shear vibration, while the impact and friction heat can be reduced by using an oil film with either a large normal damping or small tangential damping. Given that its amplitude and fluctuation are closely related to shear rate, effective viscosity, entrainment velocity, and curvature radii, the improved combined stiffness and damping can be obtained by rationally matching the geometric and operating parameters.

Changjiang Zhou - One of the best experts on this subject based on the ideXlab platform.

  • An adhesive wear model for helical gears in line-contact mixed Elastohydrodynamic Lubrication
    Wear, 2019
    Co-Authors: Hongbing Wang, Changjiang Zhou
    Abstract:

    Abstract Adhesive wear in mixed Elastohydrodynamic Lubrication (EHL) has been one of the most prominent problems for heavy-loaded helical gears. However, this issue was rarely investigated in previous researches. In this work, an adhesive wear model for helical gears is established in line-contact mixed EHL. The contact parameters of the pinion and gear are derived according to the equivalent tapered roller contact model, and the load is attained in consideration of the varying contact line ratio. Then the asperity contact pressure is calculated according to Hertz's elastic contact theory and load sharing. Moreover, the sliding distances of the points on tooth surface of driving pinion and driven gear are achieved by a single point observation method, and Archard theory in dry contact is extended to the mixed Lubrication to estimate the wear rate in mixed EHL by using fractional film defect. The modified Archard's wear model is then employed in formulating and accounting for the gear tooth wear. Effects of surface roughness, geometrical parameters and working parameters on wear depth of the driving pinion are furtherly investigated. The results show that the wear depth in mixed EHL is lower than that under dry contact, which indicates that tooth wear can be reduced with the reasonable lubricants. As the surface roughness becomes large, the asperity contact pressure, the tooth surface temperature and wear depth are increased. Additionally, the wear depths decrease with the increase in module, helix angle, pressure angle, tooth width or rotation speed but increase with input torque.

  • stiffness and damping models for the oil film in line contact Elastohydrodynamic Lubrication and applications in the gear drive
    Applied Mathematical Modelling, 2018
    Co-Authors: Changjiang Zhou, Zeliang Xiao
    Abstract:

    Abstract Innovative stiffness and damping models for oil films are developed to account for the impacts in both normal and tangential directions. Given that these models are applied to a gear drive in line contact Elastohydrodynamic Lubrication (EHL), the combined stiffness is derived from the stiffness of both the oil film and gear tooth while the combined damping is established from the damping of these parts. The effects of three fundamental parameters (contact force, rotation speed, and tooth numbers) of the gear drive in line contact EHL on the combined stiffness and damping are then investigated. The results reveal that the small normal and tangential stiffness of the lubricant can alleviate meshing impact and shear vibration, while the impact and friction heat can be reduced by using an oil film with either a large normal damping or small tangential damping. Given that its amplitude and fluctuation are closely related to shear rate, effective viscosity, entrainment velocity, and curvature radii, the improved combined stiffness and damping can be obtained by rationally matching the geometric and operating parameters.