Lubricants

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2 pages, 154 KiB

Open AccessEditorial

Friction and Lubrication of Sliding Bearings

by Shih-Chieh Lin

Lubricants 2023, 11(5), 226; https://doi.org/10.3390/lubricants11050226 - 17 May 2023

Cited by 1 | Viewed by 988

Abstract

Bearings are essential components of machines, as they provide the low friction and energy consumption required for motion [...] Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

Research

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12 pages, 10343 KiB

Open AccessArticle

Measurement for Lubricant Distribution in an Angular Contact Ball Bearing and Its Influence Investigation

by Baogang Wen, Yemin Li, Meiling Wang and Yang Yang

Lubricants 2023, 11(2), 63; https://doi.org/10.3390/lubricants11020063 - 03 Feb 2023

Cited by 4 | Viewed by 1903

Abstract

Oil lubrication is widely adopted in rolling bearings, the characteristics of which affect the oil film formation and friction state, and also the heat generation and dissipation characteristics. However, it is difficult to measure the internal lubrication of rolling bearings in practice, which [...] Read more.

Oil lubrication is widely adopted in rolling bearings, the characteristics of which affect the oil film formation and friction state, and also the heat generation and dissipation characteristics. However, it is difficult to measure the internal lubrication of rolling bearings in practice, which is of great importance for lubrication and structure design. In this work, one measurement system for lubricant distribution was built and installed on a test rig to obtain original pictures of the lubricant in bearings. Grayscale images were obtained by picture processing to characterize the lubricant distribution, and the image pixels were evaluated for the characterization of lubricant volume. Finally, the measurement of the lubricant distribution in the angular ball bearing was carried out under different lubrication and cage groove conditions, and their influences were investigated. The results show that the lubricant distribution is affected by the oil jet nozzle angle, operating speed, and cage structure. The lubricant capacity among balls and the cage pocket in bearings gradually increased with the increase in the nozzle angle and the depth of the cage grooves, but decreased with the increasing operating speed. The experimental results are helpful to provide a basis for the structure and lubrication design of ball bearings. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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22 pages, 8808 KiB

Open AccessArticle

A Design for High-Speed Journal Bearings with Reduced Pad Size and Improved Efficiency

by Thomas Hagemann, Daniel Vetter, Sören Wettmarshausen, Michael Stottrop, Alexander Engels, Christoph Weißbacher, Beate Bender and Hubert Schwarze

Lubricants 2022, 10(11), 313; https://doi.org/10.3390/lubricants10110313 - 17 Nov 2022

Cited by 6 | Viewed by 1736

Abstract

Improving efficiency is a general task in the design process of high-speed journal bearings. A specific fixed-pad bearing geometry featuring reduced pad length and additional design measures with the intention of reducing frictional power loss is investigated, experimentally and theoretically, for a journal [...] Read more.

Improving efficiency is a general task in the design process of high-speed journal bearings. A specific fixed-pad bearing geometry featuring reduced pad length and additional design measures with the intention of reducing frictional power loss is investigated, experimentally and theoretically, for a journal diameter of 500 mm up to surface speeds of 94 m/s and unit loads of 5.0 MPa. To model fluid flow in the bearing outside the lubricant gap, an extension to Elrod’s cavitation algorithm based on assuming the inertia of fluid flow is proposed. Validation of the extended thermo-elasto-hydrodynamic lubrication (TEHL) model shows good agreement between measurement and prediction in wide operating ranges, however, with systematic tendencies of the remaining deviations. Furthermore, measured local pressure and film thickness distributions indicate a complex formation of cavitation with an influence of axial flow that is not covered by pure Couette-flow in the cavitation region. Measured as well as predicted data prove increased bearing efficiency for high rotor speeds. To provide understanding on the impact of the applied design measures improving efficiency, their combination is separated into the individual ones. Reduced axial and peripheral pad length both contribute almost equally to the reduction in power loss and improve its value by 37% compared to the standard design. Finally, further steps to deeper identify the behavior of the bearing are comprehensively discussed. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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13 pages, 2778 KiB

Open AccessArticle

Influence Analysis of Lubricant Recesses on the Working Capacity of the Bridge Span Spherical Bearing

by Yuriy O. Nosov and Anna A. Kamenskikh

Lubricants 2022, 10(11), 283; https://doi.org/10.3390/lubricants10110283 - 28 Oct 2022

Cited by 4 | Viewed by 1235

Abstract

The load on transport and logistics systems is increasing every year. This is due to car park growth around the world. Thus, increasing bridge structure durability is an urgent task for bridge-building companies. This study analyses the contact deformation of spherical bearing elements [...] Read more.

The load on transport and logistics systems is increasing every year. This is due to car park growth around the world. Thus, increasing bridge structure durability is an urgent task for bridge-building companies. This study analyses the contact deformation of spherical bearing elements through an anti-friction polymer layer with different geometrical configurations of recesses for the lubricant, i.e., annular grooves and spherical holes. The material of the anti-friction layer (a modified polytetrafluoroethylene (PTFE)) is modelled within the framework of the deformation theory of plasticity. The procedure of automating the numerical model construction depends on the input parameters, including the thickness of the layer, the basic geometrical parameters of the recesses for the lubricant, and the distance between the rows of recesses, etc. The influence of the arrangement of filling sliding anti-friction layers on recesses for lubricants in the form of spherical holes on the contact deformation behaviour of bridge bearings has been considered. The reduction of lubricant volume in the sliding anti-friction layer with the geometry of recesses in the form of spherical holes ranges from 26 to 48.4%, depending on the filling scheme, has been found. In this case, structures with lubrication recesses in the form of spherical holes have several advantages, including a more uniform distribution of contact parameters in the interface areas of the steel plates with the anti-friction layer, reduction of the maximum level of the plastic deformation intensity, displacements along the normal relative to the free end of the sliding layer, and the settlement of the bearing. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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20 pages, 16631 KiB

Open AccessArticle

Comparative Analysis of the Work of Bridge Spherical Bearing at Different Antifriction Layer Locations

by Anatoliy A. Adamov, Anna A. Kamenskikh, Anastasia P. Pankova and Veronika I. Strukova

Lubricants 2022, 10(9), 207; https://doi.org/10.3390/lubricants10090207 - 29 Aug 2022

Cited by 7 | Viewed by 2236

Abstract

The novel results reported here present qualitative and quantitative regularities of the deformation behavior of a spherical bearing with a different location and inclination angle of the antifriction layer. A number of topical problems encountered during the assessment of the performance bearings are [...] Read more.

The novel results reported here present qualitative and quantitative regularities of the deformation behavior of a spherical bearing with a different location and inclination angle of the antifriction layer. A number of topical problems encountered during the assessment of the performance bearings are considered in the work. The spherical bearings of the bridge span are investigated. Structures are load-bearing elements of transport systems. They perceive thermal power loads from the bridge span. The temperature problem is not considered in this study. In this paper, a comparative analysis of the bridge spherical bearing operation at different antifriction layer locations was performed. Two bearing geometries are considered: the interlayer is pressed in a spherical segment (classical geometry); the interlayer is pressed into a recess located in the lower steel plate. The six modern antifriction materials considered proved suitable to some extent as contact unit sliding layers for various purposes. Additionally, the influence of the inclination angle of the antifriction layer end face on the structure operation for all sliding layer material variants was analyzed. It has been established that the bearing design with an interlayer in the lower steel plate has a more favorable deformation behavior. Changing of the inclination angle of the antifriction layer end face leads to a decrease in the maximum level of contact parameters and deformation characteristics for all the considered structures. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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12 pages, 3756 KiB

Open AccessArticle

Nonlinear Vibration Induced by Friction in a Ball Joint System

by Jaeyoung Kang

Lubricants 2022, 10(9), 201; https://doi.org/10.3390/lubricants10090201 - 26 Aug 2022

Cited by 1 | Viewed by 1345

Abstract

In this paper, the nonlinear oscillations induced by friction in a ball-on-socket system are investigated. The nonlinear time response was obtained by solving the differential equations of the friction-noise model of the finite element ball with multiple modes. The different patterns of motion [...] Read more.

In this paper, the nonlinear oscillations induced by friction in a ball-on-socket system are investigated. The nonlinear time response was obtained by solving the differential equations of the friction-noise model of the finite element ball with multiple modes. The different patterns of motion were analyzed via the bifurcation diagram, Poincare map, and recurrence plot. The Lyapunov exponents of the discontinuous system with distributed contact were calculated using the Muller method. From the analysis, it is shown that a friction-noise of a ball joint can retain periodic, quasi-periodic, or chaotic oscillations with respect to tilted contact. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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18 pages, 5848 KiB

Open AccessArticle

Design and Performance Analysis of Dual Membrane Restrictor for Hydrostatic Bearing

by Shih-Chieh Lin, Yu-Hsiang Lo, Yu-Hsin Lin, Wei-Ting Tung and Ta-Hua Lai

Lubricants 2022, 10(8), 179; https://doi.org/10.3390/lubricants10080179 - 08 Aug 2022

Cited by 3 | Viewed by 1470

Abstract

In this paper, a dual membrane restrictor design was proposed to improve the stiffness performance of the compensated hydrostatic bearing. Theoretical models for the proposed dual membrane restrictors were derived. Analysis of these models showed that a high stiffness region could be achieved [...] Read more.

In this paper, a dual membrane restrictor design was proposed to improve the stiffness performance of the compensated hydrostatic bearing. Theoretical models for the proposed dual membrane restrictors were derived. Analysis of these models showed that a high stiffness region could be achieved at the desired loading region through the proper selection of the design parameters. A series of simulations were conducted to study the variations in the design parameters on the stiffness and clearance variations. It was found that the dimensionless membrane stiffness in the inlet restrictor,

K_{m i}^{*}

, was the most dominant parameter for the performance of the compensated bearing system. The main advantages of the proposed dual membrane restrictor are the increase in flexibility by providing high stiffness at the desired loading region; and improving the stiffness performance of the bearing system especially at the desired loading region. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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9 pages, 2516 KiB

Open AccessArticle

Tribological Characteristics of Nano-Lubricated High-Speed Rolling Bearings Considering Interaction between Nanoparticles and Rough Surface

by Xiaojie Tang and Junning Li

Lubricants 2022, 10(6), 117; https://doi.org/10.3390/lubricants10060117 - 06 Jun 2022

Cited by 5 | Viewed by 1721

Abstract

The embedding situation between various nanoparticles and rough surfaces affects the lubrication characteristics of rolling bearings. If not properly handled, this can easily lead to wear damage of rolling bearings. Therefore, the friction and wear mechanism of nano-lubricated high-speed rolling bearings under various [...] Read more.

The embedding situation between various nanoparticles and rough surfaces affects the lubrication characteristics of rolling bearings. If not properly handled, this can easily lead to wear damage of rolling bearings. Therefore, the friction and wear mechanism of nano-lubricated high-speed rolling bearings under various nanoparticle embedded states is studied in this manuscript. Mixed oils containing different sized SiO₂ nanoparticles and dispersants are prepared, and then the tribology test of nano-lubricated high-speed rolling bearings considering the interaction between various nanoparticles and the rough surfaces is conducted. The friction and wear properties such as coefficient of friction, wear volume and real-time temperature rise of high-speed rolling bearings under different embedding conditions are revealed, and the anti-wear mechanism of the nano-lubricated high-speed rolling bearings is obtained. The results show that compared to the complete non-embedded state, the complete embedded state of different nanoparticles effectively improves the anti-wear effect of the bearing. When the nanoparticle mixed oil is added, the bearing still has good anti-wear performance under the conditions of high speed and lack of oil. As for the light loaded rolling bearing adopted with nano-mixed oil, the coefficient of friction is appropriately increased, as well as the skid reduced, while the wear of the rolling bearing is effectively reduced. This research will provide theoretical basis and important reference for nano-lubrication and its application in aviation rolling bearings. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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20 pages, 6965 KiB

Open AccessArticle

Thrust-Bearing Layout Design of a Large-Sized Hydrostatic Rotary Table to Withstand Eccentric Loads for Horizontal Boring Machine Applications

by Hua-Chih Huang and Shen-Hen Yang

Lubricants 2022, 10(4), 49; https://doi.org/10.3390/lubricants10040049 - 22 Mar 2022

Cited by 6 | Viewed by 2514

Abstract

There is an increasing demand for large-sized hydrostatic rotary tables due to the industrial need for the precision machining of large workpieces for wind generation, aerospace, shipbuilding, and national defense applications. As a consequence, under eccentric loads, the deformation of the large-sized hydrostatic [...] Read more.

There is an increasing demand for large-sized hydrostatic rotary tables due to the industrial need for the precision machining of large workpieces for wind generation, aerospace, shipbuilding, and national defense applications. As a consequence, under eccentric loads, the deformation of the large-sized hydrostatic rotary table of a horizontal boring machine would negatively affect machining precision. Indeed, the hydrostatic thrust-bearing recess layout design is the main factor that affects the rotary table’s resistance against deformations caused by eccentric loads. This study focused on the capillary-compensated constant-pressure large-sized hydrostatic rotary table for a horizontal boring machine. ANSYS software was used to simulate the thermal and structural deformation of the worktable under eccentric loads. In addition to the original layout of the hydrostatic thrust bearing, three other bearing recess layouts, which involved two different recess diameters, were designed in order to examine the deformation of the worktable under eccentric loads. The results showed that, in terms of a single-ring hydrostatic thrust-bearing layout, a larger recess diameter resulted in a smaller worktable deformation compared to a smaller recess diameter; in terms of a dual-ring hydrostatic thrust bearing layout, the worktable deformation was smaller than that of the single-ring layout with a larger recess diameter. Under the spatial and geometric constraints of the worktable, adopting a hydrostatic thrust bearing with a dual-ring recess layout would minimize the worktable deformation under eccentric loads. For thermal deformation in a single-ring hydrostatic bearing pad layout, however, a larger recess diameter resulted in a larger worktable thermal deformation compared to a smaller recess diameter. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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13 pages, 4593 KiB

Open AccessArticle

Influence Analysis of the Antifriction Layer Materials and Thickness on the Contact Interaction of Spherical Bearings Elements

by Anatoliy A. Adamov, Anna A. Kamenskikh and Anastasia P. Pankova

Lubricants 2022, 10(2), 30; https://doi.org/10.3390/lubricants10020030 - 18 Feb 2022

Cited by 8 | Viewed by 2702

Abstract

Bearings are the supporting elements of bridges. They perceive vertical and horizontal loads from the bridge span. Spherical bearings are one of the construction common types. The material and configuration of the anti-friction layers determine the bearing performance. The paper performed the contact [...] Read more.

Bearings are the supporting elements of bridges. They perceive vertical and horizontal loads from the bridge span. Spherical bearings are one of the construction common types. The material and configuration of the anti-friction layers determine the bearing performance. The paper performed the contact deformation analysis of spherical bearing elements at a nominal vertical load of 1000 kN. The six types of the spherical sliding layer material are considered: ultra-high molecular weight polyethylene (UHMWPE) from three different manufacturers, modified polytetrafluoroethylene (PTFE), and composite materials by PTFE with two different forms of reinforcing bronze inclusions. Young’s modulus, Poisson’s ratio, and strain curve are obtained experimentally for spherical sliding layer materials. Paper considered the influence of the sliding layer material on the contact parameters and deformation characteristics of the structure with a standard interlayer thickness by 4 mm. Research observed significant the composite interlayer deformation and the appearance of “no contact” zones on the mating surfaces. The option of increasing the sliding layer thickness up to 6–8 mm is considered. A decrease is observed in the maximum level of contact parameters by increase of the sliding layer thickness. The influence of the anti-friction layer materials becomes insignificant on the bearing deformation with an increase of the spherical sliding layer thickness. Full article

(This article belongs to the Special Issue Friction and Lubrication of Sliding Bearings, Volume II)

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