Lubricants

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26 pages, 8019 KiB

Open AccessArticle

Tribo-Dynamic Investigation of Cryogenic Ball Bearings Considering Varying Traction Parameters

by Shijie Zhang, Shuangshuang Jia, Yuhao Zhao, Jing Wei and Yanyang Zi

Lubricants 2025, 13(8), 352; https://doi.org/10.3390/lubricants13080352 - 5 Aug 2025

The traction behavior in cryogenic solid-lubricated ball bearings (CSLBBs) used in liquid rocket engines (LREs) affects not only the dynamic response of the bearing but also the lubricity and wear characteristics of the solid lubrication coating. The traction coefficient between the ball and [...] Read more.

The traction behavior in cryogenic solid-lubricated ball bearings (CSLBBs) used in liquid rocket engines (LREs) affects not only the dynamic response of the bearing but also the lubricity and wear characteristics of the solid lubrication coating. The traction coefficient between the ball and raceway depends on factors such as contact material, relative sliding velocity, and contact pressure. However, existing traction curve models for CSLBBs typically consider only one or two of these factors, limiting the accuracy and applicability of theoretical predictions. In this study, a novel traction model for CSLBBs is proposed, which incorporates the combined effects of contact material, relative sliding velocity, and contact pressure. Based on this model, a tribo-dynamic framework is developed to investigate the tribological and dynamic behavior of CSLBBs. The model is validated through both theoretical analysis and experimental data. Results show that the inclusion of solid lubricant effects significantly alters the relative sliding and frictional forces between the rolling elements and the raceway. These changes in turn influence the impact dynamics between the rolling elements and the cage, leading to notable variations in the bearing’s vibrational response. The findings may offer valuable insights for the wear resistance and vibration reduction design of CSLBBs. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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29 pages, 10070 KiB

Open AccessArticle

The Influence of MoS₂ Coatings on the Subsurface Stress Distribution in Bearing Raceways

by Bing Su, Chunhao Lu and Zeyu Gong

Lubricants 2025, 13(8), 336; https://doi.org/10.3390/lubricants13080336 - 30 Jul 2025

Viewed by 276

Abstract

Many low-temperature applications, such as rocket engines and liquefied natural gas (LNG) transport pumps, necessitate ultra-low-temperature operational environments. In these conditions, the properties of lubricating oils and greases are significantly influenced by temperature, leading to the widespread adoption of solid lubrication. Currently, there [...] Read more.

Many low-temperature applications, such as rocket engines and liquefied natural gas (LNG) transport pumps, necessitate ultra-low-temperature operational environments. In these conditions, the properties of lubricating oils and greases are significantly influenced by temperature, leading to the widespread adoption of solid lubrication. Currently, there is no international research regarding the influence of bearing coatings on the subsurface stress distribution in raceways. The Lundberg–Palmgren (L-P) theory states that subsurface stress variations govern bearing lifespan. Therefore, this paper utilizes existing formulas and Python programming to calculate the subsurface stress field of the inner raceway in a MoS₂ solid-lubricated angular contact ball bearing. Furthermore, it analyzes the impacts of factors such as coating material properties, slide-to-roll ratio, traction coefficient, and load on its subsurface stress field. The results reveal that for solid-lubricated ball bearings, as the load increases, the maximum subsurface stress shifts closer to the center of the contact area, and the maximum subsurface shear stress becomes more concentrated. As the traction coefficient increases, the stress on the XZ-plane side increases and its position moves closer to the surface, while the opposite trend is observed on the other side. Additionally, the maximum value of the subsurface von Mises stress is approximately 0.64P₀, and the maximum value of the orthogonal shear stress component τ_yz in the subsurface is approximately 0.25P₀. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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23 pages, 9293 KiB

Open AccessArticle

Numerical and Experimental Investigations of Oil Return Efficiency in Tapered Roller Bearings Under Oil Jet Lubrication

by Yu Dai, Cheng Yu, Hongmei Wu, Jianfeng Zhong, Xiang Zhu and Gang Wang

Lubricants 2025, 13(8), 333; https://doi.org/10.3390/lubricants13080333 - 30 Jul 2025

Viewed by 151

Abstract

Tapered roller bearings are extensively utilized in the aerospace industry owing to their superior load-carrying capacity and extended service life. However, the majority of research conducted by scholars on the subject of bearing lubrication has focused on ball and cylindrical roller bearings. There [...] Read more.

Tapered roller bearings are extensively utilized in the aerospace industry owing to their superior load-carrying capacity and extended service life. However, the majority of research conducted by scholars on the subject of bearing lubrication has focused on ball and cylindrical roller bearings. There is a paucity of research on the internal lubricants and air distribution of tapered roller bearings under oil jet lubrication conditions. This paper presents a computational fluid dynamics (CFD) simulation model specifically designed for the oil jet lubrication of tapered roller bearings. The flow field inside the bearing cavity is analyzed under various operating conditions, and the impact of different parameters on lubrication performance is quantitatively assessed using the oil return efficiency as a metric. Additionally, an experimental test stand for the jet lubrication of tapered roller bearings was developed. The simulated oil return efficiency was compared with experimental data, revealing discrepancies within 10%, thereby validating the accuracy of the CFD model. The findings suggest that directing the oil jet toward the smaller end of the bearing, appropriately increasing the nozzle flow rate, and utilizing positive jetting can significantly improve the lubrication performance of tapered roller bearings. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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16 pages, 9251 KiB

Open AccessArticle

Topology Optimization of Textured Journal Bearings

by Hanqian Kong, Chunxing Gu, Di Zhang and Lanfei Wu

Lubricants 2025, 13(6), 251; https://doi.org/10.3390/lubricants13060251 - 4 Jun 2025

Viewed by 581

Abstract

The journal bearing, a critical component of the rotating shaft, is influenced by various factors including friction, wear, and heat effects under actual working conditions. This study developed an advanced approach for optimizing the performance of journal bearings with surface texture. This approach [...] Read more.

The journal bearing, a critical component of the rotating shaft, is influenced by various factors including friction, wear, and heat effects under actual working conditions. This study developed an advanced approach for optimizing the performance of journal bearings with surface texture. This approach allows for finding the influences of bearing parameters such as journal clearance, rotational speed, and shaft eccentricity ratio on the optimization results. The results show that whether under smaller journal clearances, higher rotational speeds, or larger shaft eccentricity ratios, the formation of intricate bifurcation patterns and enhanced branching in surface textures is consistently promoted. The optimized texture’s shape leads to a reduction in texture depth while significantly improving both the load-carrying capacity (LCC) and oil film thickness. This approach precisely determines the spatial and depth characteristics of texture elements, ensuring their optimal placement and geometry, and offers valuable insights and directions for future research. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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24 pages, 10171 KiB

Open AccessArticle

Analysis of Skidding Characteristics of Solid-Lubricated Angular Contact Ball Bearings During Acceleration

by Shijie Zhang, Yuhao Zhao, Jing Wei and Yanyang Zi

Lubricants 2025, 13(5), 218; https://doi.org/10.3390/lubricants13050218 - 14 May 2025

Viewed by 465

Abstract

Solid-lubricated rolling bearings are widely used in the aerospace field and are key components to support spacecraft rotors. During the start-up of the engine, the sharp acceleration may cause bearing skidding, resulting in damage of the solid lubricating film and a reduction in [...] Read more.

Solid-lubricated rolling bearings are widely used in the aerospace field and are key components to support spacecraft rotors. During the start-up of the engine, the sharp acceleration may cause bearing skidding, resulting in damage of the solid lubricating film and a reduction in the remaining useful life of the bearing. However, the existing research on the tribo-dynamic responses of solid-lubricated ball bearings mostly relies on semi-empirical tribological models, which are limited in their ability to reveal the micro–macro sliding mechanisms of the ball–raceway contact interface. In this paper, a novel tribo-dynamic model for solid-lubricated angular contact ball bearings is developed by applying Kalker’s rolling contact theory to the Gupta dynamic model. The interpolation method is adopted to calculate contact parameters to improve the model’s efficiency. Using the proposed model, the dynamic response of the bearing in the acceleration process is studied, and the mechanism and influence characteristics of skidding, over-skidding, and creepage of the rolling element are analyzed. The results show that the main reason for skidding is that the traction force is not enough to overcome the resistance, and the gyroscopic effect is the main cause of over-skidding, which follows the principle of conservation of the angular momentum of the ball. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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16 pages, 7401 KiB

Open AccessArticle

Analytical Method for Predicting Wear Life of Angular Contact Ball Bearings Under Variable Loading Based on Mixed Lubrication

by Xiaoyan Mu, Gong Cheng, Shaojiang Dong, Liang Yi and Hongliang Liu

Lubricants 2025, 13(5), 212; https://doi.org/10.3390/lubricants13050212 - 12 May 2025

Viewed by 645

Abstract

In aerospace technology, angular contact ball bearings are required to exhibit extremely high operational precision, necessitating real-time monitoring of their wear status to conduct pre-failure analysis. Although extensive studies have been conducted on the wear characteristics of angular contact bearings, further in-depth research [...] Read more.

In aerospace technology, angular contact ball bearings are required to exhibit extremely high operational precision, necessitating real-time monitoring of their wear status to conduct pre-failure analysis. Although extensive studies have been conducted on the wear characteristics of angular contact bearings, further in-depth research is still required to enhance the accuracy of bearing life predictions. To address the imprecision in wear life prediction for angular contact ball bearings, this article proposes a refined wear calculation model based on dynamic load distribution. The model calculates the dynamic load distribution between the inner and outer rings and the raceway under mixed lubrication conditions. Integrating the dynamic load distribution methodology with the wear calculation model, the dynamic contact characteristics of angular contact bearings can be more accurately characterized. Building on this foundation, a dynamic analysis model considering dynamic wear in the bearing contact zone is established. The vibration characteristics of bearings under varying loads are analyzed, and vibration experiments under different load conditions are conducted. Through vibration spectrum analysis, the influence patterns of wear characteristic frequency bands in the wear model on the pre-failure state of bearings are further elucidated. This study provides a theoretical basis for bearing wear life prediction analysis. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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22 pages, 1849 KiB

Open AccessArticle

Investigating Film Thickness and Friction of an MR-Lubricated Journal Bearing

by Gerben van der Meer and Ron van Ostayen

Lubricants 2025, 13(4), 171; https://doi.org/10.3390/lubricants13040171 - 8 Apr 2025

Viewed by 803

Abstract

Magnetorheological (MR) fluids are frequently reported to have potential as lubricants for hydrodynamic bearings operating at high loads, but no comprehensive effort has been made to investigate their performance under a variety of operating conditions. This paper, therefore, presents an extensive experimental and [...] Read more.

Magnetorheological (MR) fluids are frequently reported to have potential as lubricants for hydrodynamic bearings operating at high loads, but no comprehensive effort has been made to investigate their performance under a variety of operating conditions. This paper, therefore, presents an extensive experimental and numerical investigation of an MR-lubricated hydrodynamic journal bearing subjected to different loads and magnetic fields, and compares these results to those of an oil-lubricated bearing. It is shown that by increasing the magnetic field strength, the performance characteristics of the bearing can be changed from low hydrodynamic friction and a high transition speed to high hydrodynamic friction and a low transition speed. Furthermore, it was found that the way in which these characteristics scale with increasing load differs for the MR- and oil-lubricated bearings. With MR lubrication, the relative change in characteristics with the application of a magnetic field is smaller at higher loads, due to the strong shear-thinning rheology of MR fluids. To include these effects in the model, a basic relation for the apparent MR viscosity as a function of shear rate, temperature, and magnetic field strength is introduced. Finally, the bearing was made from a polymer to improve wear resistance under MR lubrication, but a comparison with a Reynolds equation-based numerical model indicates possible performance degradation due to shape errors, which is a known issue with this bearing material. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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37 pages, 12247 KiB

Open AccessArticle

Enhancing Fault Diagnosis: A Hybrid Framework Integrating Improved SABO with VMD and Transformer–TELM

by Jingzong Yang, Xuefeng Li and Min Mao

Lubricants 2025, 13(4), 155; https://doi.org/10.3390/lubricants13040155 - 31 Mar 2025

Viewed by 436

Abstract

Rolling bearings, as core components in mechanical systems, directly influence the overall reliability of equipment. However, continuous operation under complex working conditions can easily lead to gradual performance degradation and sudden faults, which not only result in equipment failure but may also trigger [...] Read more.

Rolling bearings, as core components in mechanical systems, directly influence the overall reliability of equipment. However, continuous operation under complex working conditions can easily lead to gradual performance degradation and sudden faults, which not only result in equipment failure but may also trigger a cascading failure effect, significantly amplifying downtime losses. To address this challenge, this study proposes an intelligent diagnostic method that integrates variational mode decomposition (VMD) optimized by the improved subtraction-average-based optimizer (ISABO) with transformer–twin extreme learning machine (Transformer–TELM) ensemble technology. Firstly, ISABO is employed to finely optimize the initialization parameters of VMD. With the improved initialization strategy and particle position update method, the optimal parameter combination can be precisely identified. Subsequently, the optimized parameters are used to model and decompose the signal through VMD, and the optimal signal components are selected through a constructed two-dimensional evaluation system. Furthermore, diversified time-domain features are extracted from these components to form an initial feature set. To deeply mine feature information, a multi-layer Transformer model is introduced to refine more discriminative feature representations. Finally, these features are input into the constructed TELM fault diagnosis model to achieve precise diagnosis of rolling bearing faults. The experimental results demonstrate that this method exhibits excellent performance in terms of noise resistance, accurate fault feature capture, and fault classification. Compared with traditional machine learning techniques such as kernel extreme learning machine (KELM), extreme learning machine (ELM), support vector machine (SVM), and Softmax, this method significantly outperforms other models in terms of accuracy, recall, and F1 score. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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22 pages, 5002 KiB

Open AccessArticle

Thermal–Mechanical Coupling Model of a Double-Piece Inner Ring Ball Bearing Based on ADAMS Secondary Development

by Yujun Xue, Fanjing Meng, Yongjian Yu and Haichao Cai

Lubricants 2025, 13(4), 154; https://doi.org/10.3390/lubricants13040154 - 31 Mar 2025

Viewed by 442

Abstract

The double-piece inner ring ball bearing is an important part of an aero-engine. An excessive bearing temperature leads to bearing thermal expansion, lubricating oil performance degradation, and other problems that seriously affect the service life and reliability of the bearing. Thus, it is [...] Read more.

The double-piece inner ring ball bearing is an important part of an aero-engine. An excessive bearing temperature leads to bearing thermal expansion, lubricating oil performance degradation, and other problems that seriously affect the service life and reliability of the bearing. Thus, it is important to study the temperature field of a double-piece inner ring ball bearing. In this study, considering the heat exchange of lubricant circulating in the oil tank–tubing–bearing and the influence of the flow field in the bearing chamber on the bearing’s temperature rise, a modified transient thermal network equation for an oil tank–tubing–bearing system was established. Based on ADAMS software and considering the thermal–mechanical coupling effect on the bearing’s contact force, a thermal–mechanical coupling dynamic model for double-piece inner ring ball bearings was established. Combined with the bearing dynamics and modified transient thermal network equation, a thermal–mechanical coupling transient temperature field model for double-piece inner ring ball bearings was constructed. A temperature rise test was carried out on a double-piece inner ring ball bearing, and the accuracy of the bearing temperature rise simulation model was verified by the test results. The model can simulate the oil temperature change process, calculate the heat absorbed by the lubricating oil more accurately, and provide a theoretical basis for the design of bearing and lubrication systems. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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25 pages, 13823 KiB

Open AccessArticle

Thermal Analysis of Grease-Lubricated Double Row Tapered Roller Bearings

by Xianwen Zhou, Zhenyu Ge, Xuejun Li, Miaohong Rao and Qingkai Han

Lubricants 2025, 13(2), 84; https://doi.org/10.3390/lubricants13020084 - 14 Feb 2025

Viewed by 818

Abstract

A steady-state thermal model of double-row tapered roller bearings (DTRB) with grease lubrication under a combined load is established in this paper. The influence of the internal load distribution on the temperature allotment of bearings in the circumferential, axial, and radial directions is [...] Read more.

A steady-state thermal model of double-row tapered roller bearings (DTRB) with grease lubrication under a combined load is established in this paper. The influence of the internal load distribution on the temperature allotment of bearings in the circumferential, axial, and radial directions is considered. Firstly, the local heat generation of the bearing is calculated based on the kinematic relationship inside the bearing, the internal load distribution, and the rheological properties of the grease. Then, combined with the heat dissipation analysis of the bearing, the three-dimensional steady-state temperature field of the DTRB is obtained. Ultimately, an analysis is conducted to examine how working conditions, including radial load, axial load, and rotational speed, impact the allotment of temperature fields in a DTRB along its circumferential, axial, and radial directions. The theoretical analysis outcome agrees with the experimental test outcome, providing theoretical guidance for the analysis of the bearing’s three-dimensional temperature field. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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12 pages, 2383 KiB

Open AccessArticle

Experimental Verification and Multi-Physics-Based Computer-Aided Engineering Simulation Methods for Dynamic Characteristics Analysis of Gas Foil Bearings at Lift-Off State

by Tai-Yuan Yu and Pei-Jen Wang

Lubricants 2025, 13(2), 75; https://doi.org/10.3390/lubricants13020075 - 10 Feb 2025

Cited by 1 | Viewed by 990

Abstract

This paper presents an analysis of the dynamic characteristics observed and studied during the startup process of a gas foil radial bearing. It utilizes a comparison of both experimental data and three-dimensional fluid–solid interaction computational fluid dynamics simulations to investigate a gas foil [...] Read more.

This paper presents an analysis of the dynamic characteristics observed and studied during the startup process of a gas foil radial bearing. It utilizes a comparison of both experimental data and three-dimensional fluid–solid interaction computational fluid dynamics simulations to investigate a gas foil bearing with three bump-type pads. The analytical model employs the fluid–structure interaction finite element method to examine the relationship between the components and the thin working fluid film within the bearing. This analysis was conducted under various operational conditions, including ambient pressure and temperature, shaft rotational speed, and the load applied to the shaft within the bearing. The foil structure of the bearing was modeled by representing the top and bump foils as a series of linear springs that are interconnected with the rigid housing. Meanwhile, the hydrodynamic pressure distribution acting on the top foil was modeled as a gas film operating under steady-state lubrication conditions. The comprehensive three-dimensional multi-physics model was developed using a commercial computer-aided engineering package, enabling independent finite element calculations for both fluid and solid domains. Following these calculations, the model exchanged analysis results across the interface between domains, allowing simulations to continue until the system achieved a quasi-steady state. An in-house experimental system was designed to evaluate the performance of the gas foil bearing under different working conditions, including the load applied to the shaft and the rotational speed. The experiment investigated the operational state of a gas foil radial bearing under ambient pressure (1 bar), ambient temperature (303 K), rotational speeds ranging from 1.5 to 9.5 krpm, and a load of 0.5602 kgw. Some operational conditions of the bearing were defined as boundary condition inputs for the simulation model. The model’s results, notably the predicted lift-off rotational speed of the bearing, show strong alignment with results from in-house experiments. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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Review

Jump to: Research

29 pages, 1122 KiB

Open AccessReview

Trends in Lubrication Research on Tapered Roller Bearings: A Review by Bearing Type and Size, Lubricant, and Study Approach

by Muhammad Ishaq Khan, Lorenzo Maccioni and Franco Concli

Lubricants 2025, 13(5), 204; https://doi.org/10.3390/lubricants13050204 - 6 May 2025

Cited by 1 | Viewed by 886

Abstract

A tapered roller bearing (TRB) is a specialized type of bearing with a high load-to-volume ratio, designed to support both radial and axial loads. Lubrication plays a crucial role in TRB operation by reducing friction and dissipating heat generated during rotation. However, it [...] Read more.

A tapered roller bearing (TRB) is a specialized type of bearing with a high load-to-volume ratio, designed to support both radial and axial loads. Lubrication plays a crucial role in TRB operation by reducing friction and dissipating heat generated during rotation. However, it can also negatively impact TRB performance due to the viscous and inertial effects of the lubricant. Extensive research has been conducted to examine the role of lubrication in TRB performance. Lubrication primarily influences the frictional characteristics, thermal behavior, hydraulic losses, dynamic stability, and contact mechanics of TRBs. This paper aims to collect and classify the scientific literature on TRB lubrication based on these key aspects. Specifically, it explores the scope of research on the use of Newtonian and non-Newtonian lubricants in TRBs. Furthermore, this study analyzes research based on TRB size and type, considering both oil and grease as lubricants. The findings indicate that both numerical and experimental studies have been conducted to investigate Newtonian and non-Newtonian lubricants across various TRB sizes and types. However, the results highlight that limited research has focused on non-Newtonian lubricants in TRBs with an Outer Diameter (OD) exceeding 300 mm, i.e., those typically used in wind turbines, industrial gearboxes, and railways. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System, 3rd Edition)

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