Bearing Surface Research Articles

Investigation on the performances of thrust ball bearing with a novel oil self-transportation biomimetic composite guiding surface

Improving the lubrication condition of oil-starved rolling bearings is a proven method to improve their reliability and service life. In this study, a composite surface texture was designed inspired by the microscopic structure of cactus spine, pitcher plant and blood clam. Superhydrophobic surface coating technology was also employed. An oil self-transportation biomimetic composite surface was developed on the guiding surface of a thrust ball bearing. Experimental results show that the biomimetic composite surface effectively drives oil for high-speed directional transport. The biomimetic composite guiding surface bearing demonstrated excellent best vibration and friction torque performance. Compared to conventional bearing, it has an overall vibration performance improvement of 37.4 %, as well as a significant reduction in friction torque of 43.3 % and wear of 72.2 %. We conclude that oil self-transportation biomimetic composite surfaces on rolling bearings can significantly improve the lubrication condition.

Using a bonded solid film lubricant to prevent fretting wear in the axle journal bearings of rail vehicles

Fretting degrades the inboard inner ring and the backing ring contact surfaces of axle journal roller bearings used in railway applications. This study attempts to prevent fretting wear between them as well as fretting wear particles from entering the axle bearing interior without introducing new bearing components. It has been reported that coating metallic surfaces with bonded solid film lubricants improves lubricity and wear resistance while reducing fretting wear. To evaluate the impact on fretting wear prevention, a full-size railway axle bearing that was coated a backing ring side face with a bonded solid film lubricant was rotated. The findings demonstrate that applying the bonded solid film lubricant to the backing ring side face does not prevent the axle bearings from fretting. The surface temperature probably exceeds the heat-resistant temperature of the solid film lubricant because of the fretting friction.

Isolated humeral distalization in reverse total shoulder arthroplasty: a biorobotic shoulder simulator study

BackgroundHumeral distalization is inherent to reverse total shoulder arthroplasty (rTSA) and is often produced with concomitant humeral lateralization via the level of the humeral head cut, implant positioning, implant neck shaft angle, and polymer insert thickness. Biomechanical data on the isolated effects of humeral distalization remain limited but could be important to consider when optimizing postoperative rTSA shoulder function. This study investigated the effects of isolated humeral distalization on shoulder biomechanics using a biorobotic shoulder simulator. MethodsEight fresh-frozen cadaveric shoulders were tested using custom polymer inserts that translated the bearing surface 0, +5, +10, and +15 mm along the humeral stem axis, producing isolated distalization without lateralization. Specimens underwent passive elevation in the scapular plane with a static scapula to assess glenohumeral range of motion. Scapular plane abduction motion trajectories were then performed, driven by previously collected scapulothoracic and glenohumeral kinematics from rTSA patients. The effect of isolated distalization on passive elevation was tested using mixed-effects linear regression and the effect on muscle force, joint reaction force, and muscle excursion during active scapular-plane abduction was tested using statistical parametric mapping random effects analysis. ResultsMaximum passive scapular plane elevation increased with humeral distalization (4° per 5 mm distalization). During active elevation, deltoid and rotator cuff muscle forces, and joint reaction forces, increased up to 37% per 5 mm of distalization. Simulated deltoid muscle excursion was altered with increasing distalization but amounted to no more than 0.8 mm change from baseline per 5 mm of distalization. Rotator cuff muscles were consistently lengthened throughout abduction, up to 1.6 mm per 5 mm of distalization. These trends were observed across various patient motions. ConclusionsIsolated humeral distalization caused dramatic increases in the muscle forces required to perform scapular-plane abduction. Joint reaction forces increased correspondingly. These results suggest that implant and surgical strategies to generate deltoid muscle tension without humeral distalization may promote better active range of motion and more durable long-term outcomes over approaches that rely on distalization.

What is the Most Optimal Bearing Surface for Minimizing Instability after Revision Total Hip Arthroplasty?

What is the Most Optimal Bearing Surface for Minimizing Instability after Revision Total Hip Arthroplasty?

Comparative postoperative prognosis of ceramic-on-ceramic and ceramic-on-polyethylene for total hip arthroplasty: an updated systematic review and meta-analysis.

To compare the clinical outcomes between ceramic-on-ceramic (CoC) and ceramic-on-polyethylene (CoP) bearing surfaces in patients undergoing total hip arthroplasty (THA) through a pooled analysis and evidence update. We performed a systematic literature search using PubMed, Embase, Cochrane Library and Web of Science up to March 2023 for studies that compared the bearing surfaces of CoC and CoP in patients undergoing THA. The primary outcomes were the incidence of common postoperative complications and the rate of postoperative revision. The secondary outcome was the Harris Hip Score. A total of 10 eligible studies involving 1,946 patients (1.192 CoC-THA versus 906 CoP-THA) were included in the evidence synthesis. Pooled analysis showed no significant difference in the rates of common postoperative complications (dislocation, deep vein thrombosis, infection, wear debris or osteolysis) and of revision. After eliminating heterogeneity, the postoperative Harris Hip Score was higher in the CoC group than in the CoP group. However, the strength of evidence was moderate for the Harris Hip Score. CoC articulations are more commonly used in younger, healthier, and more active patients. While the performance of conventional polyethylene is indeed inferior to highly cross-linked polyethylene, there is currently a lack of sufficient research comparing the outcomes between highly cross-linked polyethylene and CoC bearing surfaces. This area should be a focal point for future research, and it is hoped that more relevant articles will emerge. Given the limited number of studies included, the heterogeneity and potential bias of those included in the analysis, orthopaedic surgeons should select a THA material based on their experience and patient-specific factors, and large multicentre clinical trials with >15 years of follow-up are needed to provide more evidence on the optimal bearing surface for initial THA.

Air Foil Thrust and Journal Bearing Coatings: A Review

Abstract Surfaces of air foil thrust and journal bearings in high-speed turbomachinery are coated to improve their operational integrity, particularly when the aerodynamic load-carrying capacity is reduced during instances of startup and shutdown. Surface coatings, as protective barriers in air foil bearings, can mitigate the adverse effects of direct surface interactions on such occasions. This article provides an in-depth review of the body of important research conducted for the study of coated air foil thrust and journal bearings, highlighting the state of the art in coating technology. The review features the role of composite coatings, designed to provide favorable thermal, mechanical, and frictional characteristics. This article also highlights the trends in the selection of coatings for air foil bearings, pertinent to desired thermo-mechanical performance.

Mechanism analysis of burn-up failure for needle roller bearing at high-speed gear in manual transmission

Adequate lubrication conditions of needle roller bearings are crucial for the normal operation of transmission. Addressing the burn-up and adhesion failures of needle roller bearings during transmission bench trials, two rigid body rotation physical models were developed to analyze and model the lubrication effect on the inner and outer surfaces of needle roller bearing. Through theoretical analysis and lubrication simulation, it was found that under the critical condition of d/D=0.553, the centrifugal force F on the outer ring surface of the needle bearing was related to the density of lubricant, rotational speed, as well as the angle and size of oil hole, rather than the position of the oil holes; Moreover, the centrifugal force F on the needle roller bearing at input shaft was related to the speed of transmission gear and was also associated with the clearance size between needle roller and cage. Theoretical analysis, simulation, and experimental results have demonstrated that the lubrication performance of needle roller bearings during operation at lower rotary speed gears was inferior to that at higher speed gears, and the lubrication was also less effective when the cage clearance was narrower. Employing angled oil inlets (holes), appropriately enlarging the diameter of oil inlets (holes), and increasing the clearance width between needle roller and cage will contribute to the improvement of lubrication effect.

Observation of wear around surface crack of PEEK thrust bearing under rolling contact fatigue in water

Abstract Rolling bearings are important mechanical elements for machines. Poly-ether-ether-ketone (PEEK) polymer is a suitable material for bearings in water and corrosive conditions because of its excellent water and chemical resistance. Some study had been examining rolling contact fatigue (RCF) tests in water; however, the competition between cracks propagation and wear on the surface of PEEK bearing in water was not clear. In the present study, in order to evaluate the crack propagation and wear process, RCF test with PEEK thrust bearings at 3750 [N] in water was carried out. The lengths of the surface cracks and the profiles of the grooves were observed at different number of cycles. In addition, so as to identify the cracks which cause the flaking, start-stop test was carried out. We found the surface crack, which was initially observed at 4.62×105 cycles, were gradually worn down and completely disappeared at 6.32×105 cycles. We concluded that rolling contact fatigue caused some surface cracks of PEEK to wear down in water condition.

Outcomes of fixed versus mobile-bearing medial unicompartmental knee arthroplasty.

The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution. Prospectively collected data were reviewed for all primary cemented medial UKAs performed by seven surgeons from January 2006 to December 2022. A total of 2,999 UKAs were identified, including 2,315 FB and 684 MB cases. The primary outcome measure was implant survival. Secondary outcomes included 90-day and cumulative complications, reoperations, component revisions, conversion arthroplasties, range of motion, and patient-reported outcome measures. Overall mean age at surgery was 65.7 years (32.9 to 94.3), 53.1% (1,593/2,999) of UKAs were implanted in female patients, and demographics between groups were similar (p > 0.05). The mean follow-up for all UKAs was 3.7 years (0.0 to 15.6). Using revision for any reason as an endpoint, five-year survival for FB UKAs was 97.2% (95% CI 96.4 to 98.1) compared to 96.0% for MB (95% CI 94.1 to 97.9; p = 0.008). The FB group experienced fewer component revisions (14/2,315, 0.6% vs 12/684, 1.8%; p < 0.001) and conversion arthroplasties (38/2315, 1.6% vs 24/684, 3.5%; p < 0.001). A greater number of MB UKAs underwent revision due to osteoarthritis progression (FB = 21/2,315, 0.9% vs MB = 16/684, 2.3%; p = 0.003). In the MB group, 12 (1.8%) subjects experienced bearing dislocations which required revision surgery. There were 15 early periprosthetic tibia fractures (0.6%) in the FB group compared to 0 for MB (p = 0.035). In similar patient populations, FB UKAs demonstrated slightly higher survival than a commonly used MB design. Adverse event profiles differed by bearing type, with an increased risk of bearing dislocation and OA progression with MB designs, and early periprosthetic tibia fractures for FB designs.

Physical description and model validation of welded joint fatigue damage evolution

AbstractFor welded structures, the concept of damage is highly abstract and difficult to describe, leading to a lack of physical foundation and universality for existing fatigue damage accumulation models. A new fatigue damage parameter definition based on remaining bearing capacity is proposed in this paper, which is constructed by the equivalent stress on the remaining bearing surface and the equivalent stress intensity factors along the crack front curve. Tension and three‐point bending fatigue tests under two‐level loading block sequences were conducted, and the real fatigue damage evolution processes were obtained by combining measured crack front information and FEA simulation. Five damage accumulation models were utilized to estimate the fatigue damage evolution processes of the two specimens. Results show that there are differences in describing the damage evolution processes and predicting the early fatigue lives. The Rege model is most consistent with the measured data, demonstrating its applicability and effectiveness.

Estimation of Friction for a Hydrodynamic Sliding Bearing for the Turbulent Regime From Single-Phase and Two-Phase Fluid Flow Behaviour

The hydrodynamic plain bearing relies on the generation of a lubricant film through the rotational movement of the journal. As the journal rotates, it creates a layer of lubricant between the bearing and journal surfaces. This lubricant film separates the two surfaces, preventing direct contact and minimizing friction and wear. The high speeds can lead to severe conditions such as cavitation due to rapid oil evaporation, which introduces a new phase into the flow. In this study, it is anticipated that a two-phase flow will occur through the shaft-bushing conjunction because of the rupture of the lubricating film near the contact outlet. Pressure disturbances above these rupture zones may induce vapor-cavity formation at a small scale. A numerical analysis was conducted by solving Navier–Stokes continuity equations and vapor-transport equations. The k-epsilon model was used to analyze friction at the fluid-bearing interface for the turbulent regime. The results indicate that higher flow velocity values and pressure were observed in the case of two-phase flow compared to one-phase flow.

Molecular dynamics simulation of hybrid structure and mechanical properties of DLC/Ni-DLC thin films

To improve the mechanical properties of the rolling body surface of wind power bearings, extend its service life. In this study, a large-scale molecular/atomic parallel processor LAMMPS was introduced, and then the process of magnetron sputtering technology in the preparation of DLC/Ni-DLC thin films on the 42CrMo substrate material was simulated. The effects of deposition parameters such as sputtering temperature, sputtering voltage, deposition air pressure, and Ni doping on the residual stress, film base bonding, and organizational structure of the thin films were investigated. The simulation results show that for different deposition parameters, the atomic tensile and compressive stresses existed simultaneously in DLC/Ni-DLC films, and the residual stresses were between − 0.504–5.003 Gpa and − 2.11–0.065 Gpa, respectively; the doping of Ni effectively improved the distribution of hybrid structure and the mechanical properties of the DLC films, and the ratio of the sp3 hybrid structure in the film organization was about 2.56 times higher than that of the non-doped films, and the membrane base bonding force was increased by 32.78% and the residual stress is reduced and transitioned from tensile stress to compressive stress. In addition, it was observed that the thickness of the mixed layer of DLC/Ni-DLC films with the substrate was not increased after the thickness of the mixed layer was extended to about 2 nm. Nickel doping and reasonable control of deposition parameters help to reduce the residual stress and improve the bonding strength of the film by changing the organizational structure of the film, which provides an important theoretical and scientific basis for the preparation of low-stress, high-performance and long-life DLC films and the wide application of rolling bodies for wind power bearings under complex working conditions.

Stability Analysis of the Secondary Motion of a Textured Piston

Piston–cylinder pairs are very common in industrial mechanisms. While a piston is primarily designed for axial reciprocating motion, the occurrence of secondary motions—lateral and rotational—due to the small clearance between the piston and the cylinder may lead to frictional contact, energy loss, wear and an increase in unwanted leakage. This study focuses on mitigating the secondary motion of a ringless piston. The influence of a Rayleigh step bearing and partial surface texturing with numerous micro-dimples on the dynamic stability of the secondary motion is studied. A linear model was used to obtain the trajectory of the secondary motion and Floquet theory was applied to analyze the stability and draw stability maps. The influence of various texturing and step parameters, including the dimple area density and aspect ratio for partial texturing, as well as the length and depth of treatment for both partial texturing and step profiles, on the stability of the secondary motion was examined. The normalization method is presented, enabling the expansion of the results for various operating conditions and geometries. Conclusions and guidelines regarding the optimal parameters, in terms of a wider stability range and higher decay rate, are formulated.

A Study on Micro-Pit Texture Parameter Optimization and Its Tribological Properties

In this paper, the effect of micro-dimple textures (produced by a laser) on the tribological properties of bearings is investigated. This study offers guidelines to reduce the friction torque of the bearing pair and addresses the problem of difficult start-ups after shutdowns. Micro-pits with different texture diameters and depths were machined on the surface of journal bearings. Then, the impact of several different texture parameters on the tribological performance of the bearing pairs was studied using an orthogonal experimental design. Subsequently, the surface morphology of the bearings before and after the friction and wear test was observed using scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). These observations were then used to determine the type/state of friction and wear, which also improves our understanding of how texture affects the service life of bearings. The results indicate that the bearings’ micro-pit surface hardness follows an approximate parabolic spatial distribution that decreases along the micro-pit wall. Furthermore, the laser processing of surface textures was found to cause hardening in certain areas, and the chemical composition of elemental carbon and oxygen at the inner surface of processed bearings increased by 31.1% and 7.9%, respectively. Moreover, abrasive wear was identified as the primary form of wear. The textured surface’s antifriction mechanism primarily functioned to trap particles, which acted as a secondary lubrication source and altered the lubrication states by serving as a medium for supplied lubricants. The results confirm that a suitable selection of texture parameters can not only effectively reduce the friction coefficient without shortening the service life of the bearing pair but also facilitate the smooth start-up of the rotor–bearing system.

DetachSense rubber bearing for convenient axial load prediction using active sensing and Bayesian-optimized deep neural network

Rubber bearings serve as key components in seismic isolation structures, rendering accurate monitoring of their axial loads essential. In previous research efforts, a smart rubber bearing (SRB) was introduced based on an active sensing method to achieve axial load monitoring. However, maintaining the wave generator and vibration sensor in the interlayer of the rubber bearing and structure presents significant challenges, making replacement of the generator and sensor difficult. Therefore, this study presents the DetachSense Rubber Bearing (DSRB) as a solution. By placing transducers on the non-loaded surface of a rubber bearing, convenient replacement and substitution of the transducers can be achieved without compromising the isolation performance of the bearing. A deep-learning framework optimized using Bayesian algorithms was employed to predict the axial load of the rubber bearing. This study examined the effects of various connection methods, feature extraction, and reconstruction techniques. Experimental tests were conducted on full-scale LNR600 DSRB bearings, and the data obtained were subjected to a prediction analysis. The results demonstrated that the combination of bolted connections and wavelet packet decomposition for feature extraction yielded the most favorable detection outcomes, with a prediction error of 0.34 MPa.

Dynamic and stability analysis of crescent geometry-possessing textured journal bearing using nanolubricant

PurposeThis study aims to find the dynamic performance parameters of the journal bearing with micro geometries patterning the arc (crescent) shape textures provided in three specific regions of the journal bearing: the full, the second half and the increasing pressure region. The dynamic behavior of textured journal bearings has been analyzed by computing dynamic parameters and linear and non-linear trajectories.Design/methodology/approachThe lubricant flows between the bearing and journal surface are governed by Reynold’s equation, which has been solved by finite the element method. The dynamic performance parameters such as stiffness, damping, threshold speed, critical mass and whirl frequency ratio are examined under various operating conditions by considering various ranges of eccentricity ratios and texture depths. Linear and non-linear equations of motion have been solved with Ranga–Kutta method to get journal motion trajectories. Also, the impact of adding aluminum oxide and copper oxide nanoparticles to the base lubricant in combination with arc-shaped textures is analyzed to further see any enhancement in the performance parameters.FindingsThe findings demonstrated that direct stiffness and damping parameters increased to their maximum level with six textures in the pressure-increasing region when compared with the untextured surface. Also, nanoparticle additives showed improvements above the highest value attained with no inclusion of additives in the same region or quantity of textures.Originality/valueEngineers may design bearings with improved stability and overall performance if they understand how texture form impacts dynamic properties.

IMPACT OF LOADS ON LOCOMOTIVE MOTOR AXLE BEARINGS ON THE CONDITIONS OF FORMATION OF OIL FILM ON FRICTION SURFACES

During the active operation of locomotives, a significant portion of failures (up to 20 %) is attributed to the malfunction of motor-axial bearings. This is due to the imperfection of the lubrication system of the motor-axial bearings, the proper functioning of which largely depends on various factors such as climatic conditions, the level of wear of lubricating oil, and lubrication devices, among others. There is a need to improve the existing lubrication systems for motor-axial sliding bearings. One of the methods to address this issue involves examining the factors influencing the lubrication process of the friction surfaces of motor-axial bearings and the conditions of lubricant material supply. The article provides calculations of the loading forces on the motor-axial bearings, their action vectors, and analyzes the impact of these parameters on the ability to form an oil film on the friction surfaces of motor-axial bearings. To determine the magnitude of the load, technical specifications of the locomotive were used, and the relationship between power usage and locomotive speed was analyzed. The study involved an analysis of recent publications regarding the generation of contact pressure force between the contact surfaces of friction pairs, the magnitude of which exceeds permissible limits, considered one of the primary factors leading to bearing failure. Additionally, the existing bearing lubrication system used on the locomotive was analyzed, its shortcomings were identified, and methods for addressing these issues were discussed. The calculations were performed for the 2TE116 locomotive with traction electric motors ED-118B, based on the operational characteristics of the locomotive in the speed range of 0-80 km/h.

Influence of the rough surface and speed of crankpin bearing on the power of the engine

To fully evaluate the influence of the rough surface (σ) and speed (ω) of the crankpin bearing on the engine power, a combination model of the slider crank mechanism and crankpin bearing’s lubrication is established to calculate the mathematical equations for the simulation. Three indexes of the bearing-capacity (W), friction-force (F), and friction-coeficient (μ) are used to evaluate the influence of the change of the crankpin bearing’s speed and rough surface on the engine’s power. The study shows that increasing ω not only effectively reduces the load capacity of the crankpin bearing but also increases the F and μ in the engine’s crankpin bearing, thereby directly reducing the engine’s power. Besides, the reduction of ω also reduces the bearing-capacity of the crankpin bearing. To optimize the engine’s power, the engine’s speed should be maintained at 2000 r/min to improve the engine’s power. In addition, under the effect of the rough surface of the crankpin bearing, the W of the crankpin bearing is insignificantly affected by the change of the rough surface while both the F and μ are greatly affected. In particular, the maximum F at σ = 8 μm and σ = 10 μm is increased by 68.3 % and 77.7 % in comparison with the maximum F at minimum value of σ = 2 μm, respectively. Therefore, in the design of the engine, the rough surface of the crankpin bearing should be reduced to improve the engine’s power. Additionally, the design parameters of the crankpin bearings should also be optimized to further improve the engine’s power.

Analysis of capacitive discharges in motor bearings under different operation conditions

AbstractDespite being a well‐known problem, bearing faults are still one of the major challenges that the industry face. The growing use of voltage source inverters imposed the alertness of possible bearing damage due to their high‐frequency signals. The aim of this paper is to investigate the effect of capacitive discharges on a rolling element bearing to obtain a series of faulty bearings with different deterioration levels. An ageing test bench is built to generate bearing roughness using Electric Discharge Machining. The purpose is to study the effect of operation conditions, such as frequency of drive, amplitude of shaft voltage, radial load level as well as rotational speed, on the capacitive discharge occurrence within the bearing. Having the desire to further understand this phenomenon, the influence of each parameter on the discharge activity and the discharge waveform is analysed. A worst‐case scenario is conducted and applied to a series of bearings. Finally, the bearing damage is examined, and a quantitative fault detection method is presented based on a microscopic inspection of the bearing's surface.

CAC-YOLOv8: real-time bearing defect detection based on channel attenuation and expanded receptive field strategy

Bearing defect detection plays a crucial role in the intelligent production of chemical transmission equipment, where timely identification and handling of defective bearings are essential. However, in practical large-scale industrial production, product surface defects are often complex, diverse, and exhibit significant variations in appearance, posing severe challenges to the discriminative ability and detection efficiency of bearing defect detection algorithms. This paper proposes a real-time bearing surface defect detection algorithm, CAC-YOLOv8, which designs the Channel Attenuation Network (CAN) and Compound Pooling Pyramid Spatial Pyramid Pooling Fast (CPPSPPF) structure. Specifically, the model introduces the Channel Attenuation Network to achieve parallel feature extraction, deep feature processing, and feature fusion under different channel numbers, capturing critical features related to bearing defects and thereby improving the inference speed. Subsequently, based on the concept of overlapped receptive fields, a CPPSPPF structure is constructed, utilizing multiple iterations of max-pooling operations with smaller pooling kernel sizes to prevent information loss while expanding the receptive field, thereby strengthening the capturing ability of features at different scales. The experimental results indicate that the proposed CAC-YOLOv8 bearing surface defect detection algorithm, compared to the YOLOv8 model, achieved a 0.3% improvement in mAP@0.5, reduced model size by 14.4%, and enhanced model inference speed by 33.3%. This enables the CAC-YOLOv8 model to significantly improve the real-time performance of bearing defect detection while maintaining high-precision detection. The performance in practical industrial detection demonstrates that the proposed approach has achieved outstanding results in both speed and accuracy.