Cylindrical Bearings Research Articles

Capabilities of Software Package Gearacl for Design Gearings and Transmission Elements

Creation of a mathematical model of gearing operation belongs to one of the most knowledge-intensive fields of knowledge. Interdisciplinary research is being conducted to develop the model. For practical use, the results of this work are embodied in strength analysis standards. Due to the complexity of the processes occurring in gearings, performing analysis of one pair of gears today requires not only significant time costs from the engineer, but also a deep understanding of hundreds of pages of calculation techniques described by groups of interrelated standards. The calculation formulae include clarifying coefficients, the contribution and values of which are determined by a group of specialists developing the standard, based on research of analysis result coordination, experimental data and calculations performed using the finite element method. To perform the analysis, the designer needs knowledge about the principles of choosing coefficient values and their meaning. Performing the analysis of gearings according to the standard is a time-consuming process that can be correctly performed only by an engineer with experience in designing gearings. To facilitate the work of the engineer, software products both domestic and foreign were created. However, the trends of recent years require replacement of foreign software products. In 2022, the specialists of the Central Institute of Aviation Motors developed the Gearacl software package, which allows replacing foreign products in the volume required by the aviation industry enterprises in the field of cylindrical gearings, shafts and bearings analysis. Modern analysis methods have been introduced into the software package. This article is devoted to the capabilities of the Gearacl software package.

Study on the wear characteristics of cylindrical needle bearings on the crankshaft of RV decelerator

PurposeThe purpose of this study is to systematically analyze the wear of cylindrical needle bearings in rotary vector reducers under temperature rise and identify the influencing factors.Design/methodology/approachBased on the dynamic characteristics of the RV-20E reducer, the time-varying contact force of the cylindrical needle bearing and the entrainment speed of the inner and outer raceways were calculated. A mixed elastohydrodynamic lubrication model of the needle bearing, considering friction and temperature rise, was established using a dynamic rough tooth surface model. The model solved for the oil film thickness, contact stress and wear conditions of the bearing raceway contact area. The effects of the number of rolling needles, the diameter of rolling needles and surface strength on the wear characteristics were analyzed.FindingsThe results of this study show that the oil film thickness, oil film pressure and surface scratches of cylindrical needle bearings exhibit an uneven, patchy distribution under the combined effects of friction and temperature rise. When the radius of the rolling needle is less than 1.44 mm, inner ring wear is less than outer ring wear. Conversely, when the radius exceeds 1.44 mm, inner ring wear is greater. The optimal rolling needle radius is 1.6 mm. Increasing the number of rolling needles and enhancing the yield strength of the contact surface significantly extend bearing life.Originality/valueThis study provides valuable recommendations for optimizing bearing structural parameters and material characteristics in the design of rotary vector reducers.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2024-0242/

ON THE ISSUE OF ENSURING THE OPERABILITY OF FREIGHT CAR AXLE BOXES

The article is devoted to analysing the reliability of freight car axle boxes. Wheelsets and axle boxes are especially important for ensuring the traffic safety of trains. The study examined cases of cars uncoupling from a train along the route due to technical faults resulting in delays in train movement. The analysis covered the period of 1995–2023. It found that failures of car axle boxes and automatic brakes predominated. After a significant decrease from 2000–2014, the number of roller axle box failures in recent years fluctuated at 30% of the total number of uncouplings. The analysis obtained a dependency for the change in car detachments due to roller bearing failures, calculated per 1,000 cars in the operating fleet. Despite fluctuations in the number of railcars, the safety level of operations in recent years remained virtually at the same level. The study highlighted that excessive heating accompanies damage in the elements of the axle box unit. It considered methods for detecting possible failures and their advantages and disadvantages. The authors identified the primary causes of axle box component failures. Cylindrical bearings and end mountings remain the most dangerous for failure probability. We demonstrated that the axle box design with cylindrical bearings has a fundamental flaw. Axial forces are perceived through the rolling friction of the ends of the rollers against the ring flanges, leading to the formation of ‘chevron’ scratches and dents on the roller ends, which are stress concentrators. The study established that the surface of the axle box housing is constantly in contact with the side frame of the freight car bogie and wears out. It results in pinching of the axle box body and contributes to the appearance of additional permanent forces acting on the axle box assembly. The end-bearing mounts are weakened and destroyed. Skewed rollers in the bearings cause fatigue failure of the rolling races. It leads to increased heating of the axle box assemblies and uncoupling of the car. A promising direction is the improvement of axle box bodies. Keywords: rolling stock, traffic safety, reliability, axle box assembly, roller bearing, axle box body, failure.

An Analysis of the Stress–Strain State of a Layer on Two Cylindrical Bearings

A spatial problem of elasticity theory is solved for a layer located on two bearings embedded in it. The bearings are represented as thick-walled pipes embedded in the layer parallel to its boundaries. The pipes are rigidly connected to the layer, and contact-type conditions (normal displacements and tangential stresses) are specified on the insides of the pipes. Stresses are set on the flat surfaces of the layer. The objective of this study is to obtain the stress–strain state of the body of the layer under different geometric characteristics of the model. The solution to the problem is presented in the form of the Lamé equation, whose terms are written in different coordinate systems. The generalized Fourier method is used to transfer the basic solutions between coordinate systems. By satisfying the boundary and conjugation conditions, the problem is reduced to a system of infinite linear algebraic equations of the second kind, to which the reduction method is applied. After finding the unknowns, using the generalized Fourier method, it is possible to find the stress–strain state at any point of the body. The numerical study of the stress state showed high convergence of the approximate solutions to the exact one. The stress–strain state of the composite body was analyzed for different geometric parameters and different pipe materials. The results obtained can be used for the preliminary determination of the geometric parameters of the model and the materials of the joints. The proposed solution method can be used not only to calculate the stress state of bearing joints, but also of bushings (under specified conditions of rigid contact without friction on the internal surfaces).

Confirming dark groove microstructural alterations as WEC initiation first stage in cylindrical roller thrust bearings lubricated with WEC critical oil

In a recent work, after conducting disc-on-disc tests under the influence of hydrogen, the authors identified microstructure alterations, the so-called dark grooves, as possible initial stages of WEC formation. In this work, the aim is to investigate whether dark grooves also constitute the initial stages of WEC in cylindrical roller thrust bearings (CRTBs) tested under the influence of WEC-critical oils. BEM simulations of the roller/washer contact were conducted to identify the coordinates of the maximum subsurface shear stresses, the region in which the first stages of failure are likely to start. Subsequently, CRTB tests were carried out, where prematurely stopped bearings were characterized considering the BEM results. The initial signs of failure i.e., the dark grooves consisting of nanopores and nanograins, were found in the maximum subsurface shear stress regions indicated by the BEM simulations.

Influence of micro-texture radial depth variations on the tribological and vibration characteristics of rolling bearings under starved lubrication

Surface micro-texturing involves creating microscopic pits or textures, serving as lubricant reservoirs to enhance lubrication distribution, potentially reducing friction and wear. This study specifically delves into the influence of varied depth patterns of pits on the operational performance of textured rolling bearings under severe lubrication conditions. Five distinct patterns with a fixed pit diameter (250 µm) and different depth variations (concave, decreasing, increasing, convex, and horizontal) were introduced on the shaft rings of cylindrical roller thrust bearings using the laser marking method. Wear tests were conducted under starved lubrication condition. Wear loss and signal analysis highlight the profound effect of depth variations, whereby bearings with shallow pits near the outer side of their working surfaces exhibit longer lubrication times, improved tribological performance, and enhanced vibration characteristics. Notably, the convex pattern stands out for providing comprehensive and favorable tribological and vibration properties. This research contributes valuable insights for the optimal design of micro-textures for rolling bearings, paving the way for enhanced efficiency and reliability in mechanical systems.

Modeling the line contact on an elastic half-space with the statistical approach: Self-affine fractal roughness and numerical framework

This paper presents a line contact model for describing the normal contact between rough surfaces with self-affine fractal roughness based on the statistical approach. An iterative algorithm combining the Levenberg-Marquardt (LM) method with penalty function is proposed to overcome the limitation of restricted indentation depth. Results show a competitive relationship between the plasticity index and the fractal dimension on the real contact area. Besides, nonlinear characteristics between force and area appear when the elastic modulus of the substrate is larger than that of the asperity. Furthermore, the wavy machining texture leads to a great increase in the maximum pressure. The current work can be used for modeling the transmission interfaces involving line contact, such as gears and cylindrical rotor bearings.

Experimental investigation of the static and dynamic damping behaviour of antifriction bearings

ABSTRACT This paper experimentally investigates the vibration-damping behaviour of four different antifriction bearings. Both static and dynamic analyses have been employed to study the damping behaviour. Experiments are conducted on a custom-made rotor bearing test rig, and the results are analysed with the OROS NV-Gate data collection system at DE (Drive end) and NDE (Non-drive end). Free vibration analysis is used to determine natural frequencies. The half-power bandwidth and logarithmic decrement methods are used to get the damping ratios. Furthermore, force vibration tests are carried out on different bearings with varying operating characteristics to support the static analysis results. The results demonstrate that the damping capacity of tapered roller bearings is superior, followed by cylindrical, spherical and self-aligned bearings. The contact between rolling elements and raceways plays an essential role in the damping capability of such bearings. The result of current research has prospective applications in the design of high-performance rotor bearing systems.

Electrical Impedance Spectroscopy for Precise Film Thickness Assessment in Line Contacts

In this article, we focus on utilising electrical impedance spectroscopy (EIS) for the assessment of global and contact impedances in roller bearings. Our primary objective is to establish a quantitative prediction of lubricant film thickness in elasto-hydrodynamic lubrication (EHL) and investigate the impedance transition from ohmic to capacitive behaviour as the system shifts from boundary lubrication to EHL. To achieve this, we conduct measurements of electrical impedance, bearing and oil temperature, and frictional torque in a cylindrical roller thrust bearing (CRTB) subjected to pure axial loading across various rotational speeds and supply oil temperatures. The measured impedance data is analysed and translated into a quantitative measure of lubricant film thickness within the contacts using the impedance-based and capacitance-based methods. For EHL, we observe that the measured capacitance of the EHL contact deviates from the theoretical value based on a Hertzian contact shape by a factor ranging from 3 to 11, depending on rotational speed, load, and temperature. The translation of complex impedance values to film thickness, employing the impedance and capacitance method, is then compared with the analytically estimated film thickness using the Moes correlation, corrected for inlet shear heating effects. This comparison demonstrates a robust agreement within 2% for EHL film thickness measurement. Monitoring the bearing resistance and capacitance via EIS across rotational speeds clearly shows the transition from boundary to mixed lubrication as well as the transition from mixed lubrication to EHL. Finally, we have observed that monitoring the electrical impedance appears to have the potential to perform the run-in of bearings in a controlled way.

The Effect of Hot Pressing on the Mechanical Properties of Metal Composites (AI/Sic) Result from Metallurgical Processes with Heating Temperature Variations in Bushing Making

The manufacture of Al/SiC alloy matrix composites has been widely carried out by researchers through powder metallurgy techniques. Bushings are slit cylindrical type bearings that serve to support the shaft. Bushings can be made by powder metallurgy, to get the perfect compaction process, compaction can be done by high temperature or Hot Pressing. A hot press will make the powder softer/plastic, making it easier during the perfect compaction process. For this reason, heating must be controlled in order to obtain a homogeneous product. Al/SiC metal matrix composites are alloyed materials of different types of materials, as matrices in this case are aluminum and as reinforcement are SiC particles (ceramics) made by powder metallurgy techniques. In this study, the Al/SiC composite composed of 70% Al - 30% SiC and Hot Pressing temperature variations of 100, 150 and 200°C with a pressure of 5000 kg and a holding time of 10 minutes. In the sintering process, the temperature used is 450, 500 and 550°C with a holding time of 2 hours. The results of this study show, in hardness testing it is known that the value of bushing hardness increases as the temperature of Hot Pressing increases.

Modelling and Simulation of Aerodynamic Cylindrical Bearings Using ANSYS Hydrodynamic Bearing Element Types

Modern power engine concepts and environmental restrictions demand oil-free lubrication of rotors, for example, by gas bearings. However, the stiffness and damping properties ruling the rotor’s dynamics are poorly documented for aerodynamic bearings and simple calculation methods are lacking. Based on the similarity between aerodynamic and hydrodynamic journal bearings, it is investigated to what extent the hydrodynamic bearing element types of the commercial FE program ANSYS are also suitable for air bearings. Within these elements, the compressibility of the gas is neglected. After verification of the ANSYS hydrodynamic element types with literature data for cylindrical hydrodynamic bearings, the stiffness and damping coefficients of a cylindrical aerodynamic bearing are calculated by using the ANSYS hydrodynamic element types. In the examined speed range, the results agree well with literature data that consider gas compressibility. Therefore, the FE elements designed for hydrodynamical journal bearings may also be used for simulating cylindrical aerodynamic bearings. The presented calculation approach provides a compact and easy-to-use method for rotordynamic simulations with cylindrical aerodynamic bearings in a single development environment.

Study on seismic performance of functionally integrated cylindrical steel damper bearing with energy dissipation and spacing

The bridge bearing serves as a crucial constituent that can exert a substantial influence on the seismic performance of the bridge structure. When subjected to seismic events, conventional fixed-type bearings transmit considerable seismic forces, leading to detrimental effects on the bridge piers. The damage incurred by the fixed-type bearings can result in significant relative displacement between the pier and girder, which can potentially contribute to the unseating. To effectively control the seismic damage to bridge piers and the relative displacements between the pier and girder, as well as to facilitate controllable design of bridge seismic behaviors, a novel functional integration approach was developed: the functionally integrated cylindrical steel damper bearing (FICSDB). The FICSDB incorporated certain functionalities, such as seismic isolation, energy dissipation, and displacement limitation. Specifically, following the constructional details and operational mechanisms of the FICSDB, the mechanical model was initially derived. Subsequently a series of cyclic shear tests were conducted on the FICSDB. Certain results were obtained as follows. (1) The bearing’s sliding performance remained relatively stable. (2) The cylindrical damper effectively achieved the desired objectives of energy dissipation and spacing, thereby exhibiting exceptional fatigue resistance. (3) The components demonstrated close cooperation, which ensured the overall stability and controllability of the FICSDB’s mechanical behavior. (4) The effectiveness of the FICSDB was validated through numerical calculations with the application of a continuous girder bridge as a case study. The results revealed that, in comparison to traditional fixed-type bearings, employing the FICSDB significantly reduced internal forces exerted on the bridge piers during rare seismic events. Additionally, when compared to conventional isolation bearings, the FICSDB realized the excellent minimization of the relative displacement between the pier and girder. Therefore, the FICSDB can enable the dual control of the pier damage and unseating, thereby facilitating the controlled design of bridge seismic behaviors.

RETRACTED ARTICLE: Influence of Chief Vein on Tribological Behavior of Vein-Bionic Textured Rolling Element Bearings Under Starved Lubrication

We, the Editors and Publisher of Tribology Transactions, have retracted the following article: Chao Zhao, Lixia Ying, Donghui Li, Di Wang & Jiashuai Hu (2023) Influence of Chief Vein on Tribological Behavior of Vein-Bionic Textured Rolling Element Bearings Under Starved Lubrication, Tribology Transactions, 66:4, 760–770, DOI: https://doi.org/10.1080/10402004.2023.2226694. Since publication, significant concerns have been raised about the fact that this article appears to have substantial reuse of figures and images, as well as text overlap with the following article, by one of the same authors, which is not clearly cited or referenced: Chao Zhao, Risheng Long, Yimin Zhang, Yibing Wang, Yueyong Wang. Influence of characteristic parameters on the tribological properties of vein-bionic textured cylindrical roller thrust bearings. Tribology International, Vol. 175, 107861 (2022). https://doi.org/10.1016/j.triboint.2022.107861. Table 2 in the Tribology Transactions article bears significant similarity to Table 3 in the Tribology International article. The data in the Tribology Transactions article appears to be rearranged and select subsets to present in graphs appear to be relabeled to make them look like new and different results. We have also identified some background images, such as test rig set up, that appear copied from the Tribology International article to the Tribology Transactions article without acknowledgement of the original source. Upon query, the author has not been able to provide a satisfactory explanation for this significant level of overlap. As this is a serious breach of our Editorial Policies, we are retracting the article from the journal. The corresponding author has agreed to retract the article. We have been informed in our decision-making by our editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Fault Diagnostics and Faulty Pattern Analysis of High-Speed Roller Bearings Using Deep Convolutional Neural Network

Abstract In this article, vibration-based fault diagnostics and response classification have been done for defective high-speed cylindrical bearing operating under unbalance rotor conditions. An experimental study has been performed to capture the vibration signature of faulty bearings in the time domain and for different speeds of the unbalanced rotor. Two-dimensional phase trajectories are generated by estimating the time delay and embedding dimension corresponding to vibration signatures. Qualitative analysis involves the implementation of a deep convolutional neural network (DCNN) utilizing the phase portraits as input to classify the nonlinear vibration responses. Comparison with the state-of-art classifiers such as artificial neural network (ANN), deep neural network (DNN), and k-nearest neighbor (KNN) is presented based on classification accuracy values. Thus, the values obtained are 61%, 67%, 72%, and 99% for ANN, DNN, KNN, and DCNN, respectively. Hence, the proposed intelligent classification model accurately identifies the dynamic behavior of bearing under unbalanced rotor conditions.

Research on the Tribological Behavior of Textured Cylindrical Roller Thrust Bearings with Different Distributions of Pits and Nylon Cages under Dry Condition

Differing from the published documents on the effect of texture distributions of sliding tribo-pairs on their friction and wear properties, this study introduced eight patterns to reveal the influence of different distributions of pits on the tribological behavior of textured rolling element bearings with nylon cages under dry condition, namely: Outside-1/4 (OS1/4), Outside-1/2 (OS1/2), Outside-3/4 (OS3/4), Inside-1/4 (IS1/4), Inside-1/2 (IS1/2), Inside-3/4 (IS3/4), Bothside-1/3 (BS) and full (FP). A fiber laser marking system was used to prepare them on the raceways of the shaft washers of cylindrical roller thrust bearings (81107TN). A vertical universal wear test rig was used to obtain their coefficients of friction under an axial load of 2600 N and a rotating speed of 250 RPM, without any lubricant provided. Their wear losses and worn surfaces were characterized. The influence mechanism of different distributions on the tribological properties was also discussed. The results show that the self-lubricating performance of nylon cages can ensure the continuous operation (≥5 h) of cylindrical roller thrust bearings under dry condition. The influence of outside-distributed patterns on the friction and wear properties of bearings is significant. The friction-reducing effect and wear resistance of full textured group is improved but not the best. The friction-reducing and anti-wear behavior of OS1/2 is similar to that of FP. In this work, OS3/4 can provide the best tribological performance under self-lubricating conditions. Compared with the data of smooth bearings, its average coefficient of friction and wear loss can be reduced by 37.68% and 38.85%, respectively. This work would provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

Influence of Tribolayer on Rolling Bearing Fatigue Performed on an FE8 Test Rig—A Follow-up

The tribological contact between raceways and rolling elements is essential for rolling bearing performance and lifetime. The geometrical description of these contacts is well known and can be used in several mechanical simulation tools. The material description, especially of the near-surface volume after interaction with lubricants, is not as simple. In particular, the Schaeffler FE8-25 test with cylindrical roller thrust bearings exhibits different failure modes depending on the lubricant chemistry. The main failure mechanisms of this test are sub-surface fatigue damage due to WECs (White Etching Cracks) and/or surface-induced fatigue damage (SIF). The harsh test conditions with mixed friction at high speeds and multiple slip conditions over the raceway width additionally provides different tribological conditions on a small area. This leads finally to the formation of certain tribological layers on the raceway because of the interaction of the surface with the lubricant chemistry under local frictional energies, which are worth investigating. The characterization of the layers was performed by the two less time-consuming, spatially resolved analysis methods of µXRF and ATR FTIR microscopy adapted by Schaeffler. This paper shows the results of this research and offers new approaches to optimizing rolling bearing testing and predicting the risk of early failures.

Accurate Modeling and Control System Design for a Spherical Radial AC HMB for a Flywheel Battery System

Different from common cylindrical magnetic bearings, the spherical radial AC HMB has obvious advantages in suppressing the gyroscopic effect, thus it is very suitable for application in flywheel battery systems. In this study, a precise mathematical model of suspension forces is deduced adopting wide-area and universal modeling theories in detail for the spherical radial AC HMB. Different from the traditional Maxwell tensor method based on a cylindrical two-dimensional coordinate system, the improved Maxwell tensor method based on a spherical coordinate system has a wider range and versatility. Then, the detailed explanation about the accuracy, wide-area and universality are given. Further, based on the model, the control system is designed, which includes the overall schematic, hardware and software designs. Finally, stiffness and performance tests are conducted. The good results of the stiffness tests indicate the error between the proposed model and the force-deflection stiffness test results is less than 2.8%. The good performance test results show that, based on the established model and control system, the rotor will soon return to equilibrium position under the disturbance of vehicle action.

Designing The Estimation of The Need for Spare Parts and Inventory Policy on The D32 CP8 Compressor Machine

Based on damage data owned by PT XYZ, the compressor engine that has a history of high damage is the D32 CP8 Compressor Engine. Critical components of the D32 CP 8 Compressor are determined using a risk matrix. The critical components selected from the D32 CP8 Compressor Engine are Screw Motor, Refrigerant Air Cooler, and Cylinder Bearing Oil Cooler. This study uses the Reliability Centered Spares (RCS), Min-Max Stock, and Reorder Point (ROP) methods. The data collection and processing results obtained the need for critical components in the next 1 year based on the MTTF critical component data. These calculations show that the value of the required spare parts for the Motor Screw, Refrigerant Air Conditioner, and Cylinder Bearing Oil Cooler in a year is 8 components. The minimum Stock of the Screw Motor is 3 components, the maximum stock is 8 components, ReOrder Point point is 4 components. The minimum stock of 4 component air coolers, maximum stock of 7 components, ReOrder Point when 3 components. The minimum stock of a Cylindrical Bearing Oil Cooler is 2 components, the maximum stock is 6 components, and the ReOrder Point is when there are 2 components.

Optimization of the radial bearing geometry by the dimensional analysis

In order to improve the working capacity and life of bearing units, the dimensional analysis of the inner geometry of a cylindrical radial bearing was carried out. The assembly component, composed by the outer diameter dimensions of the raceway of the inner race, the inner diameter of the outer race and the two diameters of the rollers, was considered as a dimension chain. It is recommended, in order to reduce wear and friction losses, to produce the diametrical dimensions of the roller according to the fifth accuracy degree. It is established that the cause of the axial clearance between the roller and the double-flanged race is the distance between the contact points on the right and left flanges with the horizontal position of the roller, as well as the diagonal distance. Tolerances for ring dimensions, for such a combination, are recommended to accept with respect to accuracy degree 6.

A New Design Method of Cylindrical Bearings Based on a Simplified Thermohydrodynamic Lubrication Model

A New Design Method of Cylindrical Bearings Based on a Simplified Thermohydrodynamic Lubrication Model