High-speed Bearings Research Articles

Increasing of wear resistance of the graphitized steel

Purpose. Graphitized steels are alloys, in which carbon is partly in form of graphite inclusions. Due to this such steels possess good antifriction properties, wear resistance, heat conductivity and a variety of other mechanical properties, which decently distinguish them from cast irons. However, such steels are not studied enough and practically are not used in mechanical engineering. Purpose of the work is the research of the possibility of wear resistance increase for graphitized steels in the conditions of metal-to-metal dry friction sliding to use them in the railway systems. Methodology. Graphitized hypoeutectoid, eutectoid and hypereutectoid steels have been used as a research material. Experimental alloys have been studied in the condition after thermal hardening. Hardness of alloys has been determined by the Vickers method. Wear resistance of steels has been studied in the conditions of metal-to-metal dry friction sliding with the use of МI-1 friction machine (disk to disk). Findings. Data, which allow assessing the wear resistance of experimental graphitized steels depending on carbon, silicon and copper content have been obtained in this work. The regression dependence obtained as a result of statistical processing of the experimental data allowed determining an optimal chemical content of the steel, which is characterized by high wear resistance. Originality. A dependence describing carbon, silicon and copper content on the specimen's weight loss during metal-to-metal dry friction tests has been obtained in the work. Practical value. The optimized content of the graphitized steel can be used for production of products working in the conditions of wear such as brake blocks of rolling stock, separators of high-speed bearings, dies and others.

Research on Commercial Vehicle Clutch Release Bearing Fatigue Life Prediction Model

Commercial vehicle clutch release bearings working at high speed, strong vibration,high temperature, damp and easy pollution conditions. Fatigue life analysis is based on the release bearing rings or rolling body began to appear fatigue spalling, in which this kind of phenomenon is under cyclic stress. The contact stress distribution is not uniform, the contact stress is mainly concentrated near the surface; influenced by the geometry and physical properties and lubrication of the surface significantly. Contact between the two types of fatigue crack extension methods: fatigue crack surface under expansion and surface fatigue crack propagation. The surface crack growth mainly originated from two kinds of cases: crack caused by surface pre crack and contact between the two surface asperity each other. New life prediction model for the release bearing based on L-P theory and Tallian model ,in which influence factors of fatigue life is introduced on the smelting process, surface defect, surface roughness, residual stress, elastohydrodynamic lubrication oil film,environmental cleanliness, temperature, the effect of varying load characteristics and other factors of fatigue life. The results show that: the clutch release bearing life prediction model of new and more close to the real conditions of automobile clutch, provide the theory basis for the development of a new generation high-speed heavy-duty clutch release bearing of the commercial vehicle.

Development of Load System for High-Speed Railway Rolling

High-speed railway rolling bearings are tested on a special test rig, where large transit axial and radial load is applied. Design of loading structure and electro-hydraulic servo loading system are used in the rig to simulate the real operating conditions of the bearings. A segment control strategy using different control parameters in different conditions is presented in this paper, for reducing the gap effect when the direction of the axial load is changed. This method effectively reduces the load response time to meet the technical requirements of the test rig.

Dynamic Analysis of High-Speed Hybrid Thrust Bearings

An analysis is conducted and solutions are provided for the dynamic performance of high speed hybrid thrust bearing. By adopting bulk flow theory, the turbulent Reynolds equation is solved numerically with the different orifice diameter and supply pressure. The results show that increasing supply pressure can significantly improve the bearing stiffness and damping, while the orifice diameters make a different effect on the bearing stiffness and damping.

Research and Experiment on the Thermal Characteristics of Hybrid Ceramic Bearings

The high-speed hybrid ceramic bearing system is simulated by FLUENT, and its temperature rise characteristics under different situations are tested. Meanwhile, an experiment is performed to verify the results. It also shows that simulation with FLUENT is a very useful and low cost method in finishing some complex experiments for substitute.

Nonlinear dynamic analysis of high speed bearings due to combined localized defects

In this paper, the dynamic behavior of a high-speed rotating shaft under the combined localized defects on outer race, inner race and rolling element has been analyzed. An adaptive algorithm based on wavelet packet decomposition and Hilbert transform is used to extract the bearing fault characteristic component from the vibration signals. The reverse Biorthogonal wavelet 5.5 is considered as the most appropriate wavelet for decomposing the bearing vibration signal, on the basis of the maximum energy-to-Shannon entropy ratio criterion. The imperial trend suggested in diagnosing the combined localized defects of rolling bearing is based on experimental analysis at various rotor speeds. The results are presented in the form of envelope analysis, bifurcation diagrams and Poincaré maps that show the appearance nonlinearity in the dynamic response due to the rotor speed and the presence of combined localized defect. Significant peaks are reported at BPFO, BSF, FTF and modulation of BPFI with rotational frequency in envelope spectrum. Fundamental train frequency also shows noticeable excitation. A modified mathematical model shows good agreement with experimental results.

High-Speed Bearing Technologies for Wastewater Treatment Applications

High-Speed Bearing Technologies for Wastewater Treatment ApplicationsReview of High-Speed magnetic and airfoil bearings history and development is presented. Principles of operation of each technology are then explained in detail. A discussion on application of both technologies to the wastewater treatment blowers follows. Airfoil bearings offer a low cost but higher risk high-speed bearing solution for turbo blowers, whereas magnetic bearings offer dynamic...Author(s)Aleksandra IrvingJoseph IbetsSourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2013ISSN1938-6478DOI10.2175/193864713813667458Volume / Issue2013 / 20Content sourceWEFTECCopyright2013Word count91

Research on the Diagnosis Method of the High-Speed Rolling Bearing

The rolling bearing is the common component in machinery, especially the high-speed rolling bearing. The running state will influence the performance of the whole machine directly. In this paper, it will analyze the design of filter and the fault characteristics frequency. And, through the examples, the paper designs the testing system and verifies the method effectively and reliably.

Development and Validation of a Three-Dimensional Multiphase Flow Computational Fluid Dynamics Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines, this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach, resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach, including cavitation and air entrainment for high-speed turbomachinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty-type gas turbine journal bearings.

Bearing Retainer Designs and Retainer Instability Failures in Spacecraft Moving Mechanical Systems

Bearing retainer instability is one of the major causes of failure in the ball bearings used in spacecraft systems. These bearing failures lead to mission failure or performance degradation of the spacecraft. The instability is characterized by intermittent torque fluctuations and severe audible noise in both low- and high-speed bearings. It also generates severe transient forces that result in high cage wear or fracture. A series of retainer designs was made and the possibility of instability under various operating conditions of a momentum/reaction wheel used in a spacecraft was studied. Various tests such as run-in test, temperature test, and overlubrication test were conducted to study the instability and select a design that is stable under all operating conditions. The study results showed that square pocket retainers are more stable compared to circular pocket retainers.

Optimized Design of the Structure of High-Speed Railway Bearing Test Rig

This paper establishes the finite element model of main spindle in the test rig for high-speed railway bearing. Utilizing the finite element analysis software ANSYS, the modal analysis for spindle is carried on. Preliminary determination is that spindle resonance occurs. Structural optimization is carried out by increasing first natural frequency and reducing weight of main spindle in order to avoid resonance. The results showed that the position of support bearings is determined. The first natural frequency is increased by reducing spindle weight. The dynamic performance of the spindle is improved, avoiding the resonance region effectively.

Cause Analysis and Improvement of the Oil-Film Oscillation of the Centrifugal Compressor

The paper starts from the reasons of the Centrifugal Compressor’s oil-film oscillation in one factory of Longyan, and thinks oil-film oscillation is the typical one of faults of the high-speed glide bearing and happens at about two times of the critical speed. It also summarizes the features of the oil-film oscillation, analyzes the reason, and finds out that the problem is related to the load, critical speed, the relative eccentricity of the bearing, lubricating oil and the bearing’s load amount. Finally it puts forward HHT detecting methods which can accurately find the problem earlier, and proposes improvement measures which have been proved simple, convenient, and practical after half year’s experiment.

Performance Analysis of the Rayleigh Step Bearing under the Coexistence State of Fluid with Laminar Flow and Turbulence

In the design of tribology pairs, the Rayleigh step bearing is known as a bearing with the highest load capacity amongst all other possible bearing geometries. This paper mainly discusses a new high-speed bearing with shallow and deep cavities on the inner surface of the bearing, and further the physical phenomena in laminar flow and turbulence regimes was revealed. In doing so, the pressure distribution was calculated first using the continuity equations and then performances in the whole flow domain such as pressure distribution, load-carrying capacity, friction force and friction coefficient were calculated. In addition, a set of optimum geometries are shown to provide the highest load capacity for the Rayleigh step bearing under varied Reynolds number. Finally, associated conclusions were drawn by comparison between results under the coexistence state and under the laminar state.

Development of Test Rig for High-Speed Railway Rolling Bearings

The rolling bearing test rig for heavy vehicles often works under heavy load and high speed, thus it requires high performance for the main shaft and mechanical structure. In this paper a design of test rig for high-speed railway rolling bearings is presented, in which a new structure is adopted to reduce the load on the support bearings. The basic idea is to position the load in a way that they can be balanced by each other.

Research Status and Countermeasure of Temperature Rise of Hydraulic Dynamic and Static Bearing

Hydraulic dynamic and static bearing has the advantages of hydraulic pressure bearing and liquid hydrostatic bearing, with the peculiarities of higher load capacity, smallest oil film thickness, higher stiffness, and lower power and so on. It was suitable for not only high-speed precision spindle bearing but also low-speed heavy bearing. Because of the loading traits, ball mill will have a greater impact on the role of bearing, leading to the increasing temperature of bearing. The designers take many measures to reduce the temperature, but there are hardly any reports about mechanism of the increasing temperature. According to the study about the present situation and the research strategies of increasing temperature of dynamic and static bearing in the extreme conditions, this article explores the questions of the increasing temperature of dynamic and static bearing in the extreme conditions and the scarcity of this question at present, and proposes the mechanism and the research strategies of the questions of the increasing temperature of dynamic and static bearing of ball mill in the extreme conditions.

Analysis on Dynamic Characteristics of High Speed Cylindrical Roller Bearing

A nonlinear dynamics analysis mathematical model for the high-speed cylindrical roller bearing was built up. Dynamic performance parameters were got by Newton - Raphson method . The rotational velocity regularities of rollers were analyzed at different radial loads. The distribution of minimum oil-film thickness and contact load between rollers and bearing ring raceway were obtained. The results showed that number of loaded rollers increased with the increase of radial loads at a certain speed. Rollers slip seriously at lower radial loads. The rotation speed was low. The minimum oil-film thickness between loaded rollers and inner raceways was less than that of outer raceways. The results were compared with the results of SHARBERTH and comparison was made with testing results. It showed that the dynamic characteristics analysis method of high speed cylindrical roller bearing was accurate, reliable,simple and convenient for practical engineering application.

Determination of Rheological Parameters for Several Lubricants Applied in the High-Speed and High-Pressure Bearings

Traction coefficients of several domestic lubricants in various operating conditions were measured on a self-made test rig. The equations for calculating the average values of limiting shear stress and shear elastic modulus of the lubricants applied in the high-speed and high-pressure bearings were advanced. The example calculations for one lubricating oil and two lubricating grease were then made. The results show that the regression precisions of the equations above are satisfied. The equations also adapt to the other lubricants in the same operating conditions.

Elasto-Plastic Earthquake Response Analysis of High-Speed Railway Bridge Fabricated Isolation Bearings

Basin rubber bearings are frequently used in high-speed railway bridge or passenger special line railway bridge, lead rubber bearings (LRB) are infrequently used in those railway bridges nowdays, the study on earthquake-resistant capability of railway bridge fabricated isolation bearing - the intelligent and functional structure - would be beneficial in engineering practices. Elasto-plastic earthquake responses of high-speed railway bridges fabricated LRB are studied by means of the finite element program, earthquake responses of railway bridges under high-speed vehicles and different earthquake action fabricated and unfabricated isolation bearing are calculated respectively. The results show that: plastic hinge will develop at the bottom of piers in regard to railway bridges with mid-high and low pier; LRB can reduce displacement and inner forces of structures and improve earthquake-resistant capability of structures effectively.

Cryogenic Tribology of High-Speed Bearings and Shaft Seals in Liquid Hydrogen

Liquid hydrogen (LH2) is excellent in extensive storage and transportation systems, such as being used as fuel in highly efficient liquid-rocket engines. To consider the use of LH2 required for future hydrogen-energy systems, this paper presents a topical review of previous cryogenic tribology studies on the research and development of the bearings and shaft seals for LH2 turbopumps. Cryogenic tribology studies were conducted for the LE-5/LE-7 rocket engines of the Japanese H-2 rocket as well as for an advanced ultra-high-speed LH2 turbopump. The tribo-chemical formation of CaF2/FeF2 film due to the reduction power of LH2 showed excellent self-lubrication, resulting in a sound wear condition within the turbopump bearing. A new hybrid ceramic bearing with Si3N4 balls, which bearing had a single-guided retainer, tested excellently at an ultra-high speed of 120,000 rpm (3 million DN) in LH2. Seal performance for the floating-ring seals using Ag-plated metal seal-rings at ultra-high speeds was also tested.

A numerical scheme for solving a periodically forced Reynolds equation

A modified Reynolds equation is used to model the air-film in a high-speed squeeze-film bearing. The axial position of the bearing stator is prescribed as a finite amplitude periodic oscillation. A numerical approach is considered for solving the uncoupled and coupled periodic problems associated with this model. The uncoupled problem requires the computation of the squeeze-film dynamics when the rotor is held at a fixed axial position and the coupled problem incorporates the additional air–rotor interaction since the rotor position is unknown and modelled as a spring-mass-damper system. The details of a Fourier spectral collocation scheme are provided for the reduction of the modified Reynolds equation to a system of non-linear, first-order ordinary differential equations in space. Using the Matlab boundary value problem solver bvp4c this system of equations is solved to give the periodic pressure distributions and rotor heights. The high degree of accuracy in the spectral collocation scheme is demonstrated through comparison with an appropriate analytical solution. Further analysis indicates that the direct periodic solver is at least 10 times faster than the equivalent Crank–Nicholson finite-difference scheme. For changing values of a selected physical parameter the method of arc-length continuation is employed to track branches of solutions computed using the spectral collocation scheme. A selection of results is presented to demonstrate the range of accessible solutions and the robust nature of the numerical scheme. Copyright © 2010 John Wiley & Sons, Ltd.