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1
Yang, Jian Xi, Fa Yu Zhang, Jian Ting Liu i Jian Fang Zhou. "Load-Carrying Capacity Analysis for Sinusoidal Surfaces Hydrodynamic Bearing". Advanced Materials Research 295-297 (lipiec 2011): 1244–50. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1244.
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To obtain a new method to improve hydrodynamic bearing carrying capacity, hydrodynamic journal bearing’s characteristics as well as the current study direction are analyzed. According to the calculation of general cylindrical hydrodynamic journal bearing, the mathematic model for sinusoidal surface hydrodynamic bearing’s carrying capacity is established. It is used to calculate, analyze and compare these two bearings’ carrying capacity with example. The bearing, which has the characteristic of sinusoidal surface, has stronger carrying capacity than general cylindrical hydrodynamic bearing. What’s more, the improvement is more obvious when the number of waves is 3, also it has wider carrying area. Compared with other journal bearings, the journal bearing with sinusoidal surfaces has stronger carrying capacity, smaller friction moment and longer life-span. Therefore, it has extensive prospect.
2
Chen-Hui, Jia, Du Cai-Feng i Qiu Ming. "Research on Nonlinear Dynamic Characteristics and Stability of Aerodynamic Bearings". Open Mechanical Engineering Journal 8, nr 1 (16.09.2014): 243–50. http://dx.doi.org/10.2174/1874155x01408010243.
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In order to research the conical spiral groove aerodynamic bearings, the lubrication mathematical model of the bearings was established. The Reynolds equation of the laminar flow condition is used to calculate the partial differential equation of the perturbation pressure with the local finite difference method. Through calculating the stiffness and damping coefficient, the influence of the speed of law and eccentricity ratio on the dynamic characteristic coefficients has been gained. The mathematical model for the stability of the bearing-rotor system is established to study the influence law of speed influence of the law of speed and eccentricity ratio on the stability. The results show that the influence of the bearing's speed and eccentricity on the dynamic characteristics is significant. A reasonable choice of the bearing's speed and eccentricity contributes to improve the dynamic characteristics and the stability of the bearing-rotor system.
3
Lin, Xi Chen, Rui Ping Zhou i Neng Qi Xiao. "Influence Characteristics of Fluid Film Bearing’s Displacement-Load on Rotating Vibration of Rotor System". Applied Mechanics and Materials 727-728 (styczeń 2015): 567–71. http://dx.doi.org/10.4028/www.scientific.net/amm.727-728.567.
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In high load-carrying bearing-rotor system, bearings’ places usually change for load distribution or in continual work. It influences the system’s stability, and brings out different vibration response in rotor system. This article puts forward mathematical model of bearing’s stiffness under load which is calculated from bearing displacement. Then through numerical integration it studies system’s rotating vibration with different bearing settings. The results of the analysis show that bearing displacement has a great effect on dynamic characteristics of the bearing-rotor system.
4
Wang, You Qiang, i Li Jing Zhang. "Characteristics and Outline of Water-Lubricated Thordon Bearing". Advanced Materials Research 496 (marzec 2012): 355–58. http://dx.doi.org/10.4028/www.scientific.net/amr.496.355.
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Thordon is a new liner material used widely in water-lubricated bearings in virtue of its shockproof characteristic, high load and wear resistance. The category of materials used in water-lubricated bearings was briefly outlined and tribological characteristics of most of the materials were compared in the paper. The defects of the traditional water-lubricated bearing materials were listed and the advantage of the Thordon bearing was presented. The development status and the tribological characteristics of the water-lubricated Thordon bearings were studied. The application prospects of the water-lubricated Thordon bearings were introduced in the end of the paper.
5
Gao, Hang, Qing Lv i Li Gang Qu. "Influence of Groove Slotting for Micro-Sensor Embedding on Smart Bearing's Mechanical Characteristics". Key Engineering Materials 297-300 (listopad 2005): 562–66. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.562.
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It is necessary to slot a groove on the outside of the bearing’s raceway in order to embed micro-sensor for smart bearing. Reasonable choice of slotting parameters for different type of bearings is one of key problems to be solved in smart bearing design. In this paper three-dimensional solid model and corresponding mechanics model for a segment of ball bearing’s out ring are built according to some reasonable simplification and supposition of boundary condition and loading status. Further more the influence of slotting parameters on smart bearing’s mechanical characteristics is studied with FEA method. Choosing 220 type of ball bearing as an example, theoretical analysis results of influence of slotting parameters on the maximum stress and deformation of outer ring are shown. The FEA results showed that micro-sensors for smart bearings should be manufactured flatter or the groove depth for micro-sensor embedding should be smaller soon as possible in order to insure the smart bearing’s original mechanical rigidity and strength.
6
Lu, Chen, Qian Sun, Laifa Tao, Hongmei Liu i Chuan Lu. "Bearing Health Assessment Based on Chaotic Characteristics". Shock and Vibration 20, nr 3 (2013): 519–30. http://dx.doi.org/10.1155/2013/645308.
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Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM). Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV) which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.
7
Ngo, Thi-Thao, Van-The Than, Chi-Chang Wang i Jin H. Huang. "Analyzing characteristics of high-speed spindle bearing under constant preload". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, nr 5 (1.08.2017): 568–81. http://dx.doi.org/10.1177/1350650117723484.
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Bearings play an important role in a high-speed spindle. Its characteristics are often influenced by speed and thermal effects. This paper presents an approach that combines an inverse method with a high-speed ball bearing model to determine the characteristics of a high-speed spindle bearing under constant preload in actual working conditions. With temperature distribution in the entire spindle obtained by the experimental inverse heat transfer model from the authors’ previous results, the change in bearing parameters is then calculated and subsequently replaced in the bearing model to analyze the change in bearing characteristics. As a result, thermal effects on a bearing’s dynamic contact angles, contact forces, contact stress, stiffness, and lubricant film thickness are presented. Moreover, analysis results indicate that a bearing’s stiffness and lubricant film thickness nonlinearly vary with the increase in speed, and the thermal effect significantly affects the lubricant film thickness. The results presented herein may be applied to develop a dynamic model for a high-speed spindle using a constant preload and provide useful information to avoid failure in lubrication.
8
Feng, N. S., i E. J. Hahn. "Vibration Characteristics of Hydrodynamic Fluid Film Pocket Journal Bearings". Advances in Acoustics and Vibration 2010 (27.12.2010): 1–10. http://dx.doi.org/10.1155/2010/589318.
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Theoretical analyses of hydrodynamic fluid film bearings with different bearing profiles rely on solutions of the Reynolds equation. This paper presents an approach used for analysing the so-called pocket bearings formed from a combination of offset circular bearing profiles. The results show that the variation of the dynamic bearing characteristics with different load inclinations for the pocket bearings is less than that for the elliptic bearing counterpart. It is shown that the natural frequencies as well as the critical speeds, and hence the vibrational behaviour, can also be significantly different for an industrial rotor supported by the different bearings.
9
Zheng, Yueqing, Tianwei Lai, Shuangtao Chen, Liang Chen, Liqiang Liu i Yu Hou. "Static characteristics of six pads multilayer protuberant foil thrust bearings". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, nr 2 (5.08.2016): 158–64. http://dx.doi.org/10.1177/1350650116649328.
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The multilayer protuberant foil bearing, as a new type of compliant surface foil bearing, shows a great and wide application promise. Six pads multilayer protuberant foil thrust bearings with different configurations were designed and fabricated in this study. The static characteristics of these bearings and the effects of their key configuration parameters including the thickness of top foil, the thickness of protuberant foil, and the layers of protuberant foil are investigated. The experimental results reveal that the bearings show nonconstant structural stiffness, and the stiffness mainly depends on both the load force and the configuration of the bearings. In the airborne regime, the torque of the bearing is mainly dependent on the load force rather than the rotational speed, which can be interpreted by the proportional relationship between the bearing clearance and the rotational speed. Furthermore, the experimental results also show that the maximum load capacities of the bearing are also greatly affected by the bearing configuration. With more layers of the protuberant foils and thinner top foil, the bearing shows larger maximum load capacity. The work provides some insights about the relationships between the characteristics and the configuration of the bearings.
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Keller, Jonathan, Yi Guo, Zhiwei Zhang i Doug Lucas. "Comparison of planetary bearing load-sharing characteristics in wind turbine gearboxes". Wind Energy Science 3, nr 2 (21.12.2018): 947–60. http://dx.doi.org/10.5194/wes-3-947-2018.
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Abstract. In this paper, the planetary load-sharing behavior and fatigue life of different wind turbine gearboxes when subjected to rotor moments are examined. Two planetary bearing designs are compared – one design using cylindrical roller bearings with clearance and the other design using preloaded tapered roller bearings to support both the carrier and planet gears. Each design was developed and integrated into a 750 kW dynamometer tests, the loads on each planet bearing row were measured and compared to finite-element models. Bearing loads were not equally shared between the set of cylindrical roller bearings supporting the planets even in pure torque conditions, with one bearing supporting up to 46 % more load than expected. A significant improvement in planetary bearing load sharing was demonstrated in the gearbox with preloaded tapered roller bearings with maximum loads 20 % lower than the gearbox with cylindrical roller bearings. Bearing life was calculated with a representative duty cycle measured from field tests. The predicted fatigue life of the eight combined planet and carrier bearings for the gearbox with preloaded tapered roller bearings is 3.5 times greater than for the gearbox with cylindrical roller bearings. The influence of other factors, such as carrier and planet bearing clearance, gravity, and tangential pin position error, is also investigated. The combined effect of gravity and carrier bearing clearance was primarily responsible for unequal load sharing. Reducing carrier bearing clearance significantly improved load sharing, while reducing planet clearance did not. Normal tangential pin position error did not impact load sharing due to the floating sun design of this three-planet gearbox.
11
Sawano, Hiroshi. "Relationship Between Fluid Properties and Bearing Stiffness in Water Hydrostatic Bearing". International Journal of Automation Technology 14, nr 1 (5.01.2020): 73–79. http://dx.doi.org/10.20965/ijat.2020.p0073.
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Hydrostatic bearings are important elements that directly affect machining accuracy in machine tools. Although hydrostatic bearings using water can reduce environmental influence compared with those using oil, they have low rigidity and damping properties. By investigating the properties of water used for working fluid of hydrostatic bearings, there is a possibility that the characteristics of hydrostatic bearings using water can be improved. Therefore, in this study, the relationship between the properties of water used as a working fluid of hydrostatic bearings and the characteristics of bearings was investigated. For this purpose, a hydrostatic bearing characteristics evaluation system using water was constructed. The characteristics of hydrostatic bearings were examined by varying the components and temperature of water. The experimental results show that the composition and temperature of working water affect the performance of water hydrostatic bearing.
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Goodwin, M. J., P. J. Ogrodnik, M. P. Roach, L. K. Lim i Y. Fang. "Steady Load-Carrying Capacity of Recessed Hydrodynamic Bearings". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, nr 4 (grudzień 1995): 255–62. http://dx.doi.org/10.1243/pime_proc_1995_209_436_02.
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Oil-film hydrodynamic bearings are one of the most common forms of bearing used in rotating machinery. Because of their effect on system unbalance response and stability, care has to be exercised in the design of machines running in hydrodynamic bearings—for example they cannot usually be used in machines operating at high rotational speeds when the steady load on the bearing is low. A novel form of hydrodynamic bearing which incorporates recesses in the bearing surface has been proposed by the authors which improves the dynamic characteristics; however, earlier work has not fully assessed the steady load characteristics of such bearings vis-à-vis conventional bearings for example. The aim of this paper is to present the results of experimental work on several designs of the proposed novel bearings, to assess the bearing's performance and to compare it with that of conventional bearings. The results of the work show that the steady load-carrying capacity is adversely affected by the inclusion of recesses in the bearing surface, but that this is only a marginal effect provided that the number of recesses and their geometry are selected with care.
13
Wu, Dengyun, Jianwen Wang, Hong Wang, Hongxing Liu, Lin Lai, Tian He i Tao Xie. "An Automatic Bearing Fault Diagnosis Method Based on Characteristics Frequency Ratio". Sensors 20, nr 5 (10.03.2020): 1519. http://dx.doi.org/10.3390/s20051519.
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Bearing is a key component of satellite inertia actuators such as moment wheel assemblies (MWAs) and control moment gyros (CMGs), and its operating state is directly related to the performance and service life of satellites. However, because of the complexity of the vibration frequency components of satellite bearing assemblies and the small loading, normal running bearings normally present similar fault characteristics in long-term ground life experiments, which makes it difficult to judge the bearing fault status. This paper proposes an automatic fault diagnosis method for bearings based on a presented indicator called the characteristic frequency ratio. First, the vibration signals of various MWAs were picked up by the bearing vibration test. Then, the improved ensemble empirical mode decomposition (EEMD) method was introduced to demodulate the envelope of the bearing signals, and the fault characteristic frequencies of the vibration signals were acquired. Based on this, the characteristic frequency ratio for fault identification was defined, and a method for determining the threshold of fault judgment was further proposed. Finally, an automatic diagnosis process was proposed and verified by using different bearing fault data. The results show that the presented method is feasible and effective for automatic monitoring and diagnosis of bearing faults.
14
Polyakov, Roman, Leonid Savin i Denis Shutin. "Reliability Improvement of Rotor Supports by Combining Rolling-Element Bearings and Fluid-Film Bearings". Applied Mechanics and Materials 630 (wrzesień 2014): 188–98. http://dx.doi.org/10.4028/www.scientific.net/amm.630.188.
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Reliability of rotating machinery is determined to a considerable degree by the bearing units. For several applications the requirements in rotation speed, bearing load and maximal vibration level are so extreme that neither rolling-element bearings nor fluid-film bearings could provide necessary performance characteristics during all regimes of operation. Hybrid bearings, which are a combination of rolling-element and fluid-film bearings, can improve performance characteristics and reliability of the rotor-bearing systems. The aim of this work is to analyze the advantages and disadvantages of the hybrid bearings. Known real applications of hybrid bearings are discussed. Analysis shows that depending on the application different hybrid bearing types could improve dynamic characteristics and life time of the bearing unit, increase load capacity and DN limit of the rolling-element bearing.
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Polyakov, Roman, Leonid Savin i Alex Fetisov. "Analysis of the conditions for the occurrence of the effect of a minimum of friction in hybrid bearings based on the load separation principle". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, nr 2 (21.05.2018): 271–80. http://dx.doi.org/10.1177/1350650118777143.
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Reliability of rotating machinery is determined to a considerable degree by the bearing units. For several applications the requirements in rotational speed, bearing load and maximal vibration level are so extreme that neither rolling-element bearings nor fluid-film bearings could provide necessary operating characteristics during all regimes of operation. Hybrid bearings, which are a combination of rolling-element and fluid-film bearings, can improve performance characteristics and reliability of the rotor-bearing systems. A hybrid bearing, where a rolling-element bearing and a fluid-film bearing are positioned parallel to the vector of external load (PLEX), has the following advantages compared to a single bearing, whether rolling-element or fluid-film one: increase of life expectancy, load capacity increase, friction reduction, thermal regime enhancement, increase of stiffness, and damping properties. The present paper presents the results of theoretical and numerical research of friction characteristics of PLEX in mixed sliding and rolling friction, i.e. combination of viscous and rolling contact friction, regime. The conditions of minimum friction effect occurrence have been substantiated, and rational relations between characteristics of hybrid rolling-element bearings and fluid-film bearings needed for provision of such effect have been experimentally proven. Finally, the paper presents recommendations regarding design of such hybrid bearings for heavily loaded bearing nodes of rolling mills.
16
Qiu, Ming, Zhi Lun Gao, Guo Feng Wang i Long Chen. "Tribological Properties of Spherical Plain Bearings with Self-Lubricating PTFE Woven Liners". Advanced Materials Research 338 (wrzesień 2011): 607–10. http://dx.doi.org/10.4028/www.scientific.net/amr.338.607.
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The friction and wear behaviors of three kinds of spherical plain bearings with PTFE fabric composite liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at different oscillating frequencies. With the help of SEM and EDS, the differences of worn surfaces of the three spherical bearings were investigated. The results indicate that the fiber woven with PTFE effects the friction and wear characteristics of bearing, the tribological properties of bearing with Kevlar/PTFE fiber woven liner is the best in the three kinds of bearing. The abrasive wear are appeared on the surface of wore liners of bearingⅠ,while bearingⅡappeared normal wear, bearing III showed serious adhesive wear and abrasive wear.
17
Guo, Zhiqiang, Shenlong Li, Wei Wu i Liuyang Zhang. "Quasi-Static Load Sharing Characteristics of a Planetary Gear Set with Planet Journal Bearings". Applied Sciences 10, nr 3 (7.02.2020): 1113. http://dx.doi.org/10.3390/app10031113.
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The quasi-static load sharing characteristics of a planetary gear set with planet journal bearings are numerically investigated. The application of journal bearings instead of rolling bearings in planetary gear sets is an alternative to increase the rotation speed. Therefore, an effective analysis method is needed to estimate the dynamic performance of a planetary gear set with planet journal bearings. Here, an available load sharing factor computation method is developed considering the effect of the variable journal bearing stiffness. Results of an experiment are used to validate the effectiveness of the computation method. Furthermore, the load sharing characteristics of a planetary gear set with planet journal bearings are influenced by bearing parameters and operating conditions significantly due to the changing bearing stiffness of journal bearings. The effects on the load sharing factor and the bearing stiffness are studied in detail simultaneously based on the proposed analysis method. The load sharing factor of a planetary gear set with planet journal bearings has a similar variation with the bearing support stiffness under the same load. These researches provide a theoretical basis for the application of journal bearings in planetary gear sets.
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Schüler, Eckhard, i Olaf Berner. "Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves". Lubricants 9, nr 2 (10.02.2021): 18. http://dx.doi.org/10.3390/lubricants9020018.
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In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.
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Lee, Dong-Soo, i Dong-Hoon Choi. "A Dynamic Analysis of a Flexible Rotor in Ball Bearings with Nonlinear Stiffness Characteristics". International Journal of Rotating Machinery 3, nr 2 (1997): 73–80. http://dx.doi.org/10.1155/s1023621x97000080.
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This paper presents an effective analysis approach for a flexible rotor in ball bearings with nonlinear stiffness characteristics to obtain realistic dynamic behavior results. The ball bearing is modeled in five degrees of freedom and the nonlinear stiffness characteristics of the bearing are completely described as functions of combined loads and spin speed. For dynamic behavior analysis of the nonlinear rotor-bearing system, a transfer-matrix method is iteratively used until the bearing displacements and the shaft displacements at every bearing location converge to the same values. The results show that the nonlinear stiffness characteristics of ball bearings significantly influence system dynamic behaviors and the proposed analysis approach for the nonlinear rotor-bearing system is effective.
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Baroud, Charles, Ilene Busch-Vishniac i Kristin Wood. "Induced Micro-Variations in Hydrodynamic Bearings". Journal of Tribology 122, nr 3 (10.08.1999): 585–89. http://dx.doi.org/10.1115/1.555405.
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Fluid-structure interactions in hydrodynamic bearings result in load carrying and drag forces which give the bearing its characteristics. While these bearings offer many benefits as machine components, one of their shortcomings is their limited efficient range. In this paper, we demonstrate the use of micron-scale actuators to actively control the thrust and drag forces on a slider bearing. We show that for a set of control parameters, we are able to affect the performance of a bearing by more than 100 percent during operation, increasing the bearing’s range of operation. [S0742-4787(00)01602-7]
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Liu, Yang, Jiyuan Han, Siyao Zhao, Qingyu Meng, Tuo Shi i Hui Ma. "Study on the Dynamic Problems of Double-Disk Rotor System Supported by Deep Groove Ball Bearing". Shock and Vibration 2019 (26.02.2019): 1–12. http://dx.doi.org/10.1155/2019/8120569.
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Aiming at the analysis of the dynamic characteristics of the rotor system supported by deep groove ball bearings, the dynamic model of the double-disk rotor system supported by deep groove ball bearings was established. In this paper, the nonlinear finite element method is used combined with the structural characteristics of deep groove ball bearings. Based on the nonlinear Hertz contact theory, the mechanical model of deep groove ball bearings is obtained. The excitation response results of the rotor system nodes are solved by using the Newmark-β numerical solution method combined with the Newton–Raphson iterative method. The vibration characteristics of the rotor system supported by deep groove ball bearings are studied deeply. In addition, the effect of varying compliance vibration (VC vibration) caused by the change in bearing support stiffness on the dynamics of the system is considered. The time domain and frequency domain characteristics of the rotor system at different speeds, as well as the influence of bearing clearance and bearing inner ring’s acceleration on the dynamics of the rotor system are analyzed. The research shows that the VC vibration of the bearing has a great influence on the motion of the rotor system when the rotational speed is low. Moreover, reasonable control of bearing clearance can reduce the mutual impact between the bearing rolling element and the inner or outer rings of the bearing and reduce the influence of unstable bearing motion on the vibration characteristics of the rotor system. The results can provide theoretical basis for the subsequent study of the nonlinear vibration characteristics of the deep groove ball bearing rotor system.
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Lu, Zhi-wei, Jun-an Zhang i Bo Liu. "Research and Analysis of the Static Characteristics of Aerostatic Bearings with a Multihole Integrated Restrictor". Shock and Vibration 2020 (29.02.2020): 1–11. http://dx.doi.org/10.1155/2020/7426928.
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In order to further study the performance of aerostatic bearing, an aerostatic bearing with a multihole integrated restrictor was proposed in this paper. Based on the physical model of aerostatic bearings, the governing equation was established, deduced discretely, and solved numerically by the finite-difference method and flow balance principle in Cartesian coordinates. The bearing capacity and stiffness of aerostatic bearings have been analyzed, and the relevant experimental research has been carried out in this paper. The results showed that the number of orifices in the integrated restrictor had a significant effect on the bearing capacity, and the maximum bearing capacity of a nine-hole integrated throttling bearing was approximately 1.9 times greater than that of a single-hole bearing. The bearing stiffness was greatly affected by the diameter of the orifices, and the optimum bearing stiffness was determined. The corresponding gas film clearance also changed accordingly.
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Fukui, S., R. Matsuda i R. Kaneko. "On the Physical Meanings of Λ/Q˜p0 and σ/Q˜p0 in Molecular Gas Film Lubrication Problems". Journal of Tribology 118, nr 2 (1.04.1996): 364–69. http://dx.doi.org/10.1115/1.2831310.
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To estimate molecular gas film lubrication (MGL) characteristics, we propose a modified bearing number Λ′ and a modified squeeze number σ′, which are, respectively, the conventional bearing Λ and squeeze number σ divided by the relative Poiseuille flow rate Q˜p0. Using Λ′ and σ′, the linearized MGL problem can be reduced to the continuum gas film lubrication problem and the MGL characteristics can be exactly estimated, if the characteristic flow rate corresponding to the spacing, Q˜p0, is known. For nonlinear MGL problems, the lubrication characteristics can be verified to be roughly estimated by Λ′ and σ′ both in rectangular slider bearings and in circular squeeze-film thrust bearings.
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Lin, C. R., i H. G. Rylander. "Performance Characteristics of Compliant Journal Bearings". Journal of Tribology 113, nr 3 (1.07.1991): 639–44. http://dx.doi.org/10.1115/1.2920672.
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This investigation of compliant journal bearings is directed toward the fundamental behavior characteristics which are necessary when compliance is factored into the final design. Analytical determintation of performance characteristics are shown as a function of the bearing flexibility. As the deformation coefficient increases, load capacity decreases, the cavitation angle and friction coefficient increase, attitude angle may increase or decrease, stability is improved for attitude angles less than 0.8, and minimum film thickness will occur near the two sides of the bearing.
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Sun, Huer, Zhao Jian Yang, Qun Long Liang i Xin Yu Pang. "Characteristics Identification of Overlapping Vibration Signals on Mallat". Advanced Materials Research 97-101 (marzec 2010): 4375–78. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4375.
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In rotor-bearing system running, vibration signals measured were an kind of Multi-vibration source signals which is overlapping each other. These overlapping signals were difficult to be separated by the ordinary methods, which is adverse to precisely estimate faults of rotor-bearing system in running. In this paper, a test rig was set up to simulate mis-alignment faults; collected vibration signals of bearings were decomposed and reconstructed by algorithm of Mallat. Reconstructed signal can reflect detail character s of bearings vibration. And vibration signals characteristics of fault rotor were effectively identified.
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Masaki, Nobuo, i Shigenobu Suzuki. "Restoring Force Characteristics of Laminated Rubber Bearings Under Various Restraining Conditions". Journal of Pressure Vessel Technology 126, nr 1 (1.02.2004): 141–47. http://dx.doi.org/10.1115/1.1637643.
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We conducted the measurement of restoring force characteristics of laminated rubber bearings under various restraining conditions. In the experiment, we provided three laminated rubber bearings with various second shape factors S2=3,4,4.94. The restoring force is obtained by using a newly designed combined loading test apparatus. By using this apparatus, the laminated rubber bearing could be subjected to shear, compressive and rotational deformations independently. In this experiment, we defined the degree of restraint as the ratio of the bending moment to the restricting bending moment which was measured when the rotation angle of the laminated rubber bearing was zero radian. This means that the flanges on both sides of the laminated rubber bearings were kept parallel during horizontal deformations. From the experiment, it was confirmed that restoring force characteristics were affected by the degree of restraint. Some reduction in restoring forces was observed when the degree of restraint was small. In particular the laminated rubber bearing with a small second shape factor, namely the rubber bearing, had a slender shape, easily buckling under small horizontal displacement. It was also confirmed that bending stiffness of the laminated rubber bearing had shear strain dependency and vertical load i.e., surface pressure dependency. The results of this experiment reveal that we should consider the reduction of the restoring force if the upper or lower structure of the laminated rubber bearing is not sufficiently rigid.
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Tu, Wenbing, Jinwen Yang, Wennian Yu i Ya Luo. "Contact characteristic and vibration mechanism of rolling element bearing in the process of fault evolution". Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 235, nr 1 (5.01.2021): 19–36. http://dx.doi.org/10.1177/1464419320985707.
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The vibration response of rolling element bearing has a close relation with its fault. An accurate evaluation of the bearing vibration response is essential to the bearing fault diagnosis. At present, most bearing dynamics models are built based on rigid assumptions, which may not faithfully reveal the dynamic characteristics of bearing in the presence of fault. Moreover, previous similar works mainly focus on the fault with a specified size without considering the varying contact characteristics as the fault evolves. This paper developed an explicit dynamics finite element model for the bearing with three types of raceway faults considering the flexibility of each bearing component in order to accurately study the contact characteristic and vibration mechanism of defective bearings in the process of fault evolution. The developed model is validated by comparing its simulation results with both analytical and experimental results. The dynamic contact patterns between the rolling elements and the fault, the additional displacement due to the fault and the faulty characteristics within the bearing vibration signal during the fault evolution process are investigated. The analysis results from this work can provide practitioners an in-depth understanding towards the internal contact characteristics with the existence of raceway fault and theoretical basis for rolling bearing fault diagnosis.
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Wang, Jianmei, Zhixiong Li, Sadoughi Mohammadkazem, Min Cai, Jianfeng Kang i Yanan Zhang. "Stability characteristics of lubricating film in mill oil-film bearings". Industrial Lubrication and Tribology 70, nr 1 (8.01.2018): 201–11. http://dx.doi.org/10.1108/ilt-12-2016-0318.
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Purpose The stability characteristics of an oil film directly influence the safety and service life of mill oil-film bearings. However, very limited work has been done to address the stability characteristics of mill oil-film bearings. To this end, this paper aims to investigate the stability characteristics of mill oil-film bearings through theoretical and experimental analysis. Design/methodology/approach For the first time, a special designed experiment platform was developed to investigate the stability characteristics of mill oil-film bearings. In addition, a theoretical model of lubricating film of the tested bearings was established to analyze the oil-film stability. The theoretical results were compared with the experimental results. Findings The comparison results demonstrate that the critical influential factors on the bearing stability were the eccentricity ratio and the ratio of bearing length to diameter. The mill bearing was likely to be unstable under a small load and at a high rotational speed. Practical implications The paper includes implications for suitable operation conditions in practical use of mill oil-film bearings. Originality/value This paper fulfills an identified need to investigate oil-film stability of mill bearings for practical applications.
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ZHU, KE-QIN, i JIE PENG. "HYDRODYNAMIC CHARACTERISTICS OF ER FLUID FLOWS IN JOURNAL BEARINGS". International Journal of Modern Physics B 17, nr 01n02 (20.01.2003): 205–8. http://dx.doi.org/10.1142/s0217979203017345.
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A numerical analysis is performed on the hydrodynamic characteristics of electrorheological(ER) fluid flows in journal bearings based on the basic hydrodynamic equations. The flow field is assumed to be incompressible and isotropic, the Bingham plastic model is used to describe the behavior of ER fluids. The effect of bearing eccentricity ratio and applied electric field intensity has been studied attentively. It shows that control of the journal bearing through external electric field is much more feasible in high eccentricity ratio bearing than in low eccentricity ratio one.
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Shi, Zhifeng, Jing Liu i Shaojiang Dong. "A numerical study of the contact and vibration characteristics of a roller bearing with a surface crack". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 234, nr 4 (30.01.2020): 549–63. http://dx.doi.org/10.1177/1464420720903075.
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Roller bearings are key parts in different machineries. As one of the major incipient failure models in the bearings, the surface crack will be enlarged to be a large spalling failure. Moreover, the abrupt changes in the contact characteristics caused by the crack zone would produce unacceptable impulses, which can affect the bearing vibrations. Thus, a study of the contact characteristics and vibrations of the bearings including the surface crack could be conducive for the incipient fault monitoring methods. To overcome this issue, a finite element model is proposed to obtain the influences of the depth and slope angle of a surface crack on the contact characteristics in a roller bearing. The relationships between the contact characteristics (contact deformation, width and stiffness) and crack sizes (depth and slope angle) are established. To study the influences of the surface crack sizes on the bearing vibrations, a dynamic model of the roller bearing considering the surface crack is also proposed. An experiment is introduced to verify the proposed method. It seems that the crack depth and slope angle can greatly affect the contact and vibration characteristics of the bearing. This study provides a helpful numerical approach for understanding the contact and vibration characteristics of roller bearings with various surface cracks.
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Kodnyanko, Vladimir, Stanislav Shatokhin, Andrey Kurzakov, Yuri Pikalov, Maxim Brungardt, Lilia Strok i Iakov Pikalov. "Theoretical Investigation on Performance Characteristics of Aerostatic Journal Bearings with Active Displacement Compensator". Applied Sciences 11, nr 6 (16.03.2021): 2623. http://dx.doi.org/10.3390/app11062623.
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Active aerostatic bearings are capable of providing negative compliance, which can be successfully used to automatically compensate for deformation of the machine tool system in order to reduce the time and improve the quality of metalworking. The article considers an aerostatic radial bearing with external combined throttling systems and an elastic displacement compensator, which is an alternative to aerostatic bearings with air flow rate compensators. The results of the mathematical modeling and theoretical research of stationary and nonstationary modes of operation of bearings with slotted and diaphragm throttling systems are presented. A counter-matrix sweep method has been developed for solving linear and nonlinear boundary value problems in partial derivatives with respect to the function of the square of the pressure in the bearing gap and inter-throttling bearing cavities for any values of the relative shaft eccentricity. A numerical method is proposed for calculating the dynamic quality criteria, and the transfer function of the dynamic compliance of a bearing with small displacements is considered as a linear automatic control system with distributed parameters. An experimental verification of the theoretical characteristics of the bearing was carried out, which showed a satisfactory correspondence among the compared data. It is shown that bearings with a throttle system have the best quantitative and qualitative load characteristics. The possibility of optimal determination of the values of a number of important parameters that provide the bearing with optimal performance and a high stability margin is established. It is shown that bearings with an elastic suspension of the movable sleeve allow one to compensate for significant movements, which can be larger than the size of the air gap by an order of magnitude or more. In these conditions, similar bearings with air flow compensators would be obviously inoperative.
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Zhang, Xing Hui, Jian She Kang, Jian Min Zhao i Hong Zhi Teng. "Enhanced Fault Diagnosis of Bearings in Gearbox Based on Lucy-Richardson Deconvolution and Discussion". Applied Mechanics and Materials 764-765 (maj 2015): 264–68. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.264.
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Bearings are one of the most important components in rotating machineries. Their failures will lead to great production loss and increase the maintenance cost. So, condition monitoring work of bearings can save and avoid the potential loss caused by bearing fault. Lucy-Richardson deconvolution (LRD) algorithm, as an image processing technique, started to be used in bearing fault diagnosis. However, only data of bearings working in electric motor are used to validate the method. In engineering cases, most bearings are working in gearbox. Therefore, the bearing fault signals are very weak compared to the gear vibration signal. It is usually difficult to detect the bearing fault in this case. LRD algorithm is used to enhance the bearing fault diagnosis and some characteristics in this case are discussed. Experiment data analysis demonstrates that LRD can enhance the periodic impulse signal effectively. Otherwise, if the desired fault signal is weak compared to non-desired signal, then, the desired fault signal will be continued weaken by LRD which is not benefit to bearing’s incipient fault detection.
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Jia, Chenhui, Zhiwu Cui, Shijun Guo i Wensuo Ma. "Research on dynamic characteristics of gas film of spherical hybrid gas bearings based on computational fluid dynamics". Transactions of the Canadian Society for Mechanical Engineering 44, nr 1 (1.03.2020): 23–37. http://dx.doi.org/10.1139/tcsme-2018-0134.
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A realizable k–ε turbulence model for spherical spiral groove hybrid gas bearing films was established based on computational fluid dynamics (CFD). A six degrees of freedom passive grid was used to calculate the gas film pressure distribution, bearing capacity, and dynamic characteristic coefficients numerically. The gas flow field dynamic and static pressure coupling mechanism was studied. The effects of the rotation speed, gas film thickness eccentricity ratio, and gas supply pressure on the dynamic and static pressure bearing capacity, and dynamic characteristic coefficients during operation were analyzed as a method of research into the mechanical mechanisms of gas bearing stability. The CFD calculation analysis can simulate the complex gas flow in the transient flow field of the gas film and determine reasonable operation parameters to optimize the dynamic and static pressure coupling effects, which can improve the gas film bearing capacity, dynamic characteristics, and operational stability of gas bearings.
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Shyu, Shiuh Hwa, i Yu Wei Chen. "Dynamic Characteristics of Rotor-Bearing System with a Labyrinth Seal". Key Engineering Materials 739 (czerwiec 2017): 169–81. http://dx.doi.org/10.4028/www.scientific.net/kem.739.169.
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In this paper, the dynamic characteristics of rotor-bearing system with a labyrinth seal are investigated. The dynamic coefficients of labyrinth seal and the whirl speeds of rotor-bearing system are analyzed. The simplified rotor-bearing model consists of a rigid disk and a flexible shaft. The rotor-bearing system supported by two ball bearings, which are modeled as the spring-damper systems. A labyrinth seal supports one of the rigid disks. The perturbation approach has been applied to the governing equations of the bulk-flow model to calculate the dynamic coefficients of labyrinth seal. The Finite Element Method (FEM) is utilized to model the flexible-rotor system. The numerical results show the labyrinth seal effect on the dynamic characteristics of rotor-bearing system, which depend on a great variety of parameters such as geometry of the labyrinth seal.
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Lin, Jaw-Ren, i Li-Ming Chu. "Dynamic characteristics of exponential slider bearings lubricated with a ferrofluid – Shliomis model". Industrial Lubrication and Tribology 70, nr 4 (8.05.2018): 673–79. http://dx.doi.org/10.1108/ilt-03-2016-0063.
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Purpose The purpose of this paper is to investigate the dynamic characteristics of exponential slider bearings lubricated with a ferrofluid. Because of the development of modern engineering, the increasing use of ferrofluids in lubrication fields has shown great importance. Understanding the dynamic characteristics of exponential film bearings is helpful for engineers in bearing selection. Design/methodology/approach Applying the Shliomis ferrohydrodynamic flow model and considering the squeezing action of bearing pads, a dynamic Reynolds equation is obtained for an exponential film slider bearing lubricated with a ferrofluid in the presence of a transverse magnetic field. Analytical solutions of dynamic characteristics are obtained. Findings According to the results, the ferrofluid-lubricated exponential film bearing provides better dynamic stiffness and damping characteristics than the non-ferrofluid ones, especially the bearing operating at higher values of the volume concentration parameter and the magnetic Langevin parameter. Originality/value Numerical tables of stiffness and damping coefficients for different values of the volume concentration parameter and the Langevin parameter are also included for engineering references.
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Sato, Yuichi, H. Fujino, H. Sakakida i S. Hisa. "Stability Characteristics of a Journal Bearing Mounted in an Uncentralized Squeeze Film Damper". Journal of Tribology 113, nr 3 (1.07.1991): 584–89. http://dx.doi.org/10.1115/1.2920663.
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This paper describes the stability of a journal bearing mounted in an uncentralized squeeze film damper. It is known that mounting a journal bearing in a centralized squeeze film damper improves the bearing stability. From a practical viewpoint, however, it is difficult to centralize journal bearings which support a heavy rotor, such as a steam turbine. Experimentally, we show that a journal bearing can be stabilized by mounting in an uncentralized squeeze film damper. The effect of clearance of a squeeze film damper is investigated. By using short bearing analysis, rotor trajectories are calculated. Calculated results also shows stability improvement.
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Wang, Tingting, Zhiwei Wang, Dongli Song, Weihua Zhang, Jiayuan Li i De Chen. "Effect of track irregularities of high-speed railways on the thermal characteristics of the traction motor bearing". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 235, nr 1 (27.01.2020): 22–34. http://dx.doi.org/10.1177/0954409720902359.
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The operating temperature plays a key role in the service reliability of ball bearings used in the traction motor of high-speed trains. Studies on the heat generation and temperature distributions of the bearing under the vehicle vibration environment are critical for designing the high-speed train traction motor bearing and to monitor its operation. In this paper, an SKF friction torque model that considers the inlet shear heating reduction and kinematic replenishment/starvation reduction was used to calculate the power loss of the bearing operating in a high-speed train. A thermal analysis model of the bearing, which takes into account the vehicle vibration due to track irregularities, was developed to study the thermal characteristics of the bearing operating in a high-speed train. Experiments were conducted on a service high-speed train (i.e. CRH380B) to validate the proposed bearing thermal analysis model. The thermal characteristics of the bearing and the influence of key factors on the operating temperature of the bearing under vehicle vibration due to track irregularities were studied with the proposed bearing thermal analysis model. The results show that the thermal failure of the bearing subassemblies most likely occurs at the balls region owing to the highest temperature in that region, compared to the inner and outer raceway of the bearing. The method of applying grease with appropriate kinematic viscosity should be adopted to reduce the power loss of bearing while meeting the lubrication requirement. The vehicle vibration due to track irregularities significantly influences the thermal characteristics of high-speed train motor bearings, which cannot be ignored in the thermal analysis of bearings operating in a high-speed train.
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Wan, Zhiguo, Yu Wang, Binqiang Chen, Yihua Dou i Xinjuan Wei. "The Vibration of a Transversely Cracked Rotor Supported by Anisotropic Journal Bearings with Speed-Dependent Characteristic". Applied Sciences 10, nr 16 (13.08.2020): 5617. http://dx.doi.org/10.3390/app10165617.
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This paper presents the vibration of a transversely cracked rotor supported by anisotropic journal bearings, where the speed-dependent characteristic of bearing is considered. A 3D finite element model and the contact-based approach are employed for the shaft and crack. The governing differential equations of the whole cracked rotor-bearing system were obtained by synthesizing the equations of the cracked shaft, the breathing crack and the journal bearings. In order to solve the computational difficulties caused by the high dimensions of model, the free-interface complex component mode synthesis method (CMS) is employed to reduce the order of the model. On this basis, the eigenvalue and the steady-state forced response of the cracked rotor-bearing system are obtained by the Hill’s method. Finally, the effects of the anisotropic and speed-dependent characteristics of bearings on the vibration of the system are studied. Numerical results show that both the two characteristics can significantly affect the response of the system. The anisotropy in the bearing leads to the split of resonant peaks and influence the amplitudes of the peaks. The speed-dependent characteristic mainly affects the responses at the speeds close to the resonant regions, because the parametric excitation effect of the resonance region is greater than other speeds.
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Kodnyanko, Vladimir, Stanislav Shatokhin, Andrey Kurzakov, Yuri Pikalov, Iakov Pikalov, Olga Grigorieva, Lilia Strok i Maxim Brungardt. "Numerical Modeling on the Compliance and Load Capacity of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves in the Inter-Row Zone". Applied Sciences 11, nr 12 (20.06.2021): 5714. http://dx.doi.org/10.3390/app11125714.
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Aerostatic bearings are attractive, with minimal friction losses, high durability, and environmental friendliness. However, such designs have a number of disadvantages, including low load-bearing capacity and high compliance due to high air compressibility and limited injection pressure. The article proposes a double-row aerostatic journal bearing with an external combined throttling system and longitudinal microgrooves in the inter-row zone. It is hypothesized that the use of microgrooves will reduce the circumferential flows of compressed air, as a result of which the compliance should decrease and the bearing capacity should increase. To test the hypothesis, we carried out the mathematical modeling, calculations, and theoretical study of stationary operation modes of the bearing for small shaft eccentricities in the vicinity of the central equilibrium position of the shaft and bearing capacity for arbitrary eccentricities. Formulas were obtained for the numerical evaluation of compliance for bearings with a smooth bushing surface and with longitudinal microgrooves. Iterative finite-difference methods for evaluating the fields of the squared pressure are proposed, on the basis of which the load capacity of the bearings is calculated. Experimental verification of the bearing’s theoretical characteristics was carried out, which showed satisfactory agreement between the compared data. The study of the compliance and load capacity of a microgroove bearing yielded impressive results. We show that the positive effect from the application of the improvement begins to manifest itself already at four microgrooves; the effect becomes significant at six microgrooves, and at twelve or more microgrooves, the circumferential flows in the bearing gap practically disappear; therefore, the bearing characteristics can be calculated on the basis of one-dimensional models of air lubrication longitudinal flow. Calculations have shown that for a length of L = 1, the maximum load capacity of a bearing with microgrooves is 1.5 times higher than that of a conventional bearing; for L ≥ 1.5, the bearing capacity increases twice or more. The result obtained allows us to recommend the proposed improvement for practical use in order to increase the load capacity of aerostatic journal bearings significantly.
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Li, Da Ying. "Study on CFD Solution Method for Static Characteristics of Hybrid Oil Film Bearing". Applied Mechanics and Materials 155-156 (luty 2012): 236–40. http://dx.doi.org/10.4028/www.scientific.net/amm.155-156.236.
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Reynolds equation is the fundamental equation to solve the static performance for sleeve bearings. For hydrodynamic and hydrostatic oil film bearing with three oil recesses, the specific expressions of the fluid mechanics lubrication Reynolds equation are presented. The gridding model of the bearing is proposed, the boundary condition of the bearing is set, the static characteristics are solved and the pressure distribution of the bearing is plotted by using FLUENT software. The computation results from FLUENT are considerably accordance with the computation results from finite difference method.
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Chen, Yan Long, i Pei Lin Zhang. "Bearing Fault Detection Based on SVD and EMD". Applied Mechanics and Materials 184-185 (czerwiec 2012): 70–74. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.70.
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While bearing fault signals are strongly interferenced by noise, diagnosis using EMD directly for bearings fault becomes incorrect. A scheme based on Singular Value Decomposition(SVD) and Empirical Mode Decomposition(EMD) is proposed for solving this problem. Aiming at bearing fault signal characteristics, SVD preprocesses sampled signals to denoise. Then preprocessed signals are analyzed by EMD. Fault characteristic frequency can be obtained by spectrum analysis for Intrinsic Mode Functions(IMFs). This method is useful to detect fault of bearings and a comparison is made between it and EMD. The results show that this scheme can diagnose fault correctly under strong noise.
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Sahto, Muhammad Punhal, Wei Wang, Ali Nawaz Sanjrani, Chengxu Hao i Sadiq Ali Shah. "Dynamic Performance of Partially Orifice Porous Aerostatic Thrust Bearing". Micromachines 12, nr 8 (20.08.2021): 989. http://dx.doi.org/10.3390/mi12080989.
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The aerostatic thrust bearing’s performance under vibration brings certain changes in stiffness and stability, especially in the range of 100 to 10,000 Hz, and it is accompanied by significant increase in fluctuations due to the changes in frequency, and the size of the gas film damping. In this research work, an analysis is carried out to evaluate the impact of throttling characteristics of small size orifice on stiffness and stability optimization of aerostatic thrust bearings. There are two types of thrust bearing orifices such as: partial porous multiple orifice and porous thrust bearings and their effects on variations in damping and dynamic stiffness are evaluated. A simulation based analysis is carried out with the help of the perturbation analysis model of an aerostatic thrust bearing simulation by using FLUENT software (CFD). Therefore, two models of aerostatic thrust bearings—one with the porous and other with partial porous orifice are developed—are simulated to evaluate the effects of perturbation frequencies on the damping and dynamic stiffness. The results reveal a decrease in the amplitude of dynamics capacity with an increase in its frequency, as well as a decrease in the damping of partial porous aerostatic thrust bearings with an increase in the number of orifices. It also reveals an increase in the radius of an orifice with an increment of damping of bearing at the same perturbation frequency and, with an increase in orifice height, a corresponding decrease in the damping characteristics of bearings and in the dynamic stiffness and coefficient of damping of bearing film in the frequency range less than 100 Hz.
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Matlapudi, Janardhan Chander, Prudhvi Kanth Gunti, Datta Sriram Sigatapu i Niranjana Behera. "Evaluation of static and dynamic characteristics of hydrodynamic spiral-grooved journal bearings using the CFD". Engineering review 39, nr 2 (2019): 197–204. http://dx.doi.org/10.30765/er.39.2.9.
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Performance of plain journal bearings can be different by inserting inserting grooves of different cross-sections either on the journal or a bearing surface. This paper presents the prediction of load carrying capacity, stiffness, and damping coefficients of spiral-grooved bearing using the Computational Fluid dynamics (CFD) technique. The spiral grooves have been provided on the rotor surface. The error between the predicted values of these parameters using the CFD and the experimental value is low. A comparative analysis of performance has also been carried out between a grooved journal bearing and a plain journal bearing. The load carrying capacity of plain journal bearing is high when compared to spiral grooved journal bearing. At higher eccentrcity ratios, stability of a spiral-grooved journal bearing is comparatively better than a plain bearing.
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Yan, Ruzhong, Liaoyuan Wang i Shengze Wang. "Investigating the influences of pressure-equalizing grooves on characteristics of aerostatic bearings based on CFD". Industrial Lubrication and Tribology 71, nr 7 (9.09.2019): 853–60. http://dx.doi.org/10.1108/ilt-11-2018-0411.
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Purpose The purpose of this study is to reveal the influence law of pressure-equalizing grooves on aerostatic bearings and improve the static performance of bearings by optimizing the distribution form of grooves. Design/methodology/approach In view of two kinds of common restrictor distribution forms on the thrust surface, the linear and the rectangular, six kinds of pressure-equalizing groove schemes were proposed – the line-shape, the extended-shape, the S-shape, the oblong-shape, the X-shape and the reticular-shape. Based on the analysis of lubrication theory of the orifice-type aerostatic bearing, the numerical simulations of different bearings were carried out. The pressure distributions and static characteristic curves of different bearings were obtained. Findings The study reveals that the adoption of the pressure-equalizing grooves can substantially improve the load capacity and static stiffness of the bearing and make the bearing maintain a uniform stress, which enhances operating accuracy and life of the bearing. The superior function of the reticular-shape groove is highlighted. Originality/value The research results can effectively guide the optimization design of aerostatic bearings and provide a crucial technical reference for application of ultra-precision aerostatic supporting system.
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Chetti, B. "Elastohydrodynamic Analysis of an Offset Journal Bearing Lubricated with Couple Stress Fluid". International Journal of Engineering Research in Africa 2 (czerwiec 2010): 53–62. http://dx.doi.org/10.4028/www.scientific.net/jera.2.53.
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This work is an investigation of the performance characteristics of an offset journal bearing lubricated with a fluid with couple stresses taking into consideration the elastic deformation of the liner. The couple stresses might be expected to appear in noticeable magnitudes in liquids containing additives with large molecules. The modified Reynolds equation has been solved using the finite difference method. Load carrying capacity, attitude angle, side leakage and friction coefficients are determined for various values of couple stress parameter of a rigid and deformable bearing. It is found that, the static characteristics of journal bearings lubricated with couple stress fluids are improved compared to journal bearings lubricated with Newtonian fluids. It is concluded that, the elastic deformation of the bearing has significant influence on the bearing characteristics.
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Jia, Chenhui, Huanji Pang, Wensuo Ma i Ming Qiu. "Analysis of dynamic characteristics and stability prediction of gas bearings". Industrial Lubrication and Tribology 69, nr 2 (13.03.2017): 123–30. http://dx.doi.org/10.1108/ilt-09-2015-0134.
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Purpose The prediction model to estimate the stability of a rotor-bearing system is established, which can predict the stability of gas bearings by applying Routh–Hurwitz stability criterion. This paper aims to provide the theoretical foundation for controlling actively the bearing running stiffness and damping and stemming the instability of a gas film. Design/methodology/approach The nonlinear dynamic lubrication analysis mathematical model of spherical hybrid gas bearings is established. Perturbation control equation is derived by the partial derivative method. The finite difference method is used to discrete the perturbation control equation in generalized coordinate system, and the difference expression of perturbation pressure is derived. The relational expression which involves the relationship between the dynamic characteristic coefficients of HSGHGB systems and perturbation pressure is deduced. So, the transient perturbation pressure distribution of a three-dimensional micro gas film, nonlinear gas film force, dynamic stiffness and dynamic damping coefficients of bearings are numerically computed using VC++6.0 programs. Findings The results show that the influence of supply pressure, speed and eccentricity on the dynamic characteristics of bearings is significant. Originality/value The influence law of supply pressure, speed and eccentricity ratio on the dynamic stiffness and damping coefficients of HSGHGB systems is researched. The prediction model to estimate the stability of rotor-bearing system is established, which can predict the stability of gas bearings by applying the Routh–Hurwitz stability criterion.
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Guo, Tie Neng, Ya Hui Cui i Li Gang Cai. "A General Method for the Modeling of Bearing Systems". Advanced Materials Research 721 (lipiec 2013): 402–8. http://dx.doi.org/10.4028/www.scientific.net/amr.721.402.
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Based on force analysis of angular contact ball bearings, this paper proposes a generic mathematical modeling method. This paper conducts in-depth research for these aspects: all directions of the stiffness characteristics under different load conditions of angular contact ball bearings, internal contact deformation and the change of bearing parameters. This article eventually gets the variation of the bearing characteristics under different load conditions.
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Wu, Zheng-Hai, Ying-Qiang Xu i Si-Er Deng. "Analysis of Dynamic Characteristics of Grease-Lubricated Tapered Roller Bearings". Shock and Vibration 2018 (13.11.2018): 1–17. http://dx.doi.org/10.1155/2018/7183042.
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Tapered roller bearings (TRBs) are applied extensively in the field of high-speed trains, machine tools, automobiles, etc. The motion prediction of main components of TRBs under grease lubrication will be beneficial to the design of bearings and the selection of lubricating grease. In this study, considering the dynamic contact relationship among the cage, rollers, and raceways, a multibody contact dynamic model of the TRB was established based on the geometric interaction models and grease lubrication theories. The impacts of load, grease rheological properties, and temperature on the roller tilt and skew and the bearing slip were simulated by using the fourth-order Runge–Kutta method. The results show that the roller tilt angle in the unloaded zone is obviously larger than that in the loaded zone, while the roller skew angle in the unloaded zone is smaller than that in the loaded zone. As the speed increases, the roller tilt and skew and the bearing slip become more serious. Bearing preload can effectively reduce the bearing slip but will make the roller tilt and skew angle increase. The roller skew angle and the bearing slip decrease with the increase of the grease plastic viscosity. The roller tilt angle increases with the increase of the plastic viscosity. The yield stress of the grease has little effect on motions of the roller and cage. The influence of temperature on the roller and cage motions varies with the type of grease used.
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MAYOROV, S. V., A. V. GORIN, I. V. RODICHEVA i I. G. USIKOVA. "INFLUENCE OF MACRO AND MICRO DEFLECTIONS ON LOADING CAPACITY, FLOW RATE AND ENERGY CHARACTERISTICS OF FLUID FRICTION BEARINGS". Fundamental and Applied Problems of Engineering and Technology 6 (2020): 106–13. http://dx.doi.org/10.33979/2073-7408-2020-344-6-106-113.
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The influence of technological deviations on the performance of fluid friction bearings is considered. A mathematical model of a hydrodynamic sliding bearing is presented, based on a joint numerical solution of the Reynolds equation and additional relations to take into account the microroughness of the bearing surfaces. Analysis of the numerical results made it possible to assess the effect of roughness on the bearing capacity, consumption and energy characteristics of fluid friction bearings.
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Choy, F. K., M. J. Braun i Y. Hu. "Nonlinear Transient and Frequency Response Analysis of a Hydrodynamic Journal Bearing". Journal of Tribology 114, nr 3 (1.07.1992): 448–54. http://dx.doi.org/10.1115/1.2920904.
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The traditional approach is to characterize the behavior and performance of fluid film hydrodynamic journal bearings by means of linearized bearing analysis. The objective of this paper is to examine the nonlinear characteristics of the said journal bearing. Results based on bearing stiffness characteristics, steady and transient vibration orbits, and frequency response functions obtained from both linear and nonlinear bearing simulations are compared with each other. Conclusions are drawn from the results obtained from a prototypical bearing configuration used as an example in this analysis.