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1
Dewrance, John. "MACHINERY BEARINGS". Journal of the American Society for Naval Engineers 9, n. 1 (18 marzo 2009): 104–17. http://dx.doi.org/10.1111/j.1559-3584.1897.tb00708.x.
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Ying, Feili, e Xu Jie. "Automatic Fault Detection Method of Rotating Machinery Bearing Based on Complexity Analysis". Journal of Physics: Conference Series 2717, n. 1 (1 marzo 2024): 012030. http://dx.doi.org/10.1088/1742-6596/2717/1/012030.
Testo completoAbstract (sommario):
Abstract In order to improve the working condition stability of rotating machinery bearings, an automatic fault detection method of rotating machinery bearings based on complexity analysis is proposed. The parameters of rotating machinery bearings are detected by using discrete sensor detection method, and the fault characteristics of rotating machinery bearings are extracted by fault type parameter extraction method. The complexity of rotating machinery bearings is detected by wavelet transform and fuzzy logic analysis. Considering the load mutation, noise disturbance, control strategy and other factors of rotating machinery bearings, the fault diagnosis and feature analysis model of rotating machinery bearings is established. The clustering and feature detection of rotating machinery bearings’ fault types are realized by the method of discrete complexity fusion clustering. Based on adaptive feedback compensation and parameter estimation, the output diagnostic error is taken as the fault detection index parameter, and the feature estimation in normal state and fault state is realized by harmonic level detection, so as to realize automatic fault detection of rotating machinery bearings. The simulation results show that this method has high accuracy and small deviation in fault detection of rotating machinery bearings, which improves the ability of automatic fault diagnosis.
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Vekteris, Vladas, Andrius Trumpa, Vytautas Turla, Vadim Mokšin, Gintas Viselga e Eugenijus Jurkonis. "Diagnosing faults in rolling-element bearings of rotor systems equipped with vibration dampers". Advances in Mechanical Engineering 12, n. 4 (aprile 2020): 168781402091541. http://dx.doi.org/10.1177/1687814020915417.
Testo completoAbstract (sommario):
This article considers problems arising from conventional techniques used to diagnose faults in the rolling-element bearings of rotor-bearing systems, with dampers used in centrifugal milk processing machinery. Such machines include milk separators and related processing machinery. The article asserts that where the rotor-bearing system is equipped with vibration dampers, conventional fault diagnostic measurements produce inadequate results. Hence, for rotor-bearing systems of this type, this article suggests a different way to diagnose faults in bearings and monitor conditions.
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Hou, Yu, Qi Zhao, Yu Guo, Xionghao Ren, Tianwei Lai e Shuangtao Chen. "Application of Gas Foil Bearings in China". Applied Sciences 11, n. 13 (5 luglio 2021): 6210. http://dx.doi.org/10.3390/app11136210.
Testo completoAbstract (sommario):
Gas foil bearing has been widely used in high-speed turbo machinery due to its oil-free, wide temperature range, low cost, high adaptability, high stability and environmental friendliness. In this paper, state-of-the-art investigations of gas foil bearings are reviewed, mainly on the development of the high-speed turbo machinery in China. After decades of development, progress has been achieved in the field of gas foil bearing in China. Small-scale applications of gas foil bearing have been realized in a variety of high-speed turbo machinery. The prospects and markets of high-speed turbo machinery are very broad. Various high-speed turbomachines with gas foil bearings have been developed. Due to the different application occasions, higher reliability requirements are imposed on the foil bearing technology. Therefore, its design principle, theory, and manufacturing technology should be adaptive to new application occasions before mass production. Thus, there are still a number of inherent challenges that must be addressed, for example, thermal management, rotor-dynamic stability and wear-resistant coatings.
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Goodwin, M. J., P. J. Ogrodnik, M. P. Roach, L. K. Lim e Y. Fang. "Steady Load-Carrying Capacity of Recessed Hydrodynamic Bearings". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, n. 4 (dicembre 1995): 255–62. http://dx.doi.org/10.1243/pime_proc_1995_209_436_02.
Testo completoAbstract (sommario):
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.
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Tóth, Dániel. "Investigation of Bearing Failures Using Vibration Analysis". Design of Machines and Structures 12, n. 2 (2022): 126–32. http://dx.doi.org/10.32972/dms.2022.022.
Testo completoAbstract (sommario):
Bearings are important components of most machinery and their working conditions influence the operation of the entire machinery. Even if bearings are being used under excellent conditions, sooner or later material fatigue will occur. Besides other things poor operating environment contaminated or peculiarly moist areas and improper handling practices cause premature failures. This article focuses on vibration analysis methods for detecting bearing failures and presents a special lifetime test procedure.
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Manjunatha, G., e H. C. Chittappa. "Bearing Fault Classification using Empirical Mode Decomposition and Machine Learning Approach". Journal of Mines, Metals and Fuels 70, n. 4 (20 giugno 2022): 214. http://dx.doi.org/10.18311/jmmf/2022/30060.
Testo completoAbstract (sommario):
Industrial machinery often breakdowns due to faults in rolling bearing. Bearing diagnosis plays a vital role in condition monitoring of machinery. Operating conditions and working environment of bearings make them prone to single or multiple faults. In this research, signals from both healthy and faulty bearings are extracted and decomposed into empirical modes. By analyzing different empirical modes from 8 derived empirical modes for healthy and faulty bearings under different fault sizes, the first mode has the most information to classify bearing condition. From the first empirical mode eight features in time domain were calculated for various bearing conditions like healthy, rolling element fault, outer and inner race fault. The feature extraction of vibration signal based on Empirical Mode Decomposition (EMD) is extensively explored and applied in diagnosis of fault in rolling bearings. This paper presents mathematical analysis for selection of valid Intrinsic Mode Functions (IMFs) of EMD. These chosen features are trained and classified using different classifiers. Among them K-star classifier is most reliable to categorize the bearing defects.
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Koike, Hitonobu, Takashi Honda, Katsuyuki Kida, Edson Costa Santos, Justyna Rozwadowska, K. Houri, M. Uryu, Yuji Kashima e Kenji Kanemasu. "Influence of Radial Load on PEEK Plastic Bearings Life Cycle under Water Lubricated Conditions". Advanced Materials Research 217-218 (marzo 2011): 1260–65. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1260.
Testo completoAbstract (sommario):
Radial ball bearings made of metal, ceramics and plastics are commonly used as important components in industrial machinery. Usage of high performance engineering plastic polymers is increasing progressively as a replacement for metal components due to the latest markets demands. Poly-ether-ether-ketone (PEEK) is a promising material for precision-machined custom bearings, products that are expected to suit special market needs. In the present study, PEEK radial ball bearings were manufactured by lathe machining under different parameters and their rolling contact fatigue (RCF) resistance under water lubricated conditions was investigated. We observed the surface of the bearings prior and after testing by laser confocal microscope. The wear loss was measured by weighing the bearings before and after test. Cracks and/or flaking failures were identified on the bearing surface after testing. From the RCF tests results, we found that, at water lubricated conditions, crack initiation occurred later in the material that was machined at slower feed rate while at dry condition, the feed rate had little influence on the wear loss and cracking. Wear loss in the case of bearings tested under water was much less severe than that of bearings tested at dry conditions.
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Ravikumar, R. N., K. J. Rathanraj e V. Arun Kumar. "Experimental Studies on Air Foil Thrust Bearing Load Capabilities Considering the Effect of Foil Configuration". Applied Mechanics and Materials 813-814 (novembre 2015): 1007–11. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.1007.
Testo completoAbstract (sommario):
Abstract. Foil bearings are self-acting hydrodynamics bearings used to support lightly loaded high speed rotating machinery. The advantages that they offer to process fluid lubricated machines usingworking fluid as a lubricant (ambient air) physically non-contacting high speed operation. Foil bearings have been considered as an alternative to conventional bearings with the capacity to cater for high-speeds and hostile environment (high temperature). However, the lack of load carrying capacity at relatively lower speeds limits their applications in heavy turbo machinery and as such are highly suitable in lightly loaded, high speed turbo machinery like small gas turbines.This paper discusses the design and assessment of dynamic characteristics in terms of load carrying capabilities as a function of speed, gap between the bearing and the runner as well as shape of foils for an air foil thrust bearing. The effects of various bearing parameters like foil thickness, number of foils fixed circumferentially and along the axis of rotation and with foil geometry configuration. Characteristics of performance defined essentially in terms of load carrying capabilities and static stiffness have been used for evaluation. Experiments were conducted both for angular foils (with inner edge height less than outer edge height) and square foils by varying number of foils. The experimental results shows that the effect of foil configuration enhances the load carrying capabilities of air foil thrust bearing.
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Bhatti, Saima, Asif Ali Shaikh, Asif Mansoor e Murtaza Hussain. "New Approaches of Stochastic Models to Examine the Vibration Features in Roller Bearings". Applied Sciences 14, n. 4 (17 febbraio 2024): 1616. http://dx.doi.org/10.3390/app14041616.
Testo completoAbstract (sommario):
Machinery components undergo wear and tear over time due to regular usage, necessitating the establishment of a robust prognosis framework to enhance machinery health and avert catastrophic failures. This study focuses on the collection and analysis of vibration data obtained from roller bearings experiencing various fault conditions. By employing a combination of techniques sourced from existing literature, distinct configurations within vibration datasets were examined to pinpoint the primary defects in roller bearings. The significant features identified through this analysis were utilized to formulate optimized stochastic model equations. These models, developed separately for inner and outer race fault features in comparison to healthy bearing features under random conditions, offer valuable insights into machinery prognosis. The application of these models aids in effective maintenance management, optimization of machinery performance, and the minimization of catastrophic failures and downtime, thereby contributing to overall machinery reliability.
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Polyakov, Roman, Leonid Savin e Denis Shutin. "Reliability Improvement of Rotor Supports by Combining Rolling-Element Bearings and Fluid-Film Bearings". Applied Mechanics and Materials 630 (settembre 2014): 188–98. http://dx.doi.org/10.4028/www.scientific.net/amm.630.188.
Testo completoAbstract (sommario):
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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Imlach, J., B. J. Blair e P. E. Allaire. "Measured and Predicted Force and Stiffness Characteristics of Industrial Magnetic Bearings". Journal of Tribology 113, n. 4 (1 ottobre 1991): 784–88. http://dx.doi.org/10.1115/1.2920693.
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Closed-loop stiffness and load capacity (force) equations have been developed for industrial magnetic bearings. Two sets of magnetic bearings have been constructed using these equations as a design basis. These bearings have been installed in two canned motor pumps. The predicted force and stiffness values from the equations are compared to experimental measurements to determine their validity. When obvious sources of error were eliminated, agreement within 10 percent was obtained for development pump’s magnetic bearings. Agreement was generally better for this pump than for the demonstration pump. By employing these equations, along with easily measured current and displacement information from magnetic bearing equipped machinery, actual stiffness’ and bearing loadings can be determined for operating equipment. Thus, the range of information available from magnetic bearings is extended to include static and dynamic loadings as well as shaft orbits and critical speed and damping information (Humphris et al., 1989). This enhances their use as diagnostic and preventative maintenance tools which are built into machinery and can be used on line.
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ŻYWICA, Grzegorz, Małgorzata BOGULICZ e Paweł BAGIŃSKI. "MODELLING AND ANALYSIS OF ROTATING SYSTEMS WITH GAS FOIL BEARINGS UNDER TRANSIENT OPERATING CONDITIONS". Tribologia 272, n. 2 (30 aprile 2018): 167–73. http://dx.doi.org/10.5604/01.3001.0010.6345.
Testo completoAbstract (sommario):
Gas foil bearings are on the cutting edge of bearing systems that spread worldwide. Although it is a common practice to apply such systems to high-speed fluid-flow machinery, their modelling and analysis still pose a number of problems. This article describes the methodology used to assess dynamic properties of a rotor-bearings system supported by foil bearings. Particularly close attention has been paid to the system operation in a transitional state during which a gaseous lubricating film is formed. The conception for the description of the rotor support characteristics was implemented in a computer program that is still under development. The approach that has been taken makes it possible to analyse the system properties throughout a whole range of rotational speeds. Another approach used in the past enabled for analyses of the dynamic performance of rotors, but only on the condition that bearing operation is correct (i.e. only fluid friction in bearing is present). The new model allows for much broader analyses of bearings operation, as confirmed by the obtained results. The article discusses exemplary results of analyses and shows a way one can assess the dynamic properties of rotating machinery equipped with foil bearings even when analysed under transient operating conditions.
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Ramos, Leandro Ito, Douglas Jhon Ramos e Gregory Bregion Daniel. "Evaluation of textured journal bearings under dynamic operating conditions in rotating machinery". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, n. 6 (5 novembre 2019): 842–57. http://dx.doi.org/10.1177/1350650119887568.
Testo completoAbstract (sommario):
In order to obtain rotating machinery with improved energy efficiency, the approach of surface texturing journal bearings has been adopted to reduce the viscous dissipation in the lubricant. A possible reduction in shear viscous forces in the bearings of rotating machines could reduce the amount of heat released along its operation, resulting in a lower operating temperature that tends to improve journal bearings performance and the machine’s energetic efficiency. Thus, this work aims to investigate the texturing of journal bearings under dynamic loading conditions, considering the application in rotating systems. For this, computational simulations are performed through a rotating system model constructed by means of the finite element method in which the hydrodynamic journal bearings that support the rotor are modeled by Reynolds’ equation using the finite volume method and the full multigrid technique. The numerical results show that textured journal bearings can be applied to rotating machines, providing reductions in shear viscous forces. However, the magnitude of this reduction should be carefully evaluated, as the Reynolds cavitation model was applied to ensure a lower computational spent time and thus enable the simulations involved in this study. The novelty of this study is related to determining the appropriate distributions and geometric parameters of the textures for the journal bearing under dynamic load condition considering its equivalent static load condition what tends to drastically reduce computational time to perform this procedure, representing an important alternative for industrial application.
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Gaikwad, Prof Jitendra, Vinit Mundhada, Hrucha Nagre e Hrutvij Patil. "Bearing Fault Detection using Vibration Analysis". International Journal for Research in Applied Science and Engineering Technology 12, n. 5 (31 maggio 2024): 4644–53. http://dx.doi.org/10.22214/ijraset.2024.62569.
Testo completoAbstract (sommario):
Abstract: In the current scenario, condition monitoring is an essential technique for the maintenance of machinery. Various methods such as vibration analysis, temperature analysis, and wear and debris analysis have been introduced, with vibration analysis proving to be the most effective for detecting machine faults. This study focuses on bearing fault detection using vibration analysis. Bearing faults generate impact forces that alter vibration patterns. We examined the vibration patterns of a 0.25HP PMDC motor under different load conditions and at varying RPMs, comparing good and faulty bearings to detect inner and outer race bearing faults. Inner race defect detection is challenging under poor signal-to-noise ratio (SNR) conditions due to the vibration signal being masked by other vibrations. To enhance SNR, Principal Component Analysis (PCA) was utilized, and Artificial Neural Networks (ANN) algorithms were employed. Rotating machinery, widely used in industries such as petroleum, automotive, HVAC, and food processing, relies on bearings for rotational or linear movement, reducing friction and stress. Rolling Element Bearings (REBs) offer a favorable balance of friction, lifetime, stiffness, speed, and cost. Thus, real-time monitoring and diagnosis of bearings are critical to prevent failures, enhance safety, avoid unforeseen production downtime, and reduce costs. This study proposes an approach based on Wavelet Transform and ANN to analyze vibration signals from rolling element bearings and to identify and classify component defects.
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Guo, Caiping. "Optimal Design of Sliding Bearings Based on Artificial Intelligence Algorithm and CFD Simulation". Wireless Communications and Mobile Computing 2022 (12 aprile 2022): 1–11. http://dx.doi.org/10.1155/2022/5448332.
Testo completoAbstract (sommario):
Sliding bearings have a long history, simple manufacturing, and low cost. However, the function of sliding bearings is very large. As a key component of rotating machinery, thrust sliding bearing is directly related to the overall performance of the machine. The machines that can be seen in life, whether simple or complicated, have been used. However, with the development of science and technology and economy, all kinds of new things have been inoculated. One of the current issues is how sliding bearings can continue to keep machinery stable. CFD is the abbreviation of English computational fluid dynamics (computational fluid dynamics). It is developed with the development of computer technology and numerical computing technology. Simply put that CFD is equivalent to “virtually” doing experiments on the computer to simulate the actual fluid flow. The purpose of this article is to study the optimal design of sliding bearings by artificial intelligence algorithms and CFD simulation. This paper uses intelligent design methods to optimize the appearance, shape, and manufacturing process of sliding bearings and to carry the bearing capacity, friction coefficient and temperature rise of sliding bearings. Comprehensive research then establishes the objective function. The finite element algorithm, genetic algorithm, and matrix theory are used to calculate the stability of the sliding bearing under various conditions. The artificial intelligence algorithm is used to sort the calculated data. The CFD simulation is used to obtain the most reasonable result. Algorithm, as well as the appearance, shaft diameter, and material of the plain bearing, maintains stability under various conditions. The experimental data show that the classification using artificial intelligence algorithms and CFD simulation can significantly improve the performance of sliding bearings. It is found that the relationship between the sliding bearings is related to the speed, the diameter of the bearing, and other factors. Experimental data show that artificial intelligence algorithms and CFD simulation can provide reliable data references for the optimal design of sliding bearings, and the optimized sliding bearings can meet the stability under relevant conditions.
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Kirk, R. G. "Evaluation of AMB Turbomachinery Auxiliary Bearings". Journal of Vibration and Acoustics 121, n. 2 (1 aprile 1999): 156–61. http://dx.doi.org/10.1115/1.2893958.
Testo completoAbstract (sommario):
The use of active magnetic bearings (AMB) for turbomachinery has experienced substantial growth during the past two decades. The advantages for many applications make AMB’s a very attractive solution for potentially low loss and efficient support for both radial and thrust loads. New machinery must be shop tested prior to shipment to the field for installation on-line. For AMB turbomachinery, one additional test is the operation of the auxiliary drop or overload bearings. A major concern is ability of the selected auxiliary bearing to withstand the contact forces following an at speed rotor drop. The proper design of AMB machinery requires the calculation of the anticipated loading for the auxiliary bearings. Analytical techniques to predict the rotor transient response are reviewed. Results of transient response evaluation of a full-size compressor rotor are presented to illustrate some of the important parameters in the design for rotor drop.
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Srinivasan, S., E. H. Maslen e L. E. Barrett. "Optimization of Bearing Locations for Rotor Systems With Magnetic Bearings". Journal of Engineering for Gas Turbines and Power 119, n. 2 (1 aprile 1997): 464–68. http://dx.doi.org/10.1115/1.2815597.
Testo completoAbstract (sommario):
This paper presents a method for quickly evaluating the effect of changes in bearing location on bearing design for stability of rotating machinery. This method is intended for use by rotating machinery designers to select the “best” bearing locations prior to the bearing design process. The purpose of the method is to improve the design process by separating the problem of determining the “best” bearing locations from that of determining the actual bearing design. The method is independent of the type of bearing employed. For each candidate bearing configuration, the method provides a scalar measure of the relative ability of bearings to meet stability specifications. Within certain limits, the stability specifications are defined by the designer. The scalar measure is used to rank the candidate bearing locations and thereby select the best one. The scalar measure is compared to a practical measure of magnetic bearing design such as the infinity norm of the controller for an example design of a multistage centrifugal compressor.
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Deng, Linfeng, Aihua Zhang e Rongzhen Zhao. "Intelligent identification of incipient rolling bearing faults based on VMD and PCA-SVM". Advances in Mechanical Engineering 14, n. 1 (gennaio 2022): 168781402110729. http://dx.doi.org/10.1177/16878140211072990.
Testo completoAbstract (sommario):
Rolling bearings are the key components of rotating machinery. Incipient fault diagnosis of bearing plays an increasingly important role in guaranteeing normal and safe operation of rotating machinery. However, because of the high complexity of the fault feature extraction, the incipient faults of rolling bearings are difficult to diagnose. To solve this problem, this paper presents a new incipient fault intelligent identification method of rolling bearings based on variational mode decomposition (VMD), principal component analysis (PCA), and support vector machines (SVM). In the proposed method, the bearing vibration signals are decomposed by using VMD, and a series of intrinsic mode functions (IMFs) with different frequencies are obtained. Then, the energy and kurtosis values of each IMF are calculated to reveal the intrinsic characteristics of the vibration signals in different scales. Finally, all energy and kurtosis values of IMFs are processed via PCA and subsequently fed into SVM to achieve the bearing fault identification automatically. The effectiveness of this method is verified through the experimental bearing data. The verification results indicate that the proposed method can effectively extract the bearing fault features and accurately identify the bearing incipient faults, and outperform the two compared methods obviously in identification accuracy and computation time.
20
Tulupov, Viktor D., Mikhail A. Sleptsov e Aleksandrs A. Briedis. "Ways to Improve the Reliability of Bearings in Traction Induction Machines". Vestnik MEI 2, n. 2 (2021): 60–70. http://dx.doi.org/10.24160/1993-6982-2021-2-60-70.
Testo completoAbstract (sommario):
The problem of electric rolling stock traction machinery failures caused by electrical erosion of bearings is addressed. Damages inflicted to traction machinery bearings as a result of electric current flowing through them have been known since long ago. In recent time, however, damages of this kind have become more frequent, because frequency and voltage converters for control of three-phase inductor motors are widely used in the electric rolling stock. An overview of factors causing the occurrence of stray currents generated in frequency converter driven traction motors and sources of these currents is presented. Electric current flows through rolling bearings in the area of the contact between the rolling elements with inner and outer rings, thus causing damage to the bearing metal components' rolling surfaces and degrading the quality of lubricants. To study and analyze the currents through bearings, the stray capacitances existing in traction machines are determined, and their calculation methods are defined, the necessity of which is stemming from the fact that these capacitances influence the generation of parasitic currents. The stray capacitances in traction machines include the capacitance between the stator windings and the stator core pack, the capacitance between the stator windings and the rotor, the capacitance between the rotor and the stator core pack, and the capacitances of the bearings. From the electrical point of view, bearings may also be regarded as capacitances. As long as there is a continuous lubricant film between the inner ring and outer rings and the rolling elements, the bearings behave as capacitors. A difference of potentials across the bearing elements may lead to electrostatic discharges and, hence, to discharge currents through the bearings. One of possible ways to enhance the reliability of traction machine bearing units is to use insulated bearings. The change in the impedance of bearings with ceramic coating and hybrid rolling elements depending on the applied voltage frequency and operating temperature is calculated and analyzed. Conclusions regarding the expediency of using hybrid bearings having rings made of bearing steel and rolling elements made of bearing silicon nitride (Si3N4) are drawn.
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Liu, Yuan, Yaguang Jin, Gaoyu Cui e Gongtian Shen. "Study and Application on the Early Damage Signal Characteristics of Ultra-Low-Speed and Heavy-Load Rolling Bearings of Large Amusement Machinery". Insight - Non-Destructive Testing and Condition Monitoring 65, n. 5 (1 maggio 2023): 270–77. http://dx.doi.org/10.1784/insi.2023.65.5.270.
Testo completoAbstract (sommario):
Ultra-low-speed and heavy-load bearings are widely used in large amusement machinery. Their breakdown results in great economic losses and possibly even personal injuries. Using their damage signal characteristics to quickly identify early damage is an effective means of preventing accidents. In this study, to determine the early damage signal characteristics of the ultra-low-speed and heavy-load slewing mechanism, a typical ultra-low-speed and heavy-load bearing rotation experimental platform and signal testing system are designed and built, so as to simulate the operation of the rolling bearings of large amusement machinery with ultra-low speed and heavy load. Next, by constructing different bearing damage sizes and operating conditions, the vibration signal characteristics of different degrees of crack damage are analysed, along with the signal variation law of the same damage under different operating conditions. The effectiveness and practicability of this method are verified through the application analysis of a slewing bearing of a typical piece of large amusement machinery. The results of this study provide a reference for quickly identifying early damage in similar equipment and determining the damage state.
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Lai, Tianwei, Yu Guo, Wei Wang, Yu Wang e Yu Hou. "Development and Application of Integrated Aerodynamic Protuberant Foil Journal and Thrust Bearing in Turboexpander". International Journal of Rotating Machinery 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/8430943.
Testo completoAbstract (sommario):
Foil bearing provides compliant support and moderate Coulomb friction for rotor-bearing system, which is conducive to stability and reliability of high speed rotating machinery. In this paper, both hydrodynamic lubricated foil journal and foil thrust bearings are applied in a 150 m3·h−1 turboexpander for air separation. In the bearings, protuberant foil is chosen as the supporting subfoil due to its merits of easy fabrication and assembly. Static loading and deflection of the bearings are tested, respectively, before integration into the turboexpander. Afterwards, the loading and deflection curves of the journal and thrust bearings are polynomial fitted using least-square method. Then, performance tests are carried out on the rotor-bearing system, including transient speed-up, high speed, and speed-down processes. In the tests, the turboexpander supported by the hydrodynamic foil bearings operates smoothly with repeatability. Maximal rotor speed of the turboexpander reaches 52000 rpm with hydrodynamic lubricated protuberant foil bearings.
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Rutuja Mane e Abhinandan Admuthe. "Design and Development of Experimental Test Rig for Fault Diagnosis of Ball Bearing Using Fuzzy Logic Concept". International Journal of Engineering and Management Research 13, n. 4 (31 agosto 2023): 158–63. http://dx.doi.org/10.31033/ijemr.13.4.20.
Testo completoAbstract (sommario):
Rolling element bearings are frequently employed in industry. Many machine-related issues are linked to bearing failures. To minimize downtime and preserve product quality in a highly automated production, an online detection system is required. Condition-based monitoring for deep groove ball bearings is becoming more common. All rotating machinery uses these bearings extensively to accommodate both static and dynamic loads. Techniques for condition-based monitoring can be utilized to diagnose bearing defects to prevent this failure. So, it is important to study these faults present in the machines. The techniques for fault detection will be described in this paper. We are discussing Fast Fourier Transform (FFT) technique. In FFT, we obtain frequency-relationship graphs, and based on peak frequencies, we predict faults. A detailed analysis using the FFT Methodology is done to find out the possible faults, and finally validate with MATLAB software. For the aim of bearing diagnostics, the system performs vibration analysis. More advanced diagnostic systems use fuzzy logic and classification methods to identify the state of the machinery. These techniques enable the creation of more automatic and trustworthy diagnostic systems.
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Su, Zhimin, Jianbo Zhang, Yimou Cai e Dongjiang Han. "Experimental Research on Dynamic Characteristics of a Multi-Disc Rotor System Supported by Aerostatic Bearings". Lubricants 12, n. 5 (27 aprile 2024): 151. http://dx.doi.org/10.3390/lubricants12050151.
Testo completoAbstract (sommario):
Gas bearings have the advantages of small friction loss, wide applicable speed range, no pollution, etc., and have important application prospects in micro and small high-speed rotating machinery. However, due to its compressibility and low viscosity, its dynamic stability in high-speed rotating machinery is the key to constraining its development. The experimental study of shaft system dynamics is the main means to explore the mechanism of rotor behavior. On the test platform of dynamic characteristics of multi-disc rotor system supported by aerostatic bearings, experimental research on the nonlinear dynamic characteristics of a rotor system was carried out, and nonlinear vibration test and analysis methods, such as axial orbits, bifurcation diagrams, and spectral characteristics, were adopted, and vibration phenomena, including the critical rotational speed accumulating energy and low-frequency accumulating energy, were presented and the vibration characteristics of bearing fracture faults were presented. The bearing supply pressure and rubber damping pad were introduced as a method to suppress the low-frequency vibration of the aerostatic bearing rotor system, and its vibration-reduction effect was verified by experiments. The above results can provide technical support for vibration control and fault diagnosis of rotor systems supported by aerostatic bearings.
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Zheng, Yuhuang. "Predicting Remaining Useful Life Based on Hilbert–Huang Entropy with Degradation Model". Journal of Electrical and Computer Engineering 2019 (3 febbraio 2019): 1–11. http://dx.doi.org/10.1155/2019/3203959.
Testo completoAbstract (sommario):
Prognostics health management (PHM) of rotating machinery has become an important process for increasing reliability and reducing machine malfunctions in industry. Bearings are one of the most important equipment parts and are also one of the most common failure points. To assess the degradation of a machine, this paper presents a bearing remaining useful life (RUL) prediction method. The method relies on a novel health indicator and a linear degradation model to predict bearing RUL. The health indicator is extracted by using Hilbert–Huang entropy to process horizontal vibration signals obtained from bearings. We present a linear degradation model to estimate RUL using this health indicator. In the training phase, the degradation detection threshold and the failure threshold of this model are estimated by the distribution of 600 bootstrapped samples. These bootstrapped samples are taken from the six training sets. In the test phase, the health indicator and the model are used to estimate the bearing’s current health state and predict its RUL. This method is suitable for the degradation of bearings. The experimental results show that this method can effectively monitor bearing degradation and predict its RUL.
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Luo, Dong Song, e Zheng Fan. "Wavelet Algorithm in Rotating Machinery Fault Feature Extraction". Advanced Materials Research 823 (ottobre 2013): 451–55. http://dx.doi.org/10.4028/www.scientific.net/amr.823.451.
Testo completoAbstract (sommario):
A method of Rotating Machinery fault feature extraction based on wavelet transform and Hilbert demodulation is been studied. On the basis of rotating machinery fault mechanism and spectral characteristics, wavelet transform is used to be decompose the vibration acceleration signals of bearing faults into different frequency bands, Which is then used to achieve accurate fault information by Hilbert demodulation. The result shows the method can effectively improve the frequency resolution and realize accurate extraction of fault feature, and it has certain practical value for industrial production of rotating machinery faults diagnosis when applied to the production industry. Key words: Rotating Machinery; bearings; Wavelet algorithm; Hilbert demodulation
27
Qiang, Mingchen, Qi Zhao, Shaohang Yan, Xue Liu, Yu Hou e Tianwei Lai. "Performance Prediction of High-Speed Hydrogen Gas-Lubricated Herringbone Grooved Journal Bearing". Applied Sciences 12, n. 13 (24 giugno 2022): 6432. http://dx.doi.org/10.3390/app12136432.
Testo completoAbstract (sommario):
The liquefaction of hydrogen is considered to be a crucial process in the large-scale utilization of hydrogen energy. In hydrogen liquefaction, hydrogen turbo-expander is a key refrigerating machine for high liquefaction efficiency. Performance of the turbo-expander is directly affected by the hydrogen gas bearings. To obtain a deep understanding of the performance characteristics of hydrogen gas bearings, the static and dynamic characteristics of herringbone grooved journal bearings under hydrogen and other lubricating gases were numerically calculated and compared. The bearing load capacity and critical mass of hydrogen gas bearings were slightly lower than those of helium-, air- and nitrogen-lubricated bearings. To improve the performance of the hydrogen gas bearings used in high-speed turbo-machinery, the influence of working conditions was analyzed. It is found that the load capacity of hydrogen gas bearings can be improved by increasing the ambient pressure, reducing the gas film clearance, and raising the bearing eccentricity ratio. Meanwhile, the critical mass increases, and the bearing dynamic stability is enhanced.
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Polyakov, Roman, Leonid Savin e 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, n. 2 (21 maggio 2018): 271–80. http://dx.doi.org/10.1177/1350650118777143.
Testo completoAbstract (sommario):
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.
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Xu, Dong, Yong Cheng Xu, Xun Chen, Yong Min Yang e Xing Lin Li. "A Series of New Nonlinear Dynamic Equations of Rolling Element Bearing Systems". Advanced Materials Research 118-120 (giugno 2010): 896–901. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.896.
Testo completoAbstract (sommario):
As one of the key parts of rotating machinery, rolling bearing is the primary fault source, therefore it is urgent to research failure mechanism and its evolution process. First, the number of laden rollers of rolling bearings in different states without radial clearance and preload is summed up, and then nonlinear analytical equations and an additional equation are proposed. To some extent it will be helpful for researching the fault evolution process of rolling element bearings combined with fatigue theories. Further they will conduce to analyze and predict the remaining life of ball bearings.
30
Li, Peng, Min Wang, Xiao Li Qi, Jian You Feng, Xiao Hui Liu, Run Qiu Tang e Wen Ying Zhao. "Analysis of the Mechanical Properties of Slewing Bearings Using Finite Element Method". Applied Mechanics and Materials 224 (novembre 2012): 286–94. http://dx.doi.org/10.4028/www.scientific.net/amm.224.286.
Testo completoAbstract (sommario):
Slewing bearings are the basic structural components widely used in construction machinery industry. Their stress status and distribution have great influence on the service life. A finite element approach for a single-row slewing bearing is established based on the bilinear isotropic model. The stress status at different loading conditions is simulated with the bearing geometric and material parameters. The result shows that the numerical simulation is reasonable in comparison with the analytical result obtained by Hertz’s theory and provides reliable design guideline for slewing bearings.
31
Gogazeh, Muhammad Mustafa, Hasan Abdelrazzaq Al Dabbas e Nabil Wanas Musa. "Mathematical Model and Theoretical Investigation of the Performance of Journal Bearing using a discretized Reynolds Lubrication Equation with Finite Width". WSEAS TRANSACTIONS ON APPLIED AND THEORETICAL MECHANICS 18 (31 dicembre 2023): 327–35. http://dx.doi.org/10.37394/232011.2023.18.31.
Testo completoAbstract (sommario):
Hydrodynamic journal bearings are widely used for a large number of applications such as rotating turbo machinery, axial flow compressors, axial flow turbines, and internal combustion engines. These types of journals are used to support high loads high speed rotating turbo machinery elements mainly shafts and attached components and also for enhancing the quality of these machines. In this work, the importance of journal bearing and an overview of the Reynolds hydrodynamic equation in three dimensions have been studied using the Boundary Value finite-difference method. The second-order nonlinear partial differential equation has been solved using numerical iterations approach with MATLAB software. The numerical solution of the transient Reynolds equation has been studied to investigate the Pressure distribution, pressure gradient as well film lubricant thickness on journal bearings. A numerical solution using ANSYS FLUENT has been applied to investigate the main parameters that have the main influence on the performance of the journal bearing and bearing performance.
32
Ciupitu, Liviu, Andrei Tudor, Doru Turcan e Daniel Sandor. "Vibration Diagnosis of Electric Motor’s Bearings". Advanced Materials Research 463-464 (febbraio 2012): 1725–28. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.1725.
Testo completoAbstract (sommario):
Recently technologies like vibration monitoring or acoustic measurement help the maintenance to improve the OEE (overall equipment effectiveness) factor. For example SKF company uses for fault detection vibration and temperature sensors and vibration signal processing techniques that differentiate between normal machinery process vibrations and abnormal vibrations caused by machinery faults. The fault can be eliminated or monitored until maintenance and repairs can be organized in a cost-effective way. The type of pattern with frosted or fluted features on the bearing inner or outer race it's often found on the electrical motors bearings due to electric discharge inside motor. This defect can decrease the asset life time from months to days and could lead to catastrophic defects.
33
Mogal, Shyam, R. V. Bhandare, V. M. Phalle e P. B. Kushare. "Fault Diagnosis and Prediction of Remaining Useful Life (RUL) of Rolling Element Bearing : A review state of art". Tribologia - Finnish Journal of Tribology 41, n. 1−2 (15 luglio 2024): 28–42. http://dx.doi.org/10.30678/fjt.141503.
Testo completoAbstract (sommario):
Fault diagnosis of rolling element bearings is a critical aspect of machine maintenance and reliability. Bearings are extensively used in various industrial applications, and their failure can lead to costly downtime and equipment damage. Rotating machinery under continuous overload conditions can indeed significantly degrade bearing life and lead to various other issues. To identify issues in rolling element bearings (REB), several techniques and methods are employed. Diagnosing faults in ball bearings while simultaneously estimating the Remaining Useful Life (RUL) of the bearing is a crucial aspect of predictive maintenance. This can be achieved through a combination of signal processing techniques, machine learning methods, and RUL prediction models. The estimation of a bearing Remaining Useful Life (RUL) is of significant importance in predictive maintenance strategies to avoid unexpected failures, reduce downtime, and optimize maintenance costs. This literature review aims to explore the methodologies, techniques, and advancements in predicting the remaining useful life of bearings.
34
Liew, A., N. S. Feng e E. J. Hahn. "A non-linear transfer matrix technique for statically indeterminate rotor bearing systems". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 215, n. 11 (1 novembre 2001): 1343–55. http://dx.doi.org/10.1243/0954406011524720.
Testo completoAbstract (sommario):
Transfer matrix (TM) methods have long been used to obtain the vibration behaviour of linearized rotor bearing systems. Recently the technique has been enhanced to find the unbalance response of statically determinate systems with hydrodynamic bearing type non-linearities. This paper further extends the non-linear approach to statically indeterminate systems, enabling application to practical rotating machinery. The technique is illustrated on simple unbalanced rotor bearing systems with two and four bearings. It is shown that, in statically indeterminate systems, unbalance may affect not only the orbit size and shape but also the load distribution between the bearings.
35
Zhao, Qi, Mingchen Qiang, Yu Hou, Shuangtao Chen e Tianwei Lai. "Research Developments of Aerostatic Thrust Bearings: A Review". Applied Sciences 12, n. 23 (22 novembre 2022): 11887. http://dx.doi.org/10.3390/app122311887.
Testo completoAbstract (sommario):
In aerostatic thrust bearings (ATBs), a high-pressure gas film with a certain bearing capacity and stiffness is formed by passing high-pressure gas between the moving surface and the static surface. Aerostatic bearings have outstanding advantages in the following aspects: high precision, high speed, and long service life, etc. They are widely used in many fields, such as high-speed air spindles, precision machine tools, air-bearing guideways, turbine machinery, and high-speed drills. With the pursuit of higher efficiency and high-precision machining machinery, there is an increasing demand for high-performance ATBs. Much effort has been spent on the study of ATBs, such as improvements in load capacity and stiffness, and the enhancement of stability. Some significant progress has been achieved. In this paper, the research developments of ATBs are summarized from several aspects, such as theoretical models and experimental methods, static performance, dynamic performance, and applications. In addition, insights on the breakthrough and development trends of ATBs are put forward. It is hoped that this paper can provide some guidance for the design and application of ATBs.
36
Korotkov, Alexander, Lidia Korotkova e Denis Vidin. "Study of the quality of plain bearings, used in mining machinery". E3S Web of Conferences 402 (2023): 10029. http://dx.doi.org/10.1051/e3sconf/202340210029.
Testo completoAbstract (sommario):
Plain bearings are an important part of many large and critical units and assemblies used in the mining industry. They are widely used in power equipment, powerful pumps, compressors, electric motors and internal combustion engines (ICE). Plain bearings usually include an anti-friction bushing, part of the shaft surface (bearing journal) and an oil layer between them. These are complex and critical parts in which dangerous defects may occur and which directly affect the durability, accuracy and reliability of the entire assembly. To ensure high reliability of equipment with plain bearings used in complex equipment, it is necessary to ensure their quality control, as well as a sufficient level of monitoring the technical condition and diagnosing emerging defects. This is one of the main operational tasks that the personnel of the maintenance and diagnostic services of enterprises have to constantly solve. This paper presents a comparative analysis of the quality of plain bearings for internal combustion engines of various manufacturers. The performance properties of bearings are given depending on the composition. The results of chemical analysis of the base, cover and intermediate layers of ICE liners are presented. Comparative characteristics of plain bearings are given in terms of the chemical composition of the layers and their thickness for various manufacturers: Cummins POL (Poland), Cummins CCEC (China), WETZ (Russia). Recommendations are formulated to improve the performance of plain bearings.
37
Qian, Xue Ming, Lan Duan e Chen Chen Yi. "Research on Expert System of Bearing Design". Applied Mechanics and Materials 556-562 (maggio 2014): 1267–70. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.1267.
Testo completoAbstract (sommario):
In the design of machinery, Calculating and validating of bearings are exertive. Artificial Intelligence is the requirement of future design. This paper proposes a bearing expert system based on multiple reasoning, which highly improves the efficiency and quality of bearing design. The system and implementing method can be farther used in intelligent mechanical design.
38
Jiang, Miao, e Yang Xiang. "Prediction on the Remaining Useful Life of Rolling Bearings Using Ensemble DLSTM". Shock and Vibration 2023 (20 marzo 2023): 1–16. http://dx.doi.org/10.1155/2023/3742912.
Testo completoAbstract (sommario):
As a significant component of rotation machinery, bearing plays a role in supporting and transmitting power. However, bearings are subject to complex operating conditions and are prone to failure. To avoid ineffectiveness and improve the reliability of bearings, a data-driven method is used to predict the remaining useful life (RUL). However, this method is less stable and can only forecast the RUL of bearings under training sample conditions. An ensemble deep, long-term, and short-term memory (EDLSTM) method is proposed to solve this problem. First, the feature of the forecast-bearing RUL was extracted including time-domain features, frequency-domain energy features, and Shannon entropy. Then, a deep long- and short-term memory network prediction model of the bearing RUL was constructed. To resolve the instability of DLSTM predictions, multiple DLSTMs were ensembled using the maximum information component (MIC) criterion. The model i trained using bearing data with different failure modes under difficult operating conditions to improve the predictive stability of the model. Finally, an EDLSTM was constructed to achieve the bearing RUL prediction. In the prediction result of the training set, the cumulative relative accuracy (CRA) was above 0.9 for most of the bearings. According to the experimental results in the test set, the mean CRA was over 0.80. For some of the bearing’s RUL, the CRA was more than 0.90. The above results show that the proposed approach can effectively predict the RUL of a bearing and has a more stable prediction ability than the bagging integration method.
39
Sumate, Sathitbunanan, e Wirote Ritthong. "Friction Tests of Ball Bearings with Comparison of Lubricants". Applied Mechanics and Materials 866 (giugno 2017): 375–78. http://dx.doi.org/10.4028/www.scientific.net/amm.866.375.
Testo completoAbstract (sommario):
The ball bearings are the rotating components which are widely spread to moving parts for all machinery operation in general industry. This paper presents the ball bearing resistance tool which has a proper size and can handle the maximum load of 300 kg by using an electric power. The ball bearing resistance tool was used to test the bearings No. 6011 cm. The series of tests was performed in the ball bearings lubricated; engine oil SAE 10W/40, auto transmission fluid Dexron, and hydraulic oil. The rotational speeds for testing were vary; 500, 600 and 700 rpm respectively. At each speed, there were various weight; 50, 70, 90,110,130,150, and 170 kg respectively. The results show that the hydraulic oil generated the smallest coefficients of friction and energy efficiency for ball bearing operation.
40
Cheng, Li, Xintao Xia e Liang Ye. "Chaotic prediction of vibration performance degradation trend of rolling element bearing based on Weibull distribution". Science Progress 103, n. 1 (2 dicembre 2019): 003685041989219. http://dx.doi.org/10.1177/0036850419892194.
Testo completoAbstract (sommario):
Rolling element bearings are used in all rotating machinery, and the degradation performance of rolling element bearings directly affects the performance of the machine. Therefore, high reliability prediction of the performance degradation trend of rolling element bearings has become an urgent research problem. However, the degradation characteristics of the rolling element bearings vibration time series are difficult to extract, and the mechanism of performance degradation is very complicated. The accurate physical model is difficult to establish. In view of the above reasons, based on the vibration performance data of rolling element bearings, a model of bearing performance degradation trend parameter based on wavelet denoising and Weibull distribution is established. Then, the phase space reconstruction of the series of bearing performance degradation trend parameter is carried out, and the prognosis is obtained by the improved adding weighted first-order local prediction method. The experimental results show that the bearing vibration performance degradation parameter can accurately depict the degradation trend of the bearing, and the reliability level is 91.55%; and the prediction of bearing performance degradation trend parameter is satisfactory: the mean relative error is only 0.0053% and the maximum relative error is less than 0.03%.
41
Medeiros, Everton C., Airton Nabarrete, Marcela A. Cruchaga, Willy R. P. Mendonca e Mauro H. Mathias. "Numerical and Experimental Evaluation of Hydrodynamic Bearings Applied to a Jeffcott Test Bench". International Journal of Acoustics and Vibration 26, n. 1 (30 marzo 2021): 64–69. http://dx.doi.org/10.20855/ijav.2020.25.11732.
Testo completoAbstract (sommario):
Merging analytical and numerical models with experimental results improve the behaviour predictions of mechanical elements applied to rotor machinery, such as the bearings. This work aims to present the design of a hydrodynamic bearing prototype, a comparison and validation between the numerical and experimental results of critical speeds, and the differences of behaviour when the bush geometries and lubrication are changed. The bush geometries and the fluid film properties are analysed by measuring the dynamic behaviour of a rotor supported by these bearings. The experimental evaluation is based on measuring the Jeffcott test bench supported in a pair of bearings, showing the anisotropic behaviour caused by the stiffness difference in horizontal and vertical directions. It also presents an optimization of bushings for isotropic conditions when they were changed for different geometries (elliptical, offset halves) and different materials with boundary lubrication. This detailed study shows how the dynamic behaviour of rotating machinery can be predicted using numerical models and its validation by a test rig. Results also show how the vibration occurs if the bushes geometries are modified or its lubrication condition is changed.
42
Ghoneam, S. M., M. A. Asy, A. G. Embaby e E. A. Elhadhody. "DYNAMIC ANALYSIS OF ROTOR SYSTEM WITH ACTIVE MAGNETIC BEARINGS USING FINITE ELEMENT METHOD". International Journal of Engineering Applied Sciences and Technology 7, n. 1 (1 maggio 2022): 09–16. http://dx.doi.org/10.33564/ijeast.2022.v07i01.002.
Testo completoAbstract (sommario):
The rotor is a key element of rotating machinery that can be used in different of mechanical devices such as gas turbines, industrial compressors, motors, and aero engines. The dynamic analysis of a rotor system with active magnetic bearings is presented in this paper. This system consists of a flexible shaft with a rigid disk and flexible bearings. An sys Workbench is used to study a 3D simulation of a finite element model. Correct estimation of the rotor's natural frequencies and mode shapes is required for rotating machinery safety procedures. In order to compute the natural frequencies and mode shapes of this system, in the first case it is assumed a free-free system in which no bearings are used, and the natural frequencies and mode shapes are calculated without rigid body modes. In the second case, the natural frequencies and mode shapes are determined with bearing stiffness. The natural frequencies are also evaluated using finite elements based on matlab code. A comparison between the two methods was carried out.
43
Darwis, Sutawanir, Nusar Hajarisman, Suliadi, Achmad Widodo e Rejeki Wulan Islamiyati. "Exploring Pattern Recognition for Bearing Fault Diagnosis". STATISTIKA Journal of Theoretical Statistics and Its Applications 22, n. 2 (30 dicembre 2022): 175–82. http://dx.doi.org/10.29313/statistika.v22i2.1128.
Testo completoAbstract (sommario):
Traditional bearing sensory diagnostic include touching and hearing rely on personal experience, and for more complex system are unable to meet the needs of equipment fault diagnosis. The research on bearing fault diagnosis is developing significantly. Bearings are used in rotating machinery and most machinery failures are caused by bearing failures. The fault diagnosis of bearings is an important research area. The core of bearing fault diagnosis is the pattern recognition of fault features. The key of pattern recognition is to develop a reasonable classifier. Intelligent pattern recognition has been developed such as principal components, support vector machine, neural network. In this study, a bearing fault diagnosis based on exploring pattern recognition is proposed. The key to pattern recognition is to design a significant classifier. A number of features from bearing vibration of normal and fault bearing are extracted and processed using principal components of correlation matrix. Plot of principal components shows the visualization of normal and fault bearing and the classifier is chosen subjectively. The principal components exploration will be confirmed using least squares support vector machine. The parameter of support vector machine estimated using heuristic optimization particle swarm optimization. The proposed method can be applied in the detection of faults of bearing
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Du, Fengming, Dawei Li, Xiaoxia Sa, Cong Li, Yang Yu, Chengdi Li, Jingsi Wang e Weiwei Wang. "Overview of Friction and Wear Performance of Sliding Bearings". Coatings 12, n. 9 (5 settembre 2022): 1303. http://dx.doi.org/10.3390/coatings12091303.
Testo completoAbstract (sommario):
Sliding bearings are critical components of the internal combustion engine. Friction and wear occur in the contact area between the shaft and the bearing. Significant wear can occur in poor working conditions or after a long service time, leading to the failure of the sliding bearing and affecting the reliability of the machinery. It is essential to investigate the wear performance of sliding bearings, understand their wear mechanism, predict their service life, and select wear-resistant materials and surface treatments. This paper reviews the current status and prospects of sliding bearing wear research, focusing on the classification of sliding bearing wear tests, wear testing machines, wear test research, wear prediction models, and future research prospects.
45
Iordanoff, I., P. Stefan, R. Boudet e D. Poirier. "Dynamic Analysis of a Thrust Bearing—Effect of Misalignment and Load". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, n. 3 (settembre 1995): 189–94. http://dx.doi.org/10.1243/pime_proc_1995_209_424_02.
Testo completoAbstract (sommario):
The ABG SEMCA, specialists in air-conditioning machinery, has considered the concept of small turbines with high rotation speeds (50 000–80 000 r/min). Air radial and thrust bearings are particularly well adapted for this kind of turbine. The load on the thrust bearing can be directed on one way or en the other. Therefore two thrust bearings are needed in order to support a bidirectional load However, some problems of stability have been found in the non-loading thrust bearing. This paper deals with a dynamic analysis of a thrust bearing and outlines the bad effects of misalignment on the unloaded thrust bearing and the importance of the sector angle on stability.
46
Guijosa, J. M. M., e Z. C. Feng. "Stability analysis of a rigid rotor on tilting-pad journal bearings". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 214, n. 3 (1 marzo 2000): 243–51. http://dx.doi.org/10.1243/1350650001543142.
Testo completoAbstract (sommario):
Tilting-pad journal bearings are used in many rotating machinery applications. They are known to have superior performance in comparison with fixed geometry cylindrical bearings. Previous analysis by other investigators on the rotor stability has shown that the pad inertia is the main limiting factor on the bearing performance. In this paper, that analysis is extended to examine the bifurcation types that are associated with the loss of stability in order to gain insight into whether the linear stable regions are robust under finite perturbations. The effect of pad friction force on the rotor stability is also examined. Furthermore, the analysis is extended to bearings with four pads.
47
Wang, Hua Qing, Yong Wei Guo, Jian Feng Yang, Liu Yang Song, Jia Pan, Peng Chen e Hong Fang Yuan. "Fault Diagnosis Based on Acoustic Emission Signal for Low Speed Rolling Element Bearing". Advanced Materials Research 199-200 (febbraio 2011): 1020–23. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1020.
Testo completoAbstract (sommario):
The fault of a bearing may cause the breakdown of a rotating machine, leading to serious consequences. A rolling element bearing is an important part of, and is widely used in rotating machinery. Therefore, fault diagnosis of rolling bearings is important for guaranteeing production efficiency and plant safety. Although many studies have been carried out with the goal of achieving fault diagnosis of a bearing, most of these works were studied for rotating machinery with a high rotating speed rather than with a low rotating speed. Fault diagnosis for bearings under a low rotating speed, is more difficult than under a high rotating speed. Because bearing faults signal is very weak under a low rotating speed. This work acquires vibration and acoustic emission signals from the rolling bearing under low speed respectively, and analyzes the both kinds of signals in time domain and frequency domain for diagnosing the typical bearing faults contrastively. This paper also discussed the advantages using the acoustic emission signal for fault diagnosis of rolling speed bearing. From the results of analysis and experiment we can find the effectiveness of acoustic emission signal is better than vibration signal for fault diagnosis of a bearing under the low speed.
48
Ikeda, Kazunori, Toshio Hirano, Tatsuo Yamashita, Makoto Mikami e Hitoshi Sakakida. "An Experimental Study of Static and Dynamic Characteristics of a 580mm(22.8in.) Diameter Direct Lubrication Tilting Pad Journal Bearing". Journal of Tribology 128, n. 1 (19 agosto 2005): 146–54. http://dx.doi.org/10.1115/1.2114929.
Testo completoAbstract (sommario):
Direct lubrication tilting pad journal bearings (DLTPJ bearings) have rarely been applied to large-scale rotating machinery, such as turbines or generators, whose journal diameters are more than 500mm. In this paper, static and dynamic characteristics of a 580mm(22.8in.) diameter DLTPJ bearing were studied experimentally using a full-scale bearing test rig. In the static test, distribution of metal temperature, oil film pressure, and bearing loss were measured in changing oil flow rate, with mean bearing pressure ranging up to 2.9MPa. The maximum metal temperature of the DLTPJ bearing was compared to that of a conventional flood lubrication bearing, and it was confirmed that the direct lubrication could increase load capacity. In the dynamic test, spring and damping coefficients of oil film were obtained by exciting the bearing casing that was floated by air bellows. These data will be used for analysis and design of steam turbine rotors and their bearing systems. Also, vibration of pads was investigated because metal failure on upper pads due to vibration has been found in some actual machines. In order to generate oil film pressure on the surface of upper pads, a Rayleigh-step was machined there, and it was confirmed that vibration was reduced by the Rayleigh-step.
49
Heshmat, Hooshang. "Operation of Foil Bearings Beyond the Bending Critical Mode". Journal of Tribology 122, n. 1 (27 luglio 1999): 192–98. http://dx.doi.org/10.1115/1.555342.
Testo completoAbstract (sommario):
A series of experiments were conducted to determine a foil bearings ability to operate in the region of the bending mode of a flexible rotor. Three different bearings, spaced at three different positions along the shaft, were tested in order to make super-bending-critical operation possible. This was achieved with a proper bearing design located at an optimum position with respect to the bending nodes. After proper trim balancing the bearings passed the 34,100 rpm first bending critical and went on to operate up to 85,000 rpm, 2.5 times the bending critical. Throughout, the amplitudes of vibration remained small. The documented ability of these bearings to operate in the domain of a flexible rotor’s bending mode makes these bearings a prime candidate for the high-speed machinery of modern technology. [S0742-4787(00)02401-2]
50
Sun, Junyu, Liyu Chen, Pengfei Qian e Bing Zhang. "Oil Cavitation Morphology Analysis of Textured Cylindrical Rotating Friction Pair on Circular-Disk End Faces". Machines 10, n. 11 (7 novembre 2022): 1036. http://dx.doi.org/10.3390/machines10111036.
Testo completoAbstract (sommario):
Cavitation is a destructive hydraulic phenomenon; it causes damage to small hydraulic machinery and large water-conservancy projects, and cavitation and cavitation corrosion problems are long-standing problems for hydraulic machinery experts. Micro-textures are often machined onto the end face near the indirect contact point to increase the oil film bearing capacity and reduce the transfer torque in hydraulic machinery, but the pressure disturbance caused by the texture dimple and boundary can induce cavitation. To delay or eliminate cavitation on the textured surface of equipment such as mechanical seals and dynamic bearings, the cavitation effect of a cylindrical texture on a rotating frictional pair was investigated from theoretical, imitational, and experimental perspectives. Low pressure is extremely important for inducing cavitation; once cavitation conditions are met, a full bubble can be formed in about 0.015 s. Cavitation mainly occurs at the outer radius of the rotating end face, i.e., in the high-speed region. There is a mutual mass transfer between gas and liquid phases when cavitation occurs, but the generation of cavitation bubbles is faster than its collapse, thus causing an increasing cavitation region.