This thesis incorporates an array of Contact Potential Difference (CPD) sensors to measure and monitor the degree of skew in the rolling elements of a spherical roller bearing. Skewing is the motion of a roller as it turns about an axis normal to the roller race interface. Roller skew is generated as part of the kinematic effects of roller bearings. Skew monitoring is important for bearing design as it is an indirect measure of bearing life. For the purpose of this thesis, roller skew was measured utilizing multiple pairs of CPD probes located around the bearings outer raceway at varying points of the loading zone. These CPD probes are not in direct contact with the rollers, but in close proximity to their surface (through the bearing outer ring). The skew angle measured is related to different operating conditions such as applied load, shaft speed, and lubrication. The pair of CPD probes detected a signal as the roller surface passed by and the phase difference between the two distinct signals measured the skew angles in the range of 0.016 to 1.10. The shaft is rotated both clockwise and counterclockwise to capture any probe misalignment which was in the range of 0.5 up to 2.0 . This thesis also provides a model for the probe signal as a spherical roller surface passes the probe surface.

The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000�F) magnetic bearing system using High Temperature Permanent Magnets (HTPM), developed by the EEC. The entire system consisted of two radial bearings, one thrust bearing, one motor and 2 sets of catcher bearings. This high temperature magnetic bearing system will be used in high performance, high speed and high temperature applications like space vehicles, jet engines and deep sea equipment. The bearing system had a target design to carry a load equal to 500 lb-f (2225N). Another objective was to design and build a test rig fixture to measure the load capacity of the designed high temperature radial magnetic bearing (HTRMB) called Radial Bearing Force Test Rig (RBFTR). A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1000 �F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces even if half the coils have failed. The permanent magnet bias of the radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and also increases the system efficiency because magnetic field of the HTPM is used to take up the major portion of the static load on the bearing. The bias flux of the homopolar radial bearing is produced by the EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed using the Radial Bearing Force Test Rig (RBTFR) to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.

What is bearing management? It can be defined as follows¡G To achieve the best quality of the rotary machinery, the supervisor in charge shall possess the comprehensive knowledge, such as, to make the plan schedule and teamwork through the management method, to review the design and selection constantly, to do the problem analysis and the proper decision making in time. The purpose is to maintain the bearing in its good condition, and accordingly, to lower the emergency shut-down and man-power loss. At the year of 2011, CSC will encounter the strike of imbalanced structure of manpower caused by the trend of retirement. Since the consistent quality of maintenance is one of the enterprise¡¦s operation costs, and is also the foundation for the profit gaining and competition with others for survival, therefore, how to efficiently pass on and refine the technical expertise to cope with this foreseeable scenario becomes one the most importance challenges for CSC at this moment. To face the above-mentioned circumstances, the Plant Engineering & Maintenance Dept in CSC is determined to take up the bearing management as one of the crucial strategy. Some steps are adopted, such as, to set up the bearing seminars and establish the disciplinary knowledge through superior-subordinate communication and coordination, and meanwhile, to set up the benchmark to regulate the Bearing Consumption Rate (BCR), to regularly assess the use of bearing basing upon the tonnage of raw steel production, and then to execute the necessary methods to modify any possible problematic situation. The objective is clear, both in financial improvement and production efficiency. The target audiences of this research are from the members who completed the course in the seminars, they now also work as the front line personnel to facilitate in the field of bearing management. Meanwhile, some in-depth interviews with the maintenance superintendents are also applied. Some detections of the outcome are as follows¡G I. It is efficient to convey the bearing education and training via the events of bearing management. II. The support from the superintendent is the direct impact on the bearing management, and also is the vital factor to improve the efficiency. III. The content of curriculum for the training and education is another impact to the improvement of efficiency and success. IV. The lecturers must be qualified, capable and knowledgeable, and acknowledged by the fellow members. V. While the motive is clear and definite, the outcome can be much more enhanced. VI. Suitable location and environment with appropriate facilities are the basis requirement to set up the training program. According to the above-mentioned outcome, this research project has made some conclusions as suggested below¡G I. Staff of managerial level must fully support the bearing management and educational training. II. The empirical exemplification and the practical exercise are the main focus in the training progress, and shall also be the criterion as for the methodology in the other field of maintenance. III. To set a solid and objective goal to get a better result. IV. To set up an operational team to establish the task of the bearing maintenance training. V. The appropriate reward will be granted for any effective cases in the maintenance of bearing. VI. Launch the website of bearing maintenance, and broadly promote bearing maintenance and educational training via e-learning.

Habilitation à diriger des recherches : Génie mécanique : Villeurbanne, INSA : 1999. / Document rédigé également en version française. Titre provenant de l'écran-titre. Bibliogr. p. 135-155.

Thesis (Ph. D.)--University of California, San Diego, 2001. / Vita. Includes bibliographical references.

Higher penetration of volatile renewable sources and increasing load demand are putting a strain on the current utility grid structure. Energy storage solutions are required to maintain grid stability and are vital components to future smart grid designs. Flywheel energy storage can be a strong part of the solution due to high cycle life capabilities and flexible design configurations that balance power and energy capacity. This dissertation focuses on developing design methodologies for advanced flywheel energy storage, with an emphasis on sizing flywheel energy storage and developing lumped parameter modeling techniques for low loss, high temperature superconducting. The first contribution of this dissertation presents a method for using an optimal control law to size flywheel energy storage and develops a design space for potential power and energy storage combinations. This method is a data driven technique, that utilizes power consumption and renewable generation data from a particular location where the storage may be placed. The model for this sizing technique includes the spinning losses, that are unique to flywheel energy storage systems and have limited this technology to short term storage applications, such as frequency and voltage regulation. For longer term storage solutions, the spinning losses for flywheels must be significantly reduced. One potential solution is to use high temperature superconducting bearings, that work by the stable levitation of permanent magnet materials over bulk superconductors. These advanced bearing systems can reduce losses to less than 0.1% stored energy per hour. In order to integrate high temperature superconducting bearings into flywheel system designs, accurate and reduced order models are needed, that include the losses and emulate the hysteretic, non-linear behavior of superconducting levitation. The next two contributions of this dissertation present a lumped parameter axissymmetric model and a 3-D lumped parameter transverse model, which can be used to evaluate bearing lifting capabilities and transverse stiffness for flywheel rotor designs. These models greatly reduce computational time, and were validated against high level finite element analysis, and dynamic experimental tests. The validation experiments are described in detail. / text

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In this thesis, a novel approach is presented for blade loss simulation of an aircraft gas turbine rotor mounted on rolling element bearings with squeeze film dampers, seal rub and enclosed in a flexible housing. The modal truncation augmentation (MTA) method provides an efficient tool for modeling this large order system with localized nonlinearities in the ball bearings. The gas turbine engine, which is composed of the power turbine and gas generator rotors, is modeled with 38 lumped masses. A nonlinear angular contact bearing model is employed, which has ball and race degrees of freedom and uses a modified Hertzian contact force between the races and balls and for the seal rub. This combines a dry contact force and viscous damping force. A flexible housing with seal rub is also included whose modal description is imported from ANSYS. Prediction of the maximum contact load and the corresponding stress on an elliptical contact area between the races and balls is made during the blade loss simulations. A finite-element based squeeze film damper (SFD), which determines the pressure profile of the oil film and calculates damper forces for any type of whirl orbit is utilized in the simulation. The new approach is shown to provide efficient and accurate predictions of whirl amplitudes, maximum contact load and stress in the bearings, transmissibility, thermal growths, maximum and minimum damper pressures and the amount of unbalanced force for incipient oil film cavitation. It requires about 4 times less computational time than the traditional approaches and has an error of less than 5 %.

Baigiamajame darbe pateikta literatūros šaltinių apžvalga susijusi su riedėjimo guolių defektų diagnostika. Darbe sukurta lėtaeigių riedėjimo guolių (iki 380 aps/min) esančių „INVERFORM“ džiovyklinių mašinų grupėse tyrimų metodika bei atlikti eksperimentiniai tyrimai. Pagrindinis šių tyrimų tikslas – sukurti patikimą tyrimų metodą, skirtą eksploatuojamų lėtaeigių sferinių riedėjimo guolių defektams diagnozuoti ir techninei būklei įvertinti. Metodas buvo sukurtas išsamių guolių korpusų virpesių matavimų ir virpesių duomenų formatų analizės pagrindu, mašinai dirbant natūralios eksploatacijos sąlygomis. Gautos diagnostinių tyrimų išvados patvirtintos mašinos periodinio planinio metu vizualiai apžiūrėjus ir įvertinus guolių techninę būklę. / This paper represents a review of literature which is associated with a slow speed rolling bearings diagnostics. In this work the methodology for a slow speed rolling bearings (rotational speed up to 380 rpm) experimental researches is created. Slow speed with double row self-alignment spherical roller bearings is located in drying machines “INVERFORM”. Also experimental researches have been done and analyzed in this work. The main objective of this research - to establish a reliable research method to diagnose defects and evaluate technical condition of operating slow speed spherical rolling bearings. The method has been developed based on detailed bearings vibration measurements and vibration data formats analysis, when machine works at natural operating conditions. Obtained diagnostic research findings adopted during machines routine periodic visual examination and assessment of technical condition of the bearings.

No description available.