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1
Viitala, R. (Risto). "Dynamic radial bearing force measurement of flexible rotor." Master's thesis, University of Oulu, 2018. http://urn.fi/URN:NBN:fi:oulu-201809062733.
Full textAbstract:
Dynamic characteristics of a paper machine roll have been widely investigated for decades. Vibration of the rolls decrease the paper quality and excites the structures of the paper machine. Therefore, vibration must be avoided and kept at its minimum. Vibration of a rotor develops periodic radial bearing forces, which are connected to the amplitude and the frequency of the vibration. Vibration based forces are unnecessary dynamic forces, which increase the bearing load in addition to unavoidable rotor mass and the external loads of the process. This experimental study presents the amplitudes of the dynamic bearing force caused by a vibrating rotor and enables further measurements and research about the correlation between the radial bearing force and e.g. acceleration data. During the research knowledge about the dynamic behavior of the rotor and developed forces can be increased. The improved knowledge leads to a lower bearing force level, which decreases the oversizing of the structures, enables the design of lighter and more cost-effective structures, extends the lifespan of the machine and improves the quality of the end product. The dynamic radial bearing force amplitudes of a paper machine roll are merely available through simulation models, since physical force sensors are not mounted on the paper machines. Typically, the monitoring of a paper machine is focused on the vibrations of the paper machine rolls, since it is more relevant for to the quality of the paper than the amplitudes of force. Vibration troubleshooting and monitoring tasks have typically been realized through the easy-installed accelerometer measurements. The force measurement of the paper machine roll can produce similar information about the behavior of the rotor and its vibrations as acceleration measurement in addition to the radial force amplitudes. However, utilization of force measurements in vibration monitoring was not found based on a literature survey. The radial bearing force measurement was accomplished by building a test rig and a measurement device for an industrial-size paper machine roll. The radial bearing forces were measured as close as possible to the action point of the load to produce reliable results. The results present the force measurement data, which were acquired with the calibrated and verified measurement device implemented during this study. The measured results revealed the forces affecting on both ends of the test roll. The data was analyzed with Fast Fourier Transform (FFT) to present the forces in the frequency domain and to investigate their harmonic components. The measured forces, which were divided into harmonic components, could be discovered and destabilizing excitations could be defined more efficiently. Based on the present study high harmonic components could be distinguished with the force measurement. The results were compared with two reference measurements, which utilize acceleration and position sensors. The results cannot be generalized, since the measuring results consider only the roll of this research. The roll, the bearings, the bearing support and the foundation form the rotating system, which is always individual. Parameters and excitations affecting to the behavior of the roll are different in every roll. However, the similar behavior can be assumed to be on other flexible rotors as well and those can be measured with similar methods as the present study. In further research additional knowledge about the behavior of the roll and correlations between force, position and acceleration can be achieved for both the scientific and practical engineering purposes with the dynamic bearing force measurement and a simultaneous acceleration or position measurementPaperikoneen telan värähtelyominaisuuksia on tutkittu laajasti jo vuosikymmeniä. Värähtely heikentää paperin laatua ja aiheuttaa herätettä paperikoneen rakenteisiin. Tästä johtuen värähtely yritetään pitää minimaalisena. Roottorin värähtely aiheuttaa jaksollisia laakerivoimia, jotka ovat yhteydessä värähtelyyn. Värähtelyn aiheuttamat voimat ovat ei-toivottuja dynaamisia voimia, jotka lisäävät laakerivoimia välttämättömän roottorimassan ja muiden prosessista aiheutuvien rasitusten lisäksi. Tämä kokeellinen tutkimus keskittyy värähtelevän roottorin aiheuttamiin dynaamisiin voimiin ja mahdollistaa myöhemmän mittaamisen ja korrelaatioiden tutkimisen laakerivoimien ja esimerkiksi kiihtyvyysmittauksen välillä. Tietoa roottorin dynaamisesta käyttäytymisestä ja syntyvistä voimista voidaan parantaa tällä tutkimuksella. Paperikoneen telan dynaamisten ominaisuuksien parempi tunteminen vähentää rakenteiden ylimitoitusta, mikä mahdollistaa rakenteiden suunnittelun kevyemmäksi ja halvemmaksi, lisää koneen käyttöikää ja parantaa lopputuotteen laatua. Telan värähtelyn aiheuttamia dynaamisia laakerinvoimia on saatavilla vain simuloimalla, mikä tarkoittaa, että fyysisiä voima-antureita ei ole asennettuina paperikoneissa. Yleensä paperikoneen anturointi keskittyy paperikoneen telojen värähtelyyn, sillä se on isompi tekijä paperin laaduntarkkailussa kuin voimamittaus. Värähtelymittaukseen perustuvaa vianetsintää ja prosessivalvontaa on tehty tyypillisesti helposti kiinnitettävillä kiihtyvyysantureilla. Voimamittaus pystyy tuottamaan saman informaation roottorin käyttäytymisestä ja sen värähtelystä kuin kiihtyvyysmittaus laakerivoimien lisäksi. Kuitenkaan, voimamittausta ei käytetä värähtelymittauksiin kirjallisuusselvityksen mukaan. Laakerivoimamittaus suoritetaan rakentamalla koepenkki sekä mittalaite teollisuudessa käytettävälle paperikoneen telalle. Laakerivoimat pyritään mittaamaan mahdollisimman läheltä voimanvaikutuspistettä, että saavutettaisiin mahdollisimman luotettava tulos. Mittatulokset saatiin kalibroidulla ja verifioidulla mittalaitteella, joka oli rakennettu tämän työn aikana. Mittaustulokset paljastivat telan laakereihin syntyvät voimat kummassakin päässä telaa. Tulokset analysoitiin käyttäen nopeaa Fourierin muunnosta (FFT), jotta voimat saatiin taajuustasoon harmonisten komponenttien tutkimiseksi. Mitatut voimat ja niiden amplitudit, jotka olivat esitettyinä harmonisina komponentteina, voitiin löytää ja telan värähtelyä aiheuttavat herätteet voitiin rajata tehokkaammin. Tämän tutkimuksen perusteella voitiin huomata, että korkeat harmoniset taajuudet voitiin havaita voimamittauksella. Tuloksia verrattiin kahteen referenssimittaukseen, jotka oli toteutettu kiihtyvyys- ja paikka-antureilla. Tuloksia ei voitu yleistää, sillä mittaustulokset koskevat vain tämän tutkimuksen telaa. Tela, laakerit, laakerin tuenta ja perusta muodostivat pyörivän systeemin, mikä on aina yksilöllinen. Parametrit ja herätteet, jotka vaikuttavat telan käyttäytymiseen muuttuvat joka telassa. Kuitenkin samanlaista käyttäytymistä voidaan olettaa olevan myös toisissa joustavissa roottoreissa ja ne voidaan mitata samalla tavalla kuin tässä tutkimuksessa. Myöhemmässä tutkimuksessa voidaan saavuttaa lisäarvoa ja korrelaatioita laakerivoiman, siirtymämittauksen ja kiihtyvyysmittauksen välillä tieteellisiin ja käytännön tarkoituksiin dynaamisella laakerivoimamittauksella
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Nel, Johannes Daniel. "The development of a radial active magnetic bearing / J.D. Nel." Thesis, North-West University, 2004. http://hdl.handle.net/10394/542.
Full textAbstract:
This dissertation presents the development of a radial active magnetic bearing (AMB). With AMBs
the rotor of a machine can be suspended in the air without any direct contact between the stator and
the rotor. This makes it a frictionless bearing and eliminates the need for lubrication. The AMB
system implements a feedback control system to control the position of the rotor.
The aim of this project is to develop a radial AMB with an air gap of 1 mm and a rotation speed of
3000 rpm. Through this project basic knowledge of magnetic suspension is gained and expertise is
established at the Engineering Faculty. The model can be used for further studies and as a
demonstration model to illustrate the concept of AMBs.
The model constitutes one radial AMB and one conventional ball bearing supporting a rigid shaft.
The AMB system constitutes 1) electromagnets, 2) power amplifiers, 3) position sensors and 4) a
control system. Inductive sensors measure the air gap between the shaft and the stator in the vertical
and horizontal axis. The sensor signal is fed back to a controller that provides a control signal to the
power amplifiers. The power amplifiers control the current through the electromagnets that apply a
force on the shaft. The shaft is then suspended in the air. An air pressure turbine is used to propel
the shaft up to 3000 rpm.
A homopolar AMB configuration is implemented using mild steel for the electromagnets. The four
electromagnets used in the system are designed in terms of a required force. Linear power
amplifiers are designed to activate the electromagnets and to eliminate possible noise problems on
the sensors. Inductive position sensors are implemented producing a dc voltage proportional to the
size of the air gap.
dSpace® software is used to implement the controller. A position sensor value is read in through an
analog-to-digital converter channel and subtracted from a reference signal for the position. The
error signal is then the input of the controller. The controller sends a control signal via the digital-to-
analog converter to the power amplifiers. A PID controller is created in sirnulink®. With the aid
of dSpace® software the controller is downloaded onto the dSpace card.
Different tests are performed to characterise the system. The step responses in both axes are
measured and the percentage overshoots and settling times are determined. Impulse disturbance
tests at different speeds are used to calculate the dynamic stiffness and damping of the system.
Stable suspension was achieved with the final AMB system at rotation speeds of 3000 rpm. The
maximum deviation was found to be less than 0.11 mm from the centre position. The settling time
was less than 0.4 s and with no steady state error.
The developed AMB system has a relatively low dynamic stiffness. Future studies can be done to
find the effect that each PID parameter has on the dynamic stiffness. It is recommended that the
controller be implemented on an embedded microcontroller to eliminate the computer and the
dSpace® card.Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2005.
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Farkhondeh, Shahrbanoo. "Smart Journal Bearing with Controllable Radial Clearance, Design and Analysis." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1497976252551497.
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Hossain, Mohammad Ahsan. "High temperature, permanent magnet biased, homopolar magnetic bearing actuator." Thesis, Texas A&M University, 2006. http://hdl.handle.net/1969.1/4174.
Full textAbstract:
The EEC (Electron Energy Corporation) in conjunction with the National Aeronautics and Space Administration is researching the magnetic bearings for an alternative to conventional journal or ball bearings. The purpose of this research was to design and develop a high-temperature (1000úF) hybrid Magnetic Bearing using High Temperature Permanent Magnets (HTPM), developed by the EEC for high performance jet engines at high speeds that supply loads of 500 lbf. Another objective is to design and build a test rig fixture to measure the load capacity of the designed bearing. The permanent magnet bias of the Homopolar 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 improves the system efficiency because the magnetic field of the HTPM can suspend the major portion of the static load on bearing. A high temperature radial magnetic bearing was designed via an iterative search employing 3D finite element based electromagnetic field simulations. The bearing was designed to produce 500 lbf of force at 1000úF and the design weight is 48 lbs. The bias flux of the Homopolar radial bearing is produced by EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed 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.
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Kern, Colin. "Betriebsverhalten von thermisch und mechanisch hoch beanspruchten kunststoffbeschichteten Radial-Mehrflächengleitlagern." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-71977.
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Die vorliegende Arbeit verfolgte die Zielstellung der Substitution des etablierten Weißmetalls als Laufschicht von hydrodynamischen Mehrflächengleitlagern durch neuartige Kunststoffschichten. Dazu wurden vergleichende Bauteilversuche an Mehrflächengleitlagern mit verschiedenen Laufschichten und Bohrungsformen vorgenommen. Eine Zinnbasislegierung als Laufflächenbeschichtung diente dabei als Referenzwerkstoff. Zur Durchführung des Versuchsprogrammes kam ein vorhandener, messtechnisch neu konditionierter Turbinenlagerprüfstand zum Einsatz. Die Versuchsreihen haben durchweg positive Beurteilungen der Lagerkennwerte im untersuchten Betriebsbereich der neuen Lagervarianten ergeben. Die neuartigen Laufschichtvarianten erfüllten die hohen tribologischen und thermischen Anforderungen. Einzelne Abweichungen der ermittelten Kennwerte wurden zahlenmäßig dokumentiert und können mit bereits verfügbaren physikalischen Modellen beschrieben werden. Die Ergebnisse erwiesen sich als unabhängig von der Lagerbauform aber abhängig von der gewählten Schichtvariante. Die Untersuchungen zum Betriebsverhalten unter hydrodynamischer Dauerbelastung sowie im Mischreibungsgebiet und im Notlaufbetrieb führten zu teilweise unterschiedlichen Ergebnissen. Im Mischreibungsgebiet wiesen die untersuchten Lager kaum Unterschiede im Betriebsverhalten auf. Im Dauerversuch zeigten die Lager mit Weißmetall, Gleitlack und Keramikschicht hervorragende Eigenschaften. Die Variante Klüberplast besaß eine ungenügende Bindefestigkeit und führte zu plastischen Verformungen der Schicht infolge der hydrodynamischen Drücke. Im Notlaufbetrieb übertrafen die untersuchten Kunststoffvarianten die Standzeiten des Referenzwerkstoffs WeißmetallThe aim of this study was to identify and test an alternative liner material instead of common liner materials such as white alloy for multi-lobe radial bearings. For this purpose comparative tests with different radial bearings were carried out. The white alloy material was taken as a reference. In preparation for these test series, the measurement system of the turbine bearing test rig was upgraded. Experiments showed beneficial performances of the bearings with a plastic liner by evaluating the static and dynamic properties of different bearing geometries and liner thicknesses under a wide range of operating conditions. The new bearings fulfilled the high tribological and thermal requirements. Observed deviations of the determined parameters were documented in number and can be described with available physical models. The results were independent of the bearing type and depending on the selected liner material variant. The studies on operating performance in continuous operation in the mixed friction area and in dry running operation led to partially different results. The mixed friction tests showed little difference in the examined stock performance. The bearings with white alloy, ceramic layer and bonded coating showed excellent fatigue properties of long-term experiment. On Klüberplast insufficient bonding strength and plastic deformation of the layer due to the hydrodynamic pressure was found. In the dry running operation the investigated polymers exceeded the lifetime of the referencematerial white alloy
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Zhu, Xiangzhen. "Design of radial displacement sensor and control of a switched reluctance machine with one bearing." Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/30238.
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This project is focused on two objectives: X-Y displacement sensor design and design of switched reluctance motor with a magnetic bearing instead of mechanic bearings to support the rotor at one end. At the other end, a mechanical bearing is still used. Two types of design of low cost sensor for rotor displacement detection are presented. Both of them have very simple structure, which gives very low cost. The first presented sensor has the rotor with 12 poles permanent magnets on its surface. The experimental performance shows this sensor can detect the displacement, but it is not suitable for bearingless control because it doesn't have smooth output and can't work when motor stops. The second sensor design has a solid steel rotor and the experimental performance shows it can detect the displacement for bearingless control in terms of quick response and low cost. A magnetic bearing is realized in a single phase switched reluctance motor. The basic principle is that besides main winding, a radial force winding is employed on each stator tooth, which can generate the flux to balance the radial force in the airgaps so that the rotor can be self-supported. Mathematic analysis and simulation are pretend. The experimental results show that magnetic bearing can support the rotor in the central position regardless of the external force (within 12 N) acting on the rotor shaft. Bearingless control on a two phase switched reluctance motor with only one bearing is also designed. In the experiment, a proper switching point is chosen, which is for the control switching between two phases. Experimental results show that rotor can run with only one magnetic bearing support at 250 rpm. Although the running speed is very low, it is an important step for further research on bearingless control design.
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Choudhry, Vivek Vaibhav. "Experimental evaluation of wire mesh for design as a bearing damper." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/1233.
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Wire mesh vibration dampers have been the subject of some very encouraging experiments at the Texas A&M Turbomachinery laboratories for the past several years and have emerged as an excellent replacement for squeeze film dampers. Their capability to provide damping for a wide range of temperatures (even cryogenic), fluid free operation and ability to perform even when soaked with lubricants makes them a suitable option as a bearing damper. Experiments were conducted to investigate the effect of design parameters like axial thickness and axial compression that influence the characteristics of wire mesh as a bearing damper. Two groups of wire mesh were tested to show that the stiffness and damping are directly proportional to the axial thickness, if all the other parameters are kept constant. Tests on four wire mesh donuts of different radial thickness showed that stiffness and damping vary inversely with radial thickness. Rigorous tests were also conducted to quantify the effects of axial compression, radial interference and displacement amplitude on stiffness and damping of the wire mesh. Another novel kind of mesh damper tested was comprised of two small segments instead of a whole donut. The results showed that wire mesh exhibited good damping characteristics even when used in small segments. Empirical expressions were developed using MathCADTM worksheets, and an existing ExcelTM design worksheet was modified to include these factors. The effect of frequency variation was also included to give a comprehensive design tool for wire mesh. A new design worksheet was developed that can predict rotordynamic coefficients for a wire mesh bearing damper having a different size as well as different installation and operational conditions.
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Chatzisavvas, Ioannis [Verfasser], Bernhard [Akademischer Betreuer] Schweizer, and Wolfgang [Akademischer Betreuer] Seemann. "Efficient Thermohydrodynamic Radial and Thrust Bearing Modeling for Transient Rotor Simulations / Ioannis Chatzisavvas ; Bernhard Schweizer, Wolfgang Seemann." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/116838088X/34.
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Pavani, Renan Augusto. "Mancal magnético passivo radial por atração combinado com mancal de escora." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-19072016-115451/.
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Mancais são elementos importantes para o funcionamento adequado de muitos conjuntos mecânicos. Sendo assim, o contínuo desenvolvimento de novos tipos de mancais permite melhorar as condições atuais de funcionamento de dispositivos com necessidades específicas. Além disso, novos mancais proporcionam novos recursos para novos projetos. Este trabalho visa investigar a funcionalidade de um novo tipo de mancal rotativo híbrido resultante da combinação de um par de mancais magnéticos radiais passivos com um par de mancais de escora. Na direção radial, o eixo é mantido em posição central graças a dois mancais magnéticos compostos por imãs permanentes. Na direção axial, a restrição do movimento é devido a um par de mancais de escora localizados nas extremidades do eixo. Pelo ajuste do entreferro de cada par magnético é possível minimizar a carga axial que age em cada mancal de escora. Por meio de estudos baseados no método dos elementos finitos e experimentações, pretende-se esclarecer a relação entre os parâmetros construtivos e o desempenho do mancal. Os experimentos envolvem a verificação do desempenho do mancal por meio de um conjunto para testes, bem como um estudo de caso. O conjunto para testes possibilitou um ensaio de desgaste acelerado, onde uma esfera de aço, utilizada como pivô, manteve contato com uma superfície de PVC rígido. Tal ensaio resultou em um desgaste desprezível da superfície de contato devido à aplicação do novo conceito proposto, validando o mancal híbrido. Em relação ao estudo de caso, o mancal proposto foi empregado em uma bomba centrífuga representando um dispositivo de assistência ventricular, sendo seu desempenho discutido. Através da comparação entre algumas configurações possíveis para este tipo mancal, a rigidez radial é apresentada e discutida. Embora não constitua objeto principal deste trabalho, são discutidos os aspectos ligados ao desgaste causado pelo contato decorrente do uso dos mancais de escora, analisando o benefício do uso conjunto do mancal magnético com o mancal de escora. A expectativa é a de que este tipo de mancal possa ser utilizado em aplicações onde a existência de uma força resultante na direção radial seja muito pequena se comparada com os esforços presentes na direção axial.Bearings are important elements for the proper working of many mechanical assemblies. Thus, the continuous development of new types of bearings improves the current operating conditions of devices with specific needs. In addition, new bearings provide new resources for new projects. This research aims to investigate the functionality of a new type of hybrid rotational bearing that combines a pair of radial magnetic bearing with a pair of thrust bearings. In the radial direction, the central axis is kept in position due to two magnetic bearings comprising permanent magnets. In the axial direction, the movement is constrained due to a pair of thrust bearings located at the shaft ends. By adjusting the air gap of each magnetic pair, it is possible to minimize the axial load that acts on each thrust bearing. Through studies based on finite elements methods and experiments, the relationship between the constructive parameters and the performance of the bearing are clarified. The experiments involve the performance checking of the proposed bearing through a test bed and a case study. The test bed allows an accelerated wear test, using a steel sphere as pivot against a rigid PVC surface. This test showed that the wear of PVC contact surface was negligible due to the applications of the proposed bearing concept, validating the hybrid bearing. Regarding the case study, the bearing was used in a centrifugal pump representing a ventricular assist device, and so the performance was discussed. By comparing some possible settings for this bearing type, the radial stiffness is presented and discussed. Although it is not the main goal of this paper, it was discussed the aspects related to the wear caused by contact from the use of thrust bearings in order to analyze the benefits of using magnetic bearing with the thrust bearing. The expectation is that this type of bearing can be used in applications where there is a very small net force acting in the radial direction compared with forces acting in the axial direction.
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Vincenc, Jan. "Laboratorní simulátor pro studium radiálních kluzných ložisek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319274.
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The master’s thesis deals with a design of a radial journal bearing simulator, which is ready to implement a transparent sapphire journal bearing to an optical observation of the oil film. The first part of this thesis contains a short review of a few currently used journal bearing test rigs. The next part of the work deals with a discussion of concept variants and a definition of important parameters. The last part contains a detailed description of the designed radial journal bearing simulator. Limitations of the designed simulator and recommendations for future improvements are also discussed. The result of the presented work is the designed journal bearing simulator which will allow observing of the oil film. The work also consists a complete design documentation.
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Rašovská, Hana. "Vliv montážní vůle u radiálního kuličkového ložiska na napjatost a deformaci." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230528.
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This master thesis deals with the influence of assembly clearance on strain and stress in the radial ball bearing. The theme of this thesis was commissioned by ZKL - Research and development, a. s. For six different assembly clearances and selected ball bearing was made force-loaded static analysis of global computational models. Subsequently was made a static analysis of local computational models loaded by strain according to the results of global models. The output of analysis of local models was sizes of stress, which led to the analysis of bearing with two other models of material. For the solution of the problem was used pre/post processor Patran and solver MSC.Marc.
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Jabůrek, Petr. "Technologie výroby plechových klecí pro radiální soudečková ložiska." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228162.
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The project conceived within engineer’s studies of branch 2303T002 is subbmitting a proposal for radial bearing cage produce technology. It is also subbmitting a design solution to functional parts for blanking the “windows” and coining the “locks”. The cage will be made from sheet steel 11 300.29. This cage should replace the current one machined from the brass Ms 58 Al. According to the literary research and development experiences of the company ZKL Brno, a.s., two pairs of tools were designed. First one for blanking the “windows” and second one for coining the “locks”. Blanking punch, blanking die and coining punch will be made from the steel 19436, coining die will be made from the steel 19312. Heat-treating process will be accomplished according to the enclosed drawings. Both pairs of tools will be mounted in the press LENR 63 AU (manufactured by the company ŠMERAL Trnava), with nominal force 630 kN.
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Machač, Stanislav. "Inovace výroby soudečků valivých ložisek objemovým tvářením za studena (OTS)." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228248.
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MACHAČ Stanislav: Spherical rollers process innovation by applicaton of cold bulk forming. Diploma thesis of the attendance engineer´s studies, Institute of technology, 2nd year, 2nd level – summer term, study group 5O / 51, school year 2007 / 2008. FSI VUT Brno, department of forming and plastics, May 2008, 75 pages, 6 tables, 4 enclosures. The topic of this thesis is production innovation of spherical rollers for bearings. The innovation is based on the technology of cold bulk forming. According to the literary research and according to the current stage of production is proposed and conceived manufacturing process for cold upsetting instead of turning using in current spherical rollers production. This manufacturing process is dedicated for the bearing type 22226EJ. The production process is conceived with regard to determinate knuckle-joint press LLR 1000 (Smeral Brno, a.s.). Also with regard to determinate half-closed die upsetting and with regard to formability of the steel 100CrMn6. The proposal and check-up of tool functional parts are designed regarding the current setting of particular parts of the press. In the next part of this thesis the proposal of work-room layout dedicated for hand-filling of semi-factured product is conceived. In conclusion the comparison of spherical roller production budget between cold upsetting and turning is conceived.
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Šperka, Václav. "Vliv podstatných parametrů na velikost radiální vůle a deformačně napěťové stavy v kuličkovém ložisku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231182.
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Master thesis is focused on the research of influence of selected substantial parameters on stress – strain states in the deep groove radial ball bearing. The influence of radial load is analyzed, such as the influence of size of the bearing and row of the bearing, also influence of radial clearance is quantified. Next, the influence of thermal distribution in the bearing is analyzed for different combinations of thermal distributions and radial clearances. Conclusions from analyses are then used in the last task – suggestion of radial clearance for customer – specified assembly. Problem is solved using the finite element method (FEM) in pre/post processor MSC.Patran and solver MSC.Marc. To make analyses faster the substantial parameters are implemented in the algorithm for automatic generation of the bearing calculation (batch file).The theme of this thesis was commissioned by ZKL - Research and development, a. s.
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Novotný, Marek. "Kluzná ložiska pro vysokotlaké čerpadlo." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241836.
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The goal of this diploma thesis is to design the journal bearings for high pressure diesel pump which is part of Common rail system from Motorpal Company. This producer is also submitter of this diploma thesis and as a result it is expecting the reduction of cost price and possible transfer to the diesel oil lubrication. Firstly, there is sum up of issues of high pressure pump by Motorpal. The next part of the thesis describes the journal bearings and its construction, tribology of the journal bearings and also the overview of the materials. These materials are currently being used for securing long time usage and do not require service maintenance during lifespan period. In the practical part there is applied the Multy Body System (MBS) approach with rigid bodies and after that there are used analytic relations, which however do not include impact of movement of the journal center during dynamic stress. The thesis concludes with a comparison of results of both calculations and determination of bearing parameters, which according to the calculations ensure an achievement of hydrodynamic lubrication.
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Scherb, Bruno Johannes. "Prediction and measurement of the frictional torque characteristics of radially and axially loaded radial cylindrical roller bearings." Thesis, University of South Wales, 1999. https://pure.southwales.ac.uk/en/studentthesis/prediction-and-measurement-of-the-frictional-torque-characteristics-of-radially-and-axially-loaded-radial-cylindrical-roller-bearings(be2c737c-e073-4bed-8c6d-39d4e13fd558).html.
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Continuous design and improvements in performance of roller bearings have resulted in an increased power transmission whilst size and spatial requirements have been reduced. Radial cylindrical roller bearings have followed this trend and due to their high performance characteristics (such as high loading capacity and high rotational speed capabilities), they have obtained a firm place as high performance machine elements. An essential characteristic of a radial cylindrical roller bearing is the minimisation of frictional torque for particular operating conditions. In spite of these improvements in design and operation the bearing frictional torque is still usually calculated according to the Palmgren method first published in 1957. However, as a result of the increased performance of radial cylindrical roller bearings and a corresponding wider range of application this Palmgren method is insufficiently accurate for the prediction of frictional torques in modern bearings. Whilst the literature review in this thesis identified a variety of bearing frictional torque calculation methods, most of these methods are based on various ball bearing designs and are not necessarily applicable to cylindrical roller bearings types. As a result an accurate frictional torque prediction method is required for radial cylindrical roller bearings because of customer's demands. Consequently, the current project is combined with the development of a method of frictional torque prediction (FTP - Method), which enables the frictional torque of purely radially and radially and axially loaded radial cylindrical roller bearings to be calculated accurately. The FTP - Method is based on the physical effects producing the frictional torque in a bearing, such as the EHL - theory and a contact analysis to determine raceway rolling resistance, and in addition takes into account the frictional forces of the rib / rolling element end face rolling and sliding contact. Comprehensive experimental tests have been undertaken on different radial cylindrical roller bearing designs (including cage guided and full complement types) for a minimum of three different sizes to validate the derived equations. Good agreement was obtained between the predictions according to the FTP - Method and the measured test data for the frictional torqye of both radially and combined loaded bearings. Moreover, the thermal reference speed and the thermal limiting speed of a radial cylindrical roller bearing can be readily calculated for any operating condition using an explicit equation in the radial part of the FTP - Method. The thesis also presents a calculation program to illustrate a method of bearing design based on the thermal balance within a bearing. The bearing is initially pre-selected according to its life time requirements using a life time calculation. After the lubrication method has been defined a thermal balance can be used to design the bearing.
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Wasson, Kevin L. (Kevin Lee). "Hydrostatic radial bearings for high speed precision machine tool applications." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12287.
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Wu, Jing. "Non-synchronous vibration due to internal radial clearance in roller bearings." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92376.
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Orbán, Tomáš. "Analýza radiálních kluzných ložisek s využitím pokročilých výpočtových metod." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318790.
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This master’s thesis introduces a slide bearing analysis using the MBS software tool of FEV Virtual Engine, including real surface topography based on 3D roughness measurements. The first half of the thesis gives a brief overview about gasoline combustion engines, slide bearing usage in engines, slide bearing construction and about essential approaches for the characterization of elasto-hydrodynamic behavior. In the second half, the process of model building, rough surface measurement and preparation of analyses are described. At the end of this thesis, the results of the analyses are shown and discussed.
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Vedera, Kevin G. "An Experimental Methodology for Evaluating Power Losses of Rolling Element Bearings Subjected to Combined Radial and Axial Loads." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1522933829712819.
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Klippås, Joel. "Hertz contact influence on acoustic emission signals originating in radial bearings : Test rig construction and experimental evaluation." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70088.
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During the project a test rig was constructed in which experiments were performed on radial bearings to evaluate the acoustic emission amplitude and RMS value of the signal. The acoustic emission amplitude depends on the Hertz contact time, i.e. the time it takes for the Hertz contact to roll over its own contact length. When the load remains constant on the bearing the Hertz contact time is directly reliant on the rotational speed of the inner ring of the bearing. Two experiments were performed, one on a spherical roller bearing and another identical experiment on a spherical ball bearing. Throughout both experiments the load on the bearing remained constant and the rotational speed of the inner ring was changed, the response of the speed change was measured using an acoustic emission sensor. The experiments found a quadratic dependency between the amplitude of the acoustic emission signal and the rotational speed of the inner ring. During the experiments the bearings were lubricated using grease and a total of 195 measurements were performed on each type of bearing at 13 different rotational speeds ranging between 1 and 3000 RPM.
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Struss, John Anthony. "New Methods for the Formation of Methyl Bearing Stereogenic Centers via Methylketene Dimerization and Free Radical Additions to Allyl Bromides." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/28734.
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Two organic synthetic methods for the generation of methyl bearing chiral centers have been developed using: 1) dimerization of methylketene and 2) a free radical-based addition/elimination reaction involving allyl bromides. The first method, the asymmetric dimerization of methyl ketene, followed by an asymmetric aldol reaction and the appropriate functional group manipulations enabled us to construct the (2S, 4S, 6S) trimethylnonyl subunit found in the siphonariene class of natural products. The latter method explored the stereoselective potential of a free radical-based condensation reaction by examining compounds which are known to be able to support chiral auxiliaries and chiral Lewis acids. Additionally, substituent effect on the rates of this reaction were examined closely and found to be comparable to similar, previously examined systems. The synthetic utility, magnitude and scope of this reaction are discussed.Ph. D.
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Pazdera, Ivo. "Průmyslové čerpadlo s integrovaným elektromagnetickým systémem." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233600.
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This work is focused on innovative construction of the industrial radial sealless pump and mainly on construction of the three phase DC/AC converter based on new semiconductor technology SiC. These new semiconductor devices allow move switching frequency up to 100 kHz. For such high switching frequency new non-conventional topology of the output filter was designed. This high frequency is currently unusual in three-phase application with output voltage 400V. High switching frequency reduces size of wound components of the output filter and its presence is accepted in terms of total weight and price of the whole system. Clear sinus waveform of the output converter voltage reduces torque ripple, EMC and extend the lifetime and reliability of mechanical parts and the whole pump drive. Three phase synchronous motor is directly placed into the pump body and is designed as slotless motor. In the inlet area is the classical bearing replaced by active magnetic bearing. It is used due to possibility to pump aggressive liquids or substances where high level of cleanness has to be guaranteed.
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Nonato, Fábio 1985. "Modelo dinâmico para mancais de elementos rolantes radiais de esferas considerando os efeitos da lubrificação elastohidrodinâmica." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/262999.
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Orientador: Katia Lucchesi Cavalca DediniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A representação dinâmica dos contatos mecânicos em modelos computacionais de mancais de elementos rolantes baseia-se comumente no clássico modelo de Hertz para o contato seco, mesmo sendo a presença de um meio lubrificante imperativa para evitar o desgaste prematuro destes componentes. Desta maneira, os efeitos dinâmicos da presença de um filme fluídico nas interfaces de contato são desconsiderados, quando tais mancais são lubrificados por óleo. Com o intuito de introduzir tais efeitos em um modelo de mancal de elementos rolantes de esferas, este trabalho propõe um método baseado na aproximação dinâmica das características de cada contato lubrificado por vínculos de rigidez não linear e amortecimento viscoso. Estes vínculos dinâmicos são caracterizados a partir da resposta dinâmica da simulação completa do contato elastohidrodinâmico (EHD) elíptico, através da implementação de um integrador temporal que utiliza o método de diferenças finitas em múltiplos níveis para solução da parcela hidrodinâmica do problema. Posteriormente, aplica-se a aproximação do contato EHD por vínculos não lineares a um modelo do mancal radial de esferas, de dois graus de liberdade, com o intuito de analisar vibrações transversais no mancal, em modelos computacionais de máquinas rotativas. A comparação entre os resultados obtidos pelo modelo proposto e os valores obtidos pelo equacionamento completo por diferenças finitas mostrou ser adequada à representação do comportamento estacionário e dinâmico do contato. Observa-se a presença do enrijecimento do mancal devido à presença do filme EHD, quando analisando a resposta do mancal linearizado, efeito observável anteriormente apenas em investigações experimentais. Por fim, a integração temporal de um modelo de elementos finitos de um rotor apoiado por mancais lubrificados representou adequadamente o comportamento em frequência de uma montagem experimental de rotor. Conclui-se, portanto, que o modelo não linear proposto para o mancal de elementos rolantes radiais de esfera, sob influência da lubrificação EHD, é promissor para descrever o comportamento destes componentes quando em aplicação
Abstract: The dynamic representation of mechanical contacts in computational models of rolling element bearings is commonly based on the classic Hertz's model for the dry contact, even though the presence of a lubricant medium being essential to avoid premature wear of such components. Thus, the dynamic effects of the fluid film on the contacting interfaces are overlooked when such bearings are under oil lubrication. With the intent of introducing such effects in a radial deep groove ball bearing model, this work proposes a method based on the dynamic approximation of each lubricated contact by dynamic links of non-linear stiffness and viscous damping. Such dynamic links are characterized from the response of a complete dynamic simulation of the elastohydrodynamic (EHD) elliptic contact, through an implementation of a numerical integrator, which uses the multi-level finite difference method for the solution of the hydrodynamic portion of the problem. Afterwards, the approximation of each contact by dynamic links is applied to a complete rolling element bearing model, with two degrees of freedom, with the intent of analyzing transverse vibrations on the bearings applied to rotating machinery computational models. The comparison between the results attained through the proposed model and the values simulated using the complete finite difference model showed an adequate representation of the stationary and dynamic behaviors of the contact. When evaluating the linearized bearing model, the presence of fluid stiffening is observed, which was previously only observed through experimental investigations. Lastly, the time integration of a finite element model of a rotor supported by lubricated bearings portrayed the frequency content of an experimental set-up of the rotor adequately. It is concluded that the proposed nonlinear model for the deep grove ball bearing, under the influence of the EHD lubrication, is promising to describe the behavior of such components when on application
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
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Salles, Bruno Barbosa de Oliveira Ferreira. "Otimização da superfície de deslizamento em mancais hidrodinâmicos radiais com carregamento estático." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263511.
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Orientador: Marco Lúcio BittencourtDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho tem por objetivo desenvolver um algoritmo computacional para otimização de forma da superfície de mancais hidrodinâmicos. O algoritmo usa a teoria de lubrificação elastohidrodinâmica que leva em conta a deformação elástica do mancal devido à distribuição de pressão hidrodinâmica. Esta distribuição de pressão é calculada resolvendo-se a equação de Reynolds por meio do Método de Elementos Finitos (MEF). O MEF também foi usado para calcular a deformação radial do mancal. Uma metodologia de otimização foi então aplicada para obter um novo mancal com melhor desempenho, mudando-se apenas a geometria da superfície do mancal
Abstract: The aim of this work is to develop a computational algorithm for bearing surface shape optimization. The algorithm uses the elastohydrodynamic lubrication theory that takes into account the elastic bearing deformation due to the hydrodynamic pressure distribution. This pressure distribution is calculated by solving the Reynolds equation using the Finite Element Method (FEM). The FEM is also used to calculate the bearing radial deformation. An optimization methodology is applied to obtain a new bearing with better performance characteristics by changing only the geometry of the bearing surface
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Izuka, Jaime Hideo 1974. "Dinamica de sistema rotor-biela-pistão de compressores alternativos com mancais radiais hidrodinamicos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263067.
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Orientador: Paulo Roberto Gardel KurkaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-14T09:04:50Z (GMT). No. of bitstreams: 1 Izuka_JaimeHideo_M.pdf: 3067570 bytes, checksum: 82a84bf138484b1bf94c984320ee5486 (MD5) Previous issue date: 2009
Resumo: O objetivo do presente trabalho é a modelagem dinâmica e a simulação das cargas e dos deslocamentos correntes nos mancais de um compressor alternativo. O modelo de mancal, integrado à cinética do conjunto, permite avaliar de forma precisa a influência dos pequenos movimentos dos suportes hidrodinâmicos no comportamento global do compressor. Soluções numéricas do problema de lubrificação hidrodinâmica são pesquisadas com o uso dos métodos de diferenças finitas, volumes finitos e elementos finitos. Resultados das soluções analíticas de mancal curto e longo são comparados com as soluções dos modelos numéricos de mancal. Escolhe-se assim a implementação e uso do modelo de elementos finitos para a simulação dos mancais hidrodinâmicos utilizados no compressor. O método de Newton-Euler é utilizado para a obtenção das equações diferenciais que representam o modelo de movimento do sistema dinâmico do conjunto eixo/biela/pistão. A implementação da solução numérica de mancal hidrodinâmico integrada à cinética do sistema exige um grande esforço computacional, demandando a utilização de técnicas de processamento paralelo. Assim, apresenta-se e compara-se com a literatura, os resultados de simulação de cargas e órbitas de mancais, na operação de um compressor alternativo de refrigeração.
Abstract: The present works simulates the loads and displacements of the bearings of a reciprocating compressor. The bearing model, which is integrated to the kinetics of the system, allows a precise evaluation of the influence of small movements of the hydrodynamic supports into the global behavior of the compressor Numerical solutions of the problem of hydrodynamic lubrication are studied using the methods of finite differences, finite volumes and finite elements. Results of analytical solutions for short and long bearing are compared with the numerical models of bearings. The finite element model of hydrodynamic bearings is used in the simulation of the compressor. The Newton-Euler method is used to obtain the differential equations representing the model of motion of the crankshaft/conrod/piston dynamic system. Implementation of the integrated numerical solution for the hydrodynamic bearing and the kinetics of the system requires a large computational effort, demanding the use of parallel processing techniques. The results of simulation of orbits and bearing loads in the operation of an alternative refrigeration compressor is thus presented and compared with the literature.
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Labalme, Etienne. "Synthesis and characterizations of new fluorinated membranes bearing pendant phosphonic acid groups for PEMFC application." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2013. http://www.theses.fr/2013ENCM0013.
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Ce travail de thèse s'inscrit dans la continuité des travaux de recherche réalisés sur le développent de nouvelles membranes échangeuses de protons pour piles à combustibles de type PEMFC, porteuses de groupements protogènes acides phosphoniques. L'objectif de ces travaux est d'apporter des solutions permettant l'amélioration des propriétés physico-chimiques d'un copolymère phosphoné, le poly(CTFE-alt-VEPA) obtenu à partir de la polymérisation radicalaire de vinyl éthers et de CTFE. La première stratégie employée est une stratégie Blend. Elle consiste à ajouter un polymère fluoré commercial, le poly(VDF-co-CTFE), lors de la mise en forme de la membrane. Les membranes ainsi obtenues montrent d'excellentes propriétés mécaniques et des valeurs de conductivité protonique acceptable. Cependant, lors de l'acidification du polymère phosphoné, une légère dégradation est observée. Une nouvelle technique de réticulation a alors été mise en place afin d'augmenter la stabilité vis-à-vis des acides. La réticulation de ces membranes blend a de plus permis d'améliorer la miscibilité entre le polymère fluoré et le polymère phosphoné. Enfin, les derniers travaux de cette thèse concernent la synthèse de copolymère à bloc à partir d'une stratégie RAFT. Ainsi la polymérisation radicalaire contrôle de monomère phosphoné a pu être réaliséeThis work is a continuation of research conducted on the development of new proton exchange membrane fuel cell (PEMFC), bearing phosphonic acid as protogenic groups. The aim of this work is to provide solutions with a view to improving the physicochemical properties of a phosphonate copolymer, poly(CTFE-alt-VEPA) obtained from the radical polymerization of vinyl ethers and CTFE. The first strategy used is a Blend strategy. It consists of adding a commercial fluorinated copolymer, poly(VDF-co-CTFE), during the casting of the membrane. The membranes thus obtained show excellent mechanical properties and acceptable values of proton conductivity. However, during the acidification of membrane, a slight degradation of the phosphonate copolymer is observed. A new technique of crosslinking was then established to increase the stability versus acids. The crosslinking of the blend membranes has also helped to improve the miscibility between the fluorinated copolymer and phosphonate polymer. Finally, the last work of this thesis relate to the synthesis of block copolymer from a RAFT strategy. Thus, the controlled radical polymerization of monomer phosphonated was achieved
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Amami, Lassad. "Analyse expérimentale de la réponse dynamique d'un rotor vertical guidée par desroulements avec jeu." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2254.
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L'objectif de cette thèse est l’étude expérimentale d’un rotor vertical, complexe supporté par deux paliers à roulements et deux paliers aérostatiques. Le fort comportement non-linéaire du rotor est dû aux jeux fonctionnels existants entre les bagues extérieures des roulements et les pièces du carter en vis-à-vis.Les paliers aérostatiques sont destinés à simuler la présence des joints d’étanchéité annulaires et d’apporter de l’amortissement au rotor.Le boitier d’essai est composé d'un rotor représentatif en termes de dimensions, de masse et de répartitions des inerties d’une machine réelle. Il est constitué d’un arbre et de trois disques représentant les rouets et la turbine. Le rotor est entrainé en rotation par une turbine-Pelton et guidé par deux paires de roulements et deux paliers aérostatiques à injection radiale. Le poids du rotor monté verticalement est supporté par une butée aérostatique. Un jeu fonctionnel est prévu entre les bagues extérieures des roulements et leur logement. Les essais ont visé trois valeurs de ce jeu radial (faible, modéré et élevé). L’instrumentation du banc permet la mesure des déplacements radiaux des trois disques suivant deux directions perpendiculaires et des bagues extérieures des roulements suivant une seule direction. Les analyses vibratoires sont représentées sous formes des diagrammes « waterfalls », des diagrammes « full-spectrum » et des orbites.Les réponses dynamiques des disques et des bagues extérieures des roulements ont montré l’instauration d’un comportement non-linéaire du rotor avec l’augmentation du jeu fonctionnelThe aim of this dissertation is the experimental analysis of a vertical, complex rotor supported by two pair of ball bearings and two aerostatic bearings. The strong non-linear behavior of the rotor is due to the deadband clearance between the outer rings of the bearings and the stator.Aerostatic bearings are intended to simulate the presence of annular seals and provide damping to the rotor.The test rig is composed of a rotor that reproduces the dimensions, the weight and the inertia of a real machine. It rotor consists of a shaft and three disks representing the impellers and the turbine. The rotor is entrained by a Pelton turbine and is guided by two pairs of bearings and two radial injection aerostatic bearings. An aerostatic thrust bearing supports the weight of the vertically mounted rotor. A dead-band clearance exists between the outer rings of the bearings and the housing. The tests covered three values ofthe radial clearance, small, average and large. The instrumentation of the test rig allows the measurement of radial displacements of the three disks in two perpendicular directions and of the outer rings of the bearings in one direction. The results of the vibration analysis are presented as "waterfalls" diagrams, full-spectrum diagrams and orbits. The dynamic responses of the discs and of the outer rings of the bearings showed the appearance of a non-linear behavior of the rotor with increasing the dead-band clearance
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Chiarelli, Luis Renato. "Caracterização estática e dinâmica de um banco experimental para estudo dos coeficientes dinâmicos de um mancal radial aerostático cerâmico poroso." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18146/tde-30112017-145830/.
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Este trabalho apresenta o modelo numérico de um banco experimental onde foi feita uma avaliação sobre as características estáticas do eixo e a identificação das características dinâmicas de um mancal aerostático cerâmico poroso. Nos últimos anos, o uso da cerâmica estrutural tem crescido significativamente para a concepção e fabricação de peças mecânicas. O uso da cerâmica porosa como restritor em mancais aerostáticos pode melhorar o seu desempenho relacionado com o desgaste, a estabilidade térmica, a rigidez e capacidade de carga, permitindo que eixos trabalhem com precisão a uma velocidade acima de 20.000 rpm, com pequenas folgas (40 microns). A fim de investigar este tipo de mancal foram desenvolvidas análises estáticas para obter a rigidez do eixo de suporte, assim como do mancal aerostático cerâmico poroso e identificação dinâmica para o banco experimental. As análises estáticas indicaram a rigidez do eixo e do mancal aerostático de 20,1 kN/mm e 2,6 kN/mm, respectivamente. As análises dinâmicas indicaram que a primeira frequência natural do rotor está próximo de 1365,9 Hz, o que é muito mais elevada do que a primeira frequência natural da mancal aerostático cerâmico poroso cujo valor é 775,0 Hz. Pode-se concluir que a configuração geométrica e condições de suporte escolhidos permitem uma condição robusta para prosseguir com os testes experimentais para obter as características dinâmicas do mancal poroso.This work presents the numerical model of an experimental set-up where it was made an evaluation on the static characteristics of the shaft and the identification of the dynamic characteristics for an aerostatic radial porous bearing. In recent years, the use of the structural ceramic has grown significantly for design and manufacturing of mechanical parts. The use of ceramic porous as restrictor in aerostatic bearings can improve its perform related to the wear, thermal stability, stiffness and load capacity allowing that spindles work with precision at speed above 20.000 rpm with small clearances (40 microns). In order to investigate this kind of bearing were developed static analyses to obtain the stiffness of the support shaft, as well as aerostatic porous bearing and dynamic identification for experimental set-up. The static analysis indicated stiffness of shaft and aerostatic porous bearing of 20.1 kN/mm and 2.6 kN/mm, respectively. The dynamic analysis indicated that the first natural frequency of the rotor is close to 1365.9 Hz, which is much higher than the first natural frequency of the aerostatic ceramic porous bearing whose value is 775.0 Hz. One can conclude that geometrical configuration and support conditions choosen allow a robust condition to proceed in experimental tests to obtain dynamic characteristics of the porous bearing.
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Tomeš, Jakub. "Mobilní stavební jeřáb nosnosti 200 kg." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417078.
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This diploma thesis describes mechanical design of mobile construction crane, specified for moving Silka bricks of weight 200 kg. Thesis contains constructing solution of steel frame - boom, column and chassis. Standard purchased components are also defined in this thesis - hydraulic circuits, el. pulley assembly and wheels. Last part of thesis verifies sufficient safety of designed frame using Finite element method. Output of this thesis are mechanical drawings of welded parts of steel frame and assembly drawing of entire crane.
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Liao, Xin-Wei, and 廖信瑋. "Radial passive magnetic bearing in ball bearings supporting rotor system applications." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/yvcpxc.
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碩士中原大學
機械工程研究所
102
Nowadays, magnetic systems have been applied in the industry systems widely due to the frictionless property of magnetic systems. Magnetic systems have two kinds: passive and active magnetic systems. Active magnetic systems use electronic magnet to control the subjects, such as rotors or platforms, by controlling the current to adjust the size of magnetic force. The advantage is the system stability can be confirm via tuning the magnetic force by the feedback signals, but the disadvantage is the magnetic system need additional control system and will consume the power. Passive magnetic systems use the permanent magnets to produce magnetic force. The advantage is it can be used a widely range, but the disadvantage is its magnetic force can’t be controlled, need to calculate the magnetic force. A passive magnetic bearing and a ball bearing are combined to form a hybrid bearing system in this paper. The passive magnetic bearing is used to increase the maximum radial load capacity and reduce the ball bearing load then promote the bearing life. The reasons we chosen a passive magnetic bearing are that the passive magnetic bearing system has no friction, does not need additional control, widely using environment and cheaper than the active magnetic bearing. The coordinate ball bearing is a deep groove ball bearing. The deep groove ball bearings are one of the most widely used ball bearings. Because the load capacity and life of the ball bearing are both lower than the steel ball bearing. This paper used a deep groove ball bearing with the inner radius is 10mm, the outer radius is 19mm, and the thickness is 10mm to be a test bearing. The experiment result showed that the proposed hybrid bearing can promote the bearing life. First, we calculated the radial force and axial force for the supporting system to determine the system specifications and capacity and the need of the supporting system. Then analyzed the relationship of forces and positions of the passive magnetic bearing according to the formula of the permanent magnet and to simulate the magnetic circuit with JMAG to choose a suitable set of permanent magnets to form a result with maximum radial force and minimum axial force. Finally, the passive magnetic bearing and the deep groove ball bearing are combined to test and confirm with the simulation results.
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Li, Yuan-Chen, and 李元辰. "Radial Active Magnetic Bearing System Design and Control." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/12741084332167693045.
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碩士大葉大學
電機工程學系
102
Due to the manufacturing process of products depend on high accuracy, requirement of high precision machining technology is becoming more and more important. For this reason, manufactory reduce rust in manufacturing process environment as much as possible. Therefore non-contact technology and some related technology have attracted more and more attention. Magnetic levitation (Maglev) technology is the stable equilibrium of an object without contact and can be achieved using electric or magnetic forces. In this paper, we analyze the benefit of magnetic suspended system by magnetic levitation ball system. The radial active magnetic bearing (AMB) system was developed based on analysis of magnetic levitation ball system. This paper consists system test rig, electric circuit of position sensor, transfer equation of position sensor and electric circuit of power amplifier. Controller with PID control rule was applied to maglev ball and radial AMB system. We determined PID control parameters by Routh-Hurwitz stability criterion and wrote program with C++ language for these systems. In this research, we solved control issue of magnetic levitation ball and built the radial AMB system. Finally, we used the maglev ball system and the radial AMB system test rig performing simulations and showing the experiment results.
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Yu, Shin-Shiung, and 尤信雄. "Optimal Fuzzy Control of Radial Active Magnetic Bearing Systems." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/97015535311696230151.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
91
In this thesis, a neural-fuzzy approach to develop optimal control of a highly nonlinear radial current-controlled active magnetic bearing (AMB) systems is proposed. A linear self-constructing neural fuzzy inference network is proposed to modeling the radial current-controlled AMB system first. Then, the corresponding optimal fuzzy control design scheme is obtained to stabilize the AMB system with minimize current consumption. Simulation results show that the proposed optimal fuzzy controller can provide good performance and operate in widely range of shaft position.
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Chatzisavvas, Ioannis. "Efficient Thermohydrodynamic Radial and Thrust Bearing Modeling for Transient Rotor Simulations." Phd thesis, 2018. https://tuprints.ulb.tu-darmstadt.de/7780/1/Chatzisavvas_Dissertation.pdf.
Full textAbstract:
Hydrodynamic bearings are usually employed to support rotating machines, both in
the axial as well as in the radial direction. Both bearing types influence the vibration
behavior of rotors. Moreover, the oil-temperature influences the hydrodynamic bearing
forces. In this work, efficient thermohydrodynamic bearing models for thrust and
radial bearings are developed. Run-up simulations are performed for the identification
of the influence of the bearings on the nonlinear rotor vibrations.
The Reynolds equation, which describes the hydrodynamic pressure distribution in the
bearings, is solved using a highly efficient approach. The Global Galerkin approach,
using appropriate trial and test functions, is used for the approximation of the solution
of the Reynolds equation, leading to heavily reduced simulation times when compared
with Finite Difference or Finite Element approaches. For radial bearings, a novel
semi-analytical method is developed using also the Global Galerkin approach. The
oil-temperature in the thrust bearings is captured through the energy equation, which
is decoupled from the Reynolds equation under appropriate assumptions. For the
oil-temperature in radial bearings with full- as well as semi-floating rings a global
thermal energy balance is used between the two oil-films and the bearing ring. The
transient temperature terms in this energy balance are taken into consideration and
their significance for the numerical stability of the solver is demonstrated.
A turbocharger rotor is modeled in a multibody simulation software. The complete
system consists of a flexible shaft, a turbine and a compressor wheel, as well as a
thrust bearing and two full-floating ring bearings. The equations of motion of the
turbocharger rotor are coupled with the equations of the thermohydrodynamic bearing
models and they are solved simultaneously at each time-integration step during a run-up
simulation. The simulation results show that the oil-temperature and the gas
forces in the axial direction exert a large influence on the rotor vibrations.
The geometry of the pads in thrust bearings will be optimized using a novel approach.
In this work, statistical and neural network methods are used, avoiding the drawbacks
of optimization algorithms. Usually, thrust bearings are optimized for higher load
capacity and lower friction losses. Using the proposed optimization approach, thrust
bearings can be optimized not only for load capacity and friction losses but also
towards a better vibration behavior of the complete rotordynamic system.
The validation of the thrust and the radial bearing modeling is performed through
comparisons with experimental results. For radial bearings, a standard shaft motion
test is used and for the thrust bearing a new testing approach is implemented. The
simulation results are in a good agreement with the experimental data.
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Huang, Huei-min, and 黃慧敏. "The Development of Active Radial Magnetic Bearing and Research on its Characteristics." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/42290840096715948645.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
89
For fast progress of technology and industry, high speed and precision have become necessary in high technology systems. Because of the friction force of the rotary bearing or linear bearing, systems can not achieve advanced engineering demands. contactless bearing can be treated as no friction force when air damping is ignored. Magnetic bearing is one of the contactless bearings. It can remain contactless rotation steadily and promote its rotary precision by active control method. The aim of this thesis is to develop an active radial magnetic bearing which utilizes magnetic levitation principle with actuating function and position sensing function in one module. A complete active magnetic bearing system which control 5 degrees of freedom on 3 axes is consisted of two active axial and one radial magnetic bearing. First of all, an active radial magnetic bearing which includes 4 magnetic levitation devices with actuating function and position sensing function is developed. Each two opposed levitation devices are controlled by a conjugate control method. System identification is done by experimental process. By choosing proper control factors for the experimental approved control circuit, the spindle can be steadily controlled at the neutral position of the active radial magnetic bearing. The magnetic force and magnetic field circuits are approved by finite element method and magnetic field circuit theory. The differences between theoretical and experimental results are still remained in reasonable zone. At the end, the performance testing of radial run-out by different speed is done. In conclusion, some concepts for improvement of the active radial bearing are proposed.
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WU, ZHI-BIN, and 吳志彬. "Combination Design of Axial and Radial Regulation Function for the Active Magnetic Bearing." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3mg5vk.
Full textAbstract:
碩士國立勤益科技大學
機械工程系
106
Active magnetic bearings (AMBs) have been gradually developed and applied to industrials. For the development of a full magnetic support milling spindle system, one axial AMB and two radial AMBs should be included at least. As a result, the dimen-sion of the milling spindle is usually too large for the application of machine tools. A combination design of one axial AMB and one radial AMB is reported in this work. A permanent magnet (PM) has been embedded to provide axial force to support the rotor weight so that the force specification requirement and the dimension of the axial AMB can be reduced. On the other hand, magnetic fluxes from the two AMBs share a part of the structure to further reduce the full structure dimensions. The analysis of the pro-posed design has been introduced in this paper, including the size, materials and the regulation force strength.
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Gandhi, Varun R. "High Temperature, Permanent Magnet Biased Magnetic Bearings." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-276.
Full textAbstract:
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.
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Chen, Chih-Chun, and 陳治鈞. "Improvements of Radial Force Control Drive for a SPM Type PMSM Self-Bearing Motor." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/28086412326958112352.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
97
This paper presents a radial force control scheme for self-bearing operation of a surface permanent magnet synchronous motor. The scheme is based on a self-bearing motor which consists of a set of main and a set of fictitious suspension windings. The main winding produces rotational torque, and the suspension winding produces radial force for rotor levitation. The calculated currents for these windings are combined internally in the controller. Consequently, only a set of windings is needed to produce the controllable radial force and rotational torque in the motor. An improved force model which considered the un-balanced pull force produced by the permanent magnets is also presented. Both finite element analysis and experiment verifications are performed.
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Chen, Chia-Pin, and 陳佳斌. "Analysis, Simulation, Control and Verification of the Radial Force in a PMSM Self-Bearing Motor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/u463xe.
Full textAbstract:
碩士國立臺北科技大學
電機工程系所
98
Using magnetic bearings supporting motor drive system has zero friction, low noise, high speed, high power and etc. This is current important research for electrical machinery. There are many applications in the Industry, such as spindles of machine tool, turbo molecular pump, grinding and polishing machines, compressors and air conditioners. Self-bearing motor combines of motor and magnetic bearing characteristics of the new motor which uses windings producing motor torque radial force, so the volume of self-bearing motor is small than magnetic bearing motor. The traditional self-bearing motor has suspension windings and torque winding, known as the combined winding self-bearing motor, and running must control these two winding currents. The structure of self-bearing motor stator is constituted by the concentrated winding. Every winding has suspension current and torque current, and the complex winding self-bearing motor is same things produces torque with torque-winding current and radial force with suspension-winding current. In this thesis, a single winding self-bearing motor continue from the previous self-bearing study. Radial force of self-bearing use finite element analysis(FEA) software to Analyze, simulate , verify this force which is correct. Self-bearing is surface magnet motor, 3-phase, 4 poles, 6 slots, rated power 100W and radial force 20 N.
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Kern, Colin. "Betriebsverhalten von thermisch und mechanisch hoch beanspruchten kunststoffbeschichteten Radial-Mehrflächengleitlagern." Doctoral thesis, 2011. https://monarch.qucosa.de/id/qucosa%3A19569.
Full textAbstract:
Die vorliegende Arbeit verfolgte die Zielstellung der Substitution des etablierten Weißmetalls als Laufschicht von hydrodynamischen Mehrflächengleitlagern durch neuartige Kunststoffschichten. Dazu wurden vergleichende Bauteilversuche an Mehrflächengleitlagern mit verschiedenen Laufschichten und Bohrungsformen vorgenommen. Eine Zinnbasislegierung als Laufflächenbeschichtung diente dabei als Referenzwerkstoff. Zur Durchführung des Versuchsprogrammes kam ein vorhandener, messtechnisch neu konditionierter Turbinenlagerprüfstand zum Einsatz. Die Versuchsreihen haben durchweg positive Beurteilungen der Lagerkennwerte im untersuchten Betriebsbereich der neuen Lagervarianten ergeben. Die neuartigen Laufschichtvarianten erfüllten die hohen tribologischen und thermischen Anforderungen. Einzelne Abweichungen der ermittelten Kennwerte wurden zahlenmäßig dokumentiert und können mit bereits verfügbaren physikalischen Modellen beschrieben werden. Die Ergebnisse erwiesen sich als unabhängig von der Lagerbauform aber abhängig von der gewählten Schichtvariante. Die Untersuchungen zum Betriebsverhalten unter hydrodynamischer Dauerbelastung sowie im Mischreibungsgebiet und im Notlaufbetrieb führten zu teilweise unterschiedlichen Ergebnissen. Im Mischreibungsgebiet wiesen die untersuchten Lager kaum Unterschiede im Betriebsverhalten auf. Im Dauerversuch zeigten die Lager mit Weißmetall, Gleitlack und Keramikschicht hervorragende Eigenschaften. Die Variante Klüberplast besaß eine ungenügende Bindefestigkeit und führte zu plastischen Verformungen der Schicht infolge der hydrodynamischen Drücke. Im Notlaufbetrieb übertrafen die untersuchten Kunststoffvarianten die Standzeiten des Referenzwerkstoffs Weißmetall.The aim of this study was to identify and test an alternative liner material instead of common liner materials such as white alloy for multi-lobe radial bearings. For this purpose comparative tests with different radial bearings were carried out. The white alloy material was taken as a reference. In preparation for these test series, the measurement system of the turbine bearing test rig was upgraded. Experiments showed beneficial performances of the bearings with a plastic liner by evaluating the static and dynamic properties of different bearing geometries and liner thicknesses under a wide range of operating conditions. The new bearings fulfilled the high tribological and thermal requirements. Observed deviations of the determined parameters were documented in number and can be described with available physical models. The results were independent of the bearing type and depending on the selected liner material variant. The studies on operating performance in continuous operation in the mixed friction area and in dry running operation led to partially different results. The mixed friction tests showed little difference in the examined stock performance. The bearings with white alloy, ceramic layer and bonded coating showed excellent fatigue properties of long-term experiment. On Klüberplast insufficient bonding strength and plastic deformation of the layer due to the hydrodynamic pressure was found. In the dry running operation the investigated polymers exceeded the lifetime of the referencematerial white alloy.
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Chou, Tzu-Ting, and 周孜庭. "Investigation on The Effects of Tolerancing and Fitting Condition on The Radial Pressure and Stiffness of A Roller Bearing." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5311059%22.&searchmode=basic.
Full textAbstract:
碩士國立中興大學
機械工程學系所
107
Tolerance fit is an important feature of mechanical components, it affects the performance of assembled mechanical components. The most typical representative is the fitting condition of shaft and bearing. The state of the fit affects the pressure distribution between the shaft and the hole (radial preload), which in turn affects its radial stiffness. The general bearing fit is selected according to the conditions of use, and is selected through the catalogue or calculation table of the bearing. However, this method does not consider that the shaft and the hole often produce a clearance fit due to machining tolerances, and the radial preload cannot be formed and the radial rigidity cannot be grasped. Therefore, this study is aimed at roller bearings and exploring the distribution of the interference amount when the tolerance is matched, and analyze its radial pressure and stiffness distribution. At the same time, the expected value is analyzed as the basis for designing the bearing fit tolerance. Firstly, the distribution scale distribution corresponding to the tolerance specifications of the shaft and the hole is analyzed by the probability distribution function, and the statistical distribution of the interference of the two is analyzed by convolution method. Then, according to the amount of interference, the interface pressure and stiffness of the shaft hole mating surface are analyzed. Because the interface pressure cannot be directly obtained, this study uses numerical methods to solve. The analysis method is to assume the interface pressure first, and analyze the deformation of the shaft and the hole. The algebraic sum must be equal to the interference amount. If the two are not equal, the interface pressure is adjusted according to the stiffness of the original pressure condition, and the deformation analysis is performed again until the two are equal. At the same time, the radial rigidity of the mating surface is calculated. In this paper, a roller bearing with a diameter of 50 mm is taken as an example. Carry on analysis according to the transition fitting condition H6k5 recommended by the bearing. The results show that the matching distribution part is the gap part interference, and the expected value of interference is gap of 0.5μm, which has a big gap with the original design function. It shows that is not suitable for directly using the recommended values of the bearing catalogue, and should further select the appropriate tolerance fit according to the functional requirements. The main contribution of this research is to find that the selection of tolerances of bearing catalogue cannot meet the requirements of radial stiffness. The tolerance of the bearing should be matched according to the performance requirements.
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Carello, Christian E. "Spin-Bearing Ligands Based on the 1,2,3-Dithiazole." Thesis, 2012. http://hdl.handle.net/10214/4874.
Full textAbstract:
A 1,2,3-dithiazolyl radical, [1,2,3]dithiazolyl[4,5-f][1,10]phenanthroline, has been prepared and characterized. The EPR spectrum in toluene supports a delocalized structure with an experimental g-factor of 2.0081. Cyclic voltammetry in CH2Cl2 reveals an Ecell of 1.30 V vs. SCE with a reversible +1/0 and irreversible 0/-1 redox couple. The structure belongs to the space group P-1. Complexes of the radical with Mn2+ and Dy3+ have been obtained. The mononuclear Mn2+ complex was confirmed by elemental analysis; however, no structure was determined. The structure of the mononuclear Dy3+ complex was determined by X-ray crystallography and belongs to the space group C2/c.
An isopropyl-substituted oxobenzene-bridged bis-1,2,3-dithiazolyl radical has been prepared and characterized by EPR and cyclic voltammetry. The EPR in toluene supports a delocalized structure with an experimental g-factor of 2.0091. Cyclic voltammetry in CH3CN reveals an Ecell of 0.64 V vs SCE with a reversible +1/0 and irreversible 0/-1 and +2/+1 redox couples.
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Shun-Yuan, Luo, and 羅順原. "α-Carbonyl Radical Cyclization of Cycloalkanones Bearing an Allenic Side Chain." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/55199829837733977359.
Full textAbstract:
碩士國立清華大學
化學系
88
Abstract We prepared α-iodo ketone, and used iodo-atom transfer to form α-keto radical. α-iodo radical is cyclized with allenic side chain to form vinyl spiro compound.
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MacDonald, Daniel. "1,2,3-Dithiazolyl and 1,2,3,5-Dithiadiazolyl Radicals as Spin-Bearing Ligands Towards the Design of New Molecular Materials." Thesis, 2012. http://hdl.handle.net/10214/4000.
Full textAbstract:
A series of binuclear coordination complexes of 4-(2′-pyrimidal)-1,2,3,5-dithiadiazolyl and its selenium analogue have been prepared to examine their structural and magnetic properties. The zinc(II) coordination complex is the first example of a DTDA radical ligand N-coordinated to a diamagnetic metal center. The magnetic properties reveal that it exhibits Curie behaviour and can be used as a benchmark to compare the analogous coordination complexes which possess paramagnetic metal ions. The nickel(II) coordination complex of the selenium containing radical pymDSDA was shown to dimerize in the solid state and is the only binuclear complex thus far that has done so. The manganese(II) complex of pymDSDA is by far the most interesting and is isomorphous to the DTDA analogue. For both complexes, one of the two molecules in the asymmetric unit form chains in the solid state joined by intermolecular contacts between a sulfur or selenium atom from the radical, and an oxygen atom coordinated to a neighbouring molecule. This feature gives rise to a ground state spin greater than that of an individual binuclear coordination complex. The radical ligand is however disordered in the solid state and so these random chain lengths are dependent on the orientation of the ligands in adjacent complexes.
The 1,2,3-DTA species examined herein are related to the 4,5-dioxo-4,5-dihydronaphtho[1,2-d][1,2,3]dithiazolyl radical and the related protonated species 4-hydroxy-5H-naphtho[1,2-d][1,2,3]dithiazol-5-one. The proton from this latter compound has shown that it can be substituted with alkyl groups and this was achieved using acetyl chloride to place an acetyl group in this position. The above radical did not exhibit the strong donor properties required for metal coordination and preliminary investigations of the radical dianionic suggest that it is chemically irreversible by cyclic voltametry. The acetyl group unfortunately did not provide the chemically reversibility of interest although has established a potential route toward the substitution chemistry of this compound. The other 1,2,3-DTA compounds discussed herein are not complete, although the data acquired on the precursor compounds leading up to the radical will be discussed.