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Rommelaere, Simon. "Ball Bearing Design Tool Evaluation." Thesis, KTH, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219425.
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This report has been written during my internship/master thesis at Thales Alenia Space, Cannes, FRANCE. The subject of the thesis is ball bearing design, and is focused on the software RBSDyn. This software has been developed by CNES, the French Center for Space Studies, and is used to simulate bearings behaviors under various conditions. My mission was to verify, test and implement this software for the company. In order to do so, the first step was to understand the bearing theory, which is the first part of this report. The second step was to use the software and verify its results, which is presented in the second section. Eventually, the final goal of this internship was to create a sequence to help Thales Alenia Space engineers to design and select bearings, using this software and an Excel tool that needed to be created. Note that for confidentiality reasons, the values and names used for internal TAS mechanisms have been removed of this document.Denna rapport sammanfattar ett examensarbete som utfördes vid Thales Alenia Space, Cannes, Frankrike. Ämnet var utformning av kullager för utfällbara strukturer inom rymdindustrin och fokuserade på mjukvaran RBSDyn. Denna mjukvara har utvecklats av det franska rymdcentret CNES och används för att simulera kullagers beteende när de utsätts för olika laster. Uppdraget i examensarbetet var att verifiera, testa och implementera denna mjukvara för Thales Alenia Space. Det första steget i detta arbete var att gå igenom viktiga grundläggande samband inom kullagerteori. Det andra steget var att att verifiera resultaten från RBSDyn med de grundläggande sambanden. Det sista steget var att skapa en lämplig procedur för utformning av kullager; en procedur som ingenjörerna på Thales Alenia Space kan följa för att välja och utforma kullager för olika utfällbara strukturer. Proceduren innefattar mjukvarorna RBSDyn och Excel. Av sekretessskäl så har vissa värden och namn på utfällbara strukturer utelämnats i denna rapport.
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Ribadeneira, M. Xavier. "Ball bearing diagnostics with multiple sensors." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18963.
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Hergert, Robert J. "Rotary micro-ball bearing designs for MEMS applications." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/40060.
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Micro-electro-mechanical systems (MEMS) technology allows the fabrication of small mechanical systems in silicon using standard micro-fabrication pro- cesses. MEMS techniques have found wide acceptance in such devices as ac- celerometers, micro-mirrors, resonators, probes, and micro-tweezers to name a few. Though small linear motions are common in MEMS applications, few devices exhibit reliable rotary motion. This work explores several methods of fabricating rotary bearings using micro-balls as the support mechanism. Micro-ball bearings have several advantages over other MEMS bearing tech- nologies in that they provide robust mechanical support, require no external control systems, and basic designs require very few fabrication steps. Ball cages or retainers are common in macro-scale bearings, providing uniform spacing between the balls. Several cage designs are proposed and explored in this work: a radial ball bearing with an integrated ball cage, a dual-row style cage, and ve unique cage geometries integrated into silicon micro-turbines (SMTs.) Also, an example of a curved or angular contact race- way is presented as an example of this type of raceway geometry in MEMS devices. Each is presented with a discussion of the design considerations and fabrication process. This is followed by a characterization of the performance of each design. These studies found that the integrated cage in the radial ball bearing performs well at speeds ranging up to 20 000RPM. Minimal wear was ob- served after 6 hours of continuous testing. However, the solder bond in the cage was a common failure point in these devices, limiting the reliability and longevity. The dual groove style cage was designed to eliminate the solder bond. However, the higher frictional forces between the ball and the cage in this design resulted in higher losses during operation. Taking into account the higher losses and the added complexity of the design, it seems unlikely that this approach would be appropriate for further study. However, the design does represent a novel approach for releasing multi-wafer rotary structures and is presented here as example of this technique. Testing of the cage de- signs for the SMTs indicated that a full ring design (a full annulus with holes for the balls) performed the best of the 5 cage geometries. However, these devices do not perform as well as cage-less designs for high speed applications due to higher ctional forces and increased raceway wear at the interface be- tween the ball and the raceway edge. Finally, the curved raceway has shown excellent performance up to 2500RPM with normal loads up to 40mN in tribometer testing. SMTs with this raceway desing were also tested for over 10 million revolutions and at speeds over 70 000RPM. The test results for all of the bearings designs presented here show that the devices exhibit stable operation at low to moderately high speeds.
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Adolfsson, Erik. "Simplified finite element bearing modeling : with NX Nastran." Thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255398.
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This report was produced at the request of ABB Robotics and the work was conducted at their facilities in Västerås, Sweden. In the development of industrial robots the structures are slimmed to increase the accuracy and speed. When conducting finite element analysis on the robots the accuracy of the component modelling and definitions of the boundary conditions becomes more important. One such component is the ball bearing which consist of several parts and has a nonlinear behavior where the balls are in contact with the rings. The task given was to develop new methods to model roller bearings in Siemens finite element modelling software NX Nastran. Then conduct a strain measurement, to compare the methods to real experimental values. The goal with the report is to find one or more methods to model roller bearings, with accurate results, that can beused in their development work. The report was conducted by first doing a study on bearings and finite element modeling, and learning to use the software NX Nastran. Then the development of the methods were done by generating ideas for bearing models and testing them on simple structures. Nine methods was produced and a tenth, the method used to model bearings today, was used as a reference. The methods was used to build bearing models in a finite element model of a six axis robot wrist. Simulations were done on the models with different load cases and the results were compared to a strain measurement of the wrists real counterpart. Only six of the models were analyzed in the result, since four of the models returned results that were deemed unusable. When compiling the result data no model was found to accurately recreate the stresses in every load case. Three methods, that allow deformation, performed similarly. One of them is suggested to be used as modelling method in the future. Worst of the methods, according to the results compiled, was found to be the method used today. It fails to describe local stresses around the bearing. For continued work it is suggested that linear contact elements is studied further. Four out of five models constructed with linear contact elements failed to return satisfactory results.
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Gunduz, Aydin. "Multi-Dimensional Stiffness Characteristics of Double Row Angular Contact Ball Bearings and Their Role in Influencing Vibration Modes." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1326397623.
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Westsson, David. "Simulation of torque caused by the lubrication fluid in a ball bearing." Thesis, Umeå universitet, Institutionen för matematik och matematisk statistik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-126563.
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Hirst, Derek John. "Failure of the elastohydrodynamic lubrication of ball bearing components at very high speeds." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676730.
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Sandström, Tobias. "Condition Monitoring of Ceramic Ball Bearings in an Engine Testing Dynamometer." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183126.
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The choice of the topic addressed in this thesis aims to improve the service and maintenance on ceramic ball bearings in a specific test dynamometer and through an engineering approach develop tools for condition monitoring. The company connected to this thesis, AVL, is the world's largest privately owned company for development, simulation and testing technology of powertrains for passenger cars, trucks and large engines. Engine testing is a critical part of the business at AVL Sweden and unexpected bearing failure can result in long repair times and great economic losses due to loss of the testing time. In short terms, the methodological approach followed the following steps; first a thorough information retrieval regarding bearings and analysis was conducted. The search was deepened around areas such as hybrid ball bearings, bearing failure mechanisms, bearing defect frequencies, signal analysis and condition monitoring. After this a table for bearing damage detection was developed and a “step by step” guidance for condition monitoring. The tools where afterwards verified by simple testing to detect complications within the chosen system. The existing condition monitoring system that is used today revealed weaknesses as it lacked the feature of taking preventive measures. The system that is based on temperature measurements isn’t satisfactory enough, especially when it’s missing visual clarity. Service and maintenance according to specifications from the manufacturer should be scheduled to ensure operational and guarantees. Currently mounted accelerometers on the housing of the Dynas3 engine should be connected for collecting data and the total sum of energy should be calculated for simple monitoring of historical progression. This should be done by following the guidance in order to ensure proper data acquisition. The best way to implement condition monitoring showed to be by performing multi-parameter monitoring. The design of the condition monitoring system is highly connected to what to monitor and at what stage. One main consideration to keep in mind is that it’s very rare that manufacturing defects are the reason for bearing failure. Instead it derives from improper storage, transport, handling or dimensional errors and even in some cases by improperly implemented force analysis prior to bearing selection.Huvudämnet som behandlas i detta examensarbete syftar till att förbättra service och underhåll på keramiska kullager i en viss testdynamometer och genom ett ingenjörsmässigt tillvägagångsätt utveckla verktyg för tillståndsövervakning. Företaget som är ansluten till detta examensarbete är AVL som är världens största privatägda företag för utveckling, simulering och testteknik för drivlinor för personbilar, lastbilar och stora motorer. Motorprovning är en viktig del av verksamheten vid AVL Sverige, och ett oväntat lagerhaveri kan leda till långa reparationstider och stora ekonomiska förluster på grund av utebliven test tid. I korta termer följde den metod som använts följande steg, först genomfördes en grundlig informationssökning om lager och tillhörande analyser. Efter det fördjupades sökande kring områden som hybrida kullager, lagerskademekanismer, frekvenser kopplade till lagerskador, signalanalys och tillståndsövervakning. Efter detta framställdes en tabell för detektering av lagerskador, samt en ”steg för steg” guide för tillståndsövervakning. Verktygen för tillståndsövervakning kontrolleras efteråt, genom att enkla tester genomfördes för att upptäcka komplikationer inom det valda systemet. Det övervakningssystem som används idag avslöjade svagheter genom att sakna funktionen att vidta förebyggande åtgärder. System som är baserat på temperaturmätningar är inte tillräckligt tillfredsställande, speciellt när det saknar en visuell tydlighet. Den service och underhåll som enligt tillverkarens föreskrifter påvisas bör planeras för att säkerställa drift och garantier. Nuvarande monterade accelerometrar fästa vid motorhöljet bör anslutas för att insamla data, och den totala summan av energin bör beräknas för en enkel övervakning av det historiska utvecklingsförloppet. Detta bör göras genom att följa de riktlinjer som framställts för att säkerställa korrekt datainsamling. Det bäst passande sättet att genomföra tillståndsövervakning på i detta fall visade sig vara att utföra multiparameterövervakning. Framställningen av tillståndsövervakningssystemet är starkt förknippat med vad som skall övervakas och i vilket skede. En huvudsaklig bidragande faktor att komma ihåg är att det är mycket ovanligt att fabrikationsfel är orsaken till lagerhaveri. Istället härstammar haveriet från felaktig förvaring, transportering, hantering eller dimensioneringsfel och i vissa fall av felaktigt genomförd kraftanalys inför lagerval.
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Karlsson, Alexander, and Eric Marcus. "Evaluation of Strain and Temperature Measurements with Fiber Bragg Grating for Loss Verification and Heat Transfer of Ball Bearings." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86149.
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Volvo Cars is in a change of producing only electric and hybrid cars by 2025.Subcomponent testing is a crucial part to ensure the quality of the individual buildingblocks in an electric machine. Any way of making these tests more reliable and less timeconsuming is of great interest at Volvo. Force and temperature on bearings are especiallyhard to measure accurately, because of their placement and dynamic behavior. Accurateand reliable measurements is also a vital part in creating realistic Computer-AidedEngineering (CAE) models for simulation purposes. Simulations on bearings could lead tobetter bearing choices and accelerate the design process. This could increase bearing lifeand increase the Electrical Vehicle (EV) range due to minimized friction losses. FiberBragg Grating (FBG) sensors is a technology that has some key advantages overconventional sensors. They are immune to EMI, smaller in size, can have multiple sensorsin one fiber and can measure multiple physical quantities at the same time. Volvo Cars isinterested in investigating whether this sensor technology could be a candidate forreplacing some of the current measurement setup configurations.The project was divided into three parts, validating sensor equipment, find method forinstallation and measurement on a bearing and development of a CAE model for bearinglosses and heat transfer. To validate the sensor equipment a Measurement SystemAnalysis (MSA) was performed on two FBG fibers, one FBG isolated from strain fortemperature measurement and one FBG array with multiple sensing points. From theMSA it could be seen that the FBG temperature sensor had a total uncertainty of 3.4 °CThe FBG array had a strain uncertainty of 1.04 μ𝜀 and a temperature uncertainty of 0.4 °C.The uncertainty of both the FBG array and the FBG temperature sensor is highlydependent on the calibration of the sensitivity constant. The force measurement on thebearing was done with a concept based on the wavelength difference, produced by strain,between two FBG sensors. The concept was tested in a dynamic component rig where anaxial force could be applied, and the wavelength difference measured. The temperatureon the outer ring of the bearing was measured using an FBG isolated from strain. The testresults were promising, but since the FBG is sensitive to temperature and strain theincreased temperature difference between the two fibers affected the results. Thecalibration method needs to be compensated for the increased temperature differencebetween the fibers which is generated when the rotational speed is increased, and thiscould not be done with a single temperature measurement. The two developed CAEmodels was both constructed in MATLAB and showed similar behavior with experimentaltests done by others. To validate the models, physical test for heat transfer and bearinglosses should be performed.
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Zhang, Qingning. "Experimental and analytical investigation into the two stage turbocharging systems for diesel engines." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707566.
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The work described in this thesis aims to conduct a systematic study of the two stage turbocharging system to improve the Diesel engine transient performance as well as NOX and CO2 emissions with a focus on the improved turbocharger matching and the control of the charging system, through the use of high fidelity engine models backed by experimental results. To perform the analytical study, commercial 1D simulation software has been used in the process of system characterisation and control strategy design. To validate the analytical results, a two stage turbocharging system was installed on a production diesel engine and tested on a transient engine test bench. The test results were then used to further calibrate the 1D engine/turbocharger model. Several other technologies were also investigated in simulation to explore their potential to further improve the system. Unlike most studies in the literature, this project focused on the system benefit of the engine and turbochargers, instead of conducting optimisation solely at the component level. The engine global parameters, such as the engine fuel consumption, emission levels and the transient response were the main parameters to be considered and were also best suited to the strengths of the 1D simulation method. The interactive use of both the analytical and experimental methods was also a strong point of this study. A novel control strategy for the system was proposed and demonstrated in the simulation. Experiments confirmed the validity of this control strategy and provided data for further model calibration. The comparison of the test results of the baseline engine to those obtained with the two stage turbocharged engine system verified the benefits of the novel turbocharging arrangement and control scheme. Transient response (T1090) was improved, with a 50% faster torque rise at 1000 rpm; the fuel consumption over the NEDC was 4% lower and NOx emissions over the NEDC were 28% lower. In the meantime, the study also revealed shortcomings of the system, such as the lack of EGR control at low speed, low load condition and a mid-speed fuel consumption deterioration of 13% on average at 3000 rpm due to excessive back pressure. With a novel 1D model corroborated using test results, exploratory simulation was done to rectify the aforementioned shortcomings and to further improve the system. Simulation results showed that by implementing VGT and ball bearing technology in the high pressure stage of the two stage system, the EGR controllability at low speed was regained and the excessive back pressure at high speed was improved. Consequently, the fuel consumption was only increased by 1.3% compared to the baseline NEDC operation and the transient response was on par with the original two stage system, with only 0.05s slower in torque rise at 1000 rpm, and still 48% faster than the baseline VGT system. Furthermore, the NOx emission can be expected to be greatly improved in the upcoming more intensive drive cycles compared to the NEDC cycle, with simulation showing NEDC NOX emissions dropped by 1%, comparing to a substantial reduction of 11% in WLTC.
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Dyson, John Edwin. "Aspects of the behaviour and design of dental high speed ball bearing air turbine handpieces." Thesis, University of London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324587.
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Solomon, Nomonde. "Effect of HPGR on platinum bearing ores and the flotation response as compared to the conventional ball mill." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11277.
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Includes abstract.Includes bibliographical references.
This thesis focuses on the application of the high pressure grinding rolls (HPGR) on platinum bearing ores Merensky, UG2 and Platreef. Conventional tumbling mills such as the ball mill that are typically applied on these ore types are highly energy intensive with a small percentage of the input energy being used for actual breakage. Rapidly increasing energy costs have contributed to the rising interest of the HPGR in the platinum industry, particularly in plants processing UG2 and Platreef ores. Therefore, this thesis seeks to determine if the HPGR can be used as an alternative to the ball mill. Key aspects of interest are throughput, energy efficiency, PGE grade and recovery and PGM liberation.
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Endicott, Roger A. "Immunoregulation of T-lymphocyte proliferative activity by alveolar macrophages from mice bearing Lewis lung carcinoma tumors." Virtual Press, 1986. http://liblink.bsu.edu/uhtbin/catkey/458971.
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The immune regulatory abilities of alveolar macrophages from C57B1/6 mice bearing a metastatic variant of Lewis lung carcinoma were determined. During early stages of tumor development, or before tumors metastasized to the lungs, alveolar macrophages did not affect or slightly enhanced T-lymphocyte proliferation; as tumor growth progressed, or following tumor metastasis, alveolar macrophages suppressed the T-cell response. Macrophage suppressor activity was probably not mediated by their production of PGE, since macrophages of tumor-bearing mice secreted less 2 PGE than did macrophages of normal mice. Normal alveolar 2 macrophages or macrophages preincubated in tumor cell supernatant for a short period stimulated T-cell blastogenesis and secreted PGE during in vitro culture. However, with 2 longer exposure to tumor cell supernatant, alveolar macrophages lost the capacity to augment T-cell proliferation and secreted less PGE 2.Ball State UniversityMuncie, IN 47306
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Kucukyilmaz, Ali. "Experimental Investigation Of Residual Stresses Introduced Via Shot Peening And Their Effect On Fatigue Life Of Ball Bearings." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12611494/index.pdf.
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In this study, residual stresses introduced via application of shot peening on the raceways of bearing rings and their effect on the fatigue life was investigated experimentally. For improvement of residual compressive stress state, shot peening operation with different parameters was utilized. Residual stress measurements were conducted via X-ray diffraction technique. Optimization of residual stress state during the production of ball bearings is the main target of this study. Process parameters for shot peening and super-finishing were studied for determination of the parameters that induce the most favorable residual stress state. The fatigue life of ball bearings were determined by life cycle tests and tabulated to show the results of the study. The results of the thesis are believed to help for optimization of residual stress distribution and improvement of service life of ball bearings.
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Hjalmarsson, Joel, and Anes Memic. "FE Analysis of axial-bearing in large fans : FE analys av axialkullager i stora fläktar." Thesis, Linnaeus University, School of Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-6663.
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Detta examensarbete har utförts på Fläktwoods AB i Växjö, som producerar stora axialfläktar för olika industriapplikationer. Syftet är att öka kunskapen om fettsmorda axiella kullager genom FE analyser.
Projektet har genomförts i fem delsteg för att avgöra påverkan av en eller några få parametrar i taget. De studerade parametrarna är: elementstorlek, kontaktstyvhet, last, lagergeometri (dvs. oskulation), ickelinjär geometri och ickelinjära materialegenskaper (dvs. plasticitet).
Slutsatsen är att elementstorleken bör väljas fint nog för att ge ett jämnt resultat men grovt nog för att beräkningstiden skal vara rimlig. Kontaktstyvheten har inte stor, men tydlig, inverkan på kontakttrycket och penetrationen. Förändringar av oskulationen leder till förändringar i kontaktellipsens form medan olika laster inte påverkar formen på ellipsen, utan snarare storleken. När det handlar om plasticitet är sträckgränsen den viktigaste faktorn att beakta.
This thesis project was carried out at Fläktwoods AB in Växjö who produces large axial fans for different industry applications. The purpose is to increase the knowledge of grease lubricated axial ball bearings through FE analyses.
The project was executed into five sub steps to determine the influence of one or few parameters at a time. The studied parameters are: mesh density, contact stiffness, load, bearing geometry (i.e. osculation), geometrical nonlinearity and material nonlinearity (i.e. plasticity).
It is concluded that the mesh density should be selected fine enough to give a smooth result but course enough to give a reasonable calculation time. The contact stiffness has not a major, but a clear, impact on the contact pressure and penetration. Changes of the osculation lead to changes of the contact ellipse shape and applying different load level does not affect the shape of the ellipse but rather the size. When dealing with plasticity the yield strength is the most important factor to take in consideration.
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Dawud, Sattar J. "Analysis of the tribological behaviour of stainless and ball bearing steels sliding in the presence of sulphur extreme-pressure additives." Thesis, Aston University, 1985. http://publications.aston.ac.uk/10583/.
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Xin, Ge. "Sparse representations in vibration-based rolling element bearing diagnostics." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI051/document.
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Bien que le diagnostic des roulements par analyse vibratoire soit un domaine très développé, la recherche sur les représentations parcimonieuses des signaux de vibration est encore nouvelle et difficile pour le diagnostic des machines tournantes. Dans cette thèse, de méthodes nouvelles ont été développées, au moyen de différents modèles stochastiques, associées à des algorithmes efficaces afin de servir l’industrie dans le diagnostic des roulements. Tout d’abord, les modèles parcimonieux présentés dans la littérature sont revus. Les principales publications concernant le diagnostic des machines tournantes ont également été considérées. Enfin, en discutant des avantages et des inconvénients des représentations parcimonieuses, une interprétation des structures creuses d’un point de vue Bayésien est proposée, ce qui donne lieu à deux nouveaux modèles de diagnostic des machines tournantes. Dans un second temps, un nouveau modèle stochastique est proposé : il introduit une variable cachée relative à l’apparition d’impacts et estime le contenu spectral des transitoires correspondants ainsi que le spectre du bruit de fond. Cela donne lieu à un algorithme de détection automatique - sans besoin de pré-filtrage manuel - à partir duquel les fréquences de défaut peuvent être révélées. Le même algorithme permet également de filtrer le signal de défaut de manière très efficace par rapport à d’autres approches basées sur l’hypothèse stationnaire. La performance de l’algorithme est étudiée sur des signaux synthétiques. L’efficacité et la robustesse de la méthode sont également vérifiées sur les signaux de vibration mesurés sur un banc d’essai (engrenages et paliers). Les résultats sont meilleurs ou au moins équivalents à ceux de l’analyse d’enveloppes classique et du kurtogramme rapide. Dans un troisième temps, un nouveau schéma pour l’extraction de signaux cyclostationnaires (CS) est proposé. En considérant la variance périodique en tant que variable cachée, un filtre temporel est conçu de manière à obtenir la reconstruction intégrale des signaux CS caractérisés par une fréquence cyclique préétablie, qui peut être connue à priori ou estimée à partir de la corrélation spectrale. Un intérêt particulier de la méthode est sa robustesse lorsqu’elle est appliquée sur des données expérimentales ainsi qu’une capacité d’extraction supérieure par rapport au filtre de Wiener conventionnel. Finalement, ces exemples expérimentaux témoignent de l’utilisation polyvalente de la méthode à des fins de diagnostic de signaux composés. Pour finir, une analyse comparée utilisant le calcul rapide de la corrélation spectrale est réalisée sur une base de données publiquement disponible et largement utilisée. C’est un point crucial qui fixe un défis non-trivial à résoudreAlthough vibration-based rolling element bearing diagnostics is a very well-developed field, the research on sparse representations of vibration signals is yet new and challenging for machine diagnosis. In this thesis, several novel methods have been developed, by means of different stochastic models, associated with their effective algorithms so as to serve the industry in rolling element bearing diagnostics. First, the sparsity-based model (sparse code, in natural image processing) is investigated based on the current literature. The historical background of sparse representations has been inquired in the field of natural scenes. Along three aspects, its mathematical model with corresponding algorithms has been categorized and presented as a fundamental premise; the main publications are therefore surveyed in the literature on machinery fault diagnosis; finally, an interpretation of sparse structure in the Bayesian viewpoint is proposed which then gives rise to two novel models for machinery fault diagnosis. Second, a new stochastic model is introduced to address this issue: it introduces a hidden variable to indicate the occurrence of the impacts and estimates the spectral content of the corresponding transients together with the spectrum of background noise. This gives rise to an automatic detection algorithm – with no need of manual prefiltering as is the case with the envelope spectrum – from which fault frequencies can be revealed. The same algorithm also makes possible to filter out the fault signal in a very efficient way as compared to other approaches based on the stationary assumption. The performance is investigated on synthetic signals with a high noise-to-signal ratio and also in the case of a mixture of two independent transients. The effectiveness and robustness of the method are also verified on vibration signals measured on a test-bench (gears and bearings). Results are found superior or at least equivalent to those of conventional envelope analysis and fast kurtogram. Third, a novel scheme for extracting cyclostationary (CS) signals is proposed. By regularizing the periodic variance as hidden variables, a time-varying filter is designed so as to achieve the full-band reconstruction of CS signals characterized by some pre-set characteristic frequency. Of particular interest is the robustness on experimental data sets and superior extraction capability over the conventional Wiener filter. It not only deals with the bearing fault at an incipient stage, but it even works for the installation problem and the case of two sources, i.e. bearing and gear faults together. Eventually, these experimental examples evidence its versatile usage on diagnostic analysis of compound signals. Fourth, a benchmark analysis by using the fast computation of the spectral correlation is provided. One crucial point is to move forward the benchmark study of the CWRU data set by uncovering its own unique characteristics
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Harris, Joel Mark. "Static characteristics and rotordynamic coefficients of a four-pad tilting-pad journal bearing with ball-in-socket pivots in load-between-pad configuration." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3194.
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Silva, Levi Nascimento da 1974. "Influência da rugosidade na resistência à fadiga de rolamentos de esferas de contato angular produzidos por usinagem dura." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265857.
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Orientador: Amauri HassuiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Em virtude do aumento da concorrência, as montadoras de veículos têm exercido pressões sobre os fornecedores participantes da longa cadeia produtiva no sentido de reduzir custos e aumentar a agilidade no desenvolvimento de novos produtos, sem negligenciar a qualidade e a confiabilidade das peças. Na fabricação de autopeças, por exemplo, quando se pensa em tolerâncias pequenas e em acabamento de peças endurecidas, há discussões sobre o uso da retificação convencional ou do torneamento duro. Estudos mostram que a retificação traz maiores custos, tempos de preparação maiores e impactos ambientais negativos e apresentam, como alternativa mais eficiente, o torneamento e faceamento contínuo ou interrompido de peças endurecidas com perfis retos, como os rolamentos com discos axiais. Ao invés de rolamentos axiais, neste trabalho, foi proposto o processo de torneamento duro para fabricar as pistas de rolagem em rolamentos de esferas de contato angular utilizados em sistemas de embreagem. Neste caso, diferentemente dos rolamentos axiais com perfil reto, o tornamento foi do tipo contínuo com perfil côncavo em que, à medida que a ferramenta avança, o contato da aresta de corte com a peça e, consequentemente, a seção do cavaco gerado variam. Duas velocidades de corte foram utilizadas, sendo mantidos constantes o avanço e a profundidade de corte. Características como parâmetros de rugosidade, circularidade, raio e forma da pista, coeficientes de simetria, achatamento e razão de material, dentre outros, foram controlados e comparados com amostras com pistas retificadas. A vida em fadiga de rolamentos é determinada por uma boa lubrificação e pelo bom acabamento das pistas. Quando um dos dois falha, ocorre desprendimento de material das pistas, seguido pelo começo de fraturas abaixo da superfície de contato. Por isso, após a fabricação, o controle e a montagem das amostras, foram realizados também ensaios comparativos de durabilidade. Os resultados encontrados permitiram concluir que as pistas fabricadas por torneamento duro, com as ferramentas e parâmetros utilizados apresentaram vida útil menor que aquelas produzidas por retificação
Abstract: The automotive markets have become more competitive and the car makers push the suppliers in the productive chain to focuse on cost reduction and fast development of new products, without neglecting quality and reliability. Regarding autoparts manufacture process, with small tolerances and finishing of hard parts, there are discussions about the use of conventional grinding or hard turning. Studies show that grinding increases costs, preparation times and negative environmental impacts and point out, as more effective process, the continuous or interrupted hard turning or hard facing in hard components with straight profile, such as thrust bearings with discs. Instead of thrust bearings, the aim of this work is to propose the hard turning of raceways in contact ball bearings used in clutch systems. In this case, the turning was continuous with concave profile: while the tool moves, the cut edge contact with the component and consequently the generated chip section change. Two cut speeds were used and feed rate and cut depth have been remained constant. Characteristics like rougheness parameters, roundness, raceway radius and its profile, skewness, kurtosis and bearing ratio were measured and compared with those in specimens with ground raceways. The fatigue life in ball bearings is determined by good lubrication and raceways with good finishing. When one of them fails, it occurs material deterioration (spalling) followed by cracks under the contact surface. For that reason, after manufacturing, measurements and assembly of the specimens, comparative durability tests were performed. The results could assess that the raceways manufactured by hard turning with toolings and defined parameters showed reduced fatigue life in comparison to specimens made by grinding
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Bizarre, Leticia 1990. "Modelagem de forças de contato não lineares em mancais de elementos rolantes de contato angular." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265812.
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Orientadores: Katia Lucchesi Cavalca Dedini, Fábio Nonato de PaulaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Com a necessidade da diminuição do tempo de projeto, a utilização de modelos computacionais para simulação de componentes constitui fase fundamental no projeto preliminar de máquinas e equipamentos e permite avaliar parâmetros de projeto para minimizar testes físicos em protótipos. Dentro deste contexto, o trabalho aqui apresentado segue dando continuidade à modelagem de mancais de elementos rolantes, neste caso esferas, anteriormente desenvolvido para contato puramente radial. O estudo da dinâmica de mancais de elementos rolantes e a compreensão de sua modelagem computacional permitem conhecer sua influência sobre o sistema completo. Será inserido o modelo de lubrificação Elastohidrodinâmica (EHD) no modelo dinâmico do mancal, permitindo obter parâmetros equivalentes de rigidez e amortecimento, para posterior caracterização do mancal, utilizando uma análise no domínio do tempo. Uma vez estimada a distribuição de forças, são calculados parâmetros de carga e lubrificação, bem como a geometria no contato, os quais são utilizados no modelo EHD. Este último contém a soluçãodas equações que descrevem o comportamento da região lubrificada, empregando o método numérico de multi-níveis. Desta forma, calcula-se a pressão no contato e a espessura de filme. Utiliza-se uma aproximação para as forças não lineares na região em que a relação entre força e deformação no contato tem comportamento aproximadamente linear. Nesta região, os parâmetros físicos de rigideze de amortecimento total do conjunto esferas, pista interna e pista externa são estimados, e também para cada uma das esferas, tendo em consideração a presença do contato angularnas esferas e a aplicação de forças nas direções axial e radial
Abstract: Considering the necessity of decrease design time, the use of computer models for simulation of components is an essential phase in the preliminary design of machinery and equipment and allows to evaluate design parameters to minimize physical tests on prototypes. Inside this context, the work presented here follows continuing the modeling of rolling element bearings, in this case balls, previously developed for pure radial contact.The dynamics study of the rolling element bearings and the understanding of their computer modeling allow us to know its influence on the complete system.The model for Elastohydrodynamic lubrication (EHD) is inserted in the dynamic model of the bearing, and this allows to obtain equivalent parameters of stiffness and damping, for further characterization of the bearing using a time domain analysis.After the estimated distribution of forces, lubrication and load parameters are calculated, as well as the geometry of the contact, which are used in EHD model.The latter contains the solution of equations that describe the behavior of lubricated region, using the numerical method of multilevel.Thus, the contact pressure and film thickness are calculated.It is used an approximation to the nonlinear forces in the region where the relation between force and deformation of the contact has approximately linear behavior.In this region, the physical parameters of stiffness and damping of the complete set spheres, inner raceway and outer raceway are estimated, and also, for each sphere is taking into account the presence of the angular contact of the spheres, and the application of forces in both axial and radial directions
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestra em Engenharia Mecânica
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森, 敏彦, Toshihiko MORI, 健治 広田, Kenji HIROTA, 進幸 千田, and Shinko SENDA. "プラネタリ・ボール・ローリング (PBR) 加工による円管内外表面同時仕上げ." 日本機械学会, 2002. http://hdl.handle.net/2237/9025.
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Calderon, Salmeron Gabriel Benjamin. "Enabling More Efficient E-Mobility : Grease Development by a Novel Bearing-Grease Test Machine." Thesis, KTH, Maskinkonstruktion (Avd.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259672.
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The inclusion of electric vehicles in the automotive industry represents an opportunity for lubricating grease producers. Different speed, loads, and electric conditions are present in the bearings of the electric vehicles when compared with the conditions in a traditional internal combustion engine vehicle. Therefore, the development of new grease formulations is desired to overcome these, and other challenges introduced by this new technology. This project aims to compare two grease-thickener technologies through the installation, development, and validation of a novel high-speed bearing-grease test HSBT machine. This rig allows emulating the conditions present in the bearings of an electric vehicle. In this thesis, 6208 deep groove ball bearings were used to compare the mechanical performance of the greases. The comparative study of lithium complex and polypropylene greases was performed through the analysis of the frictional moment and self-induced temperature of the tested grease-bearing combinations. The results present the energy-saving potential of both greases and show the feasibility of using the HSBT machine as a grease testing machine. This project is the first step in an ambitious plan of enhancing e-mobility through grease research. It gives the input for future development of the machine and the creation of new standards for testing electric vehicle greases.Införandet av elfordon i bilindustrin utgör en möjlighet för smörjfettproducenter. Olika hastigheter, belastningar och elektriska förhållanden är närvarande i de elektriska fordonens kullager i jämförelse med förhållandena i ett traditionellt förbränningsmotorfordon. Detta kräver utveckling av nya fetter som kan hantera de utmaningar som uppkommer med denna nya teknik. Detta projekt ämnar jämföra två fettförtjockningstekniker genom att installera, utveckla och validera en ny höghastighetslagermaskin (HSBT-maskin) för smörjfettstestning. Denna maskin möjliggör att förhållanden som finns i lagren hos ett elektriskt fordon kan efterliknas. I denna masteruppsats användes spårkullager med beteckningen 6208 för att jämföra smörjfettens mekaniska prestanda. I denna studie jämfördes litiumkomplex- och polypropenfetter genom att analysera friktionsmomentet och den självinducerade temperaturen för de testade kullagersmörjfettskombinationerna. Resultatet av studien visar energibesparingspotentialen för båda smörjfetterna och visar möjligheten att använda HSBT-maskinen för att testa smörjfetter. Detta projekt är det första steget i en ambitiös plan att förbättra e-mobilitet genom smörjfettsforskning. Studien ger indata för framtida utveckling av elektriska maskiner och bidrar till skapandet av nya standarder för testning av fetter för elektriska fordon.
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Liew, Andrew Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A study of a rotor system with ball bearing induced non-linearities; and the development of transfer matrix techniques suitable for analysing such systems." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2003. http://handle.unsw.edu.au/1959.4/19227.
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This thesis is concerned with enhancing analysis tools for evaluating the non-linear dynamics of rotor bearing systems and in particular those where non-linearity is likely to result in aperiodic or chaotic behaviour, such as rolling element bearing systems. The tool to be enhanced was the transfer matrix approach which has been extensively used in the past for analysing linear rotor bearing systems. However, its use for evaluating non-linear behaviour has been virtually non-existent. Hence, the major aim of the thesis is to extend transfer matrix capabilities to handle non-linear systems. To this end a harmonic balance transfer matrix technique capable of analysing non-linear systems with multiple pedestal supported bearings was first developed. However, this approach is restricted to periodic response. To enable the analysis of non-linear systems with non-periodic response and provide a stability check for the harmonic balance technique, a transient transfer matrix has also been developed. The softwares for both of these newly developed transfer matrix techniques have been successfully verified for various non-linear rotor bearing systems using an established system matrix based transient rotordynamics software as the yardstick. These developments have been published in refereed journals. To investigate systems with rolling element bearings, appropriate bearing modelling which incorporates angular contact and rolling element inertia needed to be developed and incorporated into transient analysis softwares. Theoretical results from this were compared to data obtained from an experimental test rig which was designed to represent the salient features of an F/A-18 aircraft mounted accessory drive. The rig allowed for variation of bearing preload, unbalance loading and bearing support stiffness and could be run up to 17,000rpm. Full details of the design and commissioning are presented. Results showed better agreement than linear analyses but significant differences were encountered. Errors were largely due to estimated bearing parameters, in particular bearing damping, which was found to be a sensitive variable, so that agreement between theory and experiment was mainly qualitative. Other sources of error were those associated with experimental measurement and limitations of the bearing modelling. Further improvement of the bearing model is needed if better quantitative agreement is to be obtained between the predictions and experiment.
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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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Демянчук, Є. М. "Дослідження методами обчислювальної гідродинаміки рідинних динамічних сил, які діють на обойму кріогенного кулькового підшипника кочення при гідродинамічному режимі змащення." Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/82115.
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Методика дослідження включає в себе методи обчислювальної гідродинаміки. В процессі буде розлянутий турболентній потік рідини кріогенного середовища у обертовій області з прецесійним рухом. Моделювання кульового підшипника при залученні методів обчислювальної гідродинаміки. Цей процесс розглядає турбулентний потік рідини кріогенного середовища у обертальній області з прецесійним рухом обойми та кульками, що обертаються при різній швидкості обертання. Дослідження було зосереджине на аналізі динамічних сил рідини, котрі мають дію між обертовими кульками та обоймою, яка рухається по прецесії, і тут же розглядаємо область між обоймою та внутрішнім обертовим та звовнішнім нерухомими кільцями данного підшипника. Проведено порівняння моделюввань та експериментів для моменту тертя при різних швидкостях обертання. Тепловий аналіз проводився з адіабатними стінками і не враховував теплопередачу між рідиною і твердими тілами.
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Valenta, Jakub. "Vývoj metody pro hodnocení režimu mazání ve valivém ložisku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417738.
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The aim of this master’s thesis is to develop measuring methods for evaluation of the lubrication regime in a rolling bearing. The first part of thesis maps several measuring methods according to which the lubrication mode can be evaluated. Based on the assessment of this part, electrical monitoring methods were selected. For application of these methods was constructed testing device with rolling bearing. Specific measuring chains based on selected methods were designed and verified by using initial tests on a ball-on-disk tribometer. According to the results of these initial measurements was selected and applied suitable measuring chain to the selected test device. In the end, there was a successful measuring the lubrication parameter on the rolling bearing. Additionally, other tests dealing with the influence of temperature and type of oil on the measurement itself were performed.
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Hjerpe, Stefan. "Längdmätning i engreppsskördare." Thesis, Växjö University, School of Technology and Design, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-1534.
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Detta examensarbete har gjorts på uppdrag av SP Maskiner AB och berör längdmätningsenheten på skördaraggregatet SP451LF. Pulsgivaren i den befintliga längdmätningen anses inte nå en acceptabel livslängd och därför skall ett sensorlager prövas som ersättare.
Uppdraget består i att söka ett lämpligt sensorlager, dimensionera en komplett mäthjulslagring samt att ta fram ett konstruktionsförslag till prototyp på längdmätning.
Arbetet begränsas av att den omkonstruerade längdmätningen skall passa på SP451LF aggregatet. Det betyder att längdmätningens infästning mot aggregatet inte får förändras och dess yttermått måste hållas inom de gränser som aggregatets chassi tillåter.
This diploma work has been done on commission by SP Maskiner AB and affects the length meter unit on the single-grip harvester SP451LF. The pulse encoder in the present length meter has too short duration why a sensor-bearing will be tested as replacement.
The tasks are to find a suitable sensor-bearing unit, to dimension a complete measuring wheel bearing and create a construction proposal for a prototype of a length meter.
The diploma work is limited by the fact that the reworked length meter has to fit into the SP451LF harvester. That means that the length meter’s contact points on the harvester’s frame are not to be altered.
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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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Alsairafi, Abdullah Issa. "Numerical and Experimental Investigation of the Manufacturing Process of Ball BearingsFocusing on Enhancing the Aesthetics of the Outer Surface by Removing the ShiningBand." Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1527013271365695.
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Niel, Dimitri. "Etude du comportement thermomécanique de paliers à roulements pour une application hautes vitesses." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI007/document.
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Avec l’apparition de moteur électrique dans le secteur automobile, les réducteurs mécaniques fonctionnent à des vitesses de rotation de plus en plus élevées. Pour ce type de réducteur, les pertes de puissance au niveau des paliers à roulements peuvent être prédominantes pour des vitesses de rotation élevées. Ces pertes sont fortement dépendantes du comportement thermique du palier à roulement. D’où l’intérêt de développer des outils numériques permettant d’estimer les puissances générées au sein d’un palier à roulement. Cette estimation permettra en phase de pré-étude de développer un dispositif de refroidissement adapté afin d’éviter tout risque de dégradation du palier à roulement. Cette thèse présente une nouvelle approche permettant d’étudier le comportement thermomécanique de palier à roulement. Cette approche intermédiaire requiert un minimum de paramètres d’entrée (géométrie externe du palier à roulement et condition de fonctionnement). Elle utilise la méthode dite « des réseaux thermiques » pour obtenir une interconnexion entre les pertes de puissance et le comportement thermique du palier à roulement. Enfin cette approche permet de calculer la puissance dissipée au sein d’un roulement et les températures des bagues et du lubrifiant principalement pour une application hautes vitesses. Cette approche est développée pour des roulements à billes à gorge profonde et contact oblique. Des valeurs expérimentales sont nécessaires pour valider cette nouvelle approche. C’est pourquoi, un nouveau banc d’essai modulaire dédié à l’étude du comportement thermomécanique de palier à roulement a été développé. Sur ce nouveau moyen d’essai, une grande variété de paliers à roulements peut être testée pour différentes conditions de fonctionnement. Pour les premiers essais, un roulement à billes à gorge profonde lubrifié par injection est testé pour un fonctionnement hautes vitesses (produit (n×D_m) supérieur au million)Rolling Element Bearing (REB) is an essential component in mechanical transmission to reduce friction between rotating parts. Now, with the development of electrical motor in mechanical industry, REBs may work at very high rotation speed. It leads to an increase of REB power losses and temperatures. Theses power losses are strongly coupled with the REB thermal behaviour. The oil temperature has a significant impact on the kinematic viscosity which in turn affects the REB power losses. Based on thermal network approach, an intermediate model is developed in this study. This new model allows obtaining lumped information (temperature of rings) with a minimum of input data (REB external geometry and operating condition only) and by using global power loss models. This intermediate model is developed for angular contact ball bearing and deep groove ball bearing under oil jet lubrication for high speed application. Experimental data are required to validate this new approach. That why, a modular test rig is designed to obtain information on the REB thermomechanical behaviour. The new test rig developed in this study is dedicated to a wide range of REB dimensions and for different operating conditions. For the first test, a deep groove ball bearing under oil jet lubrication is studied for high speed application ((N.dm) product is higher than one million.)
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Hedberg, Joakim, and Per Rundström. "Konstruktion av lagerlösning till en TFM generator för vindkraft." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264434.
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Detta kandidatexamensarbete syftar till att konstruera ett förslag på en lagerlösning till en generator av typen TFM [1], utvecklad av Anders Hagnestål vid KTH, som är tänkt att användas i vind- eller vågkraft. Generatorn alstrar inre elektromagnetiska krafter som ger upphov till påfrestningar på dess konstruktion, inte minst på de kullager som håller generatorns struktur på plats. Valet av lager föll på ett axialkullager i hybridutförande då den betydande delen av den elektromagnetiska kraften verkar rent axiellt. Hybridlagret består av keramiska kulor mot en kulbana av lagerstål, en kombination som motstår högre tryck än axialkullager med stålkulor. Keramiska kulor används främst för att undvika problem med elektriska urladdningar mellan lagerbana och kula, vilka uppkommer på grund av switchtransienter i strömmen från kraftelektroniksystemet. Lagrets placering i generatorn är av stor vikt, något som togs i beaktning för att minimera utböjningen i konstruktionen. Fokus har lagts på att analysera utböjningen av rotorskivan och de punkter där trycket på kullagret är som störst, dvs i kontaktytan mellan kulan och lagerbanan. Hertz yttryck användes för att beräkna kontakttrycket mellan kula och lagerbana och Finita Element Metoden för att beräkna utböjningen av rotorskivan.The purpose of this Bachelor thesis project is the design of a bearing solution for a TFM generator [1], developed by Anders Hagnestål at KTH, suitable for windand wave power. The generator produces inner electromagnetic forces that puts stress on the generators architecture. The bearings will have an essential role in withstanding the force from the electromagnets. The most suitable solution was a hybrid axial bearing since the electromagnetic forces are mainly in the axial direction. The hybrid bearing consists of ceramic balls and a steel bearing race, a combination being able to withstand pressures better than axial bearings with steel balls. Ceramic balls are mainly used to avoid electrical discharges between the bearing race and balls. These discharges occur due to switchtransients in the current from the powerelectronic system. The placement of the bearing in the generator is of great importance and has to be considered to minimize the displacement of the rotor discs. The project is focused on analyzing the displacement of the rotor disc and the area with greatest pressure in the bearing, this area occurs in the contact point between the ceramic ball and the steel bearing race. Hertzian contact pressure was used for the contact pressure between the ball and the bearing race and the Finite Element Method for calculating the displacement of the rotor disc.
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Švestka, Jiří. "Studie pístového čerpadla s inversním kuličkovým šroubem a zatopeným motorem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230201.
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This thesis is focused on study of piston pump with ball screw and submersed motor. Theoretic part is about study using pump and ball screw. Equations for description of pump, motor and ball screw are in computation part. And in last part is construction of pump and valve. Valve is computed in CFD.
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Štol, Michal. "Konstrukční návrh 3-osého manipulátoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229497.
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This thesis deals with design of 3 axis manipulator which manipulate wit ball bearing and moulding of pulley. Moulding of pulley is product of injection press. Part of this work is also technical-economics valuation of manipulating possibilities with ball bearing and pulley and is determinate the most useful option. Next is work out a conception of conveyor for ball bearings and pulleys.
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Azianou, Ayao Elewovem. "Modélisation numérique de la durée de vie de roulements à bille à gorges profondes montés dans des alternateurs automobiles." Thesis, Reims, 2015. http://www.theses.fr/2015REIMS007/document.
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Les conditions de fonctionnement rencontrées dans la problématique de nouvelles générations d'alternateurs automobiles avec des chargements variables et un environnement mécanique complexe déformable ont un effet non négligeable sur le comportement mécanique du roulement et par conséquent sur sa durée de vie. Il est proposé dans ce travail une approche permettant de prendre en compte ces paramètres dans l'estimation de la durée de vie des roulements. La répartition des efforts obtenue des considérations statiques sont utilisés dans un modèle dynamique simplifié permettant de déterminer de l'état de contrainte au cours du temps dû au passage de billes sur la piste de roulement. L'approche multi-échelle de Dang Van couplée à une loi de cumul d'endommagement a permis de déterminer le nombre de cycles avant l'apparition des premiers signes de fatigue. La dernière phase du travail concerne l'aspect expérimental qui a montré que le phénomène de fatigue n'est pas la seule cause de dégradation des roulements montés dans les alternateurs automobilesThe operating conditions encountered in the new generations of automotive alternators with variable loads and a deformable complex mechanical environment have a significant effect on the mechanical behavior of the bearing and hence its fatigue lifetime. An approach that takes into account these parameters in the ball bearing fatigue lifetime has been proposed in this work. The load distribution obtained from static considerations are used in a simplified dynamic model in order to determine the time-dependent stress state due to ball rolling on the raceway. The Dang Van multiscale approach coupled with a damage law was applied to determine the number of cycles before the apparition of the first signs of fatigue. The last phase of work involves the experimental aspect that shows that the fatigue phenomenon is not the only cause of degradation of bearings mounted in automotive alternators
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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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Gomez, Chirinos José Luis. "Angle modeling of a rotating machine. Application to wind turbine surveillance." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI067/document.
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Ce travail de recherche s'inscrit dans le cadre de la surveillance des machines tournantes en régime non stationnaire et plus particulièrement la détection des défauts de roulement. Il se focalise sur la modélisation et l'analyse des variations de la vitesse de rotation instantanée. Les modèles numériques développés s'appuient sur une approche originale dite " angulaire " qui introduit explicitement les degrés de rotation libres de la machine et permet de s'affranchir de condition de fonctionnement en régime stationnaire. Un modèle de roulement à billes à gorge profonde a été développé couplant les efforts de contact normaux et tangentiels grâce à l'introduction du phénomène de résistance au roulement. Ce couplage permet d'expliquer l'origine des fluctuations de vitesse de rotation en présence de défaut de bague extérieure, phénomènes constatés expérimentalement : la présence d'un défaut sur une bague modifie périodiquement le couple de frottement. La modélisation de la liaison par engrenages est plus classique, la problématique a été de s'assurer qu'elle était compatible avec l'approche angulaire utilisée dans ces travaux. Le couplage des éléments de roulement et d'engrenage dans un modèle simple a montré que la présence de défauts de roulement provoque des variations des efforts radiaux ce qui modifie les efforts d'engrènement et en conséquence perturbe également la vitesse de rotation. Un modèle simplifié d'une éolienne a été réalisé et utilisé pour tester et valider des indicateurs spectraux de surveillance en conditions de fonctionnement non stationnaires. La comparaison avec des mesures expérimentales issues d'une éolienne a montré la robustesse du modèle. Il peut donc être exploité comme un outil d'analyse phénoménologique et de test d'indicateurs de surveillance. Il a par exemple permis de montrer l'importance des conditions de fonctionnement (charge et vitesse) sur le niveau des indicateurs utilisés en surveillance. Si besoin, les développements proposés peuvent être étendus sans difficulté à des modèles plus complexes de roulements, d'engrènements et de structures d'accueil de ces éléments technologiquesThis work has been developed within the framework of non-stationary rotating machinery surveillance with emphasis on the detection of roller bearing defects. It focuses on the modeling and analysis of instantaneous angular speed variations. The numerical models developed are based on an ``angular" approach which introduces explicitly the machine's free body rotation degrees of freedom allowing simulations in non stationary operating conditions. A deep groove ball bearing model has been developed coupling tangential and normal forces by taking into account the rolling resistance phenomenon. This coupling allows to explain the origin of angular speed fluctuations in the presence of outer race roller bearing defects, phenomena that has been observed experimentally: a roller bearing defect periodically modifies the friction torque. The description of the gear mesh has been performed by means of a classic approach where the scientific issue has been to verify the compatibility with the angular modeling, cornerstone of this dissertation. Integration of the roller bearing and the gear modeling approaches into a simple mechanical architecture has shown that the presence of bearing defects provoking variations in the rolling element-races normal forces, modifies the gear mesh forces leading to perturbations of the angular speed. A simplified wind turbine model has been used for the test and validation of non stationary surveillance spectral indicators. The robustness of the model has been shown by means of a comparison with measurements performed on a wind turbine. It has allowed to show the importance of the operating conditions (load and speed), on the level of indicators used. This means the model may be used as a tool for phenomenological analyses as well as a device to test surveillance indicators. If needed, the approaches presented may be easily extended into more complex models of bearings, gears, casings and foundations
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Lacroix, Samy. "Analyse et validation expérimentale d'un modèle de roulement à billes à quatre points de contact à bagues déformables par découplage des effets locaux et structuraux." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0073/document.
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Les roulements à billes sont l’un des composants les plus importants et les plus critiques dans les turbomachines ou dans les éoliennes. Les butées à billes rencontrées dans les pieds de pales d’éoliennes doivent supporter des chargements très élevés, avec des bagues très fines par rapport aux dimensions du palier. Le roulement à quatre points de contact à haute vitesse est un autre exemple de bagues minces, où la cinématique interne est fortement liée à la géométrie des pistes qui elle, dépend de la rigidité des bagues et des logements. Pour cette application, les pistes intérieures et extérieures sont archées et bien souvent constituées de deux demi-bagues. La souplesse de ces dernières ainsi que celle du logement modifie la géométrie interne et l’interaction entre les composants. Il est proposé dans cette thèse un modèle permettant de dimensionner des roulements à billes à quatre points de contact, principalement dans le domaine d'application des turbines aéronautiques. Ce modèle est capable de rendre compte des déformations globales des bagues et de leur logement et environnement proche. Un ensemble de travaux existants et différentes possibilités envisagées pour la mise en place d’un modèle de roulement à bagues déformables est présenté pour définir une stratégie de couplage efficace entre un modèle analytique et un modèle éléments finis. La prise en compte de la souplesse des bagues s’appuie sur la résolution préalable d’un problème semi analytique de modélisation avec bagues rigides. Ensuite un couplage entre les résultats de ce modèle et un modèle éléments finis est réalisée pour prendre en compte la souplesse des bagues. Des choix sont nécessaires pour ce couplage, notamment sur la modélisation des contacts billes/bagues par l’utilisation de forces nodales pour simuler fidèlement ces contacts. Plusieurs méthodes sont ainsi évaluées pour calculer au mieux la nouvelle géométrie de la bague, en observant son comportement lorsqu'elle est soumise au contact d'une bille. Finalement, cette souplesse est intégrée au modèle semi analytique pour comparer le comportement d'un roulement à bagues rigides à celui d'un roulement à bagues souples. Des premiers résultats numériques sur une géométrie académique montrent des variations des grandeurs internes du roulement (angles de contact, ellipse de contact) ainsi qu’une meilleure répartition du chargement. Des essais ont été réalisés pour valider expérimentalement le modèle développé dans cette thèse. Les comparaisons par mesures du déplacement axial des bagues et des ondulations en surface des bagues montrent que la souplesse du support n’est pas négligeable, même dans le cas de bagues larges. Egalement, ces essais ont démontré la pertinence du couplage entre un modèle analytique et un modèle éléments finis pour rendre compte des déformations de bagues de roulements à billes à quatre points de contactBall bearings are one of the most important and most critical part in turbomachine and wind turbine. They require a careful design in order to create reliability and economic relevance, which leads to compact bearings with high dynamic and static load capacity. Then ball bearing encountered in wind turbine must carry high loads, with thin rings regarding mean diameter of the bearing. High speed four point contact ball bearing is another example of thin rings, where internal kinematics is highly linked to raceway geometry, and raceway geometry depends on rings and housing stiffness. For this application, internal and external ring are arched and frequently made of two parts. There stiffness change the internal geometry and interaction with bearings components. It implies a change in load distribution and internal speed. As a consequence bearing and housing stiffness is an important parameter in order to estimate the admissible loads for the bearing. This thesis propose a model for the four point contact ball bearing, mainly for aeronautical turbine engine. This model can account for structural ring deformation as well as of housing deformation. Some existing work and different possibility for such a model are presented in order to define a coupling strategy between an analytical model and a finite element model. The accounting for ring stiffness rely on the resolution of a rigid ring semi analytical model. Then a coupling between this results and finite element results is done in order to account for ring stiffness. Some choices are made for the coupling, especially on ball/ring interaction by using nodal forces to model contact with fidelity. Some methods are evaluated to compute new ring geometry due to contacts with balls. Finally this stiffness is integrated in the semi analytical model in order to compare the behavior of rigid ring bearing with deformable ring bearing. First numerical results on an academic bearing shows change in internal parameter (contact angle, contact ellipse) and a better load distribution. Some experimental tests are made in order to validate the model presented in this thesis. Comparison on axial displacement and ring surface undulation shows that housing stiffness is not negligible even with large ring bearing. This tests show the relevance of a coupling between an analytical model and a finite element model in order to account for ring deformation in four point contact ball bearing
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Hebrard, Yoann. "PHM Autonome : Application au roulement intelligent." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI004.
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Dans un marché aéronautique en plein essor marqué par une croissance rapide du parc d’avions utilisées à travers le monde, l’optimisation de la maintenance devient une préoccupation pour les avionneurs. Il s’agit de maximiser la disponibilité des aéronefs tout en réduisant les couts directs d’exploitation sans compromis sur la sécurité des hommes et en respectant les contraintes environnementales. Une stratégie possible pour relever ce challenge est de renforcer la capacité à anticiper les défaillances afin de recourir à des actions préventives le plus juste possible sur les composants les plus critiques comme les roulements à billes. La mise en œuvre de processus de Prognostic Health Management (PHM) prend ainsi une part grandissante et le processus de pronostic est considéré comme l’un des principaux leviers d’action. Son déploiement requiert que le comportement du système étudié puisse être observés. Il peut ainsi bénéficier de l’apport des récentes avancées dans le domaine des microsystèmes autonomes en énergie permettant des mesures intelligentes et un transfert de données d’une manière distribuée, sans aucune aide externe. L’association de ses deux champs de recherche mène naturellement vers le roulement intelligent qui pourrait être la transition d’une maintenance programmée à une maintenance prédictive. Cependant les solutions de PHM autour du roulement et le roulement intelligent, ne restent pas moins le fruit de l’évolution des techniques et technologies de surveillance, de récupération d’énergie et de connectivité. C’est dans ce cadre que s’inscrit ce mémoire de thèse par Validation des Acquis de l’Expérience (VAE). Il s’articule en trois parties principales : motivations du VAE, état de l’art autour du roulement mécatronique et exemple de contributions autour de la récupération d’énergie et la communication sans fil à des fins de surveillanceThe aeronautic market is growing and the aircraft fleet size is becoming bigger. Maintenance optimization is a key focus for liner since objectives are to maximize the aircraft availability and to reduce the direct cost of ownership with no compromise on the flight security and safety with respect to environmental standards. To meet this challenge one possible strategy is to apply a PHM approach using the recent advance in the autonomous embedded microsystem field. This PhD work presents some work done around energy harvesting and wireless sensor to enable a smart bearing able to measure the usage and health data from the component in the purpose of predictive mainteance
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El-Tayeb, Nabil Said Mohamed. "The dynamic properties of ball bearings." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366386.
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Holland, Michael L. "Assembly Optimization for Double Row Ball Bearings." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/37009.
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This thesis is a treatise on optimal assembly methods for double row ball bearings. As with common single row bearings, double row ball bearings, consist of four general components, namely, an inner ring, an outer ring, a complement of balls and a cage or retainer to keep the balls separate. Unlike single row bearings, however, double row ball bearings have two complements of balls in two distinct parallel races. Although this double row configuration is desirable in a number of applications, it makes the bearings more difficult and expensive to assemble. In addition, current manual assembly procedures require a great deal of digital manipulation, leading to concern about carpal tunnel syndrome and other long-term repetitive motion injuries.
This thesis attempts to develop an improved assembly process for all types of double row bearings. Although the work is intended to be general, the Torrington 5203 double row ball bearing is adopted as a specific application example. This bearing's assembly difficulties and additional cost are a result of its manual Conrad assembly method and a rubber O-ring and groove used solely for bearing assembly. In the assembly process, the O-ring supports the upper balls temporarily until the two rings can be aligned concentrically, thus snapping the balls into the bearing races. This thesis addresses the replacement of the rubber O-ring and explores opportunities for bearing assembly automation.
Design synthesis of a retractable or reusable assembly component to replace the rubber O-ring supporting the upper balls during assembly is presented. A large group of design concepts are developed and evaluated, resulting in a small group of feasible designs. These feasible solutions are then tested, and a design that has the potential immediate implementation in an improved manual assembly process is proposed. In addition, two design concepts are presented as candidates for possible implementation in an automated assembly process.
Master of Science
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Levesque, George. "Critical flaw size in silicon nitride ball bearings." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041089.
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Shakya, Piyush. "Data fusion based diagnosis and prognosis of ball bearings." Thesis, IIT Delhi, 2015. http://eprint.iitd.ac.in:80//handle/2074/8174.
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Berthe, Laure. "Durée de vie des contacts rugueux roulants." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0097/document.
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La tenue des surfaces des contacts rugueux roulants est un problème crucial l’évaluation de la durée de vie des mécanismes. Cette durée de vie est conditionnée dès les premiers cycles par le rodage puis par les mécanismes de fatigue des surfaces. Le rodage est défini par le temps nécessaire à l’accommodation géométrique des surfaces rugueuses entre elles, à l’interface du contact. La charge transmise sur une faible aire de contact par rapport à l’aire apparente, crée des pressions importantes qui induisent de fortes contraintes en couche superficielle et des déformations plastiques de la microgéométrie. Cette plastification a lieu dans les tous premiers cycles puis la surface se stabilise, c’est le rodage. La répétition cyclique des sollicitations au cours du fonctionnement conduit enfin à l’endommagement du matériau et des avaries en surface telles que des micro-écailles. Après une étude bibliographique sur le contact roulant rugueux et les dispositifs expérimentaux existants, la difficulté de ce type d’analyse est mise en évidence. Elle consiste à effectuer un suivi en continu de l’évolution de l’état de surface du contact à une échelle suffisamment fine et précise. Une micromachine bi-disque a été développée afin de réaliser ce suivi quasi "in-situ" à l’échelle des rugosités permettant d’identifier les mécanismes de rodage et de dégradation. Un protocole expérimental précis permet de mesurer les surfaces antagonistes dans les premiers cycles correspondant au rodage. Les surfaces vierges mesurées sont utilisées comme paramètre d’entrée d’une simulation numérique du contact rugueux d’une sphère sur un plan. La déformée de surface numériquement obtenue à l’état stabilisé est comparée à celle mesurée expérimentalement à la fin du rodage. La très bonne superposition de ces résultats permet de valider cette méthode et les résultats numériques tels que les contraintes résiduelles et déformations plastiques. Les surfaces à l’état stabilisé obtenues, sont exploitées à travers différents critères de fatigue multiaxiaux. Les résultats numériques sont également comparés aux observations expérimentales pour déterminer le critère le plus adapté à cette analyse et permettant d’expliquer la formation de fissures et d’avaries de surfacesThe surface life of rolling rough contacts is an important problem in the evaluation of the life expectancy of a machine. This life span is conditioned by the first cycles of the running-in process and then by the surface fatigue. The running-in period is defined by the time necessary for the rough surfaces to accommodate. The real area of contact is small compared with the apparent area, hence the load creates important pressures which lead to important stresses in the superficial layer and to plastic deformation of the microgeometry. The plastic deformation takes place over the first cycles then the surface stabilizes, this is the end of running-in process. The repeated cyclic loading finally leads to material damage below the surface and to surface micropitting. After a bibliographical study on the rough rolling contact and the existing experimental test machines, the difficulty of analysing the roughness evolution is pointed out. It requires a precise, continuous monitoring of the contact surface evolution on a small enough scale. A two-disk micro-machine was developed to perform this almost "in situ" monitoring at the roughnesses scale, allowing one to identify the mechanisms of running-in and surface degradation. An accurate experimental protocol allows one to measure the opposing surfaces in the first cycles corresponding to the running-in period. The initial surfaces are used as entrance parameters for a numerical simulation of the rough contact of a sphere on a plane. The deformed surface numerically obtained in the stabilized state is compared with the measured one at the end of the running-in period. The very good agreement between these results allows one to validate this method and the numerical results such as the residual stresses and the plastic deformation. Different multiaxial fatigue criteria are applied to the numerical results obtained in the stabilized state. The results are compared to the experimental observations to determine the criterion that is the most suited for this analysis and allows one to explain the crack formation and surfaces damage
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Rühlicke, Ingo. "Jacking and Equalizing Cylinders for NASA- Crawler Transporter." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200569.
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For the transport of their spacecraft from the vehicle assembly building to the launch pads at Kennedy Space Centre, Florida, the National Aeronautics and Space Administration (NASA) is using two special crawler transporters since 1965. First developed for the Saturn V rocket the crawler transporters have been sufficient for all following generations of space ships so far. But for the new generation of Orionspacecraft which is under development now, a load capacity increase for the crawler transporter of plus 50% was necessary. For this task Hunger Hydraulik did develop new jacking, equalizing and levelling (JEL) cylinders with sufficient load capacity but also with some new features to improve the availability, reliability and safety of this system. After design approval and manufacture of the cylinders they have been tested in a special developed one-to-one scale dynamic test rig and after passing this the cylinders had to prove their performance in the crawler transporter itself. This article describes the general application and introduces the technical requirements of this project as well as the realized solution.
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Akturk, Nizami. "Dynamics of a rigid shaft supported by angular contact ball bearings." Thesis, Imperial College London, 1993. http://hdl.handle.net/10044/1/7359.
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Khanam, Sidra. "Vibration analysis and feature extraction of ball bearings with local defect." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7033.
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Toumi, Mohamed Yessine. "Étude de l'endommagement des composants mécaniques soumis à de la fatigue de roulement dans le cadre d'une maintenance prédictive : cas des butées à billes." Thesis, Reims, 2015. http://www.theses.fr/2015REIMS033.
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Le roulement est un élément essentiel dans la conception des machines tournantes. À l'échelle industrielle, sa défaillance peut avoir de coûteuses conséquences. La maintenance prédictive sert à minimiser les coûts d'entretien et à prévenir de l'état de fatigue du composant mécanique. Dans ce cadre, nous proposons une étude de l'endommagement par fatigue de contact de roulement appliquée au cas des butées à billes. Cette étude se structure en deux axes : numérique et expérimental. Le premier consiste à établir une modélisation numérique tridimensionnelle dynamique du passage cyclique d'une bille sur une bande de roulement en présence d'un indent, en utilisant la méthode des éléments finis. L'estimation de l'évolution de la taille d'un défaut d'écaillage initié en surface en fonction des cycles de chargement est effectuée. Ces résultats sont en adéquation avec les essais en laboratoire effectués dans les mêmes conditions à l'aide d'un banc d'essais de fatigue dédié aux butées à billes. Le deuxième axe consiste à déterminer un indicateur vibratoire utilisant l'analyse modale et permettant d'estimer le niveau d'endommagement de la butée à billes in situ en présence d'indent. La technique développée dans ces travaux permet de suivre l'évolution des valeurs de l'amortissement modal en fonction des cycles de vie, évolution déterminée à partir des essais en modes statique et dynamique. Cette étude contribuera à l'estimation de la durée de vie résiduelle du composant mécanique après apparition d'un écaillage en surface, en utilisant la méthode des éléments finis et en prenant compte de l'état d'endommagement de la structureThe bearing is an essential element in the design of rotating machines. In an industrial context, bearing failure can have extremely costly consequences. Predictive maintenance minimizes the intervention costs and warns about the state of fatigue of the mechanical component. In this frame, we propose a study of the rolling contact fatigue damage applied to thrust ball bearings. This study is twofold: numerical and experimental. The first axis consists in establishing a dynamic three-dimensional numerical model of the cyclic shift of a ball on a running surface in the presence of an indent, using the finite element method. An estimation of the size evolution of a surface initiated spall depending on loading cycles is also performed. These results are consistent with laboratory tests executed in the same conditions using a fatigue test rig dedicated to ball bearings. The second axis consists in determining a vibratory indicator using modal analysis to estimate the on-line structural damage level of the ball bearing in the presence of an indent. The technique developed in this work enables monitoring the evolution of the modal damping values based on the life cycles determined from tests in static and dynamic modes. This study will contribute to estimate the residual life of the mechanical component after onset of a spall using the finite element method and accounting for the structural damage state
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Nejedlý, Vladislav. "Analýza a inovace elektrických motorků pro automobily." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218796.
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In this thesis analysis and inovation of electric machines for cars is discused. There are described principles of basics DC and AC electric machines. In detail this thesis deals with small electric machines used in cars. At least, electro motor for wiper is investigated and possibilities of its inovation in different ways are also mantioned.
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Pinckney, Francis Douglas. "Air-oil mist lubrication of small bore ball bearings at high speeds." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/104537.
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Martin, M. J. "Elastohydrodynamic films and scuffing behaviour in high speed angular contact ball bearings." Thesis, Cardiff University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543267.
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