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Scherb, Bruno Johannes. "Prediction and measurement of the frictional torque characteristics of radially and axially loaded radial cylindrical roller bearings." Thesis, University of South Wales, 1999. https://pure.southwales.ac.uk/en/studentthesis/prediction-and-measurement-of-the-frictional-torque-characteristics-of-radially-and-axially-loaded-radial-cylindrical-roller-bearings(be2c737c-e073-4bed-8c6d-39d4e13fd558).html.
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Continuous design and improvements in performance of roller bearings have resulted in an increased power transmission whilst size and spatial requirements have been reduced. Radial cylindrical roller bearings have followed this trend and due to their high performance characteristics (such as high loading capacity and high rotational speed capabilities), they have obtained a firm place as high performance machine elements. An essential characteristic of a radial cylindrical roller bearing is the minimisation of frictional torque for particular operating conditions. In spite of these improvements in design and operation the bearing frictional torque is still usually calculated according to the Palmgren method first published in 1957. However, as a result of the increased performance of radial cylindrical roller bearings and a corresponding wider range of application this Palmgren method is insufficiently accurate for the prediction of frictional torques in modern bearings. Whilst the literature review in this thesis identified a variety of bearing frictional torque calculation methods, most of these methods are based on various ball bearing designs and are not necessarily applicable to cylindrical roller bearings types. As a result an accurate frictional torque prediction method is required for radial cylindrical roller bearings because of customer's demands. Consequently, the current project is combined with the development of a method of frictional torque prediction (FTP - Method), which enables the frictional torque of purely radially and radially and axially loaded radial cylindrical roller bearings to be calculated accurately. The FTP - Method is based on the physical effects producing the frictional torque in a bearing, such as the EHL - theory and a contact analysis to determine raceway rolling resistance, and in addition takes into account the frictional forces of the rib / rolling element end face rolling and sliding contact. Comprehensive experimental tests have been undertaken on different radial cylindrical roller bearing designs (including cage guided and full complement types) for a minimum of three different sizes to validate the derived equations. Good agreement was obtained between the predictions according to the FTP - Method and the measured test data for the frictional torqye of both radially and combined loaded bearings. Moreover, the thermal reference speed and the thermal limiting speed of a radial cylindrical roller bearing can be readily calculated for any operating condition using an explicit equation in the radial part of the FTP - Method. The thesis also presents a calculation program to illustrate a method of bearing design based on the thermal balance within a bearing. The bearing is initially pre-selected according to its life time requirements using a life time calculation. After the lubrication method has been defined a thermal balance can be used to design the bearing.
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Carlos, Anderson Almeida. "Relação entre o rendimento do motor de partida e o torque resistivo de um motor diesel submetido à partida em baixas temperaturas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265097.
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Orientador: Pedro Teixeira LacavaDissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-18T16:57:57Z (GMT). No. of bitstreams: 1 Carlos_AndersonAlmeida_M.pdf: 15995318 bytes, checksum: baaba56f9c2c8d35c3ae72468050a525 (MD5) Previous issue date: 2011
Resumo: Em baixas temperaturas, as condições de partida do motor tornam-se mais difíceis devido a diversos fatores, como por exemplo, a menor lubrificação devido ao aumento da viscosidade do óleo lubrificante, a diminuição da massa de ar e a diminuição das folgas entre as partes móveis do motor como virabrequim, pistão e conseqüentemente o aumento do atrito entre estas partes. Foi construído um dispositivo para estimar o torque resistivo em baixas temperaturas na faixa entre - 20°C a 0ºC em um motor diesel NGD 3,0 litros, quatro cilindros de fabricação da MWM International com o objetivo de estudar a correlação entre o rendimento do motor de partida nestas condições e o torque resistivo solicitado na partida. Este dispositivo permite o levantamento do torque resistivo nos motores diesel sem combustão, onde a lubrificação é mínima e o atrito entre as partes móveis do motor são máximas. Para a medição do torque foi utilizada uma flange de torque modelo T40 de fabricação da HBM acoplada ao dispositivo de arraste, composto por um volante e motor de partida de um motor com 9,3 litros também de fabricação MWM International e o volante do motor que foi testado, através de um eixo cardam. Os testes para o levantamento dos dados foram realizados em um "contêiner" frigorífico utilizado para transportes de cargas perecíveis, como carnes congeladas, adaptado para realização de ensaios de motores diesel a temperaturas negativas (-50ºC + temperatura ambiente) e instalado nas dependências do Centro Tecnológico da MWM International
Abstract: In lower temperatures, the conditions for starting the engine become more difficult due to several factors, eg, less lubrication due to increased viscosity of lubricating oil, the decrease in air mass and reducing the clearances between moving parts the engine crankshaft, piston and consequently increases the friction between these parts. A device was built to estimate the resistive torque at low temperatures in the range between -20°C to 0°C in a diesel engine NGD 3.0-liter four-cylinder manufacturing MWM International aiming to study the correlation between the starter motor efficiency in these conditions and the resistive torque at startup. The device allows the removal of the resistive torque without combustion in diesel engines, where lubrication is minimal and the friction between the moving parts of the engine is maximum. For measuring torque was used a model T40 torque flange from HBM manufacturing device coupled to the drag, comprising a flywheel and starter motor with a 9.3 liters also manufacturing MWM International and the flywheel was tested through a cardan shaft. Tests for the survey data were conducted in a "container" refrigerator used to transport perishable cargo such as frozen meat, suitable for testing diesel freezing temperatures (-50 ° C + ambient temperature) and installed in the premises of the Centre Technological MWM International
Mestrado
Eletrônica
Mestre em Engenharia Automobilistica
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Pew, Jefferson W. "A torque-based weld power model for friction stir welding /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1649.pdf.
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Pew, Jefferson W. "A Torque Based Power Input Model for Friction Stir Welding." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1100.
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For decades models have been developed for predicting the size of the weld nugget and heat affected zones in fusion welded structures. The basis for these models is the welding heat input, which is fairly well understood for most arc welding processes. However, this traditional approach is not as straightforward for Friction Stir Welding (FSW). To date, there is no definitive relationship to quantify the heat input for FSW. An important step to establish a heat input model is to identify how FSW process parameters affect weld power. This study details the relationship between FSW process parameters and torque for three different aluminum alloys: 7075, 5083 and 2024. A quantitative weld power and heat input model is created from the torque input. The heat input model shows that decreasing the spindle speed or increasing the feed rate significantly decreases the heat input at low feed rates. At high feed rates, feed rate and spindle speed have little effect on the heat input. Process parameter versus heat input trends are verified by measurements of the weld heat affected zones. In addition, this study outlines and validates the use of a variable spindle speed test for determining torque over a broad range of parameters. The variable spindle speed test provided significant improvements over previous methods of determining torque as this new method enabled the torque to be modeled over a broad range of parameters using a minimum number of welds. The methods described in this study can be easily used to develop torque models for different alloys and materials.
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Placati, Silvio. "Metodi numerici di interpolazione-estrapolazione in un problema di friction torque." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2365/.
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Afsharian, Reza, and Antonios Theodoropoulos. "Modular friction test rig for measuring torque and tension in threaded fasteners." Thesis, KTH, Maskinkonstruktion (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235540.
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This report describes the development of a modular friction test rig for threaded fasteners. This device can measure the shank torque and the clamp force during the tightening of threaded bolts, with a size of M3-M14 and clamp length of 30-160mm. The design allows the use of several load and torque cells and the range is up to 100kN clamp load and 200Nm applied torque. The test rig will be used for research purposes by Atlas Copco to determine the frictional characteristics in tightening and will allow the experiments on bolts with several materials, coatings and surface finishes. This report concludes to a design proposal evaluated with analytical methods and a prototype 3D model that demonstrate the working principle of the test rig. The measurements are taken from custom-made sensors that are developed with high standards, are easily interchangeable and can be calibrated individually. In addition, a device is developed to allow the user to change the stiffness of the joint. Finally, a future recommendation is made to allow the measurement of the under-head torque. This proposal is a breakthrough compared to other test rigs, and will assist in verifying the friction measurements and having high precision results.Denna rapport beskriver utvecklingen av en modulär friktionsprovrigg för gängade fästelement. Den utvecklade enheten kan mäta moment och klämkraft under åtdragning av gängade skruvar, med en storlek mellan M3 och M14 och klämlängd på 30-160mm. Designen möjliggör användning av flera last- och vridmomentceller och intervallet är upp till 100kN klämbelastning och 200Nm påfört vridmoment. Provriggen är en forskningsrigg, och den kommer att användas av Atlas Copco för att bestämma friktionsegenskaperna i åtdragning och möjliggöra experiment på skruvar av olika material, och med olika ytbeläggningar och ytbehandlingar. Denna rapport avslutas med ett designförslag, som utvärderas analytiskt och testprincipen demonstreras med hjälp av en prototyp. Mätningarna tas från skräddarsydda sensorer, som kan kalibreras individuellt och som är enkelt utbytbara. Dessutom är en anordning utvecklad för att tillåta användaren att ändra styvheten hos förbandet. Slutligen ges en rekommendation för en vidareutveckling, som möjliggör mätning av skallmomentet. Detta förslag är ett genombrott jämfört med andra existerande testriggar, och kommer att bidra till att verifiera friktionsmätningarna med hög precision.
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Sen, Osman Taha. "Dynamic Analysis of Speed-Dependent Friction-Induced Torque in a Nonlinear Brake System." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339172357.
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Villella, Matthew G. "Nonlinear Modeling and Control of Automobiles with Dynamic Wheel-Road Friction and Wheel Torque Inputs." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5198.
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This thesis presents a new nonlinear automobile dynamical model and investigates the possibility of automobile dynamic control with wheel torque utilizing this model. The model has been developed from first principles by applying classical mechanics. Inputs to the model are the four independent wheel torques, while the steer angles at each wheel are specified as independent time-varying signals. In this way, consideration of a variety of steering system architectures, including rear-wheel steer, is possible, and steering introduces time-varying structure into the vehicle model.
The frictional contact at the wheel-road interface is modeled by use of the LuGre dynamic friction model. Extensions to the existing two-dimensional LuGre friction model are derived and the steady-state of the friction model is compared to existing static friction models. Simulation results are presented to validate the model mathematics and to explore automobile behavior in a variety of scenarios.
Vehicle control with wheel torque is explored using the theory of input-output linearization for multi-input multi-output systems. System relative degree is analyzed and use of steady-state LuGre friction in a control design model is shown to give rise to relative degree singularities when no wheel slip occurs. Dynamic LuGre friction does not cause such singularities, but instead has an ill-defined nature under the same no-slip condition. A method for treating this ill-defined condition is developed, leading to the potential for the system to have relative degree.
Longitudinal velocity control and combined longitudinal and angular vehicle velocity control are demonstrated in simulation using input-output linearization, and are shown to produce improved vehicle response as compared to the open-loop behavior of the automobile. Robustness of the longitudinal velocity control to friction model parameter variation is explored and little impact to the controller's ability to track the desired trajectory is observed.
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Seo, Na Jin. "Biomechanical models of hand coupling for axial torque and push exertions effects of torque direction, hand-handle friction, and handle size on axial torque and push exertions for cylindrical handles." Saarbrücken VDM Verlag Dr. Müller, 2007. http://d-nb.info/991124189/04.
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L'Homme-Langlois, Emilie. "Accuracy of Mechanical Torque-Limiting Devices for Dental Implants." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398899960.
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Bakan, Murat. "Development Of Polymer Resin-based Wet Friction Sheet Materials And Understanding Their Interactions With Automatic Transmission Fluids." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1438257941.
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Olsson, Håkan. "Performance analysis of a low-speed high-torque hydrostatic transmission unit." Licentiate thesis, Luleå tekniska universitet, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16922.
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This thesis concerns a study of the performance of an industrial low-speed high-torque hydrostatic drive system. This type of hydrostatic transmission is commonly used in continuous operation in a wide range of heavy-duty drive applications. In many applications the transmissions have to compete with e.g. electromechanical drives, such as DC or AC electric motors combined with gearboxes. In such situations, energy efficiency is a key selection criterion in that even a small increase in the efficiency of high power industrial drives would give substantial savings. Apart from efficiency, lifetime and reliability requirements are important parameters for industrial drive systems, as unplanned stops in industrial working processes can be very costly. The work presented in this thesis is primarily focused on analysing the efficiency behaviour in the transmission, both on the system level and on the component level. Attention has also been paid to lifetime issues, with special emphasis on wear occurring in a sliding contact in a radial piston hydraulic motor. In Paper A the distribution of power losses in a variable axial piston swash plate pump is investigated. The pump under study is commonly used in stationary industrial hydrostatic transmission systems. The churning losses in the pump have been estimated experimentally by measurements in a test rig. The leakage flow and the power losses in the contacts between the piston and the cylinder and between the slipper and the swash plate respectively were simulated with the help of the simulation tool CASPAR. For the pump studied, the churning losses are significant under the operating conditions typically occurring in industrial drive applications. The simulation results indicate that the leakage to the pump casing mainly originates from the gaps between the pistons and their respective cylinders and between the slippers and swash plate. The aim of Paper B is to study two sliding contacts inside a radial piston hydraulic motor and investigate their influence on the torque and power losses. Moreover, it is investigated whether and when a change in the lubrication regime can be expected in these contacts. This is accomplished by a combination of experimental and theoretical studies, with a special focus on two lubricated sliding contacts: the distributor valve contact and the piston/cam roller contact. The theoretical analysis of the contacts indicates, among other things, that the piston/cam roller contact can enter the mixed lubrication regime at low motor speeds. At low running speeds, an increased wear rate has been noted in the contact between the cylinder bore and the piston skirt in a radial piston hydraulic motor. Paper C describes a comparative investigation into different hydraulic fluids' friction properties and wear protection abilities. To simulate the contact between the cylinder bore and the piston skirt in the hydraulic motor, tests were performed in a reciprocating test rig where the contact geometry was of the cylinder-plate type. In the model test a synthetic ester aimed at meeting the conditions in water turbine applications received a top ranking regarding both friction and wear protection properties.Godkänd; 2003; 20070217 (ysko)
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Chen, Qi. "Benchmarking of temperature and friction in axial ball bearings lubricated by a novel polymer thickened grease." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183007.
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This project concerns the benchmarking of a novel polymer thickened grease with a lithium thickened one. The new grease has shown low temperature property in the previous bearing tests on SKF-R2F. A DAQ interface was implemented using lab View for a modified four-ball machine. The result shows the temperature and friction torque profiles of the greases at different speeds. The raw data is attached with a suggested improvement for friction measurement.Det här projektet avser att jämföra ett nytt polymerbaserat fett med ett lithiumbaserat fett. Det nya fettet har påvisat låga temperaturegenskaper i det tidigare testet med ett lager av typen SKF-R2F. Ett DAQ-gränssnitt implementerades med Lab View för en modifierad fyr-kulig maskin. Resultaten visar temperaturer och friktionsmoment av fetterna vid olika hastigheter. Förslag på förbättring av friktionsmomentet är presenterat tillsammans med rådata.
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Semidey, Stephen Andrew. "Thermal design and optimization of high torque density electric machines." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48967.
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The overarching goal of this work is to address the design of next-generation, high torque density electrical machines through numerical optimization using an integrated thermal-electromagnetic design tool that accounts for advanced cooling technology. A parametric thermal model of electric machines was constructed and implemented using a finite difference approach incorporating an automated, self segmenting mesh generation. A novel advanced cooling technology is proposed to improve thermal transport in the machine by removing heat directly from the windings via heat exchangers located between the winding bundles. Direct winding heat exchange (DWHX) requires high convective transport and low pressure loss. The heat transfer to pressure drop tradeoff was addressed by developing empirically derived Nusselt number and friction factor correlations for micro-hydrofoil enhanced meso-channels. The parametric thermal model, advanced cooling technique, Nusselt number and friction factor correlations were combined with a parametric electromagnetic model for electric machines. The integrated thermal-electromagnetic model was then used in conjunction with particle swarm optimization to determine optimal conceptual designs. The Nusselt number correlation achieves an R² value of 0.99 with 95% of the data falling within ± 2.5% similarly the friction factor correlation achieves an R² value of 0.92 with 95% of the data falling within ± 10.2%. The integrated thermal-electromagnetic design tool, incorporating DWHX, generated an optimized 20 kW permanent magnet electric machine design achieving a torque density of 23.2 N-m/L based on total system volume.
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Tung, Daniel Joseph. "A Comprehensive Understanding of Machine and Material Behaviors during Inertia Friction Welding." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu14925491745339.
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Encarnação, Rodrigo Rabelo da. "Análise do torque de aperto em uniões parafusadas /." Guaratinguetá, 2019. http://hdl.handle.net/11449/181727.
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Orientador: Fernando de Azevedo SilvaResumo: As uniões parafusadas possuem uma grande aplicação na indústria, mas quando se pensa na utilização de parafusos existe uma impressão de ser um elemento de simples dimensionamento e de fácil aplicação. No entanto, o desenvolvimento de uniões por parafusos possui uma complexa sistemática de cálculo e sua montagem requer um cuidado para proporcionar o torque correto e consequentemente a pré-carga ideal. O intuito do trabalho foi a análise da pré-carga de uniões parafusadas a partir do torque de aperto. Para isso foi desenvolvido um torquímetro instrumentado com extensômetros para a aquisição do torque aplicado, foi desenvolvida também uma célula de carga para a aquisição da pré-carga aplicada na junta parafusada. Ambos os sinais foram aquisitados instantaneamente e a partir destes sinais foram feitas as análises das uniões parafusadas. Foram analisadas três condições diferentes de lubrificação para o parafuso e porca, estas foram: com lubrificação, sem lubrificação e lubrificação seca (grafite). Foram analisadas também duas condições de aplicação de torque, estas foram: torque pela porca e torque pelo parafuso. Portanto, foram analisados seis grupos diferentes de uniões parafusadas. Para cada um dos grupos foram aplicados 3 torqueamentos para cada conjunto de parafuso, porca e arruela, simulando três situações de montagem e desmontagem. Ao final foram feitas considerações sobre a influência das diferentes condições de lubrificação no torque aplicado e na pré-carga gerada na junt... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Bolted joints are broadly used in the industry, but when it comes to their use there is a false impression of being a simple component, of easy dimensioning and easy application. However, designing bolted joints requires a complex calculus systematic and its assembly requires attention in order to apply the correct torque and consequently the ideal pre-load. The purpose of this dissertation was to analyze the pre-load of bolted joints from the tightening torque. Therefore, it was developed a torque wrench with strain gauges to measure the applied torque, and also developed a load cell to collect the pre-load onto the bolted joint. Both signals were instantaneous collected, and from this data, analysis were made over the bolted joints. Three different lubrication conditions for bolt and nut were analyzed: with and without lubrication and dry lubrication (graphite). Two torque application conditions were analyzed: the torque onto the nut and onto the bolt. Therefore, six different groups of bolted joints were analyzed. For each group of bolt, nut and washer, it was applied three torques simulating three assembly and disassembly operations. At the end, considerations were made on the influence of the different lubrication conditions on the applied torque and the generated pre-load onto the bolted joint, and the influence of successive torques on a bolted joint. Torque and friction coefficient tables were generated for all the above mentioned six groups
Mestre
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JOHANNA, DOLK. "Rotary Joint Module for Lenses on Infrared Camera." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192635.
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Detta arbete utfördes på vridledsmodulen för handhållna kameror från T-serien hos företaget FLIR. Vridledsmodulen används för att hålla uppe objektivet och reglerar vinkeln på detta i jämförelse med resten av kameran. FLIR hade tidigare ett flertal lösningar för olika kameramodeller och dessa hade individuella problem när det kom till kvalitet, toleranser och hållbarhet. De tidigare lösningarna skilde sig i vilka komponenter som används och vilket vridmoment som krävs från användaren vid bruk. Företaget sökte en ny lösning för vridledsmodulen; en lösning som var skalbar. Detta innebar att den nya modulen skulle kunna användas i flera kameramodeller med olika användarmoment och olika objektiv med varierande vikt. Användarmomentet skulle kvantifieras genom att utvärdera befintliga lösningar; de funna värdena skulle sedan användas för att finna en ny lösning. Dimensionerna på modulen skulle väljas med hänsyn till dimensionerna på de tidigare lösningarna och gränssnittet mot kamerahuset. I början av projektet utfördes en förstudie genom att titta på tidigare lösningar gjorda av FLIR för att formulera krav på produkten. De verktyg som användes för detta var MATLAB för beräkningar, SolidWorks för CAD och utrustning från verkstaden för att manuellt mäta momentet. För att börja formulera koncept gjordes en brainstorm där de första koncepten förklarades genom skisser, och senare med CAD gjorda i SolidWork. Dessa koncept beräknades på genom att använda MATLAB för att hitta rätt dimensioner och komponenter. Koncepten diskuterades genom att låta berörda parter ge feedback under planerade möten. En Pugh’s matris användes för att utvärdera koncepten emot varandra, för att välja slutkoncept. De slutgiltiga koncepten var av två olika modeller. Det ena kontrollerades genom dimensioner och stålkulor, styrda av kompressionsfjädrar, som klickade i spår i en ytterring. Det andra styrdes endast genom friktionen mellan två ytor som var i kontakt med varandra under lasten från kompressionsfjädrar, där det då inte fanns distinkta klicklägen. Avsikten var att dessa två koncept skulle ha samma moment och att de skulle vara skalbara på samma sätt; genom olika förspänning av fjädrarna i applikationen.This work was done on the rotary joint module of handheld cameras in the T-series made by the company FLIR. The rotary joint module holds the lens and controls the angle in relation to the rest of the camera. FLIR’s current solutions for the rotary joint had various module solutions for different camera models and the solutions have individual problems in quality, tolerances and durability. The current solutions differ in which components that are used, in dimensions and what torque is required by the user. The company was looking for a new solution for the rotary joint module; a solution with scalability. This means that the new module were to fit in several camera models with different torques and with lenses of different weight. The torque needed by the user would be quantified by evaluating solutions used today, where these values would be applied when finding a new solution. The dimensions of the module would be in consideration to the dimensions of the earlier solutions and to the interface between the joint and the camera. In the beginning of the project a pre study was made by looking at the current solutions made by FLIR to form requirements. The tools used for this were MATLAB for calculations, SolidWorks for CAD drawings and workshop tools for manual measurements of the torque. To start forming concepts solving the problem a brainstorm was performed where the ideas were visualized using sketches, and later CAD drawings using SolidWorks. These concepts were calculated using MATLAB to find the right dimensions and components. The concepts were discussed using meetings with interested parties, to get feedback on the work and sort out the better concepts. A Pugh’s matrix was used to evaluate the concepts against each other. The final concepts were of two different models; one controlled by dimensions and steel balls, connected to compression springs, clicking into grooves, and the other controlled merely by the friction between two surfaces provided under load from compression springs, where there were no actual click positions. The intention was that these two would have the same torque and they were scalable in the same way; by pre-tensioning the springs in the application to give different loads.
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Patial, Rajat Kumar, and Jaspreet Singh. "Design and Developement of the testing methodology for the planetary friction drive." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42296.
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Разаві, Сейед Фаршад. "Гідродинамічні особливості потока аномально-в'язких рідин у конічної поверхні ковзання." Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/29180.
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Дисертаційна робота присвячена дослідженню впливу гідродинаміки в'язких і
аномально в'язких мастильних матеріалів у конічних зазорах зі змінною величиною
конусності. Подібні завдання є актуальними при дослідженні конічних опорних
підшипників, які знайшли широке застосування в гідротурбінобудуванні та інших
сферах гідромашинобудування. Одним з важливих питань у даному напрямку є
визначення крутного моменту сил в'язкого тертя в щілинних конічних зазорах.
В роботі, проведено критичний аналіз досліджень, присвячених даній темі, зроблено
висновок про недостатність досліджень і поставлена задача, розв’язання якої
пропонується в даній роботі. На підставі досліджень інших авторів виведені основні
критерії подібності, які можуть охарактеризувати цей процес поведінки рідини в
зазорі, де одна з поверхонь (внутрішня) може обертатися навколо своєї осі. Проведено
фізичне і математичне моделювання поведінки рідини в конічних підшипниках. На
підставі експериментальних досліджень були отримані функціональні залежності
визначення крутного моменту як функції частоти обертання внутрішнього конуса,
в'язкості змащує рідини, ширини щілинного зазору між конічними поверхнями.
Отримані результати були зіставлені з аналогічними даними для циліндричних
щілинних зазорів (циліндричних підшипників ковзання). Представлені рекомендації по
розрахунку основних характеристик потоку. Проведення математичне моделювання
дало можливість оцінити ступінь відмінності між результатами експерименту і теорії,
пояснити розбіжності в результатах. Одним з найважливіших моментів дослідження є
результат, пов'язаний з поведінкою аномально-в'язких рідин (деякі з мастильних
матеріалів за своєю поведінкою близькі до рідин, поведінка яких можна описати
рівнянням Освальда де Віля). Проведене моделювання процесів, що розглядаються в
конічних щілинних зазорах, дало можливість забезпечити раціональний вибір
змащувальних матеріалів для зниження моменту тертя (сил тертя) в конічних зазорах.
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Chevillotte, Christophe. "Étude biomécanique du coupe de frottement céramique-céramique dans les prothèses totales de hanche sans ciment." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10134/document.
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Le but du travail réalisé dans cette thèse était d’approfondir les connaissances en matière d’utilisation du couple de frottement céramique-céramique dans l’implantologie moderne de hanche sans ciment. L’étude clinique de 100 prothèses totales de hanche sans ciment avec un recul de 9 ans a permis de montrer la fiabilité du couple de frottement céramique en terme d’usure, de biocompatibilité et d’ostéointégration. Par la suite, la comparaison de la méthode d’implantation de ces implants (impaction du métal-back avec ou sans adjonction de vis supplémentaires) a montré que la rigidité de la céramique n’était pas incompatible avec une impaction simple du métal-back, pour des patients qui ne présentent pas de fragilité osseuse. Nous avons ensuite étudié plus particulièrement une complication de la céramique, le grincement ou squeaking. Une étude in vitro du phénomène, a permis de reproduire ce phénomène dans des conditions de lubrification optimale, avec la présence d’un troisième corps métallique entre les surfaces de frottement, suggérant l’importance des problèmes de lubrification dans la genèse du phénomène. L’analyse d’explant a conforté notre hypothèse, mettant en évidence l’importance du dessin des implants afin d’éviter les conflits prothétiques pouvant générer des particules métalliques. Enfin, l’analyse sur le long terme du phénomène de squeaking a montré son faible impact sur la survie des implants et sur la qualité de vie des patients. Ce travail, qui a associé des analyses cliniques et biomécaniques nous conforte dans l’utilisation de la céramique comme couple de frottement dans les prothèses totales de hanche sans ciment, insiste sur l’importance du dessin et du positionnement des implants pour éviter les complications qui peuvent survenir et permet de mieux connaître le problème du squeaking et ses conséquencesThe aim of the study done in this thesis was to enhance the knowledge in the use of ceramic on ceramic bearing for cementless total hip arthroplasty. A clinical study of 100 cementless total hip arthroplasty at 9 years of follow-up showed the reliability of ceramic in terms of wear, biocompatibility and osseointegration. Subsequently, the comparison of the method for implantation of the implants (press-fit with or without additional screws fixations) showed that the stiffness of ceramic was not inconsistent with a simple impaction, for patients who do not present bone fragility. We then studied a particular complication of ceramic bearing, the squeaking noise. An in vitro study of this phenomenon, allowed us to reproduce squeaking in lubricated conditions, with the presence of a third metal body between the frictions surfaces, suggesting the importance on lubrication damages in the genesis of this phenomenon. Analysis of explants has confirmed our hypothesis, highlighting the importance of implant design, to avoid impingement, potentially generating metal particles. Finally, the long-term analysis of squeaking phenomenon showed its low impact on implant survival and patient’s quality of life. This work, which involved clinical and biomechanical analysis, confirms the interest for the use of ceramics bearings in total hip arthroplasty, emphasizes the importance of implant design and implant positioning, to avoid complications, and helps for a better understanding with the problem of squeaking and its consequences
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Al-Barghouthi, Mohammad. "Extended and Unscented Kalman Filtering for Estimating Friction and Clamping Force in Threaded Fasteners." Thesis, Uppsala universitet, Signaler och system, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446422.
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Threaded fasteners tend to break and loosen when exposed to cyclic loads or potent temperature variations. Additionally, if the joint is held tightly to the structure, distortion will occur under thermal expansion issues. These complications can be prevented by identifying and regulating the clamping force to an appropriate degree – adapted to the properties of the joint. Torque-controlled tightening is a way of monitoring the clamping force, but it assumes constant friction and therefore has low accuracy, with an error of around 17% - 43%.This thesis investigates if the friction and clamping force can be estimated using the Extended and Unscented Kalman filters to increase the precision of the torque-controlled methodology. Before the investigation, data were collected for two widely used tightening strategies. The first tightening strategy is called Continuous Drive, where the angular velocity is kept at a constant speed while torque is increased. The second strategy is TurboTight, where the angular velocity starts at a very high speed and decreases with increased torque. The collected data were noisy and had to be filtered. A hybrid between a Butterworth lowpass filter and a Sliding Window was developed and exploited for noise cancellation.The investigations revealed that it was possible to use both the Extended and Unscented Kalman filers to estimate friction and clamping force in threaded fasteners. In Continuous Drive tightening, both the EKF and UKF performed well - with an averagequality factor of 81.87% and 88.38%, and with an average error (at max torque) of 3.54% and 4.09%, respectively. However, the TurboTight strategy was much more complex and had a higher order of statistical moments to account for. Thus, the UKF outperformed the EKF with an average quality factor of 93.02% relative to 24.49%, and with an average error (at max torque) of 3.50% compared to 4.19%
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Guedoiri, Ammar. "Contribution à la modélisation et à la simulation numérique du soudage par friction et malaxage." Phd thesis, Paris, ENSAM, 2012. http://pastel.archives-ouvertes.fr/pastel-00842393.
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Le soudage par friction malaxage " Friction Stir Welding " est un procédé d'assemblage de pièces en phase semi solide. Le cordon de soudure est obtenu grâce à un outil de révolution composé d'un épaulement et d'un pion. Ce procédé utilise le principe de la conversion de l'énergie mécanique en énergie thermique par frottement de l'outil avec les pièces à assembler. Ce travail de thèse est une contribution à la modélisation expérimentale et à la simulation numérique de ce procédé permettant de fournir des modèles pour aider à la compréhension des phénomènes thermiques et mécaniques ainsi que les interactions entre les paramètres de soudage. Les études expérimentales sont principalement orientées vers la caractérisation de l'écoulement de matière à l'aide de marqueurs et vers l'optimisation des paramètres du procédé. L'effet de la géométrie de l'outil (outil à pion cylindrique ou outil avec méplats) sur l'écoulement de la matière au cours du soudage est étudié. Pour représenter la géométrie de l'écoulement et prédire les champs thermiques et mécaniques à l'état stationnaire, des modèles formulés sur la base de la dynamique des fluides sont adoptés dans la présente thèse. Deux modèles thermomécaniques sont développés: (1) un premier modèle numérique construit sous Fluent permet d'étudier le comportement thermomécanique et l'écoulement au cours du soudage FSW. Une loi de comportement dépendante de la température et de la vitesse de déformation est utilisée et une discussion sur les conditions de contact entre l'outil et les plaques à souder est présentée. Les résultats de l'écoulement sont comparés avec ceux obtenus expérimentalement dans le cas de suivi des trajectoires de particules de cuivre. (2) un deuxième modèle original basé sur une procédure itérative est mis en œuvre permettant le soudage de plaque de grandes dimensions. En effet, pour une meilleure prise en compte des conditions aux limites thermiques, un modèle thermomécanique construit autour de l'outil de soudage et couplé avec un modèle thermique pour tout le reste du domaine étudié. Ce modèle permet de prendre en compte le transfert de chaleur dans l'outil et dans la plaque support. Les cycles thermiques et la plage de viscosité pour deux alliages d'aluminium (AA7020-T6 et AA6061-T3) sont analysés et comparés avec succès aux résultats expérimentaux. Les efforts et le couple de soudage calculés numériquement sont validés par rapport à la littérature.
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Gilbert, Gregory S. Jr. "Scaling a Prismatic Revolute Joint (Pr) Manipulator Using Similitude and Buckingham Pi Techniques." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36599.
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This thesis presents scaling methods for sizing a prototype micro prismatic revolute (PR) manipulator actuated by permanent magnet (PM) direct current (d.c.) gearmotors. Dimensional analysis was the principle tool used in this investigation, and addressed the problems of scaling a trajectory planner, control law, and gearmotors that exhibit internal nonlinear friction. Similitude methods were used to develop a scaleable two degree-of-freedom trajectory planner from a third order polynomial. Scaling laws were developed from Buckingham's Pi theorem to facilitate the selection process of gearmotors. Nondimensional, nonlinear, differential equations were developed to describe viscous, Coulomb and static friction in comparative PM d.c. motors. From the insights gained through dimensional analysis, a scaleable controller based on the computed torque method was developed and implemented with a cubic trajectory planner. Model and prototype PR manipulator systems were simulated using a hybrid Matlab/Simulink simulation scheme. Experimental systems were constructed with dissimilar model and prototype motors. Control was provided by an AT class PC equipped with 12-bit A/D, D/A cards operating at a sample rate of 100 Hz. The control algorithm was written in Borland 3.1 C for DOS. Results from the experimental testing showed excellent agreement between the test and simulated data and verified the viability of the scaling laws. The techniques presented in this thesis are expected to be applicable to any application that involves scaling PM d.c. micro gearmotors that have significant internal friction terms. These simple, practical tools should be especially beneficial to designers of micro robotic systems.Master of Science
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Drabison, John Stephen II. "Experimental Investigation of Judder in a Floating Disc-Caliper Braking System with Focus on Pad Geometry." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276795212.
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Zermegh, Tomáš. "Zvyšování tepelných, elektrických a mechanických vlastnosti bezpečnostních brzd." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254463.
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This thesis is dealing with a detailed analysis of electromechanical brake used in emergency situations to stop the electric motor. Environmental influences, bad material proposal or bad design parameters can significantly limit the behaviour of a brake. The thesis presents several approaches to avoid these limitations, to limit the reaction time and achieve better results. The attached programs can be used either for innovation, or for the new brake design based on the entry requirements.
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Wheeler, Jean-David. "Non-elliptical point contacts : The Torus-on-Plane conjunction." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI131/document.
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Cette thèse est dédiée à l’étude des contacts lubrifiés tore-plan sous diverses conditions. Ces contacts se situent à l’interface entre l’extrémité torique des rouleaux et le collet de la bague dans les roulements à rouleaux. La première complexité de cette étude provient de la géométrie particulière des solides concernés. La deuxième est générée par la cinématique complexe qui règne dans ces contacts. Afin de comprendre les mécanismes physiques à l’œuvre, une approche duale (expérimentale et numérique) est adoptée. Le banc d’essai Jérotrib permet une première étude basée sur l’hypothèse que le contact élastohydrodynamique tore-plan est similaire à un contact elliptique équivalent. Grâce à une méthode d’interférométrie optique en lumière blanche qui a été adaptée aux spécificités du contact en question, des mesures précises de l’épaisseur de film ont été effectuées dans un nombre significatif de conditions. Sur cette base, un modèle numérique thermo-élastohydrodynamique a été validé avec précision. Ce dernier a permis d’étudier les écoulements de fluide à l’entrée du contact afin de mettre en évidence leur influence sur le champ d’épaisseur de film. Le modèle numérique a ensuite été amélioré afin de prendre en compte la vraie forme des solides. Il a été validé en épaisseur de film par le banc d’essai Tribogyr, dans des conditions similaires à celles rencontrées dans les vrais roulements. Il a été montré que le cisaillement du fluide est responsable de l’échauffement des solides, qui diminue par suite l’épaisseur de film : ceci souligne la nécessité de modéliser cet échauffement global pour prédire la séparation des surfaces. Par ailleurs, lors de l’étude, le champ de pression et d’épaisseur de film ont perdu leurs symétries à cause de la cinématique et de la forme des solides. Toutefois, le comportement du contact est resté similaire à celui d’un contact elliptique, en dehors de certains cas limitesThis thesis is dedicated to the study of torus on plane contacts under various operating conditions. They can be found at the interface between the torus roller-end and the flange in roller bearings. The first challenge of this thesis is to deal with unusual mating geometries. The other challenge is the presence of a complex kinematic which operates in these contacts. In order to further develop the understanding of such a contact, a dual approach (experimental and numerical) is adopted. The Jérotrib test-rig enables a first study, by considering that the élastohydrodynamic torus on plane contact can be modelled by an elliptical equivalent contact. Thanks to a differential colorimetric interferometry method which was improved and adapted during the thesis, precise film thickness measurements are carried out under a rather wide range of operating conditions. A thermo-elastohydrodynamic numerical model is developed and validated by comparing its results to the ones of the test-rig. A numerical study on film forming is then proposed and the role of the contact ellipticity is investigated. The numerical model is improved in order to take into account the actual shape of the solids. A film thickness validation of the model is proposed, thanks to measurements performed on the Tribogyr test-rig. The operating conditions are very similar to the one encountered in actual bearings, and the mating solids have representative geometries: it is an actual torus-on-plane contact. It is demonstrated that the lubricant shearing is responsible for the solids temperature rise, which in its turn, reduces the film thickness. It appears mandatory to be able to predict this global warming of the bodies. It is also demonstrated that the pressure and film thickness distributions lose their symmetry because of the spinning kinematic and the solids shape. However, the behaviour of the torus-on-plane contact appears very similar to the one of an elliptical equivalent contact, apart from some limit cases
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Andersson, Martin. "Churning losses and efficiency in gearboxes." Licentiate thesis, KTH, Tribologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-152914.
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Efficient transmissions systems are key to producing competitive motor vehicles that have a smaller environmental impact. Gears are the main components in vehicle transmissions and although they are already highly efficient, there is still room for improvement. In this study, the focus falls on the lubricant used to create separating films between gears and todissipate heat. When driving, the gears churn this lubricant, giving rise to power losses that are related to the amount and properties of the lubricant. However, any attempt to reduce these losses must not compromise the required lubrication and heat dissipation. Paper A reports on the use of an FZG gear test rig to investigate power losses and heat generation for different gear immersion depths, surface roughness and coatings. The results show that lower gear roughness reduces gear mesh losses and heat generation. A polishing affect was obtained when a non-coated gear ran against a coated gear.The aim of the research reported in paper B was to increase the accuracy of efficiency testing. It investigated how and whether repeated disassembly and re-assembly of the same test equipment, as well as test performance and rig conditions, affect the measured torque loss in an FZG gear test rig. It was shown that the measured torque loss changes between one assembly and another. Repeatability between tests is crucial for accurate conclusions.The aim of the research reported in paper C was to study whether gear efficiency could be increased by a running-in procedure, which would reduce the need for a coolant. A back-to-back gear test rig was used to test two running-in loads. Higher gear mesh efficiency was seen when a higher running-in load was used.QC 20141006
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Медюх, Руслан Анатолійович, and Ruslan Mediukh. "Інформаційно-вимірювальна система визначення моменту тертя в підшипниках кочення." Master's thesis, ТНТУ ім. І. Пулюя, 2020. http://elartu.tntu.edu.ua/handle/lib/33741.
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Розроблена інформаційно-вимірювальна система для визначення момен-ту тертя в підшипниках кочення. Описано будову і принцип роботи даної установки та її характеристика. Проведено аналіз установки для вимірювання моменту тертя у підшипниках. Для підшипників кочення, що забезпечують роботу установки, приведені розрахунки моментів тертя і опис принципу роботи установки. Виконано аналіз похибок вимірювальної установки на розрахунок моменту тертя. У цій роботі були розглянуті питання аналізу і огляд методів: повного і часткового вибігу. Здійснено опис функціональної та електричної схеми установки та приведені розрахунки. Розглянуто характеристики двох опорних валів, що підтримують вал, у разі радіального, радіально-упорного та упорного підшипників.An information and measuring system for determining the moment of friction in rolling bearings has been developed. The structure and principle of operation of this installation and its characteristics are described. The analysis of the installation for measuring the moment of friction in bearings is carried out. For rolling bearings that ensure the operation of the installation, calculations of friction moments and a description of the principle of operation of the installation. The analysis of errors of the measuring installation on calculation of the moment of friction is executed. In this work the questions of the analysis and the review of methods were considered: full and partial run-out. The description of the functional and electrical scheme of the installation is made and the calculations are given. The characteristics of two support shafts supporting the shaft in the case of radial, radial thrust and thrust bearings are considered.
ВСТУП ...6 1 АНАЛІТИЧНА ЧАСТИНА ....7 1.1 Аналіз об’єкта вимірювання ...7 1.2 Огляд літератури ...14 2 ОСНОВНА ЧАСТИНА ...26 2.1 Огляд методів і засобів вимірювань ...26 2.2 Будова і принцип дії установки для вимірювання моменту тертя у підшипниках ...30 2.3 Схема та принцип роботи установки ...34 2.4 Розрахунок моменту тертя в підшипнику ...35 2.4.1 Розрахунок моменту інерції маси, що обертається ...35 2.5 Розрахунок моменту тертя методом часткового вибігу ...39 2.6 Розрахунок моменту тертя методом повного вибігу ...39 2.7 Розрахунок крутного моменту навантажувального пристрою ...40 2.8 Розрахунок потужності двигуна і навантажувального пристрою ...41 2.9 Вибір давача кутового переміщення ...42 2.10 Розрахунок черв’ячної передачі та крутних моментів ...44 2.11 Вибір двигуна ...46 2.12 Розрахунок пружини стиску ...47 2.13 Розрахунок похибки вимірювання ...48 2.14 Уточнення похибки пристрою ...49 3 НАУКОВО-ДОСЛІДНА ЧАСТИНА ...50 3.1 Принцип побудови і характеристики системи ...50 3.2 Розрахунок керуючих моментів ....50 3.3 Лістинг програми ...54 4 СПЕЦІАЛЬНА ЧАСТИНА ...56 4.1 Опис функціональної схеми ...56 4.2 Вибір та розрахунок елементів керування виконавчим пристроєм ... 59 4.3 Підбір оптопари ....65 4.4 Cхема підключення світлодіода та фототранзистора оптопари ...66 4.5 Вибір та розрахунок електромагніта ...68 4.6 Вибір конкретної схеми драйвера крокового двигуна ...69 4.7 Опис функціональної схеми пристрою ...70 4.8 Опис роботи електричної схеми ...72 4.9 Алгоритм роботи керуючої програми ...77 4.10 Блок схема алгоритму роботи ...79 5 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ ...82 5.1 Заходи безпеки при роботі пневматичних електромеханічних прист-роїв ... 82 5.2 Розрахунок запобіжних клапанів для захисту технологічного облад-нання від пошкоджень ...83 5.3 Безпека в надзвичайних ситуаціях ...88 5.3.1 Поліпшення стійкості складних машинобудівних підприємств під дією електричного імпульсу, вплив цього фактора на обслуговуючий персонал та захисні заходи ...88 5.3.2 Руйнівний вплив ЕМІ ...89 5.3.3 Екрани і пристрої захисту ...90 ЗАГАЛЬНІ ВИСНОВКИ ДО КВАЛІФІКАЦІЙНОЇ РОБОТИ...93 ПЕРЕЛІК ПОСИЛАНЬ ...94 ДОДАТКИ ...96
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Igue, Roberto T. "Experimental Investigation of a lift augmented ground effect platform." Wright-Patterson AFB, OH : Air Force Institute of Technology, 2005. http://handle.dtic.mil/100.2/ADA440437.
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Hakala, Tim. "Settling-Time Improvements in Positioning Machines Subject to Nonlinear Friction Using Adaptive Impulse Control." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1061.
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A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These displacements are achieved through the application of short duration, high intensity pulses. The relationship between pulse duration and displacement is seldom a simple function. The most dependable practical methods for control are self-tuning; they learn from online experience by adapting an internal control parameter until precise position control is achieved. To date, the best known adaptive pulse control methods adapt a single control parameter. While effective, the single parameter methods suffer from sub-optimal settling times and poor parameter convergence. To improve performance while maintaining the capacity for ultimate precision, a new control method referred to as Adaptive Impulse Control (AIC) has been developed. To better fit the nonlinear relationship between pulses and displacements, AIC adaptively tunes a set of parameters. Each parameter affects a different range of displacements. Online updates depend on the residual control error following each pulse, an estimate of pulse sensitivity, and a learning gain. After an update is calculated, it is distributed among the parameters that were used to calculate the most recent pulse. As the stored relationship converges to the actual relationship of the machine, pulses become more accurate and fewer pulses are needed to reach each desired destination. When fewer pulses are needed, settling time improves and efficiency increases. AIC is experimentally compared to conventional PID control and other adaptive pulse control methods on a rotary system with a position measurement resolution of 16000 encoder counts per revolution of the load wheel. The friction in the test system is nonlinear and irregular with a position dependent break-away torque that varies by a factor of more than 1.8 to 1. AIC is shown to improve settling times by as much as a factor of two when compared to other adaptive pulse control methods while maintaining precise control tolerances.
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Fini, Stefano. "Effect of friction, surface treatment and adhesive-reinforcement on the behavior of threaded connections. Effetto dell'attrito, dei trattamenti superficiali e dell'incollaggio sul comportamento dei collegamenti filettati." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422419.
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This study aims at analyzing the phenomena which characterize threaded connections. This type of joint has been known for thousands years (one of the first applications is attributable to Archimedes) allows transforming a torque into an axial force, typically used to lock two or more components thanks to the friction forces that arise between the connected bodies. One of the main strengths of this type of coupling is the possibility to assemble and disassemble the assembled parts; in addition, it can be applicable to almost any type of material. However, the joint system is characterized by a low efficiency: only a modest amount of the tightening torque is actually converted into axial force. In addition, the obtained axial force is typically affected by a large scatter. This behavior is due to the combined effect of two different friction effects that arise between the under-head of the screw (or nut) and the surface of the elements to be locked in the first case, and between the screw threads and female screw in the second one. The relationship between tightening torque and preload axial force is very sensitive to the effect of the various friction coefficients that rule the tribological behavior of the joint:, these coefficients have a significant variability due to the processes used to manufacture the components, and to the different tightening parameters, such as the presence of lubrication or the tightening speed. Threaded connections do have a wide array of applications, both in the field of civil engineering and in mechanics. For instance, in the automotive compartment, due to a steadily growing strive towards weight reduction and increased automation of assembly procedures, an accurate knowledge of the performance of threaded connections has recently become critical in order to achieve the safety of the junction at an adequate production cost. In order to control a threaded connection, it is necessary to focus on the three main factors that characterize its behavior: the coefficients of friction at tightening, the self-relaxation phenomenon (decrease of axial preload in the first few seconds after tightening, due to sinking of the load bearing area in the clamped parts), self-loosening (loss of axial preload, typically due to the action of external shearing forces). In the following, literature review will be presented first, then it will be shown an experimental investigation on the effect of solid lubrication on the friction coefficients, carried out for repeated tightenings and different surface treatments. Moreover, the effect of the number of engaged threads on the performance of an anaerobic threadlocking adhesive will be examined. The need for these analyses arose from the study of an in-field failure occurred in a pinion shaft of a transmission for earth moving machines, which, as it will be shown in the following, probably failed due to a combination of the aforementioned typical issues of threaded components. The research has the aim of increasing the knowledge about the effect of lubrication on the different phenomena that contribute to determining the performance of a bolted connection.Lo studio in oggetto ha come obbiettivo l’analisi dei fenomeni che caratterizzano sistemi di giunzione per attrito; come i collegamenti filettati. Questo tipo di giunzione noto ormai da millenni (una delle prime applicazioni è riconducibile ad Archimede) permette di trasformare una coppia torcente in una forza assiale, tipicamente utilizzata per bloccare due o più componenti grazie alle forze di attrito che nascono tra i corpi collegati. Uno dei principali punti di forza di questo tipo di accoppiamento è la possibilità di montare e smontare i particolari collegati oltre ad essere applicabile quasi a qualsiasi tipo di materiale. Per contro il sistema di giunzione è caratterizzato da un basso rendimento: solo una modesta quantità della coppia esercitata al serraggio viene effettivamente convertita in forza assiale. Inoltre la forza assiale ottenuta presenta tipicamente valori variabili all’interno di un ampio intervallo. Questo comportamento è dovuto all’effetto combinato di due distinti momenti d’attrito che nascono in un caso tra il sottotesta della vite o del dado e la superficie di uno degli elementi da bloccare, nell’altro tra i filetti di vite e madrevite. La relazione tra coppia di serraggio ed effettiva forza assiale ottenibile è molto sensibile all’effetto dei vari coefficienti d’attrito: questi coefficienti a loro volta presentano una significativa variabilità dovuta sia ai processi produttivi utilizzati per realizzare i vari componenti che ai diversi parametri di serraggio, come ad esempio la presenza di lubrificazione o la velocità di serraggio. I collegamenti filettati trovano ampia applicazione sia nel campo delle costruzioni civili che nel campo della meccanica, dove a causa di una sempre maggiore spinta verso una riduzione dei pesi ed una maggiore automatizzazione delle procedure di montaggio (si pensi al settore automotive), è necessario avere un accurato controllo sulle prestazioni del collegamento al fine di garantire la sicurezza della giunzione con tempi di assemblaggio e costi ridotti. Al fine di controllare un collegamento filettato occorre focalizzare l’attenzione sui tre principali fenomeni che lo governano: andamento dei coefficienti d’attrito in fase di serraggio, self-relaxation (diminuzione del tiro assiale offerto dalla vite nei primi secondi successivi al serraggio, dovuto ad un assestamento elastoplastico del materiale), self-loosening (perdita di tiro assiale nel tempo tipicamente sotto l’azione di carichi taglianti esterni). Di seguito verrà presentata una panoramica generale sull’argomento tratta dalla letteratura esistente, un’indagine sperimentale sull’effetto della lubrificazione con lubrificante solido sui coefficienti d’attrito per serraggi ripetuti e diversi trattamenti superficiali e l’effetto del numero di filetti in presa sulle prestazioni di un frenafiletti anaerobico. Queste analisi sono partite dallo studio di un caso reale di self-loosening su un collegamento filettato in un albero pignone di una trasmissione per macchine movimento terra, dove si evidenziano i vari fenomeni che caratterizzano questo tipo di collegamenti. L’attività di ricerca si pone l’obbiettivo di aumentare le conoscenze sull’effetto della lubrificazione sui diversi fenomeni che concorrono a determinare le prestazioni di un collegamento bullonato.
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Gadari, M’hammed El. "Étude expérimentale et numérique du comportement des joints à lèvre." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2304/document.
Full textAbstract:
Cela fait environ soixante ans que l'on s'intéresse à la compréhension et à la modélisation du comportement Elastohydrodynamique (EHD) des joints à lèvres. Cependant, on peut considérer que, jusqu'à présent, leur modélisation n'a pas été totalement et rigoureusement traitée. En effet, même si de nombreuses études ont été consacrées à cette modélisation, plusieurs questions ont été soulevées et font toujours l'objet de controverses entre les chercheurs, à savoir l'impact sur les performances des joints à lèvre de l'effet des surfaces texturées de l'arbre, de la loi adoptée pour le comportement mécanique des joints à lèvre, de la démarche utilisée pour l'élaboration de la matrice de compliance (matrice de souplesse), de l'importance de supposer l'arbre lisse ou rugueux, ainsi que la valeur du rapport entre la largeur du contact et la longueur d'onde du défaut suivant la direction circonférentielle de la lèvre.Dans cette thèse, nous avons tenté d'apporter de façon rigoureuse des réponses claires et précises à toutes ces questions en élaborant et en validant un outil de simulation EHD complet pour les joints à lèvre qui tienne compte de presque tous les paramètres, à savoir une loi de comportement du matériau du joint précise, une matrice de souplesse rigoureusement validée et un arbre qui peut être lisse, rugueux et/ou texturé. De plus, un second modèle analytique est proposé. Il traite le comportement vibratoire du "squeeze film", en tenant compte de la non linéarité des caractéristiques intrinsèques du joint et du filmIt's about sixty years that we are interested in understanding and modeling the Elastohydrodynamic behavior (EHD) of rotary lip seals. However, we can consider that, until now, their modeling has not been accurately treated. Even though many studies have been devoted to this model, several questions have been raised and are still the subject of controversy among researchers, namely the parameters influencing on the rotary lip seals performance, such as: the shaft surface textured, the law adopted for the mechanical behavior of lip seals, the approach used to develop the matrix of compliance, the importance of assuming the smooth or rough shaft, and finally the ratio between the width of contact and the wavelength according the circumferential direction of the lip roughness.The main goal of this thesis is to answer rigorously these questions by developing and validating a numerical tool for EHD rotary lip seals modeling, that takes into account: the lip law behavior, the compliance matrix rigorously validated by assuming smooth shaft case, or rough and textured shaft case. In addition, an analytical approach is proposed, models the vibratory behavior of the "squeeze film". This implies a nonlinear comportment that is taken into account
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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.
Full textAbstract:
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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Lung, Chen-Yu, and 龍震宇. "The Study of Influence Factors to the Frictional Torque of the Bipolar Hip Endoprostheses." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/03309563286299384705.
Full textAbstract:
博士國立陽明大學
醫學工程研究所
88
Abstract Bipolar hip endoprosthesis is one of the most popular hip joint implants in the past twenty years. The main clinical complications were influenced by the motion behavior of the bipolar hip endoprostheses. The purpose of this thesis was to investigate the factors that would influence the frictional behavior of the bipolar hip endoprostheses, then to explain the clinical motion behavior of bipolar hip endoprostheses in vivo. Four experiments were conducted in this study. An in vitro experiment of three different bipolar hip endoprostheses was first done to verify the design factors to the effect of frictional behavior of both bearings of the implant. One set of three different designed bipolar hip endoprostheses and one paired of fresh acetabulum of size 44 mm were used as the materials. The frictional torque between inner and outer bearings were measured by the material testing machine. The frictional torque of both bearings were calculated and compared to describe the motion behavior of different bipolar hip endoprostheses. The second experiment was to evaluate the load and lubricant effects to the frictional behavior of bipolar hip endoprostheses. Six sets of single designed bipolar hip endoprostheses and one fresh acetabulum of size 50 mm were used as the materials. The experimental methods were the same as described above. The load conditions were increased from 300 N to 3000 N and the increment was 300 N. The bovine serum and distilled water were also used as the lubricant for each specimen. The third experiment was to evaluate the effect of rotational speed on the frictional behavior of bipolar hip endoprostheses. The test materials and experimental methods were the same as the previous experiment. The speed conditions were increased from 1 deg/sec to 10 deg/sec、30 deg/sec and 60 deg/sec for each specimen. The forth experiment was to evaluate the size effect to the frictional behavior of bipolar hip endoprostheses. The test materials were the same as the previous experiment, but added six sets of 48 mm bipolar hip endoprostheses and one set of 52 mm bipolar hip endoprostheses. The experimental methods were also the same as the methods described in the load effect condition. Finally, after finishing all the experiments, the frictional torque of both bearings of different samples were calculated and compared to explain the motion behavior of bipolar hip endoprostheses under different conditions. In order to verify the motion behavior of the bipolar hip endoprostheses described by the frictional torque of two bearings, the original specimen of acetabulum and implants were assembled together to repeat the experiment under the same test environment. The whole experiments were recorded by a camcorder. The final results showed that the spherical roundness of the outer bearing would change the frictional torque, thus, changed the motion behavior of the bipolar hip endoprostheses. The frictional torque was dependent on the load in both lubrication conditions. The lubricants of different viscosity made no significant difference to the frictional torque of both bearings under different loading conditions. The motion behavior would start on the outer bearing at the initial stage. The movement of bipolar hip endoprostheses would then shift from the outer bearing to the inner bearing as the movement continued. As the rotation rate changed, the motion would happen on the inner bearing as rotation rate larger than 10 deg/sec under 1500 N loading condition. When the size of the outer metal shell was less than the acetabulum, the outer bearing would move. On the contrary, when the size of the outer metal shell was larger than the acetabulum, the inner bearing would move. All the repeated experiments of bipolar hip endoprostheses and acetabulum could verify the motion behavior explained by the comparison of frictional torque. The motion of the bipolar hip endoprostheses was influenced by the frictional behavior of both bearings. The frictional behavior would be changed not only by the design of the prostheses but also by the body weight of the patient, normal activity speed and the size selection of the outer shell during the surgery. Thus, to achieve a well clinical long-term outcome of the bipolar hip endoprostheses, surgeons should consider body weight, daily activity and acetabular bone quality except the indications of the patients.
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SHARMA, VIPIN KUMAR. "PERFORMANCE STUDIES OF TEXTURED JOURNAL BEARING." Thesis, 2019. http://dspace.dtu.ac.in:8080/jspui/handle/repository/17076.
Full textAbstract:
The conventional journal bearing material contains verying amounts of lead (Pb) in it.
Pb provides the anti-wear and anti-friction properties. However, Pb has hazardous effects on health and the environment and disposal of lead contained bearing and lubricant having lead particles from the bearing surface is an important issue which needs to be dealt with. Surface texturing of the bearing surface, the material of bearing surface, use of better lubricating conditions are some of the methods which could be utilized to reduce the wear and friction coefficient of the bearing material.
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Marques, Rui Bertão Patrício Martins. "Friction Torque in Thrust Ball Bearings Lubricated with Polymeric Greases." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/88901.
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Marques, Rui Bertão Patrício Martins. "Friction Torque in Thrust Ball Bearings Lubricated with Polymeric Greases." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/88901.
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TOMAR, OMBIR. "EFFECT OF CHANGE OF LENGTH ON SKIN FRICTION OF PILES." Thesis, 2017. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15962.
Full textAbstract:
Tall buildings play a key role in current urban strategies and regeneration. Development of these
building presents several problems related to the design and assessment of pile foundations.
Among these combinations of vertical, lateral and torsional forces to the piles due to the
eccentricity of wind action on vertical projections of multistoried tall buildings is of particular
interest.
. Torsional forces are also acting on the pile and IS 2911 for pile foundation has not been
considered torsional forces for pile designing but it should be considered.
Therefore, objectives of the present work are:
(1) Mechanism of applying torque to piles.
(2) Experimentally to examine basic pile soil interactions in the modal pile subjected to torque in
the context of study of torque Vs angle of twist.
A mechanism of applying torque to a single pile was thought upon and worked out accordingly.
Experiments on single pile were performed. Torque on a single pile was applied using the above
said mechanism. Experiments were performed by increasing the embedded depth of a modal
pile. When we increased the embedded depth of pile at regular intervals with the different
torques for increasing angle of twist till the failure angle of twist is achieved.
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Pinho, Samuel Pinto. "Friction torque in thrust ball bearings: influence of thickener type and concentration." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/76154.
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Pinho, Samuel Pinto. "Friction torque in thrust ball bearings: influence of thickener type and concentration." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/76154.
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Lourenço, Pedro Diogo Jesus. "Tool assisted friction welding of mild steel." Master's thesis, 2021. http://hdl.handle.net/10316/96058.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaThe present work aimed to analyse the thermomechanical conditions in Tool Assisted Friction Welding (TAFW) of mild steel, by relating the process parameters with output parameters, namely, the torque and the temperature. With this objective, linear lap welds were made in 1 mm thick plates of DC01 carbon steel. The process parameters considered in the investigation were the rotational and the traverse speeds and the tool diameter. The temperature evolution during welding was registered using a thermographic camera and the torque evolution was acquired from the welding equipment. Transverse cross-sections of the welds were cut for morphological analysis and the strength of the joints was assessed by performing tensile-shear tests. The strain distribution in the samples, acquired using Digital Image Correlation (DIC), was used in order to determine the local properties of the weld. Finally, an analysis of the torque and of the temperature evolutions, with process parameters, was also made to understand the influence of the process parameters on the joints properties.The results obtained allowed to conclude that lap welding of 1 mm thick steel plates may be carried out successfully by TAFW, using a penetration depth of only 0.1 mm. It was also found that both the traverse and rotational speeds have an important influence on the temperature distribution during welding, and in this way, on the morphology of the process affected zone (PAZ). For a constant traverse speed, the increase in the rotational speed conducts to an increase of the welding temperature. On the other hand, for a constant tool rotational speed, the increase of the traverse speed conducts to a decrease of the welding temperature. Independently of the rotational speed, all the welds produced with 1400 mm/min traverse speed were defective or not welded. All the other welds produced with the 16 mm diameter tool have strength similar to that of the base material. It was also found that the tool diameter, axial force and rotational speed strongly influence the welding torque.
O presente trabalho teve como objetivo analisar as condições termomecânicas durante a soldagem por Tool Assisted Friction Welding (TAFW), relacionar os parâmetros de entrada com os principais parâmetros de saída: binário e temperatura. Com este objetivo, foram realizadas soldaduras lineares em juntas sobrepostas utilizando um aço-carbono, DC01, com espessura de 1 mm, como material base. Os parâmetros dos processos considerados na investigação foram a velocidade de rotação e de avanço e o diâmetro da ferramenta. A evolução da temperatura durante a soldadura foi registada por uma câmara termográfica e a evolução do binário por o equipamento de soldadura. As secções transversais das soldaduras foram cortadas para fazer uma análise metalográfica, e uma análise da resistência da soldadura caracterizada pela realização de ensaios transversais de tração-cisalhamento. Durante os ensaios foi usada a aquisição de dados de deformação por Digital Image Correlation (DIC). A análise de sensibilidade do binário e da temperatura foi feita, de forma a perceber a influência dos parâmetros de entrada nas propriedades das soldaduras.Os resultados obtidos permitiram concluir que a soldadura sobreposta por TAFW em placas de aço com 1 mm de espessura e uma penetração inferior a 0.1mm podem ser realizadas com sucesso. Verificou-se também que as velocidades quer de avanço quer de rotação têm importante influência na distribuição da temperatura durante o processo, que está relacionada com a morfologia da zona afetada pelo processo (PAZ). Para uma velocidade de avanço constante o aumento da velocidade de rotação promove o aumento da temperatura do processo. Por outro lado, para uma velocidade de rotação da ferramenta constante, o aumento da velocidade de avanço promove uma diminuição de temperatura Independentemente da velocidade de rotação, todas as soldaduras produzidas a uma velocidade de 1400 mm/min apresentam defeitos ou não estão soldadas. No entanto todas as outras soldaduras produzidas com a ferramenta de 16 mm de diâmetro apresentam uma curva de Força-Deformação semelhante á do material base. Verificou-se também que a força axial, o diâmetro da ferramenta e velocidade de rotação têm forte influência na evolução do torque.
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Cousseau, Tiago. "Film thickness and friction in grease lubricated contacts. Application to rolling bearing torque loss." Tese, 2013. http://hdl.handle.net/10216/73993.
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Cousseau, Tiago. "film thickness and friction in grease lubricated contacts. application to rolling bearing torque loss." Doctoral thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/69532.
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Marinho, Albano Manuel Gonçalves. "Wear and friction torque in thrust ball and roller bearings lubricated with "windmill gear oils"." Master's thesis, 2011. http://hdl.handle.net/10216/61346.
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Pinto, Cláudio Alexandre de Barros. "Friction torque in thrust roller bearings lubricated with polymeric greases under boundary to mixed film." Master's thesis, 2015. https://repositorio-aberto.up.pt/handle/10216/79752.
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Marinho, Albano Manuel Gonçalves. "Wear and friction torque in thrust ball and roller bearings lubricated with "windmill gear oils"." Dissertação, 2011. http://hdl.handle.net/10216/61346.
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Pinto, Cláudio Alexandre de Barros. "Friction torque in thrust roller bearings lubricated with polymeric greases under boundary to mixed film." Dissertação, 2015. https://repositorio-aberto.up.pt/handle/10216/79752.
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Amaro, Pedro Miguel Pinto. "Friction torque in thrust ball and roller bearings lubricated with "wind turbine gear oils" at constant temperature." Master's thesis, 2012. http://hdl.handle.net/10216/68227.
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Amaro, Pedro Miguel Pinto. "Friction torque in thrust ball and roller bearings lubricated with "wind turbine gear oils" at constant temperature." Dissertação, 2012. http://hdl.handle.net/10216/68227.
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Wheeler, Nathan W. "Mechanical and geometric considerations for the airgapless motor." Thesis, 2018. https://doi.org/10.7912/C25D4N.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)The purpose of this thesis is to perform modeling from different perspectives for an airgapless motor. The airgapless motor is a proposed type of electric machine whose purpose is to replace hydraulic machines in low speed high torque applications. Because of the nature of the movement for this device, modeling of this device is atypical to the modeling done with other electric machines. This thesis will present the operating principle of the airgapless motor and take an analytical approach to modeling the torque and total energy in the device. In addition, this thesis will present the power electronics necessary to drive this device and offer recommendations to maximize the torque and minimize the torque ripple. MATLAB simulations are used to verify that the conclusion of this thesis are consistent with observations made by previous publications and prototypes.