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1
Bengtsson, Jonas. "Gearbox Diagnosis". Thesis, Linköpings universitet, Fordonssystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75565.
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Diagnosis based on vibration analysis is a method that has many benefits to offer. It is easy to implement the method on existing transmissions by attaching accelerometers outside the gearbox housing. If you have knowledge of the gearbox geometry, such as number of tooth on the gears and types of bearings, and any unwanted frequencies can be filtered out a good estimation of the gearbox condition can be achieved. In this thesis a number of condition indicators have been tested to identify and isolate different faults that may appear. All analysing have been done in the time domain on different synchronously averaged signals. The condition indicators have been used together with diagnosis theory from the division of Vehicular systems to create a diagnosis system able to find faults on a number of modelled signals.
2
Meisingseth, Andreas. "Demodulation Techniques in Gearbox Diagnostics". Thesis, Uppsala universitet, Signaler och System, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177275.
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This thesis covers the scope of one out of many ways to diagnose gearboxes, demodulating the excited vibrational signals to enhance fault detection and identification. The topic is not only of academic interest since the achievements that can be made by successful machine condition monitoring in the industry. It has a potential value that is close to be absurd, for example unplanned production stops is commonly known to be one of the worst nightmares for manufacturing companies and if one can detect faults in early stages one can improve the possibilityto plan a production stop and therefore increase the profit. Four demodulation algorithms were developed and implemented in MATLAB on data characterized by close to stationarity and distinctive energy centered around the harmonics of the gearmesh frequency. The resulting algorithms for narrowband phase and amplitude demodulation was shown to outperform Hilbert transform based phase and amplitude demodulation algorithms in gearbox diagnostics. One of the goals with the thesis was therefore reached; demodulation algorithms were developed and implemented on data. A comparison of these algorithms was done and a conclusion of which demodulation technique is superior was done. Experimental work was carried out on a test-rig and both local and distributed faults were introduced to two gearboxes, one kind of fault per gearbox. However, the data acquired from the test-rig showed severe non-stationarity and smeared spectrum properties even when angular resampling was performed and therefore a major drawback of the demodulation techniques was exploited since the methods for demodulation in this thesis are not applicable for signals with smeared spectrums. The other goal was therefore not accomplished; to distinguish a local fault from a distributed fault in data acquired by experimental work by applying the selected demodulation techniques.
3
Zaremba, Slawomir M. Caughey Thomas Kirk Beck J. L. "Dynamical signatures of gearbox vibrations /". Diss., Pasadena, Calif. : California Institute of Technology, 1998. http://resolver.caltech.edu/CaltechETD:etd-02082008-160817.
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Hamilton, Andrew. "Development of novel gearbox lubrication condition monitoring sensors in the context of wind turbine gearboxes". Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25910.
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Wind power has become established as an alternative power source that forms a significant proportion of national energy generation. An increasing proportion of turbines is being constructed offshore to exploit higher average wind speeds and to avoid development issues associated with onshore wind farms. Isolated locations and unpredictable weather conditions lead to increased access costs for operators when conducting scheduled and unscheduled maintenance and repairs. This has increased interest in condition monitoring systems which can track the current state of components within a wind turbine and provide operators with predicted future trends. Asset management can be improved through condition based maintenance regimes and preventative repairs. Development of novel condition monitoring systems that can accurately predict incipient damage can optimise operational performance and reduce the overall level of wind turbine generation costs. The work described in this thesis presents the development of novel sensors that may be applied to monitor wind turbine gearboxes, a component that experiences relatively high failure rates and causes considerable turbine downtime. Current systems and technology that may be adapted for use in wind turbine condition monitoring are evaluated. Lubrication related monitoring systems have been identified as an area that could be improved and are divided into those that track liberated wear material suspended in the lubricant and those that assess the state of the lubricant itself. This study presents two novel lubrication based gearbox monitoring sensors that potentially offer a low cost solution for continuous data capture. The first demonstrates the potential for active pixel sensors such as those found in digital cameras to capture images of wear particles within gearbox lubricants. Particle morphology was tracked in this system, allowing the type of particles to be correlated with the type of wear that is generated and a potential source. The second sensor uses a targeted form of infra-red absorption spectroscopy to track changes in the lubricant chemistry due to the increase in acidity. Ensuring the lubricant is functioning correctly decreases component stress and fatigue, reducing maintenance requirements.
5
Ozturk, Fatih Mehmet. "Optimum Design Of Multistep Spur Gearbox". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606749/index.pdf.
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Optimum design of multistep gearbox, since many high-performance power
transmission applications (e.g., automotive, space industry) require compact volume,
has become an important interest area. This design application includes more
complicated problems that are not taken into account while designing single stage
gear drives. Design applications are generally made by trial and error methods
depending on the experience and the intuition of the designer.
In this study, using Visual Basic 6.0, an interactive program is developed for
designing multistep involute standard and nonstandard spur gearbox according to the
American Gear Manufacturers Association (AGMA) Standards 218.01 and 2001-
B88. All the equations for calculating the pitting resistance geometry factor I, and
the bending strength geometry factor J, are valid for external spur gears that are
generated by rack-type tools (rack cutters or hobs). The program is made for twostage
to six-stage gear drives, which are commonly used in the industry.
Compactness of gear pairs and gearbox, and equality of factor of safety against
bending failure is taken as the design objective. By considering the total required
gear ratio, the number of reduction stages is input by the user. Gear ratios of every
stage is distributed to the stages according to the total gear ratio that satisfies the
required precision (from ±0.1 to ±
0.00001 on overall gear ratio) depending on the user selected constraints (unequal gear ratio for every stage, noninteger gear ratio e.g.). Dimensional design is determined by considering bending stress, pitting stress, and involute interference constraints. These steps are carried out iteratively until a desirable solution is acquired. The necessary parameters for configuration design such as number of teeth, module, addendum modification coefficient, are selected from previously determined gear pairs that satisfies the constraints by user interaction considering the performance criterion from the developed program. The positions of gears and shafts are determined automatically in order to keep the volume of gearbox as minimum while satisfying the nonlinear spatial constraints (center distance constraint for proper meshing of gear pairs, face distance constraint for proper assembly of pinion and gear having same shaft, gear interference constraint for preventing interferences between gears, shaft interference constraint for preventing interferences between gears and shafts) by using DLL (Dynamic Link Library) technology of Lingo 8.0 optimization software together with Visual Basic 6.0. If shaft interference constraint is removed then cantilevered mounting of gear pairs would also be possible, otherwise the gears should be mounted between bearings. Visual output of assembly is made by using Autodesk Inventor 7.0, automatically by the program.
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Gustavsson, Mårdestam Peter, i Adam Lundin. "Efficiency Analysis of a Planetary Gearbox". Thesis, Linköpings universitet, Maskinkonstruktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-65578.
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This Bachelor of Science thesis consists of an efficiency evaluation and creation of atheoretical model for an Atlas Copcos epicyclic gearbox. The thesis starts with atheoretical chapter containing the fundamentals of epicyclic gearing and the build of thespecific gearbox investigated. The following chapter contains former testing and theoryof power losses in a gearbox. After the theory is explained the next chapter containstesting, compromises and assumptions during testing and also results from the testing.The next chapter explains the Matlab calculation program based on the theory andmeasurements. Finally the model is validated against reference a reference model andagainst real gearbox measurements followed by some closing conclusions. The finalmodel calculates the efficiency rather well and has a linear difference. The difference isstatic since some losses have been left out, it can be fixed with an empirical correctionfactor which corrects the values and predicts an acceptable efficiency. The correctionfactor for the surface roughness also decreases the difference.
7
Arlotto, Amaury. "Engine and Gearbox Thermal Management Modeling". Thesis, KTH, Maskinkonstruktion (Inst.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235508.
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In order to improve the global efficiency of an engine within the French company Groupe PSA, a research axis focuses on gearbox thermalmanagement for a quicker reduction of its own friction losse after a cold start. The principle remains in deriving a little part of the coolant energy towards the gearbox – until now heated by its own internal frictions – as long as the impact on the engine warm-up is low enough for a global final gain. A compromise has then to be found between a gearbox performance enhancement and an engine degradation to get the better global consumption gain in the end. This will be achieved through 1D simulations thanks to the software AMESim, in parallel with Simulink and Matlab. Different cooling circuit architectures and parameters will be tested in a performance and safety point of view to find the best compromise in a pre-research phase.För att förbättra den globala effektiviteten hos en motor inom det franska företaget Groupe PSA, en forskningsaxel fokuserar på växellådans värmemanagement för en snabbare minskning av egen friktion efter en kallstart. Principen är att avleda en liten del av kylvätskenergin mot växellådan – förrän nu värms upp av sina egna inre friktioner – så länge som påverkan på motorns uppvärmning är tillräckligt låg för en global slutförbättring. En kompromiss finns då mellan en växellådans prestationsförbättring och en motornedbrytning för att få den bättre globala konsumtionsvinsten i slutändan. Detta kommer att uppnås genom 1D-simuleringar tack vare mjukvaran AMESim, parallellt med Simulink och Matlab. Olika kylkretsarkitekturer och parametrar testas i prestations- och säkerhetssynpunkt för att hitta den bästa kompromissen i en förforskningsfas.
8
Häggström, Martin. "Thermal modelling of a truck gearbox". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63753.
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The thermal regime of a gearbox is of considerable importance to its performance. Several significant gearbox parameters, such as the efficiency and fatigue life of its components, are temperature dependent. It is thus important to be able to determine the temperatures of the gearbox components during operation, but they are difficult to measure experimentally. A simulation model capable of predicting these temperatures would therefore be a valuable tool. The objective of this master’s thesis was to create a model capable of simulating the thermal regime of a truck gearbox during operation. To do this, mechanical losses in the gearbox, heat exchange with the surroundings, as well as heat transfer between components had to be accounted for. The model was created using the 1D simulation software LMS Imagine.Lab Amesim 14.0, and is based on a combination of mechanical and thermal networks. Details of the mechanical and thermal interactions between components are calculated using empirical and analytical formulas for mechanical losses and heat transfer. The result of the thesis is a model which can be used to simulate either real or idealised load cases, from which temperatures of gear wheels, shafts, bearings, housing and gearbox oil may be studied, as well as gearbox losses and heat transfer. Comparisons between simulated and measured gearbox efficiencies show good correlation. It is also shown that the model can predict oil temperatures which agree with in-vehicle measurements. Due to a lack of measurement data, most simulated component temperatures cannot be compared to measured values. However, temperature measurements performed for one of the gear wheels indicate that the model can be used to predict their temperature. In order to demonstrate the capabilities of the model, example results from both real and idealised load cases are presented.
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Juhlin-Dannfelt, Peter, i Johan Stridkvist. "Driveline Observer for an Automated Manual Gearbox". Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6947.
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The Automated Manual Transmission system Opticruise is dependent on signals from sensors located in different parts of the Scania trucks. These signals are of different qualities and have different update frequencies. Some signals and quantities that are hard or impossible to measure are also of importance to this system.
In this thesis a driveline observer for the purpose of signal improvement is developed and estimations of unknown quantities such as road incline and mass of the vehicle are performed. The outputs of the observer are produced at a rate of 100 Hz, and include in addition to the mass and road incline also the speed of the engine, output shaft of the gearbox, wheel and the torsion in the driveline. Further the use of an accelerometer and the advantages gained from using it in the observer are investigated.
The outputs show an increased quality and much of the measurement noise is successfully removed without introducing any time delays. A simulation frequency of 100 Hz is possible, but some dependency toward the stiffness of the driveline is found. The observer manages to estimate the road slope accurately. With the use of an accelerometer the road slope estimation is further improved and a quickly converging mass estimation is obtained.
10
Prakash, del Valle Carlos. "Thermal modelling of an FZG test gearbox". Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157256.
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Gearboxes are always subject of study in order to increase their efficiency. Energy losses in gear contacts are transformed into heat which is distributed among the gearbox components increasing their temperature. A thermal model of the gearbox brings the opportunity of a deeper understanding of the heat dissipated related to the power losses in the gear contact. A MATLAB program based on ordinary differential equations was developed in order to make a thermal model of an FZG test gearbox. The model is based on a thermal network where each node represents a machine element. The thermal network is composed by thermal resistances due to deformation in the gear contact, conduction, convection and radiation. With thermal resistances, power losses and thermal inertia of each element, the temperature evolution was obtained by applying the First Principle of Thermodynamics. Due to the temperature evolution, heat transfer between different elements was estimated. Additionally, experimental results from an FZG test rig were implemented in the model and also used to verify its accuracy. Furthermore, additional features to the model such as a cooling system and spray lubrication were also studied. Results show a wide capability and handling of the program in terms of thermal analysis: heat flux direction and magnitude, visual tools such as thermal network of the test gearbox, as well as the analysis of different operating conditions. With these tools, an approach to the minimum amount of lubricant necessary and other ways to quench overheating could then be reached. Keywords: Thermal network, FZG gear test rig, heat flow, temperature, MATLAB, ODE.Växellådor är ständigt ett forskningsområde för att förbättra deras verkningsgrad. Energiförluster i kuggkontakter omvandlas till värme som sprids i växellådan som sedan värmer upp komponenterna. En termisk modell av växellådan gör det möjligt för djupare förståelse hur värmen sprids i förhållande till energiförlusterna i kuggkontakten. Ett MATLAB-program baserat på ordinära differential-ekvationer utvecklades för att göra en termisk modell av en växellåda i en kuggrigg från FZG. Modellen är baserad på ett termiskt nätverk där varje nod representerar en maskinkomponent. Det termiska nätverket består av resistanser som uppstår på grund av deformation i kuggkontakten, ledning, konvektion och strålning. Med termiska resistanser, energiförluster, termisk tröghet från komponenterna och genom att applicera termodynamikens första grundsats kunde temperatur-genereringen bestämmas. Från temperatur-genereringen kunde värme-ledningen mellan komponenter uppskattas. Testresultat från en FZG-kuggrigg användes för att verifiera modellens noggrannhet. Andra egenskaper till modellen, som ett annat kylsystem och spraysmörjning studerades för att undersöka möjligheteten att adderas till modellen. Resultat visar på en bred användning av modellen i avseende på termisk analys: värmeflödets storlek och riktning, ett visuellt redskap för växellådans temperatur och hur växellådans temperatur varierar under olika driftförhållanden. Med de här redskapen kan den minsta oljemängden som behövs för att smörja kuggkontakten undersökas och hur kylning av kugghjulen kan förbättras. Nyckelord: Termiskt nätverk, FZG kugghjuls-rigg, värmeflöde, temperatur, MATLAB, ODE
11
Manresa, Pérez Álvaro, i Sanchez Ander Gonzalez. "Use of compliant mechanisms in gearbox applications". Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-18520.
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The purpose of this thesis is to prove that the use of compliant mechanisms in gearbox applications is viable. Compliant mechanisms are developed for their implementation in Scania’s hybrid asynchronous gearboxes. These mechanisms are presented as a replacement for the latch assembly currently in use to hold the position of the gear-shifting elements. The objective is to implement a compliant mechanism in order to avoid wear and increase the life cycle within the given constraints, as well as to have a better understanding of this kind of mechanisms. The presented literature study shows that bistable and tristable compliant mechanisms are the most suitable ones for this application. Titanium alloys, tool steels, and bulk metallic glasses are discussed as the best material options for compliant mechanism manufacturing. A mechanism idea generation and selection process is conducted. Finite Element Analysis (FEA) is developed with the chosen bistable and tristable compliant mechanism ideas. The tristable concept results on being inappropriate for this application, as it does not fulfil the volume and positioning constraints. The bistable device is proven to be suitable, and further analysis is carried out to study its fatigue resistance and show that it fulfils all the requirements, solving the weaknesses of the latch and absorbing the impact in the shaft. Additive manufacturing methods and injection moulding are found to be incompatible with the designed mechanisms. That is why the chosen bistable mechanism is designed to be made out of different parts. Future work is presented to strengthen the weaker points of this project.
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Pinheiro, Pedro Filipe Pinto. "Automatic management system for the AtlasCar gearbox". Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/10064.
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Mestrado em Engenharia MecânicaO veículo AtlasCar é um protótipo desenvolvido pelo Laboratório de Automação e Robótica do Departamento de Engenharia Mecânica da Universidade de Aveiro, e tem como principais objetivos o estudo de sistemas de segurança ativos e passivos, técnicas de apoio à condução e soluções para a condução autónoma. Até ao momento, uma das maiores limitações a nível da atuação de mecanismos essenciais para a condução autónoma, verificada no AtlasCar, era a ausência de um sistema que permitisse o controlo da caixa de velocidades. Embora o comutador de caixa estivesse já projetado e construído, não possuía nenhum sistema de controlo que permitisse a sua utilização. Com este trabalho pretende-se executar todo o projeto, a construção e a programação de baixo nível de um controlador robusto e eficaz para desempenhar o seu papel no âmbito do projeto AtlasCar. Um protocolo de comunicação fiável entre o firmware do presente mecanismo e o software do AtlasCar será também implementado, devido á grande responsabilidade do dispositivo em questão, de forma a permitir uma condução segura. Outros softwares acessórios á correta utilização deste mecanismo no âmbito do projecto AtlasCar, como um software de calibração e um nodo de ROS para comunicação com o mesmo serão apresentados. É também objetivo deste trabalho a realização de alguns testes de bancada, necessários de forma a comprovar o funcionamento correto quer da programação, quer do protocolo de comunicação criado, recorrendo a um simulador com Hardware-in-the-Loop simplificado, programado em Matlab.
The AtlasCar vehicle is a prototype developed by the Laboratory of Automation and Robotics at the Department of Mechanical Engineering at Aveiro University with the purpose of studying active and passive safety systems, assisted driving techniques and new solutions for autonomous driving. Until now, one of the major faults in what concerns to the actuation of the AtlasCar vehicle’s main driving systems was the absence of a mechanism that would allow the control over the AtlasCar gearbox. Although a mechanism had already been built for this purpose, it had no control system that would allow it to be automatically actuated. The purpose of this work is to present an electronic project for a robust and effective controller to this AtlasCar’s gear selector mechanism. The controller’s construction and its low-level programming is also executed. A reliable communication protocol between the firmware of the mechanism, and the AtlasCar software is also implemented, due to the high responsibility task to be performed by this actuator in the driving process. Other accessory software, like a calibrator for the gear selector mechanism and a ROS Node to perform the communication between the AtlasCar control PC and the mechanism, are also presented. It is also within the scope of this work the execution of several laboratory tests, in order to determine the robustness of both the programming and the communication protocol. These tests will be executed with a simplified Hardware-in-the-Loop simulator, written using Matlab.
13
Wendelius, Ludvig. "Development of a SimulationModel of an Automatic Gearbox". Thesis, Umeå universitet, Institutionen för fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-58488.
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A simulation model for an automatic gearbox with primary retarder has been constructedand implemented, in this thesis. Together with other modelled vehicle components, thismodel could for example be used for fuel consumption estimation or optimizing vehicleparameters.The mechanical components and the control system inside the automatic gearbox weremodelled separately and then assembled into the nal gearbox model, using the objectorientedprogramming language Modelica. Modelica ensures that each individual componentcan be reused in other models.The gearbox model was validated through a number of test cycles designed to capturedierent vehicle behaviours. The test cycles were recreated in the simulation environmentand the simulation results could be compared to a real vehicle performing the same tests.Validation showed that the model succeeded in its goal, that the implemented model isreproducing similar behaviour as the real gearbox. With gear shifts taking place in aboutthe same situations and converter locking/unlocking occurring the same time in the simulationsas in the real vehicle testing.I det här examensarbetet har en simuleringsmodell för en automatisk växellåda med primär retarder utvecklats och implementerats. Tillsammans med andra modeller från fordonoch drivlina skulle denna simuleringsmodell kunna användas för att uppskatta ett fordonsbränsleförbrukning eller till att optimera olika fordonsparametrar.De olika mekaniska komponenterna samt kontrollsystemet i växellådan modellerades separat.Dessa modeller kunde sedan sammanfogas för att bygga den slutliga växellådsmodellen.Alla modeller implementerades i det objektorienterade programmeringsspråket Modelica,som tillåter en stor återanvändningsbarhet till vardera enskild komponent.Den implementerade modellen verierades genom ett antal provcykler, utformade för attfånga olika beteenden hos växellådan. Dessa cykler har återskapats i simuleringsmiljön ochmed det kunde resultat från simuleringar jämföras mot data från ett verkligt fordon somutförde samma prov.Från verieringen har slutsatsen dragits att modellen uppfyllde målen med projektet. Målen var, att den slutliga simuleringsmodellen visar ett liknande beteende som en växellåda i ett verkligen fordon. Växlingar och låsning/upplåsning hos momentomvandlareninträande vid ungefär samma situationer i simuleringarna som i provningen med det verkligafordonet.
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Ljungbäck, Jacob. "Characterization of Cascade gearbox for wave energy converter". Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-182811.
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This Master Thesis, written in collaboration with CorPower Ocean, serves as the finalization of the author’s master degree education at KTH (Royal Institute of Technology) Stockholm. The purpose has been to characterize the Cascade gearbox which is used to convert vertical motion induced by waves to rotational motion which powers generators in the company’s future wave energy power plant. The purpose was also to suggest future improvements and shed light on any problems discovered. The method for characterizing the Cascade gearbox was to conduct physical measurements of the load sharing in the inherently overdetermined geometrical design. These data were then used to calibrate a static as well as a dynamic model also developed for this thesis. Focus has been on determining that the novel load sharing method is sufficient and that no gear takes more than the 2,5% overload during max load the gearbox is dimensioned for at any time. Also included in the thesis is an analysis of the tolerances effect on the performance of the Cascade gearbox. Results showed that the current design perform within the expected dimensioning limits. However some unexpected characteristics were discovered after analysis of the results. Because of deliberate geometric decisions half of the gears trail behind initially in one direction causing uneven load sharing and unwanted lateral forces on the rack. Also discovered was the importance of equal stiffness of the flex units, used to divide the load evenly between the gears, since the load sharing factor converges towards values directly proportional to the stiffness ratios in between them. As a conclusion it can be said that although the current design is sufficient, there is still room for improvements which could enhance life expectancy as well as load sharing performance of the Cascade gearbox.Detta examensarbete utfört i samarbete med CorPower Ocean, är det slutgiltiga steget i författarens utbildning på masternivå på KTH (Kungliga Tekniska Högskolan) Stockholm. Syftet med arbetet är att karakterisera en kaskadväxellåda som används för att omvandla vertikal rörelse från vågor till rotation som driver generatorer i företagets framtida vågkraftverk samt att utifrån resultat föreslå möjliga förbättringar och belysa eventuella problem. Den metod som använts för att karakterisera kaskadväxellådan var att via fysiska mätningar, på den testrigg placerad på KTH (Kungliga Tekniska Högskolan) i Stockholm, erhålla data för lastfördelningen i den geometriskt överbestämda konstruktionen. Dessa data användes sedan för att kalibrera en statisk och en dynamisk modell som också utvecklades för det här projektet. Huvudfokus för arbetet har legat i att ta reda på om den konstruktion som används för att fördela lasten mellan kugghjulen fungerar tillfredställande samt att säkerställa att inget kugghjul tar mer än de 2,5% överlast vid fullast växellådan är dimensionerad för vid något tillfälle. Examensarbetet inkluderar även feltoleransers inverkan på lastfördelningen i kaskadväxeln. Resultaten visade att den nuvarande konstruktionen presterar inom de specificerade dimensioneringsintervallen. Några oväntade karaktärsdrag upptäckdes dock vid analys av resultaten. På grund av en avsiktlig geometrisk oregelbundenhet släpade hälften av kugghjulen efter åt ena hållet vilket i sin tur resulterade i en ojämn lastfördelning och oönskade sidokrafter på kuggracken. Flexenheterna som används för att fördela lasten likvärdigt mellan kugghjulen skilde sig åt i styvhet. Den inverkan spridningen av dessa har på lastfördelningen belystes också eftersom lastfördelningen konvergerar mot värden direkt proportionella mot styvhetsförhållandet mellan dem. Slutsatsen från examensarbetet är att den nuvarande konstruktionen, även om den fungerar tillfredställande, lämnar utrymme för förbättringar som potentiellt kan förbättra både livslängd och lastfördelningsprestanda.
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Ivanov, Dinko. "Gearbox housing design – topology optimization through generative design". Thesis, KTH, Maskinkonstruktion (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244983.
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Detta examensarbete använder ett systematiskt tillvägagångssätt för att omkonstruera ett växellådshus till ett elektriskt fordon med avsikt att förbättra prestanda med avseende på hållfasthet, livslängd och styvhet. I examensarbetet ges även en kort beskrivning av hur växellådan fungerar, vilken roll den spelar i de elektriska fordonen, samt grundläggande teori som används vid konstruktion av liknande växellådor. Den huvudsakliga arbetsmetoden som använts för att nå målen är topologioptimering och olika lösningar har simulerats för att förenkla den framtida omkonstruktionen. Analyser av de olika resultaten har lett fram till ett grovt förslag på hur växellådshuset kan utformas. Det resultatet förkastades efter det att några extra simuleringar gjorts. Även om inget slutgiltigt förslag hittades, har detta examensarbete tagit fram en bra grund och vägvisning för att senare lyckas med uppdraget.This thesis targets a systematic approach for redesign of the gearbox housing for an electrical vehicle, with an intention to improve its performance in terms of structural integrity, durability and compliance. Throughout the work, a brief overview of gearbox purpose, position and significance in context of electric vehicles has been presented, some theoretical background concerning design of similar gearboxes is presented and underlying theoretical fundamentals are reviewed. Topology optimization has been utilized as the main method for achieving the goals and various solving runs were performed in order to ease the subsequent redesign. Interpretations of multiple result sets led to a rough outline guess of a possible solution candidate. After supplementary studies, that solution was later discarded. In the end, although no final redesign was generated, clear and comprehensive directions for achieving the targeted goal have been formulated.
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Alkhadafe, H. "Computational intelligence for fault diagnosis in gearbox systems". Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/133/.
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Employing an efficient condition monitoring system in industrial applications is an important factor in improving the quality of production and increasing the operational life of machines by revealing machine faults at the earlier stage. Damage in gearbox system is one of the most catastrophic failures in machineries. Any defects related to a gearbox will influence the performance of an entire mechanical system. A reliable and efficient fault diagnosis system is required to reduce the maintenance cost and downtime, thereby preventing machinery performance degradation and failure. Many condition monitoring and fault diagnosis systems are investigated in the literature for gearbox fault detection and diagnosis. However, there are still many challenges to tackle mainly due to the complex nature of gearbox structure, limited access to the component to be monitored and the low signal-to-noise ratio experienced especially when operating machineries under fault conditions. The aim of this research is to develop a systematic methodology for the design of condition monitoring systems for gearbox faults by investigating sensor selection, sensor location, and sensory features to be able to diagnose a fault accurately. Therefore, the goal is to select reliable techniques at each stage in order to improve the reliability of the fault diagnosis system. Different sets of experiments based on gearbox conditions are conducted using several sensors including vibration, acoustic emission, speed, and torque. Measured signals are analysed using conventional and advanced signal processing and data analysis methods including time, frequency and time/frequency domains such as Fast Fourier Transform (FFT), Short Time Fourier Transform (STFT), and Wavelet analysis (WT). Several statistical and mathematical techniques have been proposed as features extraction methods to reduce the dimensionality and select appropriate information. For this research, a single stage gearbox system with two main type of faults (pitting and broken teeth) with various degrees of damage in helical gear are used to evaluate the proposed approach. This research investigated the relationship between sensor location and detecting the fault in gearbox system. A methodology has been proposed for locating indirect monitoring sensors such as acoustic emission and vibration on gearbox to obtain high quality information regarding the behaviour of machine condition. The methodology is designed to evaluate the optimum sensor positioning for detecting faults in the gearbox system. A novel gearbox monitoring approach named an Automated Sensor and Signal Processing Selection for Gearbox system (ASPSG) has been applied to select the most reliable and sensitive sensors, features and signal processing methods based on optimal sensor location. The ASPSG approach is based on simplifying complex sensory signals into a group of Sensory Characteristic Features (SCFs) and evaluating the sensitivity of these SCFs in detecting gearbox faults. The aim of this approach is to enhance the performance of monitoring system of gearbox fault detection and to reduce the number of sensors required in the overall system and reduce the cost. To implement the suggested ASPSG approach two strategies are proposed: automated system based on Taguchi's orthogonal arrays and stepwise system using (Linear Regression (LR), Fuzzy Rule Based System (FRBS) and Principal Component Analysis (PCA), techniques ). To evaluate both strategies, four dierent classication models are employed using supervised and unsupervised neural networks. Both strategies have been implemented to prove the capability of the suggested approach. A cost reduction is performed based on removing the least utilised sensors without losing the performance of the condition monitoring system. The results show that the ASPSG approach can provide a systematic design methodology for condition monitoring systems for gearboxes and that it is capable of detecting faults in a gearbox system with less cost and reduced number of experiments. Consequently, the ndings of this research prove that the sensor location could have signicant effect on the design of the condition monitoring system and its performance.
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Abdalla, Gaballa M. A. "Planetary gearbox condition monitoring based on modulation analysis". Thesis, University of Huddersfield, 2017. http://eprints.hud.ac.uk/id/eprint/32087/.
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The epicycle gearbox or planetary gearbox (PG) is a central power transmission systems of important machines such as helicopters and wind turbines which are mission critical and high cost systems. Condition monitoring (CM) has been explored extensively in recent years to avoid any unexpected interruptions and severe accidences caused by faults PGs. Although, considerable advancements in CM techniques, there still existed significant deficiency such as insensitivity, false diagnosis and high costs in implementing such techniques in industries. To improve CM techniques, therefore, this thesis focuses on an investigation of advanced signal analysis techniques such as higher order spectra (HOS) in order to achieve full characterisation of the nonlinear modulation processes of PG dynamics and thereby develop accurate diagnostic techniques. The lumped mass model is established for modelling the dynamic behaviour of the PG under investigation, which allows the vibration behaviours to be understood for analysing different abnormalities such as tooth breakages and gear errors. This paves the way for subsequent data analytics and fault diagnostics using modulation signal bispectrum (MSB) that allows the vibration data to be examined through HOS, but it is significantly efficient in characterising the multiple and nonlinear modulations of PG dynamics alongside superior noise reduction performance. Different degrees of misalignments in the PG drive system has been investigated and successfully diagnosed using MSB analysis of vibration measurements. Moreover, the investigation included detection of tooth breakage faults of different severities in both the sun and a planet gear. The tooth faults were diagnosed using the recently developed MSB through accurately representation and estimate of residual sidebands induced by these faults. Consequently, MSB analysis produces an accurate and reliable diagnosis in that it gives correct indication of the fault severity and location for wide operating conditions. Furthermore, these fault diagnosis practices allows the establishment of residual sideband analysis approach. These residual sidebands resulting from the out-of-phase superposition of vibration waves due to asymmetric, multiple meshing sources are much less influenced by gear errors than the in-phase sidebands due to faults or new occurrences of the symmetricity. MSB can provide an accurate characterisation of the residual sidebands and consequently produces consistent diagnosis as confirmed by both simulation and experiment.
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Dogantimur, Erkan, i Daniel Johnsson. "Analysis of Accuracy for Engine and Gearbox Sensors". Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388346.
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This thesis provides a standardized method to measure accuracy for engine and gearbox sensors. Accuracy is defined by ISO 5725, which states that trueness and precision need to be known to provide a metric for accuracy. However, obtaining and processing the data required for this is not straight forward. In this thesis, a method is presented that consists of two main parts: data acquisition and data analysis. The data acquisition part shows how to connect all of the equipment used and how to sample and store all the raw data from the sensors. The data analysis part shows how to process that raw data into statistical data, such as trueness, repeatability and reproducibility for the sensors. Once repeatability and reproducibility are known, the total precision can be determined. Accuracy can then be obtained by using information from trueness and precision. Besides, this thesis shows that measurement error can be separated into error caused by the sensors and error caused by the measurand. This is useful information, because it can be used to assess which type of error is the greatest, whether or not it can be compensated for, and if it is economically viable to compensate for such error. The results are then shown, where it is possible to gain information about the sensors’ performance from various graphs. Between Hall and inductive sensors, there were no superior winner, since they both have their strengths and weaknesses. The thesis ends by making recommendations on how to compensate for some of the errors, and how to improve upon the method to make it more automatic in the future.
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Zhuang, Shengnan. "Gearbox housing topology optimization with respect to gear misalignment". Thesis, Linköpings universitet, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-87263.
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Structural topology optimization methods have existing and been improving theoretically since 1980s; however, in industry, with respect to the certain conditions, proper modification is always desired. This study develops a specific method to utilize topology optimization for gearbox housing design. Gearbox housing maintains the position of the shafts to ensure the precision of gear engagement in all operational states (Naunheimer, et al., 2010). The current housing design processing used in Vicura AB, a Swedish powertrain company, is able to achieve stiff optimal housing material distribution, but difficult to fulfil gear misalignment requirement. This work overcomes the above shortages to develop a new methodology for gearbox housing topology optimization concerning the gear misalignment as well. The paper is starting with an introduction of the previous method and its defects, followed by a discussion of three possible improvements. Only one of them is feasible and two main difficulties need to be resolved to make it applicable. One of the difficulties is finding a linear assumption of the non-linear components and the other is deriving an approach for topology optimization involving both external forces and non-zero prescribed displacements. The corresponding solutions are described subsequently in detail both theoretically and practically. Then the results by implementing the new method and also the comparison with the results getting from the old method are presented. Finally, a validation of the new method is discussed and the conclusions and comments are given.
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Yesilyurt, Isa. "Gearbox fault detection and severity assessment using vibration analysis". Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488107.
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Turner, Adam James. "Application of CFD to model an aeroengine internal gearbox". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29105/.
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This thesis describes research undertaken to improve computational modelling capability for the internal gearbox (IGB) of an aeroengine. Using the commercial computational fluid dynamics (CFD) software ANSYS FLUENT modelling methodologies for regions within the IGB have been developed, applied and refined. The IGB is a bearing chamber that houses the bearings that support the low pressure, intermediate pressure and high pressure shafts and in addition the spiral bevel gear pair that enable power to be taken from the high pressure shaft to power aircraft auxiliary systems. Within civil aeroengines parasitic power loss is a significant issue and as oil is used to lubricate and cool throughout the engine, this power loss largely manifests as increased heat-to-oil (HTO). A significant contributor to HTO is the IGB. The IGB contains complex geometry and a highly rotating two-phase flow consisting of films, droplets, ligaments and mist. Central to the IGB is the spiral bevel gear pair. Previous modelling research has shown that detailed modelling of flow behaviour is too computationally expensive for domains larger than a few teeth. Modelling the meshing gears with full flow fidelity is not yet feasible. In this thesis a significantly less computationally expensive approach is explored. The complex gear-shroud geometry is replaced by a smooth cone with momentum sources used to generate the required fluid motion. In the single phase model these momentum sources were tuned/calibrated against a full tooth model spanning four teeth. The model was capable of generating flow behaviour to within 5% of the full tooth model. Oil was added as a discrete phase with a film model but was less successful as oil motion is strongly affected by geometrical detail. A second approach to whole chamber modelling was proposed where the chamber is split into three zones and coupled via boundary conditions. Single phase investigation showed that the amount of swirl in the front chamber affects computed windage power loss with the maximum occurring at an inlet swirl number of around 0.5. The amount of swirl at gear entry does not however affect the amount of swirl at shroud exit and this shows that decoupling of the front chamber is viable. The investigations into the zonal coupling of the IGB highlighted the importance of the geometry of the rear chamber (between gear and bearing) on the flow through the gear. A study to investigate how best to model the two-phase flow in this rear chamber was conducted. Transient models showed the volume of fluid approach (VOF) to be inadequate whereas a full two-phase Eulerian model converged, yielding viable results consistent with limited qualitative experimental data. The computational model predicts significant accumulation of oil towards the bearing side of the chamber, with this oil stripping periodically through shroud exit slots to the front chamber. In the final part of the research a parametric study on several geometric features in the rear chamber was conducted using the developed two-phase modelling methodology. The chamber size, rear wall geometry, shroud exit slot location and size were investigated. The work in this thesis improves IGB modelling capability through - Establishing the capabilities and limitations of momentum source approach for full two-phase modelling of a shrouded gear - Establishing that to some extent a bearing chamber can be productively modelled as separate but linked zones - Identifying a successful modelling methodology for the high volume fraction two phase flow in the rear chamber In addition the work in this thesis shows that - For single phase flow the amount of swirl at gear inlet affects the windage power loss - The behaviour of oil in the rear chamber, including the amount trapped and the exit condition, are strongly affected by chamber geometry Guidelines for rear chamber design are also suggested.
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Bruce, Thomas. "Analysis of the premature failure of wind turbine gearbox bearings". Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/13903/.
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Wind turbine gearbox bearings are the component that leads to the most downtime of operating wind turbines due to their high failure rates. Failures occur within 10 % of bearing design life, despite the fact that they are designed to the same bearing standards that satisfactorily predict bearing lifetime in many other industrial applications. No theory has yet been widely accepted to explain the reasons for this premature failure, despite intensive research effort and many theories have been suggested both from industrial and academic researchers alike. The most widely accepted theory at the current time is that the bearing subsurface is weakened by what have been termed as white etching cracks that eventually lead to material removal from the bearing contact surfaces. Extreme loading conditions caused by a number of possible sources, which expose bearings to higher than designed contact pressures and surface traction in wind turbine operation, are investigated throughout this project. A dynamic model of a wind turbine gearbox was developed in order to calculate bearing contact stresses during transient operating conditions, which found that bearings were loading to above recommended values, even during normal operating conditions. A failed bearing from a wind turbine gearbox was then destructively investigated, leading to the conclusion that manganese sulphide inclusions were the primary cause of white etching crack initiation. These inclusions were investigated in greater detail to determine the geometry and depth of the most damaging inclusions, both in the failed bearing and on bench top test rigs. A series of hammering impact test and rolling contact fatigue tests were designed and led to the successful recreation of white etching cracks in test specimens. It was found that white etching cracks certainly initiate at MnS inclusions. These microcracks initiate due to a tensile load across inclusion tips, which are thought to be further propagated by shear loading along the cracks. Inclusion initiated microcracks have been found to develop into white etching cracks, which may link up and weaken the subsurface of bearing raceways sufficiently to cause eventual failure. Testing is carried out to find thresholds in terms of contact pressure, surface traction, impact and fatigue loading cycles, required for the formation of white etching cracks. The key contributions of this study are identification and recreation of four different types of subsurface damage at MnS inclusions by examining a failed WTGB and carrying out testing using a reciprocating hammering impact rig and a rolling contact fatigue twin disc machine. A hypothesis of the order and mechanism of these damage events is proposed in this study, as well as the development of testing methods to investigate the damage in order to support the hypotheses. Test methods are also developed to investigate the effects of some key bearing loading parameters, including impact loading, levels of contact pressure, surface traction and number of load cycles.
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Staszewski, Wieslaw Jerzy. "The application of time-variant analysis to gearbox fault detection". Thesis, University of Manchester, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.552995.
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Jones, Rhys Gareth. "The mathematical modelling of gearbox vibration under applied lateral misalignment". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/54939/.
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In the mathematical modelling of gear vibrations it is found that there is a gap between the transient models developed in academia and the steady state models frequently used in industry. It is seen that the academic models are adept at modelling the nonlinear phenomena seen during gear contact for system with only a few degrees-of-freedom, whereas the industrial models are capable of solving the linear steady state response of more complex transmission systems. The work presented in this thesis attempts to bridge the gap between the two models, through the development of a transient nonlinear model of a gear pair with increased degrees-of-freedom. An understanding of the gear contact is achieved through the use of advanced static finite element analysis with nonlinear gear contact. Through FEA the effects of gear misalignment on these contact conditions is also investigated. The findings from the FEA are then used in a mathematical model of a single stage spur gear transmission, which is developed as part of the thesis, to determine the system accelerations. The mathematical model includes the time varying mesh stiffness and the time varying and nonlinear bearing stiffness's and frictional forces. The effects of lateral misalignment seen in the FEA results are also included into the model to investigate their effects. The model parameters are then varied to determine their effects and the simulated accelerations are compared against experimental results. It is found from this comparison that although some similarities between the simulated and experimental results are achieved for the aligned case, insufficient corroboration is found for the axially and radially misaligned results to confirm the validity of the mathematical model for modelling misalignment. From this, further experimental results were requested to gain a better con- fidence in the effects of lateral misalignment.
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Krumins, Armands. "Gearbox fault detection, based on Machine Learning of multiple sensors". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301603.
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The increasing demand for higher efficiency and lower environmental impact of transmissions, used in automotive and wind energy industries has created a need for more advanced technical solutions to fulfil those requirements. Condition monitoring plays an important role in the transmission life cycle, saving resources and time. Recently condition monitoring, using machine learning has shifted from reactive to proactive action, predicting minor faults before they become significant. This thesis intends to develop a methodology that can be used to predict faults like pitting initiation, before propagating in FZG test rig, available at KTH Machine Design department. Standard sensor measurements already available like temperature, rotation speed and torque are used in this project. Four kinds of gears were used, two made of wrought, and two – of powder metal steel, each with ground or superfinish surface. After a literature review about pitting fatigue, condition indicators for these failures and machine learning were done, a statistical analysis was done, to see how the transmission behaves during testing and to have comparison material, helpful when having machine learning results. Two machine learning models, Decision Tree and Support Vector Machine were selected and trained in two combinations, either with Root Mean Square only, or with Crest Factor, Standard Deviation and Kurtosis in addition. As a result, 64 models were trained, 32 for all tests and another 32 to investigate two particular tests due to a longer pitting propagation period. New condition indicators like Standard Deviation and Signal – to – noise ratio was calculated to get more nuanced trends than just using one measurement to monitor the gearbox behavior. After comparing with the results from statistical analysis and previously done tooth profile measurements, it was concluded that the new indicators could indicate the change in gearbox operation before the first pitting initiation is detected, using tooth profile measurement.
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Polly, Joseph H. "An Experimental Investigation of Churning Power Losses of a Gearbox". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1362745236.
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Rutledge, Matthew S. "Aircraft Gearbox Dynamics Subject to Electromechanical Actuator Regenerative Energy Flow". Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1292358176.
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Simpson, D. J. A. "The object-oriented paradigm applied to the design and analysis of mechanical systems". Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/717.
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Åkerblom, Mats. "Gearbox noise : Correlation with transmission error and influence of bearing preload". Doctoral thesis, KTH, Maskinkonstruktion (Inst.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9899.
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The five appended papers all deal with gearbox noise and vibration. The first paper presents a review of previously published literature on gearbox noise and vibration. The second paper describes a test rig that was specially designed and built for noise testing of gears. Finite element analysis was used to predict the dynamic properties of the test rig, and experimental modal analysis of the gearbox housing was used to verify the theoretical predictions of natural frequencies. In the third paper, the influence of gear finishing method and gear deviations on gearbox noise is investigated in what is primarily an experimental study. Eleven test gear pairs were manufactured using three different finishing methods. Transmission error, which is considered to be an important excitation mechanism for gear noise, was measured as well as predicted. The test rig was used to measure gearbox noise and vibration for the different test gear pairs. The measured noise and vibration levels were compared with the predicted and measured transmission error. Most of the experimental results can be interpreted in terms of measured and predicted transmission error. However, it does not seem possible to identify one single parameter, such as measured peak-to-peak transmission error, that can be directly related to measured noise and vibration. The measurements also show that disassembly and reassembly of the gearbox with the same gear pair can change the levels of measured noise and vibration considerably. This finding indicates that other factors besides the gears affect gear noise. In the fourth paper, the influence of bearing endplay or preload on gearbox noise and vibration is investigated. Vibration measurements were carried out at torque levels of 140 Nm and 400 Nm, with 0.15 mm and 0 mm bearing endplay, and with 0.15 mm bearing preload. The results show that the bearing endplay and preload influence the gearbox vibrations. With preloaded bearings, the vibrations increase at speeds over 2000 rpm and decrease at speeds below 2000 rpm, compared with bearings with endplay. Finite element simulations show the same tendencies as the measurements. The fifth paper describes how gearbox noise is reduced by optimizing the gear geometry for decreased transmission error. Robustness with respect to gear deviations and varying torque is considered in order to find a gear geometry giving low noise in an appropriate torque range despite deviations from the nominal geometry due to manufacturing tolerances. Static and dynamic transmission error, noise, and housing vibrations were measured. The correlation between dynamic transmission error, housing vibrations and noise was investigated in speed sweeps from 500 to 2500 rpm at constant torque. No correlation was found between dynamic transmission error and noise. Static loaded transmission error seems to be correlated with the ability of the gear pair to excite vibration in the gearbox dynamic system.QC 20100923
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Enocksson, Staffan. "Modeling in MathWorks Simscapeby building a model of an automatic gearbox". Thesis, Uppsala universitet, Avdelningen för systemteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151891.
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The purpose of this thesis work has been to analyze the usability and the feasibility formodeling with MathWorks simulation tool Simscape by building a simplified model ofthe automatic gearbox ZF-ECOMAT 4 (HP 504 C / HP 594 C / HP 604 C). It hasbeen shown throughout the thesis how this model is build. First has systemknowledge been acquired by studying relevant literature and speaking with thepersons concerned. The second step was to get acquainted with Simscape and thephysical network approach. The physical network approach that is accessible throughthe Simscape language makes is easy to build custom made components with means ofphysical and mathematical relationships. With this background a stepwise approachbeen conducted which has led to the final model of the gearbox and the validationconcept. The results from this thesis work indicates that Simscape is a powerful tool formodeling physical systems and the results of the model validation gives a good signthat it is possible to build and simulate physical models with the Simscape software.However, during the modeling of the ZF-ECOMAT 4 some things have beendiscovered which could improve the usability of the tool and make the learning curvefor an inexperienced user of physical modeling tools less steep. In particular, a largermodel library should be included from the beginning, more examples of simple andmore complex models, the object-oriented related parts such as own MATLABfunctions should be expanded, and a better troubleshooting guidance.
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Vatkar, Shirish Talia Jorge E. "Design of a two stage epicyclic gearbox in sintered metal gears". Diss., A link to full text of this thesis in SOAR, 2007. http://soar.wichita.edu/dspace/handle/10057/1183.
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Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.."May 2007." Title from PDF title page (viewed on Dec. 29, 2007). Thesis adviser: George Talia. Includes bibliographic references (leaves 100-101).
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Unibaso, Eguzkitza Beñat, i Dobón Ismael Ismail. "Development of a flexible test platform utilizing gearbox simulators through programming". Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-12415.
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A gearbox simulator is developed as platform for testing and demonstrating purposes. For that, a rig composed by a mechanical system and electronic equipment for controlling two servomotors is used. The objective of this equipment is to simulate the forces that the gearbox would transmit to the gear lever when the gear change operation is being carried-out. To reach this goal, a program is developed in LabVIEW to command the servomotors, emulating the forces by controlling the output torque and transmitting them to the gear stick as it would be in a real gearbox, taking into account real force-angle curves. Also, a graphical user interface is developed in order to monitor the simulator performance ad ease the way the data is chosen and introduced into the software.As seen in the experiment results, the graphs present similarities in shape and magnitude, which is important in regards of feeling; a better performance could be reach suppressing some system constraints.
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Åkerblom, Mats. "Gearbox noise : correlation with transmission error and influence of bearing preload /". Stockholm : Maskinkonstruktion, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9899.
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Shen, Anne Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Optimised reduction of the radiated noise from the casing of a constant speed gearbox". Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/43020.
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This thesis presents a comprehensive methodology for predicting and minimising the noise radiated from a constant speed gearbox assembly by means of attaching optimally placed stiffening ribs on the casing. The procedure involves building an FE model of the gearbox, which is updated using modal parameters extracted from a modal test. This is followed by synthesis of the required FRFs with respect to the forcing degrees-of-freedom. The forces, which are assumed to act only at the bearings are identified from these FRFs and the measured operational velocities of the casing. The identified forces are then used to excite the updated FE model to re-calculate the vibration velocities. A boundary element method is used to calculate the final radiated sound power to be compared with that measured. The same forces are used later to excite the modified gearbox casing to determine the improvement given by optimised modification. The optimisation study minimises the vibration energy of the casing in 10% bands around critical frequencies, in this case the first two harmonics of the gearmesh frequency. To allow for errors in the model, the excitation is by white noise, so as to produce wide stop bands, rather than minimising the response at particular frequencies. The vibration energy is weighted for radiation efficiency, A-weighting, and relative source strength in the bands. The final optimal stiffener layout is validated through a final vibration and acoustic calculation on the updated gearbox model using the forces identified in the earlier steps. The study of one particular gearbox concludes that i) the proposed hybrid optimisation scheme produces a theoretical effective noise reduction of 3 dBA for the total sound power. ii) Because the gearmesh harmonics were targeted, a further 5 dB improvement was effectively gained by eliminating the tonal penalty which otherwise applied. iii) From plate studies it was demonstrated that the stiffening ribs could be attached using epoxy cement (to avoid welding) and that the properties of the cemented joint could be determined by model updating after attaching one rib, so as to obtain a better prediction of the final optimised result.
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Paya, Basir Abdul. "Vibration condition monitoring and fault diagnostics of rotating machinery using artificial neural networks". Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390220.
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Al-Balushi, Khamis Rajab Nasser. "The use of high frequency stress waves for monitoring gears". Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/10575.
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The aim of this research is to investigate the feasibility of using stress waves for condition monitoring of gears. The project involved setting up an experimental rig, carrying out experimental work, acquiring stress waves signatures, and processing the signals. It has been shown that stress waves can successfully be employed for early detection of incipient gear failure. A experimental gearbox was employed during the experiments. Miniature ultrasound transducers, both sensitive and sufficiently small, were manufactured and installed on the stationary outer race of the rolling element bearing of the gearbox to detect stress waves from the meshing gears. The stress waves signals from the transducers were digitised and digitally processed to extract relevant information. The signatures were high-pass filtered at a cut-off frequency of 200 kHz, thus representing exclusive ultrasonic frequencies. A new statistical parameter, Energy Index, was developed and performed on the stress wave signatures which were segmented to represent individual gear teeth. Along with this new parameter, the classical statistical parameters, (Peaks, RMS, Standard Deviation, Kurtosis, etc.) were also performed. Conclusive results are presented in graphical form in terms of Cumulative Energy Indices' and Energy Indices in polar form for individual gear teeth. A new algorithrn was also developed and presented for the envelope detection of signal by iterative peak detection. Although no direct comparison was made between condition monitoring of gears using stress waves and methods such as low frequency vibration analysis and wear debris analysis, it is apparent that stress waves monitoring offers a much earlier warning of incipient gear failure because the technique can detect material defonnations which are precursors to changes in the dynamic properties of gears and the occurrence of wear debris. The technique, therefore, can predict incipient failure much earlier, extending the lead-time before failure, and as a result, minimising sudden failures which may have catastrophic consequences.
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Henriksson, Mats. "Analysis of dynamic transmission error and noise from a two-stage gearbox /". Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-488.
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Svensson, Gustav, i Mischa Huisman. "Concepts for a suitable condition based monitoring system for a planetary gearbox". Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-74787.
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In the trends of technical improvements and automatization is it important for companies to keep up with the developments to be competitive on the market. SwePart Transmissions AB is a company that manufacture and develop gearboxes for the currently growing robot arms industry and the main task with this study is to investigate how to apply condition based monitoring on a new gearbox from the company. The work considers vibration analysis and testing new ideas in the oil analysis field. The tests that were performed are based on measuring the difference in impedance or magnetic field due to the increasement of wear. The results of the tests are not clear. This thesis is the beginning of a big project and therefore lies the value of this work in the new ideas and suggestions for further work.
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Marx, Alexandre Maxìme Andre. "An in-depth comparative study of direct drive versus gearbox wind turbines". Thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245060.
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The wind turbine industry is constantly growing and new concepts are flourishing to improve the performance of the turbine drive-train. Typically in conventional large-scale wind power generators, a gearbox is used between the turbine rotor and the electrical generator to increase the rotational speed from around 100 rpm to around 1200 rpm. Other technologies, such as the direct-drive ones, apply a low-speed generator to avoid using a gear and are gaining ground in recent years both in the field of research and in commercial applications. The question is very relevant whether the direct-drive concepts would widen their share of the wind turbine market in the years to come. This study aims at describing and studying analytically various wind turbine types and focuses on the distinction between gearbox systems and direct-drive systems. Comparisons of the different concepts based on their respective drive-train performance are necessary so as to determine the most cost-competitive solutions. Different technologies are examined and described precisely with their own characteristics and working principles, while potential technological advances are reviewed too. These generator solutions are compared by their efficiency, energy yield and energy losses first, and then by their costs and weights. Generally, direct-drive technologies are expected to gain higher importance in the near future, taking into consideration the gradual decrease of their costs. Gearbox systems would probably remain dominant on the market for newly installed wind turbines but the share of direct-drive systems reveals a potential growth. Wind turbine systems will continue to be improved further and their success will most probably be determined by their cost-effectiveness and their ability to cope with grid utility requirements.Vindturbinindustrin växer snabbt och konceptet blomstrar för att svara på efterfrågan på hög energibehov. För konventionella vindkraftgeneratorer används ett växel mellan turbinen och generatorn för att öka rotationshastigheten från omkring 100 rpm till omkring 1200 rpm. Annan teknik, som kallas direktdrivna, använder en låghastighetsgenerator för att bli av med växeln och denna teknik vinner terränt under de senaste åren inom forskningsområdet. Målet är att bestämma om direktdrivningskoncepten kommer att öka sin omfattning på vindkraftmarknaden under de kommande åren. Denna studie syftar till att beskriva och studera analytiskt olika vindturbintyper och att fokusera på skillnaden mellan växellådssystem och direktdrivningssystem. Jämförelser av de olika koncepten baserade på respektive drivtåg är nödvändiga för att bestämma de mest kostnadseffektiva lösningarna. Tekniken undersöks och beskrivs grundligt med egna egenskaper, arbetsprinciper och tekniska framsteg ses också. Dessa generatorlösningar jämförs med effektivitet, energiförbrukning och olika förluster först, och därefter av deras kostnader och vikter. I allmänhet förväntas direktdriven teknik vara ännu viktigare inom en snar framtid, med beaktande av minskningen av kostnader som har initierat sin nedgång. Växellådssystemen kommer förmodligen att förbli de meste installerade turbinerna, men andelen vindkraftverk med direktdrift kan växa större. Nya vindkraftverk får fortsätta utvecklas och deras framgång kommer sannolikt att bestämmas av deras kostnadseffektivitet och deras förmåga att klara kraven på nätverktyg.
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McDonald, Kyler. "An Experimental Study of Spin Power Losses of a High-Speed Gearbox". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523371969014841.
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Howard, Thomas Peter. "Development of a novel bearing concept for improved wind turbine gearbox reliability". Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/11631/.
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The wind industry has experienced rapid growth in recent years as a result of ever increasing concerns over fossil fuel power generation and the associated impact this has upon climate change. Wind turbine technology has however displayed relatively poor reliability from the outset, largely due to the highly variable nature of the wind, which subsequently places system components under extremely harsh loading conditions. Such reliability issues are becoming increasingly problematic for the wind turbine operator, as wind farms – and indeed the turbines themselves – continue to be up-scaled thus increasing the complexity and cost of maintenance, particularly in off-shore environments. Gearbox failures have been found to be responsible for a large proportion of wind turbine downtime, and this is very often linked to the failure of bearings at certain locations within the gearbox. One such critical location is the epicyclic stage, where planetary support bearings are often found to exhibit damage to a localised portion of their inner raceways, corresponding to the location of the applied load. A concept has been proposed to extend the life of such bearings by periodically rotating the normally static inner raceway so as to avoid the build of damage to one localised region. The concept has been termed the MultiLife(TM) mechanism and a key aim of this thesis was to establish proof-of-concept for this system. Initial analytical work was performed, through which it was identified that a five-fold enhancement to bearing life would be theoretically achievable. The concept was subsequently validated experimentally through testing on a bespoke test platform. In addition to this, the ultrasound technique has been explored as a means to provide early warning of bearing failure and thus support the operation of the MultiLife system. This technique has previously been proven as a method to measure the thickness of the oil films that form within bearing contacts. It was identified for this study that oil films would be too small to measure due to the low viscosity lubricants and high bearing loads utilised to accelerate bearing failures. Nonetheless, a general reduction in the amount of ultrasonic energy reflected from the rolling contact was observed during bearing failure, which was linked to a breakdown of the lubricating oil layer due to degradation of the rolling surface. In this case the ultrasound technique did not provide any advanced warning of bearing failure over more classical condition monitoring techniques; however, it was identified that the use of higher resolution ultrasound sensor arrays would enhance the capabilities considerably. Currently, very few monitoring techniques are applied to wind turbine gearbox bearings, and as a further part of this work a condition monitoring system has been installed within an operational 600kW wind turbine. A high speed shaft bearing has been instrumented with a variety of sensors, including ultrasound instrumentation, to assess the potential of such a system in providing early warning of impending gearbox failures.
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Guan, Yunpeng. "Velocity Synchronous Approaches for Planetary Gearbox Fault Diagnosis under Non-Stationary Conditions". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38636.
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Time-frequency methods are widely used tools to diagnose planetary gearbox fault under non-stationary conditions. However, the existing time-frequency methods still have some problems, such as smearing effect and cross-term interference, and these problems limit the effectiveness of the existing time-frequency methods in planetary gearbox fault diagnosis under non-stationary conditions.
To address the aforementioned problems, four time-frequency methods are proposed in this thesis. As nowadays a large portion of the industrial equipment is equipped with tachometers, the first three methods are for the cases that the shaft rotational speed is easily accessible and the last method is for the cases of shaft rotational speed is not easily accessible. The proposed methods are itemized as follows:
(1) The velocity synchronous short-time Fourier transform (VSSTFT), which is a type of linear transform based on the domain mappings and short-time Fourier transform to address the smear effect of the existing linear transforms under known time-varying speed conditions;
(2) The velocity synchrosqueezing transform (VST), which is a type of remapping method based on the domain mapping and synchrosqueezing transform to address the smear effect of existing remapping methods under known time-varying speed conditions;
(3) The velocity synchronous bilinear distribution (VSBD), which is a type of bilinear distribution based on the generalized demodulation and Cohen’s class bilinear distribution to address the smear effect and cross-term interference of existing bilinear distributions under known time-varying speed conditions and
(4) The velocity synchronous linear chirplet transform (VSLCT), which is a non-parametric combined approach of linear transform and concentration-index-guided parameter determination to provide a smear-free and cross-term-free TFR under unknown time-varying speed conditions.
In this work, simple algorithms are developed to avoid the signal resampling process required by the domain mappings or demodulations of the first three methods (i.e., the VSSTFT, VST and VSBD). They are designed to have different resolutions, readabilities, noise tolerances and computational efficiencies. Therefore, they are capable to adapt different application conditions. The VSLCT, as a kind of linear transform, is designed for unknown rotational speed conditions. It utilizes a set of shaft-rotational-speed-synchronous bases to address the smear problem and it is capable to dynamically determine the signal processing parameters (i.e., window length and normalized angle) to provide a clear TFR with desirable time-frequency resolution in response to condition variations.
All of the proposed methods in this work are smear-free and cross-term-free, the TFRs generated by the methods are clearer and more precise compared with the existing time-frequency methods. The faults of planetary gearboxes, if any, can be diagnosed by identifying the fault-induced components from the obtained TFRs. The four methods are all newly applied to fault diagnosis. The effectiveness of them has been validated using both simulated and experimental vibration signals of planetary gearboxes collected under non-stationary conditions.
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Černuško, Lukáš. "Převodovka pro pohon přední nápravy vozidla". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318518.
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Goal of the Master Thesis was to design conception of electric vehicle driveline, which is able of torque vectoring between each wheel independently and to design front axle gearbox. The aim was to use up the car on race track and to test dynamic properties of electric vehicle for follow-up development. Due to determined requirements and possible solutions the conception of driveline was designed and basic parameters were defined. The main part of the thesis contains a design of gearbox including strength calculation of gearing, the control of shafts to fatigue and elasticity limiting states, life of selected bearings. Gearbox case was subjected to FEM analysis. The last chapter uses simulation to gain vehicle acceleration. Designed electric driveline is applicable to other sport vehicles after some modifications.
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BERLATO, Francesco. "DIAGNOSTICA VIBRAZIONALE DI RIDUTTORI EPICICLOIDALI IN AMBIENTE INDUSTRIALE: PROCEDURE, IMPLEMENTAZIONE E VALIDAZIONE". Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2487841.
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Questa Tesi di Dottorato di ricerca concerne lo sviluppo,l’implementazione e la validazione sperimentale di metodologie per il monitoraggio,la diagnostica ed il controllo qualità di rotismi,basate su tecniche avanzate ed innovative di analisi sperimentale delle vibrazioni e di analisi del segnale,con particolare riferimento ai rotismi epicicloidali.L’analisi delle vibrazioni in questo tipo di rotismi è resa complessa dal movimento dei satelliti che fa variare continuamente la distanza –e conseguentemente le funzioni di trasferimento- tra le sorgenti di vibrazioni (ingranamenti e cuscinetti) ed il traduttore fisso all’esterno della corona.Ai fini diagnostici,è necessario estrarre dal segnale vibratorio complessivo il contributo di ciascuna ruota dentata mediante una procedura di media sincrona (Planetary TSA),che, nel caso dei rotismi epicicloidali,deve depurare l’effetto della variazione delle funzioni di trasferimento.Ciò è stato effettuato mediante un complesso algoritmo,già proposto in letteratura,che è stato necessario sviluppare ulteriormente ed implementare con accorgimenti specifici per renderlo applicabile ed efficiente in ambiente industriale.Come indicatori di condizione (CI) per il monitoraggio dei rotismi epicicloidali si sono studiati numerosi parametri statistici della TSA,sulla base dei risultati di campagne sperimentali condotte su un riduttore epicicloidale a 3 stadi di potenza nominale 3 kW che possono riassumersi in: a) prove su banco,al variare del carico,in presenza di difetti localizzati artificiali sulla dentatura dei satelliti; b) prova di usura accelerata su banco prova in configurazione back-to-back portata a fine vita (700 h); c) prova analoga alla b),interrotta a 250 h,quando il valore degli CI ha segnalato lo svilupparsi del pitting; d) prove su banco,al variare del carico,montando sia solari nuovi sia usurati nelle precedenti prove b) e c).Sulla base di tali prove sperimentali,è stata valutata l’efficacia delle metriche proposte in letteratura e ne sono state sviluppate di originali,maggiormente efficaci e rispondenti all’applicazione specifica in ambienti industriali.In particolare,tre metriche originali sono risultate efficaci nell’individuare l’insorgere del pitting ed il suo successivo sviluppo,anche al variare del carico e della velocità: la varianza del segnale residuo RV,la corrispondente varianza cumulativa CRV (media al tempo corrente della precedente) e una variazione migliorativa del già noto NA4,NA4mod, definito come rapporto tra il momento del quart’ordine del segnale residuo e la media corrente del quadrato della varianza del segnale regolare. Inoltre,è stato sviluppato un software dedicato all’analisi delle vibrazioni a fini diagnostici di rotismi epicicloidali,che implementa le tecniche sviluppate ed è atto ad essere impiegato in ambiente industriale; si rileva che non esistono prodotti commerciali con analoghe funzioni.Il software contiene moduli per acquisizione dei segnali vibratori,filtraggio,ricampionamento in base tempo e in base angolo,TSA,individuazione della fase dei satelliti,media sincrona per gli epicicloidali (Planetary TSA),estrazione dei segnali residui,differenza e regolari,trasformata di Fourier,PSD,Envelope,demodulazioni di ampiezza e fase,calcolo di parametri statistici e metriche specifiche per gli ingranaggi.Gli algoritmi,inizialmente implementati in Matlab,hanno richiesto accorgimenti particolari per incrementarne l’efficienza,a fronte della necessità di trattare grosse quantità di dati.Nella versione finale il software è stato implementato in linguaggio ANSI C con una riduzione dei tempi di calcolo di circa il 50%,maggiore stabilità,migliore gestione della memoria e una riduzione dei costi per l’utilizzatore finale.L’efficacia diagnostica degli algoritmi implementati è stata verificata mediante l’applicazione a numerosi dati sperimentali,ottenendo risultati complessivamente soddisfacenti.This PhD thesis concerns the development, implementation and experimental validation of methods for monitoring, diagnostics and quality control of gear systems, based on advanced and innovative techniques of experimental vibration analysis and signal processing, with particular focus on planetary gearboxes. The analysis of the vibrations in this type of gearboxes is complicated by the movement of the planets, that causes the continuous variation of the distance - and consequently of the transfer functions - between the sources of vibration (gear meshing and bearings) and the fixed transducer mounted outside the annulus. For diagnostic purposes, it is necessary to extract from the overall vibration signal the contribution of each gear by means of a synchronous averaging procedure (Planetary TSA), which, in the case of planetary gear trains, has to eliminate the effect of the variation of the transfer functions. This has been obtained by means of a complex algorithm, already proposed in the literature, but requiring further efforts for developing and implementing with specific measures to make it applicable and efficient in an industrial environment. As condition indicators (CI’s) for monitoring of planetary gear trains, numerous TSA statistical parameters have been studied, based on the results of experimental campaigns conducted on a 3 stage planetary gear unit of nominal power of 3 kW; these tests may be summarized as follows: a) tests on bench, under varying load conditions, in the presence of artificial localized defects on planet teeth; b) accelerated wear test on back-to-back test bench, arriving at life end (700 h); c) testing analogous to b), interrupted at 250 h, when the value of the CI’s has indicated the development of pitting; d) tests on bench with different loads, by mounting sun gears in good conditions or worn in the previous tests b) and c). On the basis of these tests, it has been evaluated the effectiveness of metrics proposed in literature; in addition, some original metrics have been developed, more effective and proper for the specific application in industrial environments. In particular, the results show that three original metrics are effective in identifying the onset of pitting and its subsequent development, even with varying load and speed: the variance of the residual signal RV, the corresponding cumulative variance, CRV (average of the previous one at the current time) and an improvement of the already known NA4, NA4mod, defined as the ratio between the forth statistical moment of the residual signal and the current run time average of the squared variance of the regular signal. In addition, a software dedicated to the vibration analysis for diagnostic purposes of planetary gearboxes has been developed; it implements the studied techniques and is suitable for use in industrial environments; it is worth noting that there are no commercial products with similar functions. This software includes modules for the acquisition of vibratory signals, filtering, time and angular resampling, TSA, identification of the phase of the planets, synchronous average for planetary gear units (Planetary TSA), extraction of residual, difference and regular signals, Fourier transform, PSD, Envelope, amplitude and phase demodulation, calculation of statistical parameters and specific metrics for gear diagnostics. The algorithms, initially implemented in Matlab, have required special measures to increase efficiency in the case of large amounts of data. In the final version, the software has been implemented in the ANSI C language with a reduction of computation time by about 50%, greater stability, better memory management and a reduction of costs for the end user. The diagnostic efficiency of the implemented algorithms has been verified by the application to numerous experimental data, generally obtaining satisfactory results.
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Saribay, Zihni Burçay Smith Edward C. Rao Suren B. Bill Robert C. Wang K. W. "Analytical investigation of the pericyclic variable-speed transmission system for helicopter main-gearbox". [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4689/index.html.
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Schön, Peter Paul. "Unconditionally convergent time domain adaptive and time-frequency techniques for epicyclic gearbox vibration". Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-08282007-142010.
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Al-Hamadani, Haider Rahman Dawood. "System dynamic modelling of wind turbine gearbox under normal and transient operating conditions". Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/20545/.
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Srinivasan, Vijay. "Mobility Analysis of Structure-borne Noise Paths in a Simplified Rotorcraft Gearbox System". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276884944.
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LI, MINGFENG. "ACTIVE VIBRATION CONTROL OF A GEARBOX SYSTEM WITH EMPHASIS ON GEAR WHINE REDUCTION". University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1115131866.
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Abboud, Eddy. "Simulation, mastering, and reduction of vibrations and noises in electric car gearbox transmission systems". Thesis, Paris, HESAM, 2022. http://www.theses.fr/2022HESAE026.
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Les architectures actuelles des motorisations hybrides ou électriques des véhicules automobiles incluent des transmissions par engrenages en sortie du moteur électrique, pour adapter la vitesse de rotation à celle des roues du véhicule. Ces engrenages sont la source de vibrations qui se propagent par voie solidienne jusqu'au carter du système, qui se retrouve être la sources acoustique du bruit rayonné. Ces bruits affectent le confort de l'utilisateur, notamment car ils ne sont pas masqués par le bruit du moteur électrique, très différent de celui d'un moteur thermique classique. La maîtrise de ces bruits est ainsi un enjeu majeur pour les constructeurs automobile actuels. Les sources de vibration dans les transmissions de puissance par engrenages sont nombreuses. On peut citer par exemple l'acyclisme du couple de sortie du moteur qui entraîne des fluctuations de la vitesse de rotation ou encore des phénomènes de variation périodique de la raideur d'engrènement sous couple, qui produisent une excitation vibratoire dite paramétrique, qui produit un bruit caractéristique de sirènement (whining noise en anglais). Dans ce contexte, plusieurs industriels se penchent actuellement sur la modélisation des vibrations dans les chaînes de transmission par engrenages, dans le but de prédire l'apparition des différents bruits et éventuellement d'ajuster la conception du système en conséquence. Le but de cette thèse est de mettre en place des modèles numériques afin de représenter le comportement vibratoire des systèmes d'engrenage. Dans ce contexte, plusieurs points ont été abordés: une étude paramétrique réalisée sur l'équation différentielle de l'interaction entre les engrenages permettant d'analyser et de prédire leur comportement dynamique. En parallèle, une méthode de calcul des vibrations dues à l'engrennement en utilisant la méthodes d'équilibrage des harmoniques (HBM) est proporséee. Enfin, une méthode de calcul d'un modèle réduit d'une boi te de transmission sous excitation de l'engrennement est présentéeThe current architectures of hybrid or electric motorizations of motor vehicles include transmissions by gears at the electric motor's output to adapt the speed of rotation to that of the vehicle wheels. These gears are the source of vibrations that propagate through the solid state to the system housing, the acoustic source of radiated noise. These noises affect the user's comfort, mainly because they are not masked by the noise of the electric motor, which is very different from that of a conventional combustion engine. Therefore, controlling this noise is a significant challenge for today's car manufacturers. There are many sources of vibration in geared power transmissions. For example, the engine's output torque's acyclic nature leads to rotational speed fluctuations, and periodic variations in the meshing stiffness under torque produce a so-called parametric vibration excitation, which produces a characteristic whining noise. In this context, several manufacturers are currently studying the modeling of vibrations in gear transmission systems, intending to predict the appearance of the various noises and possibly adjust the system's design accordingly. This thesis aims to set up numerical models to represent the vibratory behavior of gear systems from the understanding of the interaction between mating gears, to the dynamic presentation of a complete gearbox. Several points have been addressed in this context: a parametric study is performed on the differential equation of the interaction between gears to analyze and predict their dynamic behavior. In parallel, a method for calculating the vibrations due to the meshing process using the harmonic balancing method (HBM) is proposed. Finally, a method for calculating a reduced gearbox model under gear excitation is presented