Thematische Bibliographien / Assemblies vibrations

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Auswahl der wissenschaftlichen Literatur zum Thema „Assemblies vibrations“

Autor: Grafiati

Veröffentlicht am 18. Mai 2024

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Zeitschriftenartikel zum Thema "Assemblies vibrations"

Verma, V., D. Chionis, A. Dokhane und H. Ferroukhi. „MODELLING AND ANALYSIS OF FUEL ASSEMBLY VIBRATIONAL MODES IN PWRS USING SIMULATE-3K“. EPJ Web of Conferences 247 (2021): 21008. http://dx.doi.org/10.1051/epjconf/202124721008.

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Some of the KWU pre-KONVOI PWRs operating across Europe saw a systematic increase in the neutron noise levels over several cycles in the last decade, and subsequently, core internals’ movements, especially vibrations of fuel assemblies with specific designs were identified as one of the plausible causes. Therefore, it is important to develop computational methods that can allow to investigate and predict the reactor noise response to fuel assemblies vibrations. To this aim, the 3D nodal reactor dynamics code SIMULATE-3K is used at PSI with a special module called the ‘assembly vibration model’ that imitates time-dependent motions of fuel assemblies by dynamically modifying the water-gaps surrounding the laterally moving fuel assemblies. The varying water-gaps are represented by the variation in the corresponding two-group macroscopic cross sections generated using the lattice code CASMO-5 in 2D. The studies conducted so far to assess the methodology for full core noise simulations were based on assuming vibrations of a clamped-free cluster of fuel assemblies that are unsupported from both ends. However, as this represents a non-physical movement, further developments were made at PSI to allow simulating more realistic movements of fuel assemblies such as the cantilevered mode vibration. The updated methodology, along with evaluations of the simulated noise response to realistic vibration modes, is presented in this paper. Results show that, as expected, the radial and axial neutron noise behaviour follow the vibration pattern of the imposed time-dependent axial functions corresponding to the natural oscillation modes of the fuel assemblies, thereby providing confidence in the application of the developed methodology for numerical neutron noise analyses of the PWR cores.

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Aadnoy, Bernt Sigve. „Transversal Vibrations in Stabilized Drilling Assemblies“. Energy Sources 8, Nr. 4 (Januar 1986): 305–29. http://dx.doi.org/10.1080/00908318608946059.

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Avramov, K. V., und J. Awrejcewicz. „Localization of Vibrations in Blade Assemblies“. Journal of Vibration and Control 16, Nr. 11 (21.05.2010): 1605–22. http://dx.doi.org/10.1177/1077546309103258.

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Holmes, R., und J. E. H. Sykes. „Large-amplitude vibrations in rotor assemblies“. Journal of Sound and Vibration 133, Nr. 2 (September 1989): 337–51. http://dx.doi.org/10.1016/0022-460x(89)90930-9.

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Sharma, Gaurav, Adepu Kumaraswamy und Sangram Rath. „Enhancing Structural Vibration Damping in Marine Machinery: A Comprehensive Numerical Investigation with Modal and Harmonic Analysis“. Applied Mechanics and Materials 921 (26.04.2024): 39–56. http://dx.doi.org/10.4028/p-mrpje3.

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This article presents a comprehensive study on the damping of vibrations in a motor-pump assembly using viscoelastic and constrained layer damping treatments. The assembly's structural model, designed using SolidWorks software, is subjected to modal and harmonic analyses in ANSYS. The primary goal is to mitigate vibration amplitudes originating from the motor and pump to enhance the assembly's operational performance. Three damping treatments are investigated: Free Layer Damping (FLD), Sandwich Constrained Layer Damping (CLD), and a novel Multilayer CLD approach. The viscoelastic material is modeled using the Prony series method, and its properties are incorporated into the finite element analysis Results demonstrate that the application of damping treatments significantly reduces vibration amplitudes compared to the untreated structure. Among the treatments, the Multilayer CLD approach exhibits the highest damping efficiency, reducing the maximum amplitude by approximately 52% compared to the base structure. The study showcases the advantages of utilizing viscoelastic and constrained layer damping techniques for enhancing vibration control and operational stability in industrial assemblies. The research findings contribute to the field of structural dynamics and vibration control, offering valuable insights into the design and optimization of mechanical systems subjected to dynamic loads. This study opens avenues for further research and practical applications aimed at improving the performance and reliability of motor-pump assemblies and similar industrial equipment.

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Зиньковский, Анатолий Павлович, Анатолий Леонидович Стельмах und Сергей Николаевич Кабанник. „РЕЗУЛЬТАТЫ ОЦЕНКИ ДИНАМИЧЕСКОЙ УСТОЙЧИВОСТИ К ДОЗВУКОВОМУ ФЛАТТЕРУ ЛОПАТОЧНЫХ ВЕНЦОВ КОМПРЕССОРОВ НЕКОТОРЫХ АВИАЦИОННЫХ ГАЗОТУРБИННЫХ ДВИГАТЕЛЕЙ“. Aerospace technic and technology, Nr. 8 (31.08.2019): 78–84. http://dx.doi.org/10.32620/aktt.2019.8.12.

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The paper outlines the results of the investigation on the verification of the express method of prediction of dynamic stability for subsonic flutter using the blade assemblies of individual stages of the compressor of some types of aircraft gas-turbine engines at different modes of their operation. The paper gives a brief overview of the basic concepts of the developed express estimation method, possibilities of the determination of the stability limit for the blade assemblies for a subsonic flutter, as well as the results of the assessment of the dynamic stability of the compressor stages of some modern aircraft gas-turbine engines. Firstly, the reduced frequencies of vibrations of the blade assemblies under investigation and their critical values coincide practically. The mentioned critical values were determined from the test data for the straight cascades of the blade airfoils corresponding to two sections of the height of the blade airfoil portion. Hence it follows that the task can be solved employing only gas-dynamic parameters of the flow for one of the sections of the airfoil within the specified range of its height. Secondly, the prediction of dynamic stability for the subsonic flutter of the blade assemblies of separate compressor stages of some types of aircraft gas-turbine engines and the comparison of the obtained results with the data of bench tests, as well as the data obtained using other methods, were made. It was implied that the developed method allows one to determine the flutter limit with high accuracy, as well as make an optimal selection of the values of the reduced frequency of the blade vibrations for the specified range of the angle of attack of the sections of the blade assemblies upon the condition of its occurrence. Thirdly, the possibility to determine the nature of vibration excitation for the blade assemblies is considered using the analysis of the initiation of cracks in the blade root of the first compressor stage of the high-pressure gas-turbine engine. Moreover, it is shown that at large angles of attack (≥ 10°) an insignificant displacement of the dynamic stability limit of the blade assemblies may occur in the direction of large values of the reduced frequency of their vibrations.

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Białas, Katarzyna. „Passive and Active Elements in Reduction of Vibrations of Torsional Systems“. Solid State Phenomena 164 (Juni 2010): 260–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.164.260.

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The adverse effects of vibrations on the performance of machines and their environment are the subject of various studies. That is why already in the machine design stage the designers have to face the problem of preventing undesirable effects in the functioning of new machines as well as adapting complete machines to the requirements resulting from the current knowledge on hazards caused by these machines. There are a number of methods for preventing excessive vibrations, which have an impact on machine sub-assemblies and elements. In particular, the passive, semi-active and active vibration-reducing systems can be distinguished [4,5].

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Viebach, M., C. Lange, M. Seidl, Y. Bilodid und A. Hurtado. „NEUTRON NOISE PATTERNS FROM COUPLED FUEL-ASSEMBLY VIBRATIONS“. EPJ Web of Conferences 247 (2021): 02015. http://dx.doi.org/10.1051/epjconf/202124702015.

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The neutron flux fluctuation magnitude of KWU-built PWRs shows a hitherto unexplained correlation with the types of loaded fuel assemblies. Also, certain measured long-range neutron flux fluctuation patterns in neighboring core quadrants still lack a closed understanding of their origin. The explanation of these phenomena has recently revived a new interest in neutron noise research. The contribution at hand investigates the idea that a synchronized coolant-driven vibration of major parts of the fuel-assembly ensemble leads to these phenomena. Starting with an assumed mode of such collective vibration, the resulting effects on the time-dependent neutron-flux distribution are analyzed via a DYN3D simulation. A three-dimensional representation of the time-dependent bow of all fuel assemblies is taken into account as a nodal DYN3D feedback parameter by time-dependent variations of the fuel-assembly pitch. The impact of its variation on the cross sections is quantiﬁed using a cross-section library that is generated from the output of corresponding CASMO5 calculations. The DYN3D simulation qualitatively reproduces the measured neutron-flux fluctuation patterns. The magnitude of the fluctuations and its radial dependence are comparable to the measured details. The results imply that collective fuel-assembly vibrations are a promising candidate for being the key to understand long-known fluctuation patterns in KWU built PWRs. Further research should elaborate on possible excitation mechanisms of the assumed vibration modes.

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Hemingway, N. G. „Modelling Vibration Transmission Through Coupled Vehicle Sub-Systems Using Mobility Matrices“. Proceedings of the Institution of Mechanical Engineers, Part D: Transport Engineering 200, Nr. 2 (April 1986): 125–34. http://dx.doi.org/10.1243/pime_proc_1986_200_172_02.

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This paper indicates how vibration responses of a vehicle body produced by inputs at the rear wheels were modelled using a mobility matrix coupling method. The model simulates the multiple coupling of the sub-assemblies comprising the rear axle, rear suspension and vehicle body in the lower audio-frequency range. Such a model is useful when investigating the transmission paths along which vibrations travel into the vehicle body, subsequently generating internal noise.

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Planchard, J. „Vibrations of nuclear fuel assemblies: A simplified model“. Nuclear Engineering and Design 86, Nr. 3 (Juni 1985): 383–91. http://dx.doi.org/10.1016/0029-5493(85)90303-6.

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Dissertationen zum Thema "Assemblies vibrations"

Rahman, Aminur Khosru. „Mathematical modelling of vibrations in spindle bearing assemblies“. Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264691.

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Orbay, Gunay. „Nonlinear Vibration Of Mistuned Bladed Disk Assemblies“. Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609740/index.pdf.

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High cycle fatigue (HCF) failure has been studied extensively over the last two decades. Its impact on jet engines is severe enough that may result in engine losses and even life losses. The main requirement for fatigue life predictions is the stress caused by mechanical vibrations. One of the factors which have major impact on the vibratory stresses of bladed disk assemblies is a phenomenon called &ldquo
mistuning&rdquo
which is defined as the vibration localization caused by the loss of cyclic periodicity which is a consequence of inter&
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blade variations in structural properties. In this thesis, component mode synthesis method (CMSM) is combined with nonlinear forced response analysis in modal domain. Newton&
#8208
Raphson and arc length continuation procedures are implemented for the solution. The component mode synthesis method introduces the capability of imposing mistuning on the modal properties of each blade in the assembly. Forced response analysis in modal domain reduces the problem size via mode truncation. The main advantage of the proposed method is that it is capable of calculating nonlinear forced response for all the degrees&
#8208
of&
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freedom at each blade with less computational effort. This makes it possible to make a stress analysis at resonance conditions. The case studies presented in this thesis emphasize the importance of number of modes retained in the reduced order model for both CMSM and nonlinear forced response analysis. Furthermore, the results of the case studies have shown that both nonlinearity and mistuning can cause shifts in resonance frequencies and changes in resonance amplitudes. Despite the changes in resonance conditions, the shape of the blade motion may not be affected.

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Chu, Han-Ru. „Vibrations of disordered assemblies of three-dimensional composite blade substructures /“. The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779914824864.

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Sternchuss, Arnaud Balmès Etienne. „Multi-level parametric reduced models of rotating bladed disk assemblies“. S. l. : Ecole centrale de Paris, 2009. http://theses.abes.fr/2009ECAP0001.

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Bolmsvik, Åsa. „Structural-acoustic vibrations in wooden assemblies: : Experimental modal analysis and finite element modelling“. Doctoral thesis, Linnéuniversitetet, Institutionen för bygg- och energiteknik (BE), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-24562.

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This doctoral thesis concerns flanking transmission in light weight, wooden multi-storey buildings within the low frequency, primarily 20-120 Hz. The overall aim is to investigate how the finite element method can contribute in the design phase to evaluate different junctions regarding flanking transmission. Two field measurements of accelerations in light weight wooden buildings have been evaluated. In these, two sources; a stepping machine, and an electrodynamic shaker, were used. The shaker was shown to give more detailed information. However, since a light weight structure in field exhibit energy losses to surrounding building parts, reliable damping estimates were difficult to obtain. In addition, two laboratory measurements were made. These were evaluated using experimental modal analysis, giving the eigenmodes and the damping of the structures. The damping for these particular structures varies significantly with frequency, especially when an elastomer is used in the floor-wall junction. The overall damping is also higher when elastomers are used in the floor-wall junction in comparison to a screwed junction. By analysing the eigenmodes, using the modal assurance criterion, of the same structure with two types of junctions it was concluded that the modes become significantly different. Thereby the overall behavior differs. Several finite element models representing both the field and laboratory test setups have been made. The junctions between the building blocks in the models have been modeled using tie or springs and dashpots. Visual observation and the modal assurance criterion show that there is more rotational stiffness in the test structures than in the models. The findings in this doctoral thesis add understanding to how modern joints in wooden constructions can be represented by FE modelling. They will contribute in developing FE models that can be used to see the acoustic effects prior to building an entire house. However, further research is still needed.
Denna doktorsavhandling behandlar flanktransmission i flervåningshus med trästomme, inom det lågfrekventa området, främst 20-120 Hz. Det övergripande målet är att undersöka hur finita elementmetoden kan bidra i konstruktionsfasen för att utvärdera olika knutpunkters inverkan på flanktransmissionen. Två fältmätningar av accelerationer i trähus har utvärderats. I dessa har två olika lastkällor använts, i den första en stegljudsapparat och i den andra en elektrodynamisk vibrator (shaker). Det visades att shakern kan ge mer detaljerad information, men eftersom vibrationerna även sprider sig till omgivande byggnadsdelar vid fältmätningarna var det svårt att estimera tillförlitliga dämpningsdata även då shaker användes. Fältmätningarna följdes av två mätningar i laborationsmiljö. Dessa två experiment utvärderades med experimentell modalanalys, vilket ger egenmoder och dämpning hos strukturerna. Dämpningen för dessa trähuskonstruktioner varierar kraftigt med frekvens. Extra stora variationer registreras då en elastomer användes i knutpunkten mellan golv och vägg. Den totala dämpningen är generellt högre när elastomerer används i knutpunkten mellan golv och vägg i jämförelse med då knutpunkten är skruvad. Genom att analysera egenmoder och deras korrelationer (MAC), för samma trästruktur men med olika typer av knutpunkter, drogs slutsatsen att knutpunkten drastiskt förändrar strukturens dynamiska beteende. Flera finita elementmodeller av både fält- och laboratorieuppställningar har gjorts. I dessa har knutpunkterna mellan byggnadsdelar modellerats helt styvt eller med hjälp av fjädrar och dämpare. Visuella observationer av egenmoder och korrelationen dem emellan visar att det finns mer rotationsstyvhet i försöken än i finita elementmodellerna. Resultaten i denna doktorsavhandling har gett förståelse för hur knutpunkter i träkonstruktioner beter sig och kan simuleras med finit elementmodellering. Vidare kan resultaten bidra till utvecklingen av FE-modeller som kan användas för att kunna se de akustiska effekterna redan under konstruktionsstadiet. Dock behövs ytterligare forskning inom området.

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Longo, Lorenzo. „Experimental characterization of PWR fuel assemblies mechanical behavior under hydrodynamic and seismic-like loads“. Electronic Thesis or Diss., Ecole centrale de Marseille, 2023. http://www.theses.fr/2023ECDM0002.

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Les assemblages de combustible nucléaire dans le cœur d’un réacteur à eau pressurisée(REP) sont immergés dans un écoulement axial. Cet écoulement exerce une charge hydrodynamique sur les assemblages et est responsable de leur couplage et de leurs vibrations. De plus, lors d’un tremblement de terre ou d’un événement LOCA (Loss Of CoolantAccident), les assemblages de combustible sont soumis à de fortes oscillations. La charge hydrodynamique peut déformer les assemblages, générant une déformation arquée, tandis que des oscillations plus fortes, comme lors d’un événement sismique,peuvent être à l’origine d’impacts sur les assemblages. Afin de garantir l’intégrité et la sûreté du cœur du réacteur, les industries nucléaires souhaitent améliorer la connaissance phénoménologique des interactions fluide-structure à l’intérieur du cœur d’un réacteur à eau pressurisée. Les ingénieurs ont donc besoin de modèles numériques pour le comportement mécanique et de campagnes expérimentales pour les valider et définir leurs limites.L’étude présentée dans ce document est principalement divisée en trois campagnes expérimentales visant à étudier : les effets d’oscillation de l’assemblage dans un fluide au repos, les phénomènes de traînée sur les assemblages de combustible en régime permanent sous un écoulement et le comportement des oscillations des assemblages lorsqu’ils sont immergés dans un écoulement. Deux installations expérimentales sont utilisées :SBF (Shaking Bundle Facility) et Eudore. SBF accueille un assemblage fictif de pleine hauteur soumis à un écoulement axial sur une table vibrante. Grâce à des techniques optiques, le champ de vitesse du fluide et le mouvement de l’assemblage peuvent être mesurés. L’installation Eudore utilise trois assemblages réduits en ligne, soumis à un écoulement axial, avec la possibilité d’appliquer une excitation sismique à l’ensemble de la section d’essai. L’instrumentation développée sur Eudore permet de mesurer les déplacements des assemblages, le champ de vitesse du fluide et les forces d’impact.Les expériences réalisées sur Eudore sont simulées à l’aide d’un outil de calcul numérique développé au CEA, nommé FSCORE, basé sur une approche en milieu poreux. Cette approche permet d’accéder à un modèle de fluide équivalent et à un modèle de structure équivalent définis sur l’ensemble du domaine à partir de l’intégration spatiale d’équations locales. Les équations de mouvement du fluide équivalent et de la structure équivalente sont établies séparément, pour fournir un modèle couplé fluide-structure prenant en compte les contacts entre les assemblages.A l’aide d’un modèle analytique, les résultats expérimentaux obtenus sur Eudore sont utilisés pour retrouver le coefficient de traînée présent dans FSCORE. Les résultats expérimentaux et numériques sont largement discutés et montrent un bon accord
Nuclear fuel assemblies in Pressurized Water Reactor (PWR) core are immersed in anaxial flow. This flow exerts a hydrodynamic load on the assemblies, and it is responsible fortheir coupling and vibrations. Furthermore, during an earthquake or a LOCA event (LossOf Coolant Accident), fuel assemblies are subjected to strong oscillation amplitudes. The hydrodynamic load can deform the assemblies, generating assembly bow, while strongeroscillations, such in a seismic event, can be responsible for assemblies impacts. In order to ensure the reactor core integrity and safety, nuclear industries want to improve thephenomenological knowledge of fluid-structure interactions inside a PWR core. Thus, engineersneed numerical models for mechanical behavior of fuel assemblies and experimentalcampaigns to validate them and define their limits.The study presented in this document is mainly divided in three experimental campaignsand aim to investigate: the assembly oscillation effects in fluid at rest, the dragphenomena on steady state fuel assemblies under a flow and the assemblies oscillationsbehavior when immersed in a flow. Two experimental facilities are used: SBF (ShakingBundle Facility) and Eudore. SBF hosts one full-height surrogate assembly under axialflow on a vibrating table. By using optical technique, the velocity field of the fluid andassembly motion can be measured. Eudore facility uses three reduced assemblies in line,under axial flow with the possibility of applying seismic excitation to the entire test section.The instrumentation developed on Eudore makes it possible to measure the displacementsof the assemblies, velocity field of the fluid and the impact forces.The experiments performed on Eudore are simulated with a numerical calculation tooldeveloped at CEA, named FSCORE, based on a porous medium approach. This approachprovides access to an equivalent fluid model and an equivalent structure model defined overthe entire domain from the spatial integration of local equations. The equations of motionof the equivalent fluid and of the equivalent structure are established separately, to providea coupled model taking into account the contacts between assemblies.With the help of an analytical model, the experimental results obtained on Eudoreare used to retrieve the drag coefficient present in FSCORE. Experimental and numericalresults are widely discussed and show good agreement

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Clement, Simon. „Mise en oeuvre expérimentale et analyse vibratoire non-linéaire d'un dispositif à quatre maquettes d'assemblages combustibles sous écoulement axial“. Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4757/document.

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Cette thèse s'inscrit dans le cadre général de la tenue au séisme des coeurs de réacteurs nucléaires à eau pressurisée (REP). Plus précisément, l'objectif de cette thèse est l'étude expérimentale du couplage entre assemblages combustibles induit par un écoulement d'eau axial. Les phases de conception, réalisation et mise en service d'une nouvelle installation appelée ICARE EXPERIMENTAL sont présentées. ICARE EXPERIMENTAL a été conçue pour observer simultanément les vibrations de quatre maquettes d'assemblages combustibles (2x2) confinées sous écoulement ascendant. Une nouvelle méthode d'analyse de données combinant analyse temps-fréquence et décomposition sur modes propres orthogonaux (POD) est décrite. Cette méthode, appelée Sliding Window POD (SWPOD), permet l'analyse de signaux à plusieurs composantes dont la répartition spatiale de l'énergie et le contenu fréquentiel varient avec le temps. Dans le cas de systèmes mécaniques (linéaires et non-linéaires), le lien entre les modes propres orthogonaux obtenus par la SWPOD et les modes normaux (linéaires et non-linéaires) est étudié. Les mesures obtenues avec l'installation ICARE EXPERIMENTAL sont analysées avec la SWPOD. Les premiers résultats mettent en évidence des mouvements caractéristiques des assemblages non excités, au passage de leurs résonances. Ce couplage entre assemblages combustibles, induit par le fluide, est reproduit par les simulations réalisées à l'aide du code de calcul COEUR3D. Ce code est basé sur une approche milieu poreux pour simuler un réseau d'assemblages combustibles sous écoulement
The present study is in the scope of pressurized water reactors (PWR) core response to earthquakes. The goal of this thesis is to measure the coupling between fuel assemblies caused an axial water flow. The design, production and installation a new test facility named ICARE EXPERIMENTAL are presented. ICARE EXPERIMENTAL was built in order to measure simultaneously the vibrations of four fuel assemblies (2x2) under an axial flow. A new data analysis method combining time-frequency analysis and orthogonal mode decomposition (POD) is described. This method, named Sliding Window POD (SWPOD), allows analysing multicomponent data, of which spatial repartition of energy and frequency content are time dependent. In the case of mechanical systems (linear and nonlinear), the link between the proper orthogonal modes obtained through SWPOD and the normal modes (linear and nonlinear) is studied. The measures acquired with the ICARE EXPERIMENTAL installation are analysed using the SWPOD. The first results show characteristic behavior of the free fuel assemblies at their resonances. The coupling between fuel assemblies, induced by the fluid, is reproduced by simulations performed using the COEUR3D code. This code is based on a porous media model in order to simulate a fuel assemblies network under axial flow

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Myhre, Mikkel. „Numerical investigation of the sensitivity of forced response characteristics of bladed disks to mistuning“. Licentiate thesis, KTH, Energy Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1639.

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Two state of the art finite element reduction techniquespreviously validated against the direct finite element method,one based on classical modal analysis and another based oncomponent mode synthesis, are applied for efficient mistunedfree vibration and forced response analysis of several bladeddisk geometries. The methods are first applied to two testcases in order to demonstrate the differences in computationalefficiency as well as to validate the methods againstexperimental data. As previous studies have indicated, nonoticeable differences in accuracy are detected for the currentapplications, while the method based on classical modalanalysis is significantly more efficient. Experimental data(mistuned frequencies and mode shapes) available for one of thetwo test cases are compared with numerical predictions, and agood match is obtained, which adds to the previous validationof the methods (against the direct finite element method).

The influence of blade-to-blade coupling and rotation speedon the sensitivity of bladed disks to mistuning is thenstudied. A transonic fan is considered with part span shroudsand without shrouds, respectively, constituting a high and alow blade-to-blade coupling case. For both cases, computationsare performed at rest as well as at various rotation speeds.Mistuning sensitivity is modelled as the dependence ofamplitude magnification on the standard deviation of bladestiffnesses. The finite element reduction technique based onclassical modal analysis is employed for the structuralanalysis. This reduced order model is solved for sets of randomblade stiffnesses with various standard deviations, i.e. MonteCarlo simulations. In order to reduce the sample size, thestatistical data is fitted to a Weibull (type III) parametermodel. Three different parameter estimation techniques areapplied and compared. The key role of blade-to-blade coupling,as well as the ratio of mistuning to coupling, is demonstratedfor the two cases. It is observed that mistuning sensitivityvaries significantly with rotation speed for both fans due toan associated variation in blade-to-blade coupling strength.Focusing on the effect of one specific engine order on themistuned response of the first bending modes, it is observedthat the mistuning sensitivity behaviour of the fan withoutshrouds is unaffected by rotation at its resonant condition,due to insignificant changes in coupling strength at thisspeed. The fan with shrouds, on the other hand, shows asignificantly different behaviour at rest and resonant speed,due to increased coupling under rotation. Comparing the twocases at resonant rotor speeds, the fan without shrouds is lessor equally sensitive to mistuning than the fan with shrouds inthe entire range of mistuning strengths considered.

This thesisscientific contribution centres on themistuning sensitivity study, where the effects of shrouds androtation speed are quantified for realistic bladed diskgeometries. However, also the validation of two finite elementreduction techniques against experimental measurementsconstitutes an important contribution.

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Sternchüss, Arnaud. „Multi-level parametric reduced models of rotating bladed disk assemblies“. Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00366252.

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Les disques aubagés, que l'on trouve dans les turbomachines, sont des structures complexes dont le comportement vibratoire est généralement déterminé par l'exploitation de conditions de symétrie dans leur configuration nominale. Cette symétrie disparaît lorsque l'on assemble plusieurs de ces disques pour former un rotor ou que l'on introduit une variabilité spatiale des paramètres mécaniques (on parle de désaccordage intentionnel ou non). Le raffinement des maillages, nécessaire à une évaluation correcte de la répartition des contraintes, conduirait à des modèles de rotor complet de taille prohibitive (plusieurs dizaines de millions de degrés de liberté). L'objectif de cette thèse est donc l'introduction de méthodologies de réduction qui par combinaison de calculs acceptables permettent d'étudier de façon fine la dynamique d'ensemble sur des modèles 3D fins multi-étages et potentiellement désaccordés. L'étude des transformations de Fourier séparées des réponses de chaque étage permet, dans un premier temps, de bien comprendre les effets de couplage inter-harmonique liés au couplage inter-disque et au désaccordage. A partir de ce constat, une première méthode utilise les résultats de calculs en symétrie cyclique et à secteur encastré pour construire un modèle de secteur exact pour certains modes dits cibles et de très bonne qualité pour les autres modes. Cette méthode est ensuite étendue au cas multi-étage en construisant des bases de réduction de secteur par combinaison de solutions mono-harmoniques. Les illustrations montrent que la méthodologie proposée permet le traitement de modèles de très grande taille, tout en restant compatible avec une grande richesse de post-traitements (calculs de modes, calculs de réponses forcées, analyses de leur contenu harmonique spatial, répartition d'énergie et effets de localisation...). La méthodologie est enfin étendue à la gestion de modèles paramétrés en vitesse de rotation. L'enrichissement des ensembles de modes cibles par des calculs à trois vitesses permet ainsi une reconstruction rapide de l'évolution des fréquences pour l'ensemble d'un intervalle.

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Batou, Anas. „Identification des forces stochastiques appliquées à un système dynamique non linéaire en utilisant un modèle numérique incertain et des réponses expérimentales“. Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00472080.

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Ces travaux ont été développés dans le contexte de l'analyse vibratoire des assemblages combustibles. Ce type de structure est très complexe et a, du fait de sa géométrie, une très forte densité modale. Ainsi, afin de calculer la réponse d'une telle structure, une modélisation simplifiée est préférable. L'objectif est d'identifier des forces stochastiques induites par l'écoulement en utilisant un modèle numérique incertain et des réponses expérimentales. Pour ce problème, 4 sources d'incertitudes sont à prendre en considération : (1) Les incertitudes de modèle induites par les simplifications du modèle. (2) Les incertitudes sur les forces induites par les fluctuations statistiques de la pression turbulent. (3) Les incertitudes concernant la modélisation des forces stochastiques. (4) Les incertitudes induites par les erreurs de mesures. Les forces stochastiques ainsi identifiées sont appliquées sur le modèle simplifié stochastique pour calculer des statistiques sur les quantités d'intérêt

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Bücher zum Thema "Assemblies vibrations"

Conference on Mechanical Vibration and Noise (10th 1985 Cincinnati, Ohio). Vibrations of blades and bladed disk assemblies: Presented at the Tenth Biennial Conference on Mechanical Vibration and Noise, Cincinnati, Ohio, September 10-13, 1985. New York, N.Y. (345 E. 47th St., New York 10017): American Society of Mechanical Engineers, 1985.

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1959-, Pierre Christophe, und United States. National Aeronautics and Space Administration., Hrsg. A transfer matrix approach to vibration localization in mistuned blade assemblies. [Washington, D.C: National Aeronautics and Space Administration, 1993.

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Conference on Mechanical Vibration and Noise (11th 1987 Boston, Mass.). Bladed disk assemblies: Presented at the 1987 ASME Design Technology Conferences-11th Biennial Conference on Mechanical Vibration and Noise, Boston, Massachusetts, September 27-30, 1987. New York, N.Y. (345 E. 47th St., New York 10017): American Society of Mechanical Engineers, 1987.

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R, Little Ronald, und United States. National Aeronautics and Space Administration, Hrsg. Application of a personal computer for the uncoupled vibration analysis of wind turbine blade and counterweight assemblies. [Washington, DC: National Aeronautics and Space Administration, 1985.

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Vibrations of blades and bladed disk assemblies: Presented at the Tenth Biennial Conferenceon Mechanical Vibration and Noise, Cincinnati, Ohio, September 10-13, 1985. New York, N.Y: American Society of Mechanical Engineers, 1985.

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Inclusion of transverse shear deformation in the exact buckling and vibration analysis of composite plate assemblies. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1993.

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National Aeronautics and Space Administration (NASA) Staff. Inclusion of Transverse Shear Deformation in the Exact Buckling and Vibration Analysis of Composite Plate Assemblies. Independently Published, 2018.

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Rohman, Carrie. Afterword. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190604400.003.0007.

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The afterword reiterates it is time to risk a border-crossing in our view of art and see it as part of our shared affective becoming-excessive, as a fundamentally non-cognitive zone of self-othering that all animals engage, not just human animals. Art connects us profoundly to other creatures. The aesthetic capacity is animal; it doesn’t just approach animals or hold them in its purview. And if this is the case, then we can anticipate wholly new ways of viewing, inhabiting, and understanding artistic practices. The transporting power of art, the becoming-intense of aesthetics, the felt vibrations of aesthetic forces, and the taste for certain affect-circulating performances all have their “ancestral” lineage in animals’ aesthetic engagements. Bioaesthetics thus reminds us that the world of art includes hordes of other creatural actors and living assemblages—and that these beings have always been artistic.

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Bird, Terri. Forming. Edinburgh University Press, 2018. http://dx.doi.org/10.3366/edinburgh/9781474429344.003.0003.

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The aim of art for Deleuze and Guattari is to render perceptible forces that lie beyond perception and to capture, in what is given, the forces that are not given. They task artists with producing compounds of sensation, heterogeneous assemblages of affects and intensities, extracted from forces lying at the limits of sensibility. This chapter explores the forming of these assemblages through processes of capture orientated around practices employing sculptural methodologies. Although Deleuze and Guattari have little to say about sculpture in general or specific works, they refer to the sensations of stone and metal as vibrating according to the order of strong and weak rhythms. Drawing on the writing of Gilbert Simondon these rhythms are discussed as dynamic modulations that emphasise temporal appearance. And examined in relation to Jack Burnham’s use of systems thinking identified in the artworks, by artists such as Hans Haacke and Public Share, that register complex flows of matter-energy exchanges.

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User manual for VICONOPT: An exact analysis and optimum design program covering the buckling and vibration of prismatic assemblies of flat in-plane loaded, anisotropic plates with approximations for discrete supports and transverse stiffeners. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.

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Buchteile zum Thema "Assemblies vibrations"

Zmitrowicz, Alfred. „Vibrations of Turbine Blade Assemblies with Stick and Slip Conditions“. In IUTAM Symposium on Unilateral Multibody Contacts, 319–28. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4275-5_31.

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Zinkovskii, Anatoliy, Kyrylo Savchenko und Yevheniia Onyshchenko. „Investigation of the Nonlinearity Effect of the Shrouded Blade Assemblies on Their Forced Vibrations“. In Advanced Structured Materials, 159–68. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-75890-5_9.

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Holmes, R. „Vibration of Rotor—Bearing Assemblies“. In Vibration and Wear in High Speed Rotating Machinery, 279–97. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1914-3_17.

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Nitsche, Rainer, und Lothar Gaul. „Damping Control in Systems Assembled by Semi-Active Joints“. In Responsive Systems for Active Vibration Control, 239–51. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0483-1_8.

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Ghaffarian, Reza. „Thermal Cycle and Vibration/Drop Reliability of Area Array Package Assemblies“. In Structural Dynamics of Electronic and Photonic Systems, 519–74. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9780470950012.ch22.

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Petrov, E. „Optimization of Perturbation Parameters for Forced Vibration Stress Levels of Turbomachinery Blade Assemblies“. In Discrete Structural Optimization, 108–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-85095-0_12.

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Williams, Q. „A Vibrational Spectroscopic Study of Hydrogen in High Pressure Mineral Assemblages“. In High-Pressure Research: Application to Earth and Planetary Sciences, 289–96. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm067p0289.

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Wang, C., X. B. Xiao und X. S. Jin. „Optimization of New Noise Shielded and Vibration Damped Assemblies for High Speed Train Wheels Using FEM-BEM Simulation“. In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 51–59. Tokyo: Springer Japan, 2012. http://dx.doi.org/10.1007/978-4-431-53927-8_7.

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Schwarze, Martin, Carlo Rüger, Oliver Georgi, Hendrik Rentzsch und Holger Pätzold. „Actuator and Process Development for Vibration Assisted Turning of Steel“. In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210013.

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Due to continuous tool engagement, turning processes tend to form long chips when machining ductile materials. These chip shapes have a negative influence on process performance and productivity. One approach to improve chip breakage is superimposition of vibrations in feed direction of the turning process, which leads to a modulation of uncut chip thickness. In a joint industrial project with Schaeffler Technologies AG & Co. KG, Fraunhofer IWU developed an oscillating actuator for turning. The actuator converts a rotational movement of a drive motor into a translational vibration via an eccentric gear. The tool shank is mounted in solid joint assemblies. With this prototypical system, a cyclic movement of the tool in feed direction can be realized. The typical operating parameters of the actuator is within the range of 1...100 Hz with adjustable vibration amplitudes up to 0.6 mm peak-to-peak. A significant improvement in chip breaking during the machining of steel 1.0503 was shown in cutting tests.

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Al Sayed, B., B. Faverjon, E. Chatelet und G. Jacquet-Richardet. „Effect of contact parameter uncertainties of the dynamic behaviour of rubbing cyclic assemblies“. In 10th International Conference on Vibrations in Rotating Machinery, 613–22. Elsevier, 2012. http://dx.doi.org/10.1533/9780857094537.9.613.

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Konferenzberichte zum Thema "Assemblies vibrations"

Ste´phan, Cyrille, Marc Berthillier, Joseph Lardie`s und Arnaud Talon. „Tip-Timing Data Analysis for Mistuned Bladed Discs Assemblies“. In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50825.

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In turbomachine industry, bladed assembly vibration measurements are very important for blades behaviour estimation. These measurements are generally obtained from strain gauges. However, one of the most promising methods for the analysis of blade vibrations in rotating bladed assemblies is the Blade Tip Timing or Optical Blade Vibration Measurement method. A set of optical sensors is mounted on an engine casing, in front of a disc, and measures the times of arrival of each blade. These timings are then used to compute the vibrations of the blades. However the fundamental problem for spectral analysis of blade tip timing data is that the signals are undersampled and aliased. We propose here a new method for spectral estimation of blades responses from tip timing data that overcome these difficulties. The method proposed in this communication is based on the use of a minimum variance filter associated with an iterative updating of the autocorrelation matrix. That allows to process correctly a signal even if the number of known signal samples is less than equivalent Nyquist criterion. This approach is suitable for spectral analysis of undersampled and aliased signals. Perfomances of the spectral estimator have been evaluated for one simulated and one experimental test cases. The method seems very promising for the monitoring of mistuned bladed discs.

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Ferrari, Giovanni, Giulio Franchini, Prabakaran Balasubramanian, Kostas Karazis und Marco Amabili. „Nonlinear Vibrations of Model PWR Fuel Assemblies: Part 1 — Experimental Setup and Measurements“. In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24235.

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Abstract Nuclear fuel bundles in PWR reactors present vibrations due to coolant flow, which may result in fretting at the interface between the fuel rods and the retaining elements, named spacer grids (SGs). Seismic excitation may also occur during accidental events, such as earthquakes. In this perspective, forced vibration experiments were performed on a reduced-scale nuclear fuel bundle provided by Framatome Canada. The presence of partially loose fuel pellets inside the fuel rods was provided in the experiments. A maximum coolant flow of 5 meters per second was reached inside a water tunnel. The identification of vibration parameters was attempted in the linear regime, through modal analysis, and in the nonlinear regime, through a single-degree-of-freedom method based on harmonic balance. The value of the equivalent damping parameter was shown to increase strongly with the amplitude of the excitation, thus acting in the direction of safety. The fuel bundle presents a peculiar softening vibration behavior in the nonlinear regime, with a marked decrease of the peak vibration frequency. The comparison with other recent experiments shows that the boundary conditions constituted by SGs have a predominant effect on stiffness and damping during nonlinear vibrations. Therefore, the characterization of the boundary conditions at the SGs was attempted by means of dedicated experiments. Bending oscillations were tested in the frequency range between DC and 50 Hertz. Tests were repeated in presence and in absence of water. The resulting force-displacement loops clearly show the presence of hysteresis and of bilinear stiffness. The availability of a mathematical model for the stiffness and the damping at the boundary conditions will be indispensable for the future development of reduced-order models describing the vibrations of PWR fuel bundles.

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Marquez, Antonio, Emmanuel Omojuwa und Catalin Teodoriu. „Mitigating Downhole Vibrations in Bottom Hole Assemblies Using Finite Element Analysis“. In SPE Health, Safety, Security, Environment, & Social Responsibility Conference - North America. Society of Petroleum Engineers, 2017. http://dx.doi.org/10.2118/184420-ms.

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Salhi, Bendali, Marc Berthillier, Joseph Lardies, Philippe Voinis und Charles Bodel. „A Subspace Method for Modal Identification of Bladed Assemblies Using Blade Tip-Timing Data“. In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-28151.

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Unknown excitation forces are applied to bladed disk assemblies, such as turbines blades, leading to forced vibration responses. Non contact measurement of such vibrations using blade tip-timing data has become an industrial standard procedure and current research focuses on analysis methods for interpretation of measured vibrations. Our purpose is to develop a method for identification of the blade’s natural frequencies and damping ratios using blade tip-timing data. The method is based on a subspace analysis. Its performance is compared to the traditional Fast Fourier Transform analysis. A detailed description of these methods and results are presented.

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Kaczorowski, Damien, Jean-Mary Georges, Sandrine Bec, Andre´-Bernard Vannes, Andre´ Tonck und Jean-Philippe Vernot. „Rod Control Assemblies Wear Mechanisms“. In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22699.

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In nuclear power plants, slender tubular components are subjected to vibrations in a PHTW environment. As a result, the two contacting surfaces, tubes and their guides undergo impact at low contact pressures [1]. The components are usually made of stainless steel and it was found that the influence of the PHTW, combined with other actions (such as corrosion, erosion, squeeze film effect, third body effect and cavitation) leads to a particular wear of the material [2] [3]. Therefore, this paper aims to show that the colloidal oxides, formed on the steel surfaces in PHTW, play a principal role in the wear of the surfaces. Actually, due to the specific kinematic conditions of the contact, the flow of compacted oxides abrades the surfaces.

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Lall, Pradeep, Vishal Mehta, Jeff Suhling und David Locker. „Study of Sustained High-Temperature on the Reliability of Lead-Free Solder Joint Assemblies Under Vibration“. In ASME 2023 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/ipack2023-111984.

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Abstract Electronic parts in the automotive, downhole drilling of oil & gas, and aerospace sectors are frequently subjected to severe high strain loads. Those extreme loads may be occurring as a result of shocks, vibrations, and drop-impact circumstances. In addition, these parts are frequently exposed to severe low and high temperatures ranging from −65°C to 200°C. In such critical environment, these electronic equipment can be exposed to strain rates ranging from 1 to 100 per second. SAC solder alloys are the most often used alloys to replace tin-lead solders in electronic assembly applications. Tin, silver, and copper are the essential elements in these lead-free alloys. SAC solder alloys have proven to be successful in surface mount, wave soldering, and hand soldering applications. The primary advantage of RoHS certified lead-free solder is that it is safer than lead solder, which is a severe neurotoxic. Numerous doped solder alloys, such as SAC-Q, SAC-R, Innolot, M758 etc. have recently been introduced in electronic components. Mechanical characteristics and statistics for lead-free solder alloys are critical for enhancing electronic package durability at high temperatures and strain rates. Combined effects of higher temperatures and vibrations in electronic components might result in rapid failure. The majority of previous solder joint research has been on either vibrational stresses or thermal cycling for conventional solders like SAC105, and SAC305. SAC alloy failure mechanisms were investigated in this article at higher surrounding test temperatures up to 155°C, as well as at vibration loads of 5g and 10g levels. Harmonic vibrations at the first natural frequency was measured for the test boards with CABGA daisy-chained package at various test temperatures and vibration g-levels. Results on assembly response and resistance were collected utilizing high-speed data acquisition and highspeed imaging. A high-speed camera system was employed to catch the vibration event during testing. Stresses in solder interconnects were calculated using Finite Element Analysis simulation. The impact of g-levels, and operating temperatures on the hysteresis loop and plastic work density has been investigated. The failure mode analysis for the test board has been performed. Anand viscoplasticity material data for the solder alloys which were previously published by authors were used to capture the high-strain rate behavior and temperature dependent aging behavior of the solder junctions for FE analysis.

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Lieh, Junghsen, und Imtiaz Haque. „Semiactive Control of Vibrations in Automobiles“. In ASME 1991 Design Technical Conferences. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/detc1991-0264.

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Abstract A seven-DOF vehicle model comprising a full car body and four wheel-axle assemblies is used to investigate the influence of active and semiactive suspensions on ride performance. The active control of car body roll, pitch and bounce is based on an optimal control strategy assuming the tire deflection measurements are not available. The frequency analysis shows a significant attenuation in car body modes but a potential increase in wheel motions. Dissipative dampers with solenoid valves are used as the semiactive control mechanism. Simulation results in the time domain indicate that suboptimal values exist in the damping “on” state and an on-off damping control scheme can effectively reduce the car body motions and suspension travels.

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Delannoy, Joachim, Marco Amabili, Brett Matthews, Brian Painter und Kostas Karazis. „Identification of Non-Linear Damping of Nuclear Reactor Components in Case of One-to-One Internal Resonance“. In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66311.

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In Pressurized Water Reactors (PWR) assemblies are exposed to challenging thermal, mechanical, and irradiation loads during operation. Global core and local fuel assembly flow fields coupled with seismic excitation result in fuel assembly and fuel rod vibrations. The fact that vibrations may become excessive in certain conditions has consequences on operational safety margins in fuel assemblies designs. In order to understand how the fuel assembly responds dynamically to an external excitation, it is important to identify the main characteristics of the structures. Among them, the fuel assembly system damping is a fundamental parameter that is usually identified by a number of experiments involving fluid-structure interaction. Recent studies have shown that the damping ratio increases with the excitation force when the structure is entering large-amplitude vibrations, in which case the geometric non-linearities have to be taken into account. The present paper presents an advanced identification procedure developed to identify the system characteristics from experimental non-linear response curves obtained from forced vibration tests, accounting for fluid-structure interaction, at different excitation levels. Furthermore, the numerical tool developed in this analysis is capable of working with systems presenting one-to-one internal resonance, i.e. systems with symmetry such as circular tubes and circular cylindrical shells. The method relies on a harmonic decomposition of the displacement to cope with the data usually available by vibration measurements.

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Gad-el-Hak, Ibrahim, Njuki Mureithi, Kostas Karazis und Gary Williams. „Experimental Investigation of Jet Cross-Flow Induced Vibration of a Rod Bundle“. In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-65000.

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Abstract Flow-induced vibration (FIV) is a constant concern in nuclear power plants. Demand for better thermal performance challenges the mechanical and flow characteristics of fuel designs. In the hypothetical case of a loss of coolant (LOCA) event in a reactor, the hydrodynamic pressure would increase significantly across the baffle plates. PWRs include safety features such as Loss-of-Coolant-Accident (LOCA) holes and slots in the core periphery baffles surrounding the fuel assemblies to release the pressure build up during a LOCA event. Accordingly, these fuel assemblies are subjected to combined axial and jet cross-flow at certain axial locations along their spans due to their proximity to the LOCA holes. The jet flow could induce vibrations for fuel assemblies located near LOCA holes, which might lead to grid-to-rod fretting and thus potential fuel failure. Research on circular jet induced vibrations of rod bundles is limited. Thus, it is required to investigate the dynamical behavior of rod bundle subjected to jet flow to define the critical velocity at which the fuel rods may undergo instability. This article presents an experimental study of jet flow induced vibrations for a 6 × 6 closely packed normal square rod bundle with a pitch-to-diameter ratio of 1.32 simulating the actual PWR fuel rod dimensions. A specialized test apparatus was designed to investigate the stability effect of jet centerline offset from array centerline (jet eccentricity). From the test results the instability threshold of the rod bundle subjected to jet cross-flow is determined. The results show that the rod array vibration is affected by the jet eccentricity. Two excitation mechanisms are identified. The first is an apparent lock-in type mechanism that maybe related to shear layer or jet oscillation. The second, more important excitation, is an apparent fluidelastic instability induced by the jet flow.

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Crouzet, Fabien. „A Time-Domain Method for the Vibration of Mistunued Bladed Disk Assemblies“. In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93879.

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A chained method to compute the single mode vibration of mistuned bladed disk assemblies is proposed. Aerodynamic coupling effects are first evaluated by computing unsteady aerodynamic coefficients for a quasi-3D geometry. The code is parallelized with a decomposition domain method and validated with the 4th Aeroelastic Standard Configuration. Aerodynamic coefficients are then included in a mass-spring model of the bladed disk assembly. The chained method is applied to the last row blades of a low pressure steam turbine in which localized high levels of vibrations have been observed. The phenomenon of vibration localization found by experiments is predicted with a reasonably good accuracy. Numerical results indicate that aerodynamic coupling is predominant and highly influences mistuning sensitivity. It is also shown that the mistuned row is very sensitive to structural damping. Intentional mistuning is used as a mean to reduce the amplitude magnification on the mistuned assembly. Modifying the frequency of every two blades of the assembly has proved to efficiently reduce localization. A very similar result is obtained by locally modifying the characteristics of a few blades located in high magnification zones.

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Berichte der Organisationen zum Thema "Assemblies vibrations"

Wambsganss, M. W., J. A. Jendrzejczyk und S. S. Chen. Vibration study of the APS magnet support assemblies. Office of Scientific and Technical Information (OSTI), November 1990. http://dx.doi.org/10.2172/10138333.

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Tang, Xiaoyan, Thomas Schneider und Daniel A. Buttry. A Vibrational Spectroscopic Study of the Structure of Electroactive Self-Assembled Monolayers of Viologen Derivatives. Fort Belvoir, VA: Defense Technical Information Center, Mai 1993. http://dx.doi.org/10.21236/ada265705.

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Pope, John, und Daniel A. Buttry. Measurement of Through-Space Dipole-Dipole Coupling from Shifts in Vibrational Frequencies for a Stilbazolium Derivative Embedded in a Self-Assembled Monolayer. Fort Belvoir, VA: Defense Technical Information Center, Juli 1995. http://dx.doi.org/10.21236/ada301450.

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