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Auswahl der wissenschaftlichen Literatur zum Thema „Vibrations des assemblages“
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Zeitschriftenartikel zum Thema "Vibrations des assemblages"
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Cooley, Hazel, und Mario Vallejo-Marín. „Buzz-Pollinated Crops: A Global Review and Meta-analysis of the Effects of Supplemental Bee Pollination in Tomato“. Journal of Economic Entomology 114, Nr. 2 (22.02.2021): 505–19. http://dx.doi.org/10.1093/jee/toab009.
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Abstract Buzz-pollinated plants require visitation from vibration producing bee species to elicit full pollen release. Several important food crops are buzz-pollinated including tomato, eggplant, kiwi, and blueberry. Although more than half of all bee species can buzz pollinate, the most commonly deployed supplemental pollinator, Apis mellifera L. (Hymenoptera: Apidae; honey bees), cannot produce vibrations to remove pollen. Here, we provide a list of buzz-pollinated food crops and discuss the extent to which they rely on pollination by vibration-producing bees. We then use the most commonly cultivated of these crops, the tomato, Solanum lycopersicum L. (Solanales: Solanaceae), as a case study to investigate the effect of different pollination treatments on aspects of fruit quality. Following a systematic review of the literature, we statistically analyzed 71 experiments from 24 studies across different geopolitical regions and conducted a meta-analysis on a subset of 21 of these experiments. Our results show that both supplemental pollination by buzz-pollinating bees and open pollination by assemblages of bees, which include buzz pollinators, significantly increase tomato fruit weight compared to a no-pollination control. In contrast, auxin treatment, artificial mechanical vibrations, or supplemental pollination by non-buzz-pollinating bees (including Apis spp.), do not significantly increase fruit weight. Finally, we compare strategies for providing bee pollination in tomato cultivation around the globe and highlight how using buzz-pollinating bees might improve tomato yield, particularly in some geographic regions. We conclude that employing native, wild buzz pollinators can deliver important economic benefits with reduced environmental risks and increased advantages for both developed and emerging economies.
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Hashemi, S. M., und M. J. Richard. „Natural Frequencies of Rotating Uniform Beams with Coriolis Effects“. Journal of Vibration and Acoustics 123, Nr. 4 (01.04.2001): 444–55. http://dx.doi.org/10.1115/1.1383969.
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A Dynamic Finite Element (DFE) for vibrational analysis of rotating assemblages composed of beams is presented in which the complexity of the acceleration, due to the presence of gyroscopic, or Coriolis forces, is taken into consideration. The dynamic trigonometric shape functions of uncoupled bending and axial vibrations of an axially loaded uniform beam element are derived in an exact sense. Then, exploiting the Principle of Virtual Work together with the nodal approximations of variables, based on these dynamic shape functions, leads to a single frequency dependent stiffness matrix which is Hermitian and represents both mass and stiffness properties. A Wittrick-Williams algorithm, based on a Sturm sequence root counting technique, is then used as the solution method. The application of the theory is demonstrated by two illustrative examples of vertical and radial beams where the influence of Coriolis forces on natural frequencies of the clamped-free rotating beams is demonstrated by numerical results.
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Kaisar, Marilia. „Bluetooth Orgasms“. MedieKultur: Journal of media and communication research 37, Nr. 71 (03.01.2022): 143–60. http://dx.doi.org/10.7146/mediekultur.v37i71.125253.
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Bluetooth-operated sex toys penetrate and are penetrated by the human body, leaving code behind. This article analyzes the relationships that develop between bodies and Bluetooth-operated interactive sex toys. Resembling the pods and portals of David Cronenberg’s film eXistenZ, interactive sex toys allow us to consider how technologies relate intimately to the sexual body. I use Massumi’s work on virtuality and affect theory as a starting point from which to frame embodiment, virtuality, and the circulation of affects. Further, I consider the importance of embodiment and the translations of intensities and vibrations through digital coding among the open sexual body, the technology of the sexual machine, and the applications that foster those connections, in the context of Bluetooth-operated sex toys. This article advocates the need to consider intimate encounters between interactive sex toys and bodies as complex technological and biological assemblages, where vibrating machines and the human body’s flesh come into intimate connection through datafication.
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Giraldes, Bruno Welter, Mark Chatting und David Smyth. „The fishing behaviour of Metopograpsus messor (Decapoda: Grapsidae) and the use of pneumatophore-borne vibrations for prey-localizing in an arid mangrove setting“. Journal of the Marine Biological Association of the United Kingdom 99, Nr. 06 (01.04.2019): 1353–61. http://dx.doi.org/10.1017/s0025315419000146.
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AbstractThis study presents the first documented observations of a brachyuran crab's proactive fishing behaviour in conjunction with mangrove pneumatophores which are employed as prey-localization devices. All ecological data were recorded in situ using simple behavioural observations, visual census and field experiments. Field experiments were based on stimulus-response and ecological surveys on random displacement. Assemblages of Metopograpsus messor were observed daily performing a foraging/predatory tide-related cyclic behaviour pattern in an arid mangrove ecosystem which experiences challenging environmental conditions. Prey-localizing behaviour was observed during the flood tide when pneumatophore-borne vibrations were used to identify potential prey. The prey simulation field experiment (where a single pneumatophore was stimulated by knocking) showed that in >93% of instances a crab approached the exact pneumatophore being stimulated. As water levels increased during the tidal cycle M. messor was observed climbing pneumatophores. The crabs anchored themselves to the pneumatophore just above the water level with their pereiopods. The chelipeds were positioned in a pincher-like trap, and remained in a ‘capture-position’ waiting for prey to move within striking range. This characteristic fishing behaviour was performed daily by a population of M. messor. Ecological observations suggest that both these predatory behaviours are associated with the fish Aphanius dispar dispar in a direct prey–predator relation. Evidence suggests that these fishing behaviours evolved due to characteristics within the M. messor phylogeny (foraging in intertidal zones; daily displacement following tidal levels; high sensitivity to vibrations; and an opportunist diet) and its associated environment (presence of pneumatophores and high availability of a fish resource).
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Chen, Ke, Guojun Zhang, Rui Wu, Li Wang, Hongmei Zheng und Shunhua Chen. „Dynamic Analysis of a Planar Hydraulic Rock-Breaker Mechanism with Multiple Clearance Joints“. Shock and Vibration 2019 (04.02.2019): 1–17. http://dx.doi.org/10.1155/2019/4718456.
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Clearance exists in the joint of a mechanism because of the assemblage, manufacturing tolerances, wear, and other conditions, and it is a focus of research in the field of multibody dynamics. This study built a planar hydraulic rock-breaker model with multiple joint clearances by combining the hydraulic cylinder model, the clearance joints based on the Lankarani–Nikravesh contact force model, and the Lagrange multiplier method. Dynamic simulation results indicated that multiple clearance joints can degrade the dynamic responses of a rock-breaker model, which can be decomposed to rapid vibrations and slow movements. The rapid vibrations are excited by coupling the spring-mass system of hydraulic cylinder and clearances. The effects of the clearance size, input force, damping coefficient, and friction on the dynamic behaviour of the rock-breaker mechanism are also investigated. The friction could reduce the rapid vibration state significantly, which is feasible for practical engineering applications. As compared with the traditional models without clearances, the present model provides not only better predictions for the theoretical study of the hydraulic rock-breaker but also useful guidance for reducing the vibrations of the hydraulic rock-breaker in practical engineering applications.
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Jude, Gretchen. „Vocal Performance Through Electrical Flows: Making Current Kin“. Performance Philosophy 4, Nr. 2 (01.02.2019): 393–409. http://dx.doi.org/10.21476/pp.2019.42235.
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What do we hear in a human voice that vibrates through electrical flows? In this paper I argue for listening (and vocalizing) beyond the human in performances with audio media. I propose understanding such performance practice as engaging with what I call plasmatic voice, a phenomenon distinct from the merely additive, prosthetic conception of voice + electricity. Instead, plasmatic voice functions as instances of queer assemblage stretching to reach the radically Other that constitutes ourselves—facilitating the sense of what Alaimo (2010) terms transcorporeality, an understanding of human embodiment as “intermeshed with the more-than-human world” (2). The vibrations of plasmatic voice—as an example of Eidsheim’s (2015) intermaterial vibrational practice—loosen (post)human social constructs of race and gender and reverberate with nonhuman ecosystems, as I illustrate through analysis of musical examples.
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Carry, Andrew S., und Karl A. Rutter. „Transducer assemblage for hand‐held vibration meters“. Journal of the Acoustical Society of America 86, Nr. 6 (Dezember 1989): 2475. http://dx.doi.org/10.1121/1.398386.
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Zedgenizov, D. A., H. Kagi, V. S. Shatsky und N. V. Sobolev. „Carbonatitic melts in cuboid diamonds from Udachnaya kimberlite pipe (Yakutia): evidence from vibrational spectroscopy“. Mineralogical Magazine 68, Nr. 1 (Februar 2004): 61–73. http://dx.doi.org/10.1180/0026461046810171.
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AbstractMicro-inclusions (1 –10 μm) in 55 diamonds of cubic habit from the Udachnaya kimberlite pipe have been studied using vibrational spectroscopy. This has revealed a multiphase assemblage in cuboid diamonds from the Udachnaya kimberlite pipe. This assemblage includes carbonates, olivine, apatite, graphite, water and silicate glasses. The micro-inclusions preserve the high internal pressure and give confidence that the original materials were trapped during growth of the host diamond. The internal pressures, extrapolated to mantle temperatures, lie within the stability field of diamond and the relatively low temperatures are typical for the formation of cuboid diamonds. In contrast to previously reported data for African diamonds, the micro-inclusions in the cuboids from Udachnaya are extremely carbonatitic in composition (H2O/(H2O+CO2) ≈5 –20%) with the observed assemblage of microinclusions similar to some types of carbonatites. The low water and silica content testify that the material in the micro-inclusions of the Udachnaya diamonds was near-solidus carbonatitic melt. Vibrational spectroscopy has provided the evidence of carbonatitic melts in cuboid diamonds.
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Jovicevic, Jasna. „Flow Vertical: Composing and Improvising Original Music Inspired by Bodily Sound Vibrations“. Leonardo Music Journal 29 (Dezember 2019): 78–82. http://dx.doi.org/10.1162/lmj_a_01068.
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This text analyzes the process of composing and improvising the musical experiment Flow Vertical. This artistic exploration for chamber orchestra responds to a theory of biosignals, incorporating a putative sonic mapping of “inaudible” sound vibration of the author’s biofield as understood to be measured by an SCIO device. The interpretation and represent ation of measured frequencies influenced the creation of an “assemblage,” the system of interconnected human and nonhuman agents within the piece. The artist applied an original eight-week-long method of creation, investigating how this idea of body vibration and a specific yogic routine could aesthetically affect music.
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Laukamp, Carsten, Andrew Rodger, Monica LeGras, Heta Lampinen, Ian C. Lau, Bobby Pejcic, Jessica Stromberg, Neil Francis und Erick Ramanaidou. „Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra“. Minerals 11, Nr. 4 (26.03.2021): 347. http://dx.doi.org/10.3390/min11040347.
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Reflectance spectroscopy allows cost-effective and rapid mineral characterisation, addressing mineral exploration and mining challenges. Shortwave (SWIR), mid (MIR) and thermal (TIR) infrared reflectance spectra are collected in a wide range of environments and scales, with instrumentation ranging from spaceborne, airborne, field and drill core sensors to IR microscopy. However, interpretation of reflectance spectra is, due to the abundance of potential vibrational modes in mineral assemblages, non-trivial and requires a thorough understanding of the potential factors contributing to the reflectance spectra. In order to close the gap between understanding mineral-diagnostic absorption features and efficient interpretation of reflectance spectra, an up-to-date overview of major vibrational modes of rock-forming minerals in the SWIR, MIR and TIR is provided. A series of scripts are proposed that allow the extraction of the relative intensity or wavelength position of single absorption and other mineral-diagnostic features. Binary discrimination diagrams can assist in rapidly evaluating mineral assemblages, and relative abundance and chemical composition of key vector minerals, in hydrothermal ore deposits. The aim of this contribution is to make geologically relevant information more easily extractable from reflectance spectra, enabling the mineral resources and geoscience communities to realise the full potential of hyperspectral sensing technologies.
Dissertationen zum Thema "Vibrations des assemblages"
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K'nevez, Jean-Yves. „Etude cinématique et dynamique d'une transmission automobile à joints tripodes“. Le Mans, 2000. http://cyberdoc.univ-lemans.fr/theses/2000/2000LEMA1016.pdf.
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Ce travail traite de l'étude dynamique d'une transmission automobile à joints tripodes et a permis une analyse fine des phénomènes de martèlement, produit par l'excitation axiale du joint fixe, et le battement entre le moteur et la transmission qui conduisent à des bruits indésirables. L'analyse du martèlement et du battement a nécessité une étude mécanique détaillée de la transmission. Sur le plan cinématique, des galets ont été réduits à des contacts ponctuels et le joint coulissant a en premier lieu été considéré comme homocinétique de façon à présenter les propriétés élémentaires et fondamentales caractéristiques : mouvement de fréquence R1 le long de la rampe, de fréquence R2 le long des tourillons et mouvement de fréquence R3 du centre du triaxe dans son plan. Il a été montré ensuite que dans le cas réel, le mouvement peut se ramener à une perturbation du cas précédent. Pour la transmission complète le déphasage angulaire entre les blocs tripodes conduit aux situations extrêmes , cône et diabolo, de l'arbre intermédiaire ; des préconisations de calage entre tripodes doivent être envisagées au niveau de la production. Sur le plan dynamique, la même méthodologie a été appliquée en partant du joint homocinétique sans frottement pour aboutir au joint réel avec frottements galet sur rampe et galet sur tourillon. Les simulations obtenues montrent que les termes de frottement de roulement de galets sont prépondérants. Le déphasage angulaire entre tripodes joue un rôle important sur la synchronisation des mouvements internes des différents galets sur rampes de joints. Les résultats obtenus par rapport aux objectifs fixés qui étaient d'identifier les différents paramètres participant aux principaux bruits liés aux transmissions sont atteints : i) Le martèlement de fréquence triple est provoqué par des chocs entre les différents constituants du dispositif d'arrêt axial du joint tripode fixe (champignon sur fond de tulipe et étoile sur triaxe). Ce phénomène est diectement lié à l'effort axial qui dépend de l'orientation relative et des frottements de roulement des deux joints tripodes ; ii) Le R6 transmission proche du F2 moteur produit le battement. Il est lié essentiellement a l'évolution sextuple du couple complémentaire dû aux frottements de roulement. De plus l'influence du sens de rotation par rapport au couple a été étudiée, et a révélé un comportement dynamique de la transmission différent suivant le sens de rotation et le signe du couple moteur. Les essais expérimentaux effectués à l'aide d'une transmission instrumentée ont permis de valider les travaux présentés mais ont mis en évidence aussi un phénomène d'arc-bouttement du champignon dans le triaxe sous fort angle de brisureThis work deals with dynamics of a tripod joint automotive transmission and has permitted a detailed approach of the harshness phenomenon produced by the axial force of the fixed joint and the vibration beat between the engine and the transmission leading to undesirable noise. This analysis of harshness and beat has needed a detailed mechanical model of the transmission. Considering kinematics, the rollers have been modeled as points and the plunging joint has been assimilated to a constant velocity joint (CVT) in order to enhance its elementary and fundamental properties : R1 movement of the rollers along the tulip ramps, R2 movement of the rollers along the trunnions and R3 movement of the tripod center. In the real case, it can be shown that the real movement departs but little from the ideal case of the CVT. For the whole transmission, the angle between the two tripodes lead to the extreme two situations, cone or diabolo of the intermediate shaft ; considering the production process, optimal angle adjustments between tripodes are worth being considered. The same methods have been applied for dynamics, beginning with an ideal CVT and ending with a real joint including roller-to-ramp and roller-to-trunnion friction effects. . Derived simulations show that terms issued from the roller-to-ramp movement are prominent. The shiff angle between tripodes play an important role on the synchronisation of intelnal movements of the ramp-to-roller movements The goal of the work was to identify the various parameters responsible for the main noises of the transmissions. This goal has been obtained : i) the third frequency harshness is due to the chocks between the parts of the fixed joint ( stop on the tulip and star on the tripode). This phenomenon is directly related to the axial effort that depends on the relative orientation and the friction of the two tripode joints ; and ii) the R6 vibration close to the F2 vibration produced by the engine, is issued from the complementary torque produced by the roller-to-tulip friction. In addition, dynamics of the transmission depend on torque and velocity same or opposite sign. The experimental results using an instrumented transmission have validated the presented results but the stick of the stop on the tripode has also been put into evidence under large joint angle
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Berthou, Matthieu. „Fiabilité des assemblages sans plomb en environnement sévère“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00991011.
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Le mémoire porte sur l'étude de la fiabilité des assemblages utilisant des alliages de brasure sans-plomb en environnement sévère pour des applications électroniques. Une méthode de préparation métallographique fiable et reproductible en vue de l'analyse microstructurale est présentée. L'effet du vieillissement thermique statique sur l'évolution microstructurale de billes de brasure en SAC, la tenue à la fatigue mécanique des assemblages brasés et l'étude de l'endommagement thermomécanique sont développés. Le seul effet notable constaté après vieillissement thermique est l'augmentation des épaisseurs des intermétalliques de contact. A la suite de sollicitations mécaniques, les ruptures sont plus souvent observées dans les pistes que dans les brasures, et ne permettent pas d'incriminer des éléments de la microstructure brasée comme facteurs déterminant de propagation des fissures. Les sollicitations thermomécaniques conduisent à une recristallisation, et les fissures se propagent alors le long des joints de grains recristallisés.
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Pisapia, Stéphane [Jérémy]. „Etude du comportement vibratoire non-linéaire d'un assemblage combustible de réacteur à eau pressurisée“. Aix-Marseille 2, 2004. http://www.theses.fr/2004AIX22021.
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Cette thèse s'inscrit dans le cadre général de la tenue au séisme des cœurs de Réacteurs à Eau Pressurisée (R. E. P. ). Son but est la caractérisation, sous différents environnements (air, eau stagnante et eau sous écoulement), du comportement vibratoire non-linéaire d'un assemblage combustible par une approche expérimentale. Le modèle retenu devra contenir peu de degrés de liberté afin de pouvoir être utilisé dans les calculs d'impacts, de file d'assemblages ou de cœur completThis study is in the scope of Pressurized Water Reactors (P. W. R. ) core response calculations in the field of seismic studies. The aim of this work is to characterize experimentally the PWR fuel assembly non-linear vibratory behavior. The model obtained must be global with a few degree of freedom in order to be integrated in the calculation of the core response to seismic excitation
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Germes, Sylvain. „Propagation et dissipation des efforts mécaniques entrant dans les ossatures de caisses automobiles“. Châtenay-Malabry, Ecole centrale de Paris, 2000. http://www.theses.fr/2000ECAP0902.
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La finalité de ce travail de thèse réalisé dans l'industrie automobile, est d'améliorer le confort acoustique des véhicules. En particulier, le bruit basse fréquence résulte en partie des transferts d'énergie par voie solidienne des efforts mécaniques (moteurs, trains) vers les panneaux d'habitacle. L'objectif de ces travaux a consisté à développer des modèles de calcul fiables afin de comprendre les mécanismes de propagation mis en jeu, pour concevoir des ossatures limitant les transferts vibratoires. L'étude a porté sur des corps creux constitués de tôles soudées de faible épaisseur. Pour mette au point les outils d'analyse, des structures de complexité croissante ont été étudiées. De plus, la connaissance des vibrations entretenues a été utilisée pour bénéficier des outils de calcul et de mesure maîtrisés dans l'automobile. L'étude de la propagation des ondes a nécessité le développement conjoint de modèles de calcul et de protocoles de mesure. Une stratégie de validation des modèles a été proposée. Elle est basée sur la confrontation des calculs et des essais en analyse modale, en analyse transitoire sur les temps courts puis longs. Son application à un assemblage de corps creux a permis de dégager des règles de modélisation et des paramètres importants de mesure pour obtenir une bonne corrélation des deux caractérisations sur les temps courts. Pour étendre la validité des modèles aux temps longs, deux modèles de dissipation ont été proposés. Des outils théoriques ont été développés pour analyser les mécanismes de propagation observés à partir du modèle EF de l'assemblage de corps creux. La nature de la propagation a été expliquée, les mécanismes de conversion des ondes de flexion mis en évidence. Les modèles de propagation validés ont été utilisés pour étudier l'influence de deux connexions de corps creux sur les transferts solidiens. Finalement, une solution technique permettant d'augmenter la dissipation dans les corps creux a été proposée.
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Cheikh, Mohammed. „Réanalyse de l'équilibre des structures : application à l'étude des assemblages collés et de l'endommagement des matériaux composites“. Dijon, 1997. http://www.theses.fr/1997DIJOS079.
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Dans cette étude, nous proposons une généralisation de la méthode de réanalyse de l'équilibre des structures à la réanalyse de rigidité (géométrie et matériaux). Cette généralisation fait appel à des conditions mixtes, portant simultanément sur les efforts et les déplacements. Une application a l'endommagement decoule naturellement de cette methode et sera proposee. Cette méthode a pour avantage de donner une solution générale du système de l'équilibre, indépendamment des conditions aux limites. Du point de vue numérique, nous présentons également une méthode de résolution du système singulier par décomposition permettant d'éviter le calcul de l'inverse régularisée. Cette décomposition rejoint le concept de l'inverse partiel de Moore-Penrose. Elle permet un gain en temps de calcul et une simplicité de présentation. Elle facilite l'étude du comportement non linéaire des matériaux et notamment le cas de la variation de rigidité. La puissance de la méthode de réanalyse provient en partie de la facilité avec laquelle elle permet d'imposer des conditions cinématiques diverses. Avec l'extension proposée, toute loi mécanique pouvant s'exprimer directement ou indirectement par des conditions cinématiques ou mixtes peut être modélisée par cette méthode. Ce qui nous a permis de modéliser par exemple, des conditions portant sur le vecteur contraintes alors que cette méthode est basée sur les éléments finis en déplacements. Notre travail est divisé en deux parties : la première est consacrée à la réanalyse avec modification des conditions aux limites en chargements, en déplacements et en contraintes. La deuxième partie de cette étude est consacrée à la réanalyse de rigidité. Comme application, nous traitons le cas de l'endommagement des matériaux composites unidirectionnels.
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Ghienne, Martin. „Conception et caractérisation de liaisons boulonnées pour la réduction robuste de vibrations de structures“. Thesis, Paris, CNAM, 2017. http://www.theses.fr/2017CNAM1146/document.
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La conception des structures assemblées nécessite de disposer d'outils de simulation prédictifs permettant de minimiser les écarts entre les comportements réel et simulé de ces structures. Et ce, d'autant plus que les exigences en terme de performance du système sont élevées et qu'une conception optimale est recherchée. Lors du dimensionnement des structures assemblées, la pratique généralement adoptée en bureau d'étude consiste à définir un coefficient de sécurité permettant de tenir compte de la variabilité du comportement réel de ces structures. L'inconvénient est de conduire nécessairement à un surdimensionnement qui peut aller à l'encontre des objectifs de dimensionnement optimal de ces structures. Les liaisons sont le siège de phénomènes non-linéaires tels que le contact ou le frottement et différentes sources d'incertitude induisent une variabilité sur les caractéristiques dynamiques réelles des liaisons. Malgré les capacités des calculateurs actuels, la prise en compte conjointe des phénomènes non linéaires et des incertitudes lors de la simulation de structures assemblées complexes reste difficilement envisageable par une approche directe. L'objectif de ce travail est de proposer une approche pragmatique de caractérisation du comportement vibratoire des structures légères assemblées en tenant compte de la variabilité des paramètres des liaisons. L'intérêt de cette approche est de pouvoir être intégrée dans une phase de dimensionnement robuste. On peut ainsi envisager de dimensionner une solution d'amortissement des vibrations d'une structure assemblée en tenant compte de la variabilité du comportement réel des liaisons de cette structure. Ce travail étudie d'abord le comportement dynamique d'une structure légère réelle afin d'identifier un modèle nominal «juste suffisant» des liaisons considérées. Une approche non intrusive de caractérisation du comportement vibratoire d'une structure en présence de paramètres incertains est ensuite proposée. Cette approche, intitulée approche SMR (pour Stochastic Model Reduction), exploite le fait que la variabilité des vecteurs propres d'une structure est généralement d'un ordre de grandeur inférieur à la variabilité des fréquences propres associées ce qui permet de réduire considérablement le coût de calcul de l'approche tout en gardant une bonne précision sur l'estimation des fréquences propres aléatoires de la structure. Le principe de l'approche est alors d'adapter la modélisation stochastique à chaque fréquence propre aléatoire en fonction d'une exigence de précision globale sur l'ensemble des fréquences propres aléatoires recherchées. Le point clé de cette approche consiste à identifier le modèle stochastique adapté à chaque configuration de fréquence propre, pour cela un indicateur sans coût de calcul supplémentaire est proposé. Finalement, un modèle stochastique des liaisons de la structure considérée est proposé et l'approche SMR est utilisée dans un processus d'optimisation basé sur le principe du maximum de vraisemblance pour identifier les paramètres de ce modèle. Cette dernière étape de la démarche proposée permet alors de caractériser le comportement vibratoire de structures assemblées constituées de nombreuses liaisons en tenant compte de la variabilité du comportement de chacune des liaisons. La démarche mise en place dans le cadre de cette thèse est alors concrétisée par la proposition d'une stratégie originale de réduction robuste des vibrations d'une structure assemblée légèrePredictive models are needed to properly design assembled structures. The main issue with this kind of structure is to deal with non-linear phenomena as contact or friction while considering sources of uncertainties mainly responsible for the deviation between the effective behavior of the structure and results from deterministic simulations. This work aims to provide a pragmatic approach to characterize the vibrational behavior of light assembled structures considering the variability of parameters of the joints. This approach would be useful for robust design of solutions, such as solutions for damping vibrations, dedicated to assembled structures and taking into account the variability of the real behavior of each joint.In this work, the dynamical behavior of an actual light structure is studied in order to identify a "just sufficient" nominal model of the considered joints. A non intrusive approach is then proposed to reduce the vibrational stochastic model of a structure with random parameters is then proposed. This approach, referred as the SMR approach (for Stochastic Model Reduction approach), takes advantage of the order of variability of random eigenvectors which is usually lower than the variability of corresponding random eigenfrequencies. It then allows to significantly reduce the computational cost for a given accuracy to estimate the structure random eigenfrequencies. The cornerstone of this approach is to adapt the stochastic modeling to each random eigenfrequency depending on a global accuracy requirement on the whole set of sought random eigenfrequency. The key point is then to identify the stochastic model used for each configuration of random eigenfrequency. A computationally free indicator is then proposed. Finally, a stochastic mechanical model of the joints of the studied structure is proposed. The SMR approach is used in an optimization process based on the maximum likelihood principle to identify the parameters of this stochastic model. This last step allows to characterize the vibrational behavior of assembled structures involving many joints taking into account the variability of each joints. This work is then concluded by applying the proposed approach to the design of an original strategy for robust reduction of vibration of light structures
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Ksentini, Olfa. „Etude du dévissage spontané d'un assemblage boulonné soumis à des sollicitations transverses dynamiques“. Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0036/document.
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Cette thèse porte sur l’étude du dévissage spontané d’assemblages vissés, sous sollicitations dynamiques transversales. Un travail expérimental et numérique a été réalisé pour caractériser ce phénomène, dans des conditions proches de celles des assemblages réels. Une expérimentation a permis de provoquer le dévissage d’un boulon, en soumettant l’assemblage à des vibrations transversales par rapport à l’axe de la vis. Les effets de la précharge, du traitement de surface et de la disposition des vis ont été explorés. Ces résultats ont été confrontés avec ceux obtenus par un modèle numérique détaillé utilisant la méthode des éléments finis. Cependant, en raison de la complexité de la géométrie et des difficultés de modélisation à l’échelle locale, le temps de calcul est très important et peut être prohibitif pour une étude industrielle. Afin de remédier à cette difficulté, des modèles simplifiés ont été développés, l’un avec une approche par éléments finis associés à un connecteur cinématique, et l’autre par modélisation unidimensionnelle. Ces modèles simplifiés reproduisent correctement le phénomène du dévissage spontané et confirment leur efficacité en gain de temps de calculThis thesis focuses on the study of the self-loosening of bolted joints under transverse dynamic loads. Experimental and numerical work was carried out in order to reveal this phenomenon under conditions close to those of actual assemblies. An experiment allowed the loosening of a bolt to be caused by subjecting the assembly to transverse vibration with respect to the axis of the screw. Effects of preload, surface treatment and disposal of the screws were explored. These results were compared with those obtained by a detailed numerical model using the finite element method. However, due to the complexity of the geometry and modeling challenges at the local level, the computation time was very long and may be prohibitive for an industrial study. To remedy this problem, two simplified models were developed, one with a finite element approach associated with a kinematic connector, and one by unidimensional modeling. These simplified models correctly reproduce the self-loosening phenomenon and confirm their efficiency in terms of computation time
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Toulemonde, Charles. „Dynamique des oscillateurs à impacts“. Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0520.
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Au cours de cette thèse, la dynamique des assemblages de structures a été modélisée sous l'angle des oscillateurs a impacts. Plus particulièrement, la dynamique de ces systèmes a été envisagée de manière analytique. Les résultats théoriques de la thèse généralisent les résultats analytiques publiés jusqu'alors dans la littérature. L’étude a ainsi été étendue à l'ensemble des réponses périodiques possibles de ces systèmes : réponses périodiques impactant un nombre fini de fois par période, réponses périodiques avec phases de collage impactant un nombre infini de fois par période. Par ailleurs, les résultats présentés dans le cadre de cette thèse ne se limitent pas aux systèmes monodimensionnels, ils s'appliquent à l'ensemble des oscillateurs à impacts à plusieurs degrés de liberté. Les essais expérimentaux que nous avons menés confirment les travaux analytiques. Grâce aux méthodes analytiques que nous avons développées, il est possible de réaliser une investigation précise et rapide de la dynamique des oscillateurs à impacts. L’application de la méthode de continuation contribue, par la suite, à élargir le champ des résultats dans l'espace des paramètres. Grâce à cet outil, des diagrammes de bifurcation, de réponse fréquentielle ou de régionnement ont été construits. En ce qui concerne les réponses impactant un nombre fini de fois par période, la formulation de la dynamique employée est telle que la difficulté de la résolution du problème est rendue indépendante du nombre de degrés de liberté considérés pour modéliser la structure. L’exploitation de ce type de méthode permet ainsi d'étudier des systèmes réalistes dont le comportement non linéaire peut être très prononce, éventuellement même discontinu (impacts, frottement sec). Les outils que nous avons développés permettent d'aborder la dynamique asymptotique des assemblages boulonnes dans sa complexité.
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Peyret, Nicolas. „Dissipation de l’énergie mécanique dans les assemblages : effet du frottement en sollicitation dynamique“. Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1052/document.
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Cette thèse porte sur l'étude de l'amortissement des structures assemblées, et plus précisément de la contribution des assemblages sous sollicitations vibratoires. Le mémoire est composé de cinq chapitres traitant la problématique tant du point de vue analytique qu'expérimental. Un banc d'étude académique est proposé afin d'étudier des assemblages sous sollicitation normale constante (statique) et sous sollicitations tangentielles liées aux vibrations de la structure (dynamique). Le facteur de perte caractérisant l'amortissement de la structure est obtenu, dans un premier temps par une étude locale quasi-statique. Puis une fonction de dissipation est définie, permettant d'affiner la modélisation de l'amortissement par une étude dynamique globale. Au regard des résultats obtenus par la modélisation, une analyse expérimentale est menée. Cela afin d'isoler la contribution, à l'amortissement de la structure, des glissements partiels dans les assemblages. Pour cela, deux structures géométriquement identiques, l'une monolithique et l'autre assemblée sont étudiées. Les effets des interfaces sont analysés puis comparés aux résultats analytiques. Afin de simuler plus précisément ces effets, une modélisation prenant en compte les défauts de forme des surfaces en contact est menéeThis thesis presents a study of damping in assembled structures, or, more precisely, a study of the vibrations of assemblies under external excitations. The paper contains five chapters examining this problem from both analytical and experimental viewpoints. An academic investigation is presented as a foundation in order to study assemblies both under constant normal stresses (static), and under tangential stresses linked to the structural vibrations (dynamic). The loss factor that characterizes the damping of the structure is obtained through a quasi-static local study. Then, a dissipation function is given, which allows the refinement of the damping model through a global dynamic study. An experimental analysis is undertaken to examine the results obtained by the modeling. The objective of this analysis is to isolate the effects, at the structural damping, of partial sliding in the assemblies. To isolate these effects, two structures identical in shape and material, one assembled and one uniform, are studied. The data collected from the interfaces are analyzed, and then compared to the analytical results. In order to simulate these effects with greater precision, a modeling is undertaken that takes into account the defects of form for the surfaces in contact
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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 écoulementThe 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
Bücher zum Thema "Vibrations des assemblages"
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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.
Buchteile zum Thema "Vibrations des assemblages"
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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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jules, tavis d. „The Vibrating Plateau of Caribbean Historiographies: Re/dis/assembling Regional Educational Assemblages“. In Comparative and International Education (Re)Assembled. Bloomsbury Academic, 2022. http://dx.doi.org/10.5040/9781350286856.ch-009.
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Hoffmann, Roald, und Henning Hopf. „Learning from Molecules in Distress“. In Roald Hoffmann on the Philosophy, Art, and Science of Chemistry. Oxford University Press, 2012. http://dx.doi.org/10.1093/oso/9780199755905.003.0013.
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From the time we first got an inkling of the geometries and metrics of molecules, the literature of organic chemistry has contained characterizations of molecules as unstable, strained, distorted, sterically hindered, bent and battered. Such molecules are hardly seen as dull; on the contrary, they are perceived as worthwhile synthetic goals, and their synthesis, or evidence of their fleeting existence, acclaimed. What is going on here? Why this obsession with abnormal molecules? Is this molecular science sadistic at its core? Let’s approach these questions, first describing what is normal for molecules, so we can define the deviance chemists perceive. After a digression into the anthropomorphic language chemists generally use, and the psychology of creation in science, we will turn to the underlying, more serious concern: “What is the value of contemplating (or creating) deviance within science?” As many as 366,319 different eicosanes (C20H42) are conceivable, not counting optical isomers. And an enumeration of the components of a reasonably constrained universe of all compounds with up to 11 C, N, O, F atoms comes to >26 million compounds. An important feature of the chemical universe is that the tree of possible structures is denumerable. At the same time, the playground of chemical structures is subject to systematic elaboration, through the decoration of an underlying skeleton by functional groups of some stability. Very quickly a multitude turns into a universe. Of structure, and of function. Thinking of these molecules as fixed, rigid structures is natural—don’t they look like olive and toothpick assemblages, prettied up by computer rendering? And one can certainly get a long way in organic chemistry in the classical, mechanical mode. But the atoms in a molecule move continually, deviating, oscillating, as if held by springs, around an average position. The honey-comb structure of the benzene ring (a molecular tile, seemingly ever so flat and rigid as the one on your bathroom floor) has become an icon of chemistry just as the angled water molecule. Yet that tile is not rigid, it moves—and one can see the deformations/deviations by looking at its vibrational (what a telling name!) spectrum.
Konferenzberichte zum Thema "Vibrations des assemblages"
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Hashemi, Seyed M. „Vibration Analysis of Axially Loaded Beams Including Rotary Inertia: An Exact Dynamic Finite Element“. In ASME 2004 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/detc2004-57789.
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An ‘exact’ basis function Dynamic Finite Element (DFE) for the free vibrational analysis of axially loaded beams and assemblages composed of beams is presented. The shear deformation is neglected but the Rotary Inertia (RI) effects are taken into consideration. The dynamic trigonometric shape functions for bending vibrations of an axially loaded uniform beam element are first derived in an exact sense. Then, exploiting the Principle of Virtual Work together with the nodal approximations of variables based on these dynamic shape functions, leads to a single frequency dependent Dynamic Stiffness Matrix (DSM) that represents both mass and stiffness properties. A Wittrick-Williams algorithm, based on a Sturm sequence root counting technique, is then used as the solution method. The application of the theory is demonstrated by an illustrative example of cantilever beam where the influence of Rotary Inertia (RI) effect and different axial loads on the natural frequencies of the system is demonstrated by numerical results.
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Hashemi, S. M., und M. J. Richard. „On the Natural Frequency Calculation of Rotating Cantilever Uniform Beams With Coriolis Effects: A Dynamic Finite Element (DFE)“. In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8269.
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Abstract A Dynamic Finite Element (DFE) for vibrational analysis of rotating assemblages composed of beams is presented in which the complexity of the acceleration, due to the presence of gyroscopic, or Coriolis forces, is taken into consideration. The dynamic trigonometric shape functions of uncoupled bending and axial vibrations of an axially loaded uniform beam element are derived in an exact sense. Then, exploiting the Principle of Virtual Work together with the nodal approximations of variables, based on these dynamic shape functions, leads to a single frequency dependent stiffness matrix which is Hermitian and represents both mass and stiffness properties. A Wittrick-Williams algorithm, based on a Sturm sequence root counting technique, is then used as the solution method. The application of the theory is demonstrated by two illustrative examples of vertical and radial beams where the influence of Coriolis forces on natural frequencies of the clamped-free rotating beams is demonstrated by numerical results.
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Nishida, Akemi. „Wave Propagation Analysis of Piping Structures“. In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75760.
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It is becoming important to carry out detailed modeling procedures and analyses to better understand the actual phenomena. Because some accidents caused by high-frequency vibrations of piping have been recently reported, the clarification of the dynamic behavior of the piping structure during operation is imperative in order to avoid such accidents. The aim of our research is to develop detailed analysis tools and to determine the dynamic behavior of piping systems in nuclear power plants, which are complicated assemblages of different parts. In this study, a three-dimensional dynamic frame analysis tool for wave propagation analysis is developed by using the spectral element method (SEM) based on the Timoshenko beam theory. Further, a multi-connected structure is analyzed and compared with the experimental results. Consequently, the applicability of the SEM is shown.
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Larin, O. O. „Forced Vibrations of Bladings With the Random Technological Mistuning“. In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23099.
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An approach has been considered for analysis of forced vibrations for randomly mistuned bladed discs. It is based on stochastic reduced basis method and hypothesis of locally distributed mistuning, which could realise in blade-to-blade joints due to the deviation at the assemblage technology. The method gives an essential possibility to make an analysis using one sector model and allows for this case to use of industrial-size sector models of bladings. The numerical researches of steady-state forced vibrations of randomly mistuned bladed disk of a 3-rd stage low pressure cylinder of a steam turbine have been done.
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Claeyssen, Julio R., Rosemaira Dalcin Copetti und Teresa Tsukazan. „Matrix Vibration Formulation of Damped Multi-Span Beams“. In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14933.
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In this work we consider segmented Euler-Bernoulli beams that can have an internal damping of the type Kelvin-Voight and external viscous damping at the discontinuities of the sections. In the literature, the study of this kind of beams has been sufficiently studied with proportional damping only, however the effects of non-proportional damping has been little studied in terms of modal analysis. The obtaining of the modes of segmented beams can be accomplished with a the state space methodology or with the classical Euler construction of responses. Here, we follow a newtonian approach with the use of the impulse response of beams subject both types of damping. The use of the dynamical basis, generated by the fundamental solution of a differential equation of fourth order, allows to formulate the eigenvalue problem and the shapes of the modes in a compact manner. For this, we formulate in a block manner the boundary conditions and intermediate conditions at the beam and values of the fundamental matrix at the ends of the beam and in the points intermediate. We have chosen a basis generated by a fundamental response and it derivatives. The elements of this basis has the same shape with a convenient translation for each segment. This choice reduce computations with the number of constants to be determined to find only the ones that correspond to the first segment. The eigenanalysis will allow to study forced responses of multi-span Euler-Bernoulli beams under classical and non-classical boundary conditions as well as multi-walled carbon nanotubes (MWNT) that are modelled as an assemblage of Euler-Bernoulli beams connected throughout their length by springs subject to van der Waals interaction between any two adjacent nanotubes.
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Carassale, Luigi, Michela Marrè-Brunenghi und Stefano Patrone. „Modal Identification of Dynamically Coupled Bladed Disks in Run-Up Tests“. In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57251.
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The spin test is a standard industrial practice employed for the qualification of rotor blades and disks. The expected results are the modal properties of blades and assemblages at different rotation velocities. If a significant dynamic coupling among the blades exists, global vibration modes appear, reflecting into a set of closely spaced natural frequencies for each mode family. In case of perfectly-tuned bladed disks, the circumferential structure of the mode shapes is known and can be exploited during the identification process so that traditional single-dof models may be applied. On the contrary, the mode irregularities produced by mistuning prevents the use of single-dof models requiring the development of more sophisticated approaches. In this work, we propose a multi-dof identification technique organized as follow: 1) the FRF of the bladed disk in the neighborhood of a resonance crossing is identified by the wavelet transform of the measured response; 2) the modal parameters of the system are estimated using a mixed stochastic-deterministic subspace algorithm formulated in the frequency domain. The procedure is validated using a realistic numerical simulation.
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Gandhi, M. V., B. S. Thompson und S. Shakir. „Electro-Rheological-Fluid-Based Articulating Robotic Systems“. In ASME 1987 Design Technology Conferences. American Society of Mechanical Engineers, 1987. http://dx.doi.org/10.1115/detc1987-0056.
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Abstract The limitations of the current generation of robotic systems has triggered a new research thrust for predicting the elastodynamic response of assemblages of articulating flexible-bodied systems. This research thrust is extended herein by proposing the fabrication of robotic systems in either monolithic or ultra-advanced composite laminated high-strength, high-stiffness materials in which are incorporated electrorheological fluids. These multi-phase fluid systems, which change their rheological behavior instantaneously when subjected to an externally applied electrical field, provide a potential for tailoring the vibrational characteristics of these hybrid materials from which the structural members of the proposed robotic systems are fabricated. This paper is focused on developing the necessary design tools for predicting the vibrational response of flexible multibodied articulating systems fabricated with this new class of advanced materials. A variational theorem is developed herein as a basis for finite element formulations which can be employed to predict the elastodynamic response of these systems. A coherent combination of experimental and theoretical work on cantilevered beams is presented to demonstrate the viability of the proposed design methodology. In addition, computer simulation results are presented to demonstrate the potential payoffs in terms of superior performance characteristics of a new generation of robotic systems capitalizing on this innovative and revolutionary design philosophy.