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Understanding the dynamic behavior of fuel pins subjected to seismic loading is one of themajor concerns for the design of SFRs (Sodium-cooled Fast Reactors) and in particular for thedesign of the ASTRID prototype. In this field, two physical aspects are important: the strongnon-linearity due to the contacts (between the fuel pins and between the pins and the wrappertube) and the fluid-structure interaction with the coolant.These phenomena are taken into consideration with the fluid-elastic force model proposed byPaidoussis and a penetration impact law. Several parameters engaged with these models are tobe determined with experiments. To this end, a test bench CARNEAU equipped with a fastcamera as measurement is designed to capture the motion history of the fuel pins in water flowof different velocities and under sine sweep excitation. It is anticipated to identify the globalparameters lumping the effects of the detailed physics with modal analysis, unfortunately theexperiments were not carried out.With the parameters decided with the inspiration from the previous experiments and theoreticworks, two numeric methods have been used to exploit the model: the traditional method usingimplicit Newmark integration and the global periodic time integration (GPTI) method. Themodelling enables us to have a phenomenal analysis on the nonlinear dynamics of the fuel pins:the relatively simple global vibration and the local impact-related chatters of much smaller timescale, which is the origin of the complexity of the dynamic behavior. The two methods haveboth their advantages and limits with the impact-related problem. The direct time-integration isquite direct and can be applied for any contact rigidity, but it is difficult to cover the coexistingregimes led by the nonlinearity as it is sensible to the initial condition. The GPTI method allowsto unfold the solution branch for a varying parameter and each solution point corresponds to avibration regime, but the difficulty with the continuation leads to a limited range of contactstiffness and excitation amplitude. With an increasing amplitude, more and more solutionbranches coexist for the periodic dynamic responses of the fuel pin resulting in a greatcomplexity, the GPTI method does not neither guarantee the observation of all the possibleperiodic solutions, the direct time-integration can be complementary but not exhaustive.The fluid-structure coupling is also an essential element for the correct modeling of the system.The effects of the fluid on the structure have been taken into account in the previous model. Togo further, it is necessary to take into account the effects of the structure on the flow. To thisend, a spatial averaging method considering the space-and-time dependent RVEs has beenproposed. It makes it possible to establish the equations of motion of the fluid by averaging theNavier Stockes equation in the form of Arbitrary Lagrangian Eulerian (ALE). The couplingwith the structure is accounted for by using the hydraulic model of Paidoussis.; La compréhension du comportement dynamique des aiguilles combustibles soumises à un chargement sismique est une des préoccupations majeures pour la conception des RNR(Réacteurs à Neutrons Rapides) et notamment pour la conception du prototype ASTRID. Dans ce domaine, deux aspects physiques sont importants : la forte non-linéarité due aux contacts(entre les aiguilles combustibles et entre les aiguilles et le tube hexagonal) et l'interaction fluide-structure avec le caloporteur.Ces phénomènes sont pris en compte en utilisant le modèle de la force fluide-élastique proposé par Paidoussis et une loi de contact par pénalisation. Plusieurs paramètres associés à ces modèles sont à déterminer expérimentalement en utilisant la méthode d’analyse modale. A cet effet, un banc d'essai CARNEAU équipé d'une caméra rapide a été conçu pour visualiser la vibration des aiguilles sous écoulement d'eau à différentes vitesses et sous sollicitation dynamique de type balayage sinusoïdal. Malheureusement, les essais visagés n'ont pas pu êtreréalisés dans le cadre de ce travail.En utilisant les paramètres déterminés dans la littérature (expérimentalement ou bien par desapproches théoriques), le modèle numérique développé dans ce travail a pu être exploité en mettant en œuvre deux méthodes : la méthode traditionnelle en utilisant l'intégration de Newmark implicite et la méthode GPTI (global periodic time integration). Ces modélisations nous permettent d'avoir une analyse phénoménologique de la dynamique non linéaire des aiguilles combustible : la vibration globale, qui reste relativement simple, et les vibrations parasites liées aux contacts se produisant sur des échelles de temps beaucoup plus petites, d’où la complexité du comportement dynamique. Les deux méthodes ont leurs propres avantages etlimites pour les problèmes de contacts. La première méthode est assez directe et utilisable avec n'importe quelle rigidité de contact, mais des difficultés apparaissent pour obtenir les régimes coexistants sensibles aux conditions initiales choisies et générés par la non-linéarité. La méthode GPIT permet de déployer une branche de solution pour un paramètre variable(fréquence, amplitude de la sollicitation, ...) et chaque point solution correspond à un régime de vibration. Cependant la difficulté induite par la continuation conduit à une plage limitée de laraideur de contact et de l'amplitude de sollicitation. Avec l’augmentation de l’amplitude, de plus en plus de branches de réponses périodiques coexistent pour la dynamique de l'aiguille etprésentent une grande complexité pour l’analyse. Par ailleurs, la méthode GPIT ne garantit pas l'observation de toutes les branches, et donc la méthode d’intégration directe peut être une solution complémentaire mais ne permet pas de trouver toutes les solutions correspondantes aux comportements dynamiques des aiguilles.La prise en compte du couplage fluide structure est aussi un élément essentiel à la bonne modélisation du système. Les effets du fluide sur la structure ont bien été pris en compte dans le cadre du modèle précédent. Pour aller plus loin, une prise en compte des effets de la structure sur l’écoulement est nécessaire. Pour cela, une approche par moyenne spatiale, sur chaque Volume Elémentaire Représentative dépendante de l’espace et du temps, a été proposée. Elle permet d’établir les équations du mouvement du fluide en moyennant l’équation de Navier-Stokes sous une forme ALE (Arbitrary Lagrangian Eulerian). Le couplage avec la structure est pris en compte en utilisant le modèle hydraulique de Paidoussis.

N this thesis, the aim is to better understandwhether the nature of the connections betweenparts has an importance on the dynamic behaviourand/or on the acoustic radiation of an assembly. Toapproach the analysis, the case study consisted oftwo assembled beams where the junction is representedby a distribution of mechanical bonds (stiffnessand damping). An analytical equation of thejunction is performed. It takes into account themisalignment of the neutral fibres which couple longitudinaland flexural motions. These equationsare projected into the free-free modal bases of thedecoupled structures, which are easily accessible experimentally.In this model, the junction effects aredescribed by an intermodal coupling matrix. Thismatrix highlights the contribution of the resonantmodes in the dynamics of the junction as well asthe contribution of the radiating modes on its vibroacousticbehaviour. The study of the assemblybehaviour under different types of excitation revealstypical behaviours ranging from quasi-decouplingto coupling of motions including conversion mechanisms.The transition between these typical behavioursand its link to the junction parameters isanalysed and reveals that significant radiation canoccur due to hybridization of motions caused bythe junction. An experimental approach is obtainedand confirms the results of the model. In order toavoid an analysis dependent on the excitation, indicatorsare constructed on the basis of the inverseof the dynamic stiffness of the assembled structures,which acts as an intrinsic signature of the junction.The whole approach is applied to two study cases:glued beams and bolted beams. An opening towardsthe non-linearities at the junction is proposed as aperspective., Dans ce travail de thèse, il s'agit demieux comprendre si la nature des liaisons entrepièces a une importance sur le comportement dynamiqueet/ou sur le rayonnement acoustique d'unassemblage. Pour aborder l’'analyse, le cas d'étudechoisi est celui de deux poutres assemblées où la liaisonest représentée par une distribution de liaisonsmécaniques (raideur et amortissement). Une mise enéquation analytique de l’assemblage est réalisée. Elleprend en compte le dés-alignement des fibres neutresqui couple des mouvements de traction-compressionet de flexion. Ces équations sont projetées dans lesbases modales libres-libres des structures découpléesdont l’'intérêt et d'y accéder facilement expérimentalement.Dans cette modélisation, l'effet de la liaisonest décrit par une matrice de couplage intermodal.Cette matrice met en évidence la contributiondes modes résonants dans la dynamique de l’assemblageainsi que la contribution des modes rayonnantssur son comportement vibroacoustique. L'étude ducomportement de l'assemblage sous différents typesd'excitation met en évidence des comportements typiquesallant du quasi-découplage au couplage desmouvements incluant des mécanismes de conversions.La transition entre ces comportements typiques etson lien avec les paramètres de liaison est analysée etrévèle qu'un rayonnement significatif peut apparaîtreen raison de l'hybridation des mouvements provoquéepar la liaison. Une démarche expérimentaleest construite et confirme les résultats du modèle.Pour s'affranchir d’une analyse dépendante des excitations,des indicateurs sont construits sur la basede l'inverse de la rigidité dynamique de l’assemblagequi fait office de signature intrinsèque de la liaison.L'ensemble de la démarche est appliqué à deux casd'étude : Poutres collées et poutres boulonnées. Uneouverture vers la prise en compte de non-linéaritésà la liaison est proposée comme perspective

Successful implementation of an active vibration control system is strictly correlated to the exact knowledge of the dynamic behavior of the system, of the excitation level and spectra and of the sensor and actuator’s specification. Only the correct management of these aspects may guarantee the correct choice of the control strategy and the relative performance. Within this paper, some preliminary activities aimed at the creation of a structurally simple, cheap and easily replaceable active control systems for metal panels are discussed. The final future aim is to control and to reduce noise, produced by vibrations of metal panels of the body of a car. The paper is focused on two points. The first one is the realization of an electronic circuit for Synchronized Shunted Switch Architecture (SSSA) with the right dimensioning of the components to control the proposed test article, represented by a rectangular aluminum plate. The second one is a preliminary experimental study on the test article, in controlled laboratory conditions, to compare performances of two possible control approach: SSSA and a feed-forward control approach. This comparison would contribute to the future choice of the most suitable control architecture for the specific attenuation of structure-born noise related to an automotive floor structure under deterministic (engine and road-tyre interaction) and stochastic (road-tyre interaction and aerodynamic) forcing actions.

TEZ11196 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2018. Kaynakça (s. 97-99) var. xvi, 141 s. : res. (bzs. rnk.), tablo ; 29 cm. Dinamik etki altındaki yapıların performansları Amerika’da FEMA tarafından belirlenen kurallara göre değerlendirilmektedir. FEMA-356’ya paralel olarak revize edilen Türk deprem yönetmeliği, yeni yapılan binalarda depreme dayanıklılığı esas alan bir tasarım yapılmasını öngörür. Bu tasarımın ana ilkesi: taşıyıcı ve taşıyıcı olmayan sistem elemanlarının hafif şiddetteki depremlerde hasar görmemesi ve orta şiddetteki depremlerde hasarın onarılabilir düzeyde kalmasıdır. Şiddetli depremlerde ise can güvenliğinin sağlanması amacıyla kalıcı hasar oluşumunun sınırlandırılmasıdır. Güçlendirme, binaların deprem güvenliğini arttırmak için yapılan işlemleri içerir. Bu işlemler bazen binanın tümüne, bazen de sadece belirli taşıyıcı sistem elemanlarına uygulanır. Binanın güçlendirilmesi genel anlamda iki temel nedenle gerekebilir. Bunlardan birincisi, depremden kaynaklanan bir hasardan dolayı güvenliğin arttırılmasına ihtiyaç duyulmasıdır. İkincisi ise, herhangi bir hasar bulunmadığı halde, binanın depreme karşı yeterince güvenli olmadığının tespit edilmesidir. Her iki durumda da, binanın deprem güvenliğinin hedeflenen düzeye yükseltilmesi amacıyla güçlendirme çalışmalarına başvurulmalıdır. Özellikle deprem sonrası öncelikli kullanılacak yapıların (hastane, okul vb.) güvenli olup olmadığının ve bu yapıların deprem anındaki performanslarının nasıl olduğunun bilinmesi gerekmektedir. Bu çalışmada mevcut yapıların depreme karşı güvenliğinin denetlenmesi ve gerekli hallerde güçlendirme çalışmalarının projelendirilmesi, böylelikle ilerde yaşanabilecek can ve mal kayıplarının önlenmesi amaçlanmıştır. The performance of structures under dynamic influence is assessed according to the rules set by the Federal Emergency Management Agency (FEMA) in the United States. The Turkish Earthquake Code which was revised in parallel with FEMA-356, provide a design based on earthquake resistance in newly constructed buildings. The main theme of this design is that the carrier and non-carrier system components are not damaged in mild severe earthquakes and the damage must be remains repairable in medium severity earthquakes. İn case of severe earthquakes the purpose of this design is to limit the occurrence of permanent damage to ensure safety of life. Strengthening includes operations to improve earthquake safety of buildings. Strengthening of the building may be necessary for two main reasons. The first of these is the need to increase safety due to an earthquake-related damage. The second is to determine that the building is not durable against an earthquake even if there is no damage in the building. In both cases, strengthening studies should be applied to increase the building's earthquake safety to the targeted level. In particular, it is necessary to know whether the structures to be used primarily (hospital, school, etc.) after the earthquake are safe and how these structures are performing at the moment of an earthquake. In this study, it was aimed to control the safety of the existing structures against the earthquake and projects of strengthening work have been carried out where it is necessary thus, to prevent any loss of life and property that can potentially experienced in the future.

TEZ11527 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2017. Kaynakça (s. 221-224) var. xxxiii, 225 s. : res. (bzs. rnk.), tablo ; 29 cm. Bu çalışmada, yapıların dinamik analizinde kullanılan sönüm modelleri teorik ve deneysel olarak incelenmiştir. Bu amaçla deneylerde, sarsma tablasına sabitlenmiş farklı rijitliklere sahip üç adet tek serbestlik dereceli yapı modeli ile farklı malzeme ve geometrik özelliklere sahip sekiz adet çok serbestlik dereceli yapı modeli kullanılmıştır. Deneylerde, yapılardaki sönüm oranlarının farklı kütle, rijitlik ve ivme değerleri etkisi altında değişimi araştırılmış ve her parametrenin yapı sönüm oranı üzerindeki etkileri incelenmiştir. Çalışmanın teorik kısmında, sonlu elemanlar yöntemine dayanan SAP2000 bilgisayar yazılımı kullanılmıştır. Sayısal analizler, deneyler sonucunda elde edilen verilerden faydalanılarak, SAP2000 yazılımında oluşturulan modeller üzerinde farklı deprem verileriyle gerçekleştirilmiştir. Farklı sönüm modelleriyle gerçekleştirilen analizler ile deneyler sonucunda elde edilen verilerin karşılaştırılması yapılmıştır. Karşılaştırma neticesinde elde edilen sonuçların uyumlu olduğu görülmüş ve sonuçlar detaylı olarak sunulmuştur. In this study, the damping models used the dynamic analysis of the structures have been investigated experimentally and theoretically. For this purpose, three structure models having a single degree of freedom (SDOF) with different stiffness and eight structure models having multi degree of freedom (MDOF) with different material and geometric features have been clamped to the shake table and experimentally tested. The variation of the damping ratios on the structures has been investigated under the effects of different mass, stiffness, and acceleration values in the tests. Then, by using SAP2000 computer software based on the finite element method, numerical models have been formed by taking advantage of the result obtained in the experimental study and numerical analyses which have been performed on different earthquake data. Besides, the analyses carried out different damping models have been compared with the experimental tests results. It has been observed that the results obtained from both theoretical and experimental studies are quite compatible and the results have been presented in the thesis. Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No: FYL20155328.

Molecular machines made of proteins are highly dynamic and carry out sophisticated biological functions. The direct and dynamic high-resolution visualization of molecular machines in action is considered to be the most straightforward approach to understanding how they function but this has long been infeasible until recently. High-speed atomic force microscopy has recently been realized, making such visualization possible. The captured images of myosin V, F1-ATPase, and bacteriorhodopsin have enabled their dynamic processes and structure dynamics to be revealed in great detail, giving unique and deep insights into their functional mechanisms. © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.