Anisotropic tertiary creep damage formulations have become an increasingly important prediction technique for high temperature components due to drives in the gas turbine industry for increased combustion chamber exit pressures, temperature, and the use of anisotropic materials such as metal matrix composites and directionally-solidified (DS) Ni-base superalloys. Typically, isotropic creep damage formulations are implemented for simple cases involving a uniaxial state of stress; however, these formulations can be further developed for multiaxial states of stress where materials are found to exhibit induced anisotropy. In addition, anisotropic materials necessitate a fully-developed creep strain tensor. This thesis describes the development of a new anisotropic tertiary creep damage formulation implemented in a general-purpose finite element analysis (FEA) software. Creep deformation and rupture tests are conducted on L, T, and 45°-oriented specimen of subject alloy DS GTD-111. Using the Kachanov-Rabotnov isotropic creep damage formulation and the optimization software uSHARP, the damage constants associated with the creep tests are determined. The damage constants, secondary creep, and derived Hill Constants are applied directly into the improved formulation. Comparison between the isotropic and improved anisotropic creep damage formulations demonstrates modeling accuracy. An examination of the off-axis creep strain terms using the improved formulation is conducted. Integration of the isotropic creep damage formulation provides time to failure predictions which are compared with rupture tests. Integration of the improved anisotropic creep damage produces time to failure predictions at intermediate orientations and any state of stress. A parametric study examining various states of stress, and materials orientations is performed to verify the flexibility of the improved formulation. A parametric exercise of the time to failure predictions for various levels of uniaxial stress is conducted.

Experimentation exploring the movement of voids within carbon fiber reinforced plastics was performed using fluorescent dye infused into the laminates observed through a transparent mold under ultraviolet light. In situ photography was used as an inspection method for void content during Resin Transfer Molding for these laminates. This in situ inspection method for determining the void content of composite laminates was compared to more common ex-situ quality inspection methods i.e. ultrasonic inspection and cross-section microscopy. Results for localized and total void count in each of these methods were directly compared to test samples and linear correlations between the three test methods were sought. Test coupons were then cut from these laminates and were used to calculate the interlaminar shear strength at certain locations throughout the laminates. Although this research did not adequately observe correlations between results obtained from ultrasonic C-scans, cross-sectional microscopy and in situ photography of the surface, it was seen that the fluid dynamics of the thermosetting epoxy used in this experimentation correlated to results obtained from previous experimentation performed by students at Brigham Young University using vegetable oil as a substitute for resin.

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L'objectif de cette thèse est l'étude de la formation de nanoparticules carbonées dans un plasma basse pression. Les poussières sont créées par pulvérisation d'une couche de polymère déposée sur l'électrode d'une décharge radio fréquence à couplage capacitif. La présence des poudres perturbe et modifie les propriétés du plasma. La croissance des poudres peut notamment déclencher des instabilités basse fréquence qui évoluent avec la taille et la densité des poudres. Au centre du plasma, une région sans poudre, appelée void, est souvent observée. Cette région se caractérise en particulier par une forte luminosité. Différents diagnostics (mesures électriques, imagerie vidéo rapide, Fluorescence Induite par Laser) sont utilisées afin d'analyser ces différents comportements résultant des interactions entre le plasma et les poussières. L'analyse approfondie des instabilités a permis de mettre en évidence plusieurs régimes et d'extraire leurs principales caractéristiques comme leur durée et l'évolution de leurs fréquences. Ces instabilités se traduisent par la formation de petites "boules" de plasma qui se déplacent et interagissent au sein de celui-ci. Des phénomènes particulièrement surprenants de fusion et de division de ces boules ont été mis en évidence. Concernant le void, nos travaux ont confirmé la forte excitation présente dans cette zone. Dans la dernière partie de la thèse, la dissociation de l'aluminium triisopropoxide(ATI) est étudiée dans un plasma à l'aide de la Spectroscopie infrarouge à Transformée de Fourier. Ce diagnostic nous a permis de mettre en évidence l'évolution de la densité d'ATI en fonction des paramètres de la décharge. Nous avons également quantifié les différents composants hydrocarbonés formés par polymérisation. / The objective of this thesis is to study the formation of carbonaceous nanoparticles in a low pressure plasma. Dust particles are created by sputtering a polymer layer deposited on the bottom electrode of a capacitively coupled radio-frequency discharge. The presence of dust particles disturbs and changes the plasma properties. The growth of dust particles can trigger low frequency instabilities that evolve with the dust particle size and density. In the center of the discharge, the void, a dust-free region, is observed. It is characterized by an enhanced luminosity. Different diagnostics (electrical measurements, high speed imaging, Laser Induced Fluorescence) are used in order to understand these different behaviors resulting from plasma-dust particle interactions. Dust particle growth instabilities are investigated showing the existence of different instability regimes. Their main characteristics are extracted such as their duration and their evolution frequency. These instabilities are characterized by the formation of small plasma spheroids moving and interacting in the discharge. Several interesting phenomena are evidenced such as the merging and splitting of these plasma spheroids. Concerning the void, our investigations confirmed the high excitation occurring in this region. In the last part of the thesis, the dissociation of aluminium triisopropoxide (ATI) is studied in a plasma using Fourier Transform InfraRed spectroscopy. Thanks to this diagnostic, the evolution of ATI density has been studied as a function of the discharge parameters. We have also quantified the different hydrocarbon compounds formed by polymerization.

Les matériaux constitutifs des digues sont souvent des sables silteux dont le comportement mécanique peut manifester une « instabilité » à des états de contraintes situés bien avant la limite de plasticité de Mohr-Coulomb. Ce mécanisme de rupture pourrait expliquer plusieurs brèches dont l'occurrence n'a pas été attribuée aux mécanismes classiques de rupture de digues telle que l'érosion interne. L'objectif de cette thèse est de mieux comprendre, au regard de ce phénomène d'instabilité, le comportement mécanique d'un sable silteux provenant de la zone adjacente à une brèche de digue du Rhône lors de la crue de 2003, à l'aide d'essais triaxiaux.Les résultats sur le sable propre montrent que le matériau étudié est très sensible au phénomène d'instabilité. Ce dernier peut être prédit par une courbe d'instabilité reliant, au déclenchement de l'instabilité, le rapport des contraintes au paramètre d'état. L'analyse de ces résultats suggère qu'une forte contractance du matériau est la condition nécessaire pour que l'instabilité du sable lâche ait lieu et qu'une direction appropriée du vecteur d'incrément de contraintes est la condition suffisante.Les résultats sur les mélanges constitués du sable avec des fines montrent qu'un départ de fines, causé par exemple une érosion de type suffusion, favorise l'occurrence de l'instabilité dans les digues. Par ailleurs, ces résultats révèlent que l'indice des vides équivalent est un paramètre pertinent dans l'analyse du comportement du sable silteux. Le calcul de l'indice des vides équivalent nécessite la détermination du paramètre b pour lequel une nouvelle formule a été proposée. / The constitutive materials of dikes are often silty sands whose mechanical behavior can become unstable at stress states located well under the Mohr-Coulomb plasticity limit criterion. This failure mechanism could explain several dike breaches whose occurrence has not been assigned to conventional mechanisms of dike failure such as internal erosion. The objective of this thesis is to better understand, with respect to the instability phenomenon, the mechanical behavior of a silty sand which is collected in the area adjacent of a breach of the Rhone embankment dike during the flood of 2003, by means of triaxial tests.The test results obtained on clean sand show that this material is very sensitive to the instability phenomenon. The occurrence of the latter can be predicted by an instability curve relating, at the onset of instability, the stress ratio to the state parameter. The analysis of these results suggests that a strong contractiveness of the material is the necessary condition for instability of loose sand and an appropriate direction of stress increment vector is the sufficient condition.The test results obtained on mixtures of sand with fines show that a removal of fine particles caused by an erosion, such as suffusion for example, favors the occurrence of instability in the dikes. Moreover, these results indicate that the equivalent void ratio is a relevant parameter in analyzing the behavior of silty sand. The calculation of the equivalent void ratio requires the determination of the parameter b for which a new formula has been proposed.

This thesis re-examines Shakespeare’s creation of tragic character through the concept of ‘arrivals’. What arrives is not an ‘individual’ but what I call a ‘subject’, which is a diffused dramatic process of arriving, rather than a self-contained entity that arrives in a final form. Not all characters are ‘subjects’. A subject only arrives through dramatic ‘events’ that rupture the existing structures of the play-world and the play-text. The generators of these irruptions are found equally in the happenings of plot and in changes of poetic intensity and form. The ‘subject’ is thus a supra- individual irruption that configures new forms of language, structure, and action. Accordingly, I explain why scrupulous historicism’s need for nameable continuums is incommensurate to the irruptive quality of Shakespearean character. The concepts of ‘process’, ‘subject’ and ‘event’ are informed by a variety of thinkers, most notably the contemporary French philosopher Alain Badiou. Badiou develops an ‘evental’ model of subjectivity in which the subject emerges in fidelity to a ‘truth- event’, which breaks into a situation from its ‘void’. Also important is the process- orientated philosophy of Bergson and Whitehead, which stresses that an entity is not a stable substance but a process of becoming. The underlying connection between the philosophers I embrace – also including the likes of Žižek, Kierkegaard, Latour, Benjamin, and Christian thinkers such as Saint Paul and Luther – is that they establish a creative alternative to the deadlock between treating the subject as either a stable substance (humanism) or a decentred product of its place in the world (postmodernism). The subject is not a pre-existing entity but something that comes to be. It is not reducible to its cultural and linguistic circumstances but is precisely what exceeds those circumstances. Such an excessive creativity is what gives rise to Shakespeare’s subjects and, I argue, underpins the continuing force of his drama. But it also produces profound dangers. In Shakespeare, ‘events’ consistently expose subjects to uncertainty, catastrophe, and horror. And these dangers imperil both the subject and the relationship between Shakespeare and the affirmative philosophy of the event.