Stress-freezing photoelastic experiments are conducted using two different sets of photoelastic materials to investigate stress intensity behavior near to and coincident with bimaterial interfaces. Homogeneous, bonded homogeneous, and bonded bimaterial single edge-cracked tension specimens are utilized throughout the investigation for comparative purposes. The first series of tests involves machined cracks obliquely inclined to the direction of far field tensile loading. Mixed-mode stress intensity factors are observed and quantified using a simplified analytical algorithm which makes use of experimentally measured data. In this series of tests, the bimaterial specimens consist of a photoelastic material bonded to the same material containing a moderate quantity of aluminum powder (for elastic stiffening purposes). Moderate yet similar increases in stress intensity factors are observed in bonded homogeneous and bonded bimaterial specimens, suggesting the presence of bondline residual stresses (rather than elastic modulus mismatch) as the primary contributing factor. The second series of tests involves the bonding of mutually translucent photoelastic materials whose elastic module differ by a ratio of approximately four to one. Cracks are placed both near and coincident to the bimaterial interfaces. Mode-mixity and increases in stress intensity are found only in bimaterial specimens whose cracks are placed close to the bondline. Using the materials from the first series of tests it is shown that the increases in these near-bondline experiments are due to thermal mismatch properties (incurred during the stress freezing cycles) rather than mechanical mismatch properties. / Master of Science

Cette thèse s’inscrit dans un contexte de préoccupation internationale sur le choix de l’école par les familles et plus particulièrement, dans le contexte national français de réflexions nouvelles concernant la politique de la sectorisation : assouplissement de la carte scolaire de 2007 et depuis 2012, recherche d’une nouvelle forme de sectorisation stricte-ment applicable. En France, après deux décennies d’expériences d’assouplissement de la carte scolaire, effectuées par les gouvernements de droite comme de gauche, la mesure du 4 juin 2007 représente, même si la mesure en est finalement restée au stade de l’assouplissement, une liberté nouvelle dans l’esprit des familles sur laquelle il sera difficile de revenir. Le but de notre travail est donc double. Il s’agit d’abord de montrer, à travers l’épreuve que constitue le choix du collège pour les familles, les évolutions du rapport entre des usagers – les élèves et leurs parents - et leur service public d’éducation. Si la revendication du choix de l’école remonte au début des années 1980, lorsqu’un certain nombre de parents se sont rendu compte que tous les établissements scolaires ne se valaient pas, force est d’observer que les logiques à l’origine de cette dernière ont évolué. Si la logique marchande persiste, on note surtout l’émergence de nouvelles formes de la logique civique relatives aux droits des usagers : le droit à l’information, le droit à un établissement efficace, le bien-être de son enfant, sa sécurité etc. Nous cherchons à montrer qu’aux différents niveaux de régulation administrative – central, intermédiaire et local -, les acteurs de l’Education nationale tentent de répondre, comme les acteurs des collectivités territoriales, à ces nouvelles attentes des familles même si c’est parfois également dans le but de servir leurs propres intérêts : logiques électoralistes, éviter les défections d’un collège en peine d’attractivité etc. Le deuxième objectif de notre étude est d’identifier, dans un contexte d’assouplissement généralisé inédit, l’évolution des rapports de concurrence et de coopération entre les collèges d’un même territoire et les logiques des différents acteurs qui en sont à l’origine. Parmi les principaux résultats, nous avons pu observer que la mixité sociale et ethnique ainsi que les régulations locales et intermédiaires en matière d’offre de formation étaient des éléments prépondérants dans les rapports de concurrence et de coopérativité entre les établissements. / The present thesis, relevant of a broader concern about families' choice of school, more specifically tackles issues raisedby recent approaches on the sectorisation policies implemented in France: the 2007 relaxation of the school map and, mostly since 2012, the efforts to shape a new sectorisation model on a strict compliance basis. As the latest update of two decades of experiments with the relaxation of the school map carried out by both right-wing and left-wing governments, the Education Act of June, 4th 2007, though not venturing beyond the relaxation stage, has deeply impacted families' ways of thinking and availed them with a new sense of liberty which cannot be ignored nor brushed aside effortlessly. Consequently, the purpose of this study is twofold.First and foremost, we will consider how the relation between users – pupils and their parents – and public service education has been affected by the families' choice of secondary school – which all too often amounts to a trying experience. Demands for choice of school originated in the early 80's with a growing awareness on the parents' side that ed cational facilities were not on par, yet the logical determinants behind these demands have significantly shifted in focus. While a market-based logic remains a key factor, new forms of civic logic have surfaced which are mostly concerned with the rights of users, laying a strong emphasis on the right to information, the access to an efficient school, the well-being and safety of one's child, etc. On every level of administrative regulation, whether central, intermediate or local, the educational community as well as the local authorities have been trying to meet the families' new expectations, sometimes if only to serve special interests : garner electoral votes, contain defections from school institutions plagued by a lack of attractivity, etc. This is properly the core of our demonstration. The second – and far from secondary – purpose of our study is to delineate the evolution of the relations of competition and cooperation between secondary schools located in a same area, highlighting in the process the various actors' logics at work within this broader – and unprecedented – relaxed framework. In the course of this study, we have been able to assess, among various factors, how social and ethnic mixity, along with effective regulation of training provision on local and intermediate levels, play a preponderant and substantial part in the relations of competition and cooperation between school institutions.

Autour des années 1930, Léopold Sédar Senghor, Aimé Césaire, Léon Gontran Damas et les autres lancent le mouvement de la Négritude. Leur lutte s’oriente vers une convocation poétique et une réappropriation de l’Afrique. En effet, après la prise en compte des valeurs africaines et leur mise en pratique, il faut donc penser et écrire à la manière africaine. Les créations littéraires issues de ce mouvement littéraire étaient donc essentiellement orientées vers l’Afrique, vers cet espace topographique connu et fixe. Dans cette revendication légitime, l’identité du sujet nègre est à rechercher en Afrique, la Négritude participe donc à une sorte de « fixité identitaire ». Les années 1990 voient l’émergence d’une nouvelle génération d’écrivains africains francophones qui, pour la plupart, vivent et mènent leurs activités littéraires en Europe (Bessora, Alain Mabanckou, Kossi Efoui, Calixte Béyala, etc.). Cette quatrième génération d’écrivains africains francophones lutte contre une sorte « d’assignation à résidence » et revendiquent une littérature ouverte sur le monde. À ce sujet, Bessora, comme beaucoup d’autres écrivains de sa génération, évolue en marge d’un espace géographique fermé, elle assume son appartenance à un monde qui abolit les frontières géographiques, esthétiques et même genrologiques. Bien qu’assumant ses origines africaines, Bessora coupe tout lien avec son espace géographique pour inventer et conquérir de nouveaux territoires. Dès lors, Bessora n’écrit plus l’Afrique dans une posture figée et afro-centrée, mais elle invite plutôt à la réalisation du « Tout-Monde » glissantien. / Around Around the 1930s, Léopold Sédar Senghor, Aimé Césaire, Léon Gontran Damas and others launched the Negritude movement. Their struggle is a poetic evocation and a reappropriation of Africa. Indeed, after the taking into account of African values and their implementation, one must think and write in the African way. The literary creations resulting from this literary movement were therefore essentially oriented towards Africa, towards this fixed and known topographic space. In this legitimate claim, the identity of the Negro subject is to be sought in Africa; Negritude is therefore involved in a kind of “fixed identity”. The 1990s saw the emergence of a new generation of francophone African writers who mostly live and conduct their literary activities in Europe (Bessora, Alain Mabanckou, Kossi Efoui, Calixte Béyala, etc.). This fourth generation of francophone African writers struggle against a kind of "house arrest" and advocate a literature open to the world. In this regard, Bessora, like many other writers of her generation, evolves on the fringe of a closed geographical space; she assumes membership in a world that abolishes geographic, aesthetic and even genrologicals frontiers. While not denying her African origins, Bessora cuts all ties with her geographical space in order to invent and conquer new territories. Consequently Bessora no longer writes about Africa from a frozen and African-centered position, but rather calls for the realization of “All-World” of Glissant.

Any composite material is made up from two or more materials and therefore contains interfaces, which usually represent planes of weakness. Interfacial fractures are effectively constrained to propagate along these interfaces as mixed-mode fractures with all three opening, shearing and tearing actions (i.e. mode I, mode II and mode III), instead of kinking to maintain pure-mode-I conditions at the advancing crack front, as would typically happen in an isotropic material. This is significant because mixed-mode fracture toughness is load-dependent and not a purely intrinsic material property (although clearly the pure mode fracture toughnesses are indeed intrinsic material properties that can be determined experimentally). Therefore, in order to know the fracture toughness under general loading conditions, it is necessary to know both the interface failure criterion (that describes the fracture toughness as a function of the mode mixity), and the mode mixity of the crack under the specified loading conditions. This is a complex problem that has occupied researchers in the fracture mechanics community for decades. Consequently, the literature contains a large number of different mixed-mode partition theories. This work appears to show that, of all the partition theories assessed, Wang and Harvey s (2012a) Euler beam partition theory is able to most accurately predict the fracture toughness of a mixed-mode delamination in a fibre-reinforced polymer composite laminate. This statement is based on the outcomes of three separate studies: The first study uses data reported in the literature from a thorough programme of mixed-mode fracture testing of unidirectional and multi-directional laminates. The Euler beam partition theory is able to accurately predict the fracture toughness in all cases. Furthermore, the Euler beam partition theory, which is completely analytical, closely agrees over a large domain with Davidson et al. s (2000) independently-derived non-singular field partition theory, which was derived with the aid of experimental test results. In general, the singular-field approach based on 2D elasticity and the finite element method give poor predictions. In the second study, an original programme of mixed-mode fracture testing is carried out, which incorporates several novel aspects including new test apparatus and a methodology for testing with a wide range of applied pure bending moments. Eighty five fracture tests are performed on unidirectional glass/epoxy laminates to determine the initiation and propagation fracture toughnesses. Although the second study was inconclusive with respect to the correctness of any particular partition theory, the development of the test apparatus and test methodology are considered to be major contributions that will be useful for both design engineers and academic researchers, not only working with fibre-reinforced polymer composite laminates, but also working with other composite materials containing interfacial cracks. The third study uses digital image correlation to investigate the near-crack tip strain fields of mixed-mode delaminations to try to discover the underlying mechanics that govern the selection of a mixed-mode partition theory. The new testing apparatus is used again, and another novel testing methodology is developed. The work appears to confirm (with some caveats) that two sets of pure modes exist, that is, two pure mode I modes, and two pure mode II modes, with their numerical values roughly corresponding to those from Wang and Harvey s (2012a) Euler beam partition theory. It should be noted that, as far as the author s knowledge is concerned, Euler beam partition theory is the only one in the literature to predict the existence of two sets of pure modes. Although this work set out to conclusively determine which mixed-mode partition theory is able to most accurately predict the fracture toughness of a mixed-mode delamination in a fibre-reinforced polymer composite laminate, and also, to discover why, the outcomes cannot truly be called conclusions . Rather, they only offer strong support for Wang and Harvey s (2012a) Euler beam partition theory for predicting the fracture toughness fibre-reinforced polymer composite laminates against delamination. Despite this, the work makes major contributions that will be useful for both design engineers and academic researchers in the field, as described in the above.

Le couple franco-brésilien (composé d’un homme français et d’une femme brésilienne) est un exemple de la nécessité des constructions stratégiques de la vie conjugale et familiale selon les normes contemporaines du mariage. Le modèle de la transplantation de la femme brésilienne en France est un des moyens explicatifs du processus de socialisation conjugale et familiale de ce couple. La conjugalité est étudiée selon une démarche idéale-typique, prenant en considération les facteurs géographiques et culturels de la femme brésilienne, où la question du stéréotype est au centre de l’objet d’étude. La distance culturelle, fondatrice de cette forme de mixité conjugale, nous permet d’analyser la négociation à l’œuvre entre l’homme français et la femme brésilienne pour parvenir à l’épanouissement conjugal et familial, selon les normes établies. / The French-Brazilian couple (composed of a French man and a Brazilian woman) is an example of the necessity of the strategic constructions of the married and family life according to the contemporary norms of marriage. The model of the transplantation of the Brazilian woman in France is one way of explaining the process of conjugal and family socialization of this couple. Conjugality is studied according to an ideal-typical approach with the issue of stereotypes at the center of the object of study. Geographical and cultural factors of the Brazilian woman are taken into consideration. Cultural distance, which is at the foundation of this type of conjugal mixity, allows us to analyze the negotiation that takes place between the French man and the Brazilian woman, to reach conjugal and family fulfillment, according to the established norms.

Notre travail constitue une clef possible de lecture des multiples formes et pratiques contemporaines des sports, des loisirs sportifs et culturels dans un quartier populaire : les 3Cités, ville de Poitiers. Nous posons la question locale du quartier comme élément déterminant d'identification, de redéfinition des pratiques sportives et de requalification de l'espace public. Les pratiques sportives, mais aussi sociales et culturelles semblent inhérentes à la politique locale (les structures), municipale (la ville) et publique (l'Etat). À travers le champ des pratiques sportives et de loisirs, notre objet socio-anthropologique nous permet de comprendre dans quelle mesure le réaménagement des quartiers populaires, autrement dit, l'urbanisation de l'espace périphérique dans une ville de taille moyenne, favorise ou non, les objectifs politiques de mixité sociale, de désenclavement de l'espace, de cohésion sociale, d'intégration, de lutte contre la ségrégation sociale et d'égalité des chances. Une analyse sociodémographique de la population résidant dans un espace singulier, où cohabitent une souche française, française d'origine étrangère et étrangère, nous amène à comprendre l'évolution des formes et les attentes de la pratique sportive, mais aussi, le frein et le désengagement de cette même pratique. Nous portons une attention particulière à la pratique sportive féminine car les femmes semblent éloignées du milieu sportif à la fois institutionnel et non-institutionnel. Il s'agit de montrer en quoi la pratique féminine dans ce quartier sensible est liée aux choix du sport proposé ainsi qu'aux facteurs sociaux tels que la culture d'origine, les conditions socio-économiques et l'implication des parents dans le milieu sportif. / Our study is a one of the possible keys to understanding the various present-day types of sports activities and recreational and cultural sports practiced by the people living in the 3Cités, a working class neighborhood in Poitiers (France). We inquire about the role of the neighborhood as a defining element of identification which reshapes the pratice of sports activities and redevelops public space. Not only sports activities, but also social and cultural activities seem thus to depend both on local policies (involved in the availability of sporting facilities) and on the city and public policies. Taking into account the array of sports and recreational activities serves a socio-anthropological goal which allows us to understand whether and how the redevelopment of a working-class neighborhood (i.e. the urbanization of a peripheral space in a medium-sized city) contributes to the achievement of the political goals of integration, social mixity and cohesion. Also, we wonder whether or not this type of redevelopment may favor the struggle against geographical isolation and social segregation so as to foster equal opportunities for all. To answer these questions we provide a socio-demographical analysis of the population of an area where native-born French citizens share the space with French citizens of foreign origin and foreigners. This analysis allows us to address the two-fold issue of the evolution of the various types of sports activities and of the expectations connected with them. It is equally the opportunity to dicuss the factors impeding access to or leading to a lack of involvement in the pratice of sports activities. Consequently, we focus on the practice of sporting activities by females, since women seem to be less involved in sporting activities, in either institutional or unconventional contexts. We aim to explain how the pratice of sporting activities by females is influenced by the availability of sporting activities and by social factors such as native culture, socioeconomic living conditions ans parents' involvement in the sporting environment.

Cette étude vise à i) déterminer le trajet de fissuration et la vitesse de propagation de fissure de fatigue dans un joint soudé sollicité en mode mixte ii) de proposer une analyse des interactions fissuration par fatigue/microstructure pour deux classes d'alliages soudés et iii) de proposer des critères de propagation de fissure, basé sur l'analyse des facteurs d'intensité de contrainte (FIC) pour les trois modes de fissuration.Les essais ont été réalisés pour un acier ferritique inoxydable, K41X soudé par gaz inerte, sur des éprouvettes à entaille centrale sous sollicitation uniaxiale pour différentes orientations d'entaille. Pour un assemblage bi-matériaux d'alliages de titane, obtenu par soudure laser de Ti17 et de Ti6242, les essais ont été effectués en condition biaxiale coplanaire sur une éprouvette en croix à entaille centrale à différents taux de cisaillement macroscopique.Pour l'acier, la fissure se propage en mode mixte trans- et intergranulaire dans le métal de base, et en mode transgranulaire uniquement dans la zone fondue (ZF). Néanmoins, c'est seulement en présence de cisaillement macroscopique induit par la géométrie d'entaille que la soudure a conduit à une accélération de la vitesse de fissure par rapport au métal de base. Pour Ti17 le chemin de propagation de fissure et la vitesse de propagation sont très réguliers alors qu'ils sont extrêmement oscillants pour Ti6242, car corrélés aux aiguilles α. La vitesse de fissuration est plus faible dans Ti6242 que dans Ti17 pour une sollicitation d'équibitraction, alors qu'elle est plus élevée dans Ti6242 que dans Ti17 pour un cisaillement macroscopique. Pour les éprouvettes soudées Ti17-Ti6242, le chemin de propagation est relativement régulier dans la ZF mais peut être piloté par l'interface zone affectée thermiquement (ZAT)/ZF. La vitesse est plus élevée dans la ZF que pour les deux métaux de base, alors qu'elle n'est que peu modifiée dans les ZAT.La régularité de la propagation de fissure dans Ti17 a permis d'utiliser ce cas comme un cas de référence dans le cadre de la mécanique linéaire de la rupture et ainsi proposer un critère de ∆Keq fonction des modes de sollicitations I, II et III. Ces résultats ont été obtenus en modélisant le chemin de fissure en surface et le déversement de fissure. L'analyse comparative des propriétés des différents matériaux testés a été menée dans ce cadre. Une analyse de sensibilité à la précision de la modélisation tridimensionnelle de la géométrie de fissure met en évidence le rôle prépondérant de celle-ci sur l'estimation des FIC en mode III et par conséquent sur la valeur de ∆Keq. Cette analyse permet d'expliquer les oscillations de vitesse constatées pour l'alliage Ti6242. / This study is devoted to i) the experimental characterization of fatigue crack path and fatigue crack growth rate (FCGR) for welded materials under mixed mode of loading ii) the analysis of fatigue crack to microstructure interactions for two types of welded materials and iii) the identification of a relevant FCGR criterion function of the mode mixity.The experimental characterization was achieved for a ferritic stainless steel, welded by metal inert gas, using CCT specimens for different orientations of the notch. Biaxial testing was achieved using central crack cross-shaped specimen, varying the shear to opening loading ratio, for a dissimilar welded joint obtained by laser welding of Ti17 and Ti6242 Ti base alloys.For the ferritic stainless steel, the crack is both trans- and intergranular for the base metal, whereas it becomes mainly transgranular for the welded specimen. Nevertheless, very slight modification of the FCGR, comparing base metal and welded material, is observed. The welding was seen to be detrimental only in the case of macroscopic shear loading implied by the geometry of the notch. For Ti17, crack path is very smooth and FCGR evolves regularly as a function of the stress intensity factor (SIF). Instead of what, for Ti6242 alloy, both the crack path and the FCGR present large amplitudes of oscillation, due to a strong interaction with alpha needles. The FCGR is lower in Ti6242 than in Ti17 for equibiaxial fatigue, whereas the FCGR is higher in Ti6242 than in Ti17 for macroscopic shear fatigue loading. For welded Ti17-Ti6242 specimens, FCGR is higher than observed in base metal for crack within the fusion zone (FZ), and tends to the FCGR of the associated base metal to each heat-affected zone (HAZ-Ti17 and HAZ-Ti6242).The case of Ti17 was seen to be relevant to determine an equivalent SIF function of mode mixity within the scope of LEFM. An original criterion has been established taking into consideration mode I, II and III. The numerical model describes explicitly both surface crack path and flat to slant orientation of the crack. This criterion has been successfully applied to both Ti and Fe base alloys, for base metal as well as for welded materials in order to determine the impact of welding on FCGR. At last but not least, the sensitivity of SIF values to the accuracy of the 3D modelling of the crack surface has been tested. Thus the local roughness of the crack path is seen to drastically impact the out-of-plane shear mode, which is in turn fully consistent with acceleration/deceleration of the crack observed for Ti6242 alloy.

Structural adhesives are widely used with great success, and yet occasional failures can occur, often resulting from improper bonding procedures or joint design, overload or other detrimental service situations, or in response to a variety of environmental challenges. In these situations, cracks can start within the adhesive layer or debonds can initiate near an interface. The paths taken by propagating cracks can affect the resistance to failure and the subsequent service lives of the bonded structures. The behavior of propagating cracks in adhesive joints remains of interest, including when some critical environments, complicated loading modes, or uncertainties in material/interfacial properties are involved. From a mechanics perspective, areas of current interest include understanding the growth of damage and cracks, loading rate dependency of crack propagation, and the effect of mixed mode fracture loading scenarios on crack path selection. This dissertation involves analytical, numerical, and experimental evaluations of crack propagation in several adhesive joint configurations. The main objective is an investigation of crack path selection in adhesively bonded joints, focusing on in-plane fracture behavior (mode I, mode II, and their combination) of bonded joints with uniform bonding, and those with locally weakened interfaces. When removing cured components from molds, interfacial debonds can sometimes initiate and propagate along both mold surfaces, resulting in the molded product partially bridging between the two molds and potentially being damaged or torn. Debonds from both adherends can sometimes occur in weak adhesive bonds as well, potentially altering the apparent fracture behavior. To avoid or control these multiple interfacial debonding, more understanding of these processes is required. An analytical model of 2D parallel bridging was developed and the interactions of interfacial debonds were investigated using Euler-Bernoulli beam theory. The numerical solutions to the analytical results described the propagation processes with multiple debonds, and demonstrated some common phenomena in several different joints corresponding to double cantilever beam configurations. The analytical approach and results obtained could prove useful in extensions to understanding and controlling debonding in such situations and optimization of loading scenarios. Numerical capabilities for predicting crack propagation, confirmed by experimental results, were initially evaluated for crack behavior in monolithic materials, which is also of interest in engineering design. Several test cases were devised for modified forms of monolithic compact tension specimens (CT) were developed. An asymmetric variant of the CT configuration, in which the initial crack was shifted to two thirds of the total height, was tested experimentally and numerically simulated in ABAQUS®, with good agreement. Similar studies of elongated CT specimens with different specimen lengths also revealed good agreement, using the same material properties and cohesive zone model (CZM) parameters. The critical specimen length when the crack propagation pattern abruptly switches was experimentally measured and accurately predicted, building confidence in the subsequent studies where the numerical method was applied to bonded joints. In adhesively bonded joints, crack propagation and joint failure can potentially result from or involve interactions of a growing crack with a partially weakened interface, so numerical simulations were initiated to investigate such scenarios using ABAQUS®. Two different cohesive zone models (CZMs) are applied in these simulations: cohesive elements for strong and weak interfaces, and the extended finite element method (XFEM) for cracks propagating within the adhesive layer. When the main crack approaches a locally weakened interface, interfacial damage can occur, allowing for additional interfacial compliance and inducing shear stresses within the adhesive layer that direct the growing crack toward the weak interface. The maximum traction of the interfacial CZM appears to be the controlling parameter. Fracture energy of the weakened interface is shown to be of secondary importance, though can affect the results when particularly small (e.g. 1% that of the bulk adhesive). The length of the weakened interface also has some influence on the crack path. Under globally mixed mode loadings, the competition between the loading and the weakened interface affects the shear stress distribution and thus changes the crack path. Mixed mode loading in the opposite direction of the weakened interface is able to drive the crack away from the weakened interface, suggesting potential means to avoid failure within these regions or to design joints that fail in a particular manner. In addition to the analytical and numerical studies of crack path selection in adhesively bonded joints, experimental investigations are also performed. A dual actuator load frame (DALF) is used to test beam-like bonded joints in various mode mixity angles. Constant mode mixity angle tracking, as well as other versatile loading functions, are developed in LabVIEW® for use with a new controller system. The DALF is calibrated to minimize errors when calculating the compliance of beam-like bonded joints. After the corrections, the resulting fracture energies ( ) values are considered to be more accurate in representing the energy released in the crack propagation processes. Double cantilever beam (DCB) bonded joints consisting of 6061-T6 aluminum adherends bonded with commercial epoxy adhesives (J-B Weld, or LORD 320/322) are tested on the DALF. Profiles of the values for different constant mode mixity angles, as well as for continuously increasing mode mixity angle, are plotted to illustrate the behavior of the crack in these bonded joints. Finally, crack path selection in DCB specimens with one of the bonding surfaces weakened was studied experimentally, and rate-dependency of the crack path selection was found. Several contamination schemes are attempted, involving of graphite flakes, silicone tapes, or silane treatments on the aluminum oxide interfaces. In all these cases, tests involving more rapid crack propagation resulted in interfacial failures at the weakened areas, while slower tests showed cohesive failure throughout. One possible explanation of this phenomenon is presented using the rate-dependency of the yield stress (commonly considered to be corresponding to the maximum traction) of the epoxy adhesives. These experimental observations may have some potential applications tailoring adhesive joint configurations and interface variability to achieve or avoid particular failure modes. / Ph. D.