Thin layered systems can be considered as a solution to the repair and protection of concrete structures. This subject was studied in the current investigation. Some common uses of these systems include protection, upgrading and rehabilitation of the floor slabs,restoration of appearance of the structures, impermeability, skid resistance, wear resistance, and protection of the reinforcing steel of concrete structures against atmospheric or chemical attack. However it can be said that protection, upgrading and rehabilitation of floor slabs are the main uses for the design of modem thin layered systems. For example a thin layer of a polymer concrete with a thickness of less than 3 nun can resist a very highly concentrated load resulting from a steel wheel rolling load of 5000 N without any sign of defect. Thin layer systems therefore include traditional screeds, externally bonded steel plates, plasters and coatings as well as the more recent hi - tech. systems. Like any other structure, a thin layered system may break down as the result of many causes. Among other types of failures, delamination defect is the most common mode of failure and particularly relevant to a thin layered system. This phenomenon which mostly occur between the upper layer directly subjectedto the load and the subsequent layer, is due to debonding or slippage at the interface of the two layers. A delamination may occur at the interface of a thin layered system even without any sign of failure in other parts of the structure. Steel wheeled trolleys and fork - lift trucks are among the most anticipated types of loading and causes of failures in the thin layered systems. Different combinations of thin layered systems were prepared using some special flooring materials, both in small and large scales. Despite the lack of any standard test, the action of a steel wheel rolling load on the ready made and purpose made specimens of thin layered systems was well simulated using the Steel Wheel Rolling Load Rig. The NUROLF, Newcastle University Rolling Load Facility, was also used for simulating the action of a tyred vehicle wheel rolling load on the thin layered systems of large scale. Some simple ways for detecting any possible delamination at the interface of the thin layered systems were examined. In addition to the available material characteristics tests, a relatively new simple shear box test was proposed for defming the relationship between normal stress and the correspondings hear strength for each combination of the materials at each age of the test. The results were then used as the basis for the subsequent structural analysis. The structural analysis of the systems was carried out for both of the experiments using the finite element method and the interface technique. In spite of the simplifications made in the solution, the analytical results were consistent with the experimental results to a considerable extent. Based on the results of this investigation, a relatively constitutive procedure was concluded for predicting the behaviour of a thin layered system under the action of a wheel rolling load with regard to the delamination defect.

No description available.

O objetivo deste trabalho foi avaliar a quantidade de resina residual após a descolagem de braquetes e a perda e/ou desgaste de esmalte ocorrido durante as fases de: colagem, descolagem e remoção dos remanescentes resinosos, na área do braquete e adjacente. A amostra foi constituída de 150 pré-molares, dividida em dois grupos de acordo com o tipo de material do braquete utilizado: metálico (n=75) e cerâmico (n=75), nas duas primeiras fases do estudo, colagem e descolagem. Os procedimentos de colagem foram realizados de acordo com a International Organization for Standardization (2003), e a descolagem segundo a orientação preconizada pelo fabricante. Na fase de remoção dos remanescentes resinosos foram considerados cinco grupos de acordo com o protocolo de acabamento/polimento e prescrição dos respectivos fabricantes: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide e Jet Carbide, com auxilio de lupas telescópicas sob a magnificação 3x. A avaliação qualitativa (ARIm e ESI) foi realizada por meio de fotografias digitais (lupa estereoscópica - Olympus SZ61). A avalição quantitativa foi realizada pelo método de medição por Coordenada - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - Perfil de linha. As possíveis diferenças entre os protocolos de acabamento/polimento foram avaliadas pela análise de variância (ANOVA) e pelo teste de comparações múltiplas de Tukey. As quantidades médias de resina residual encontrada na área sob a base do braquete, após acabamento/polimento foram: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5 m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) e Jet Carbide (22,8 m ± 24,0). E na área adjacente: Diamantada FF + Soflex (14,9 m ± 13,0), Pedra Shofu (22,8 m ±19,5), Dentaurum Carbide (21,4 m ±18,5), Komet Carbide (9,6 m ± 7,7), Jet Carbide (27,8 m ± 24,5). Desta forma, constatou-se que, em geral, os protocolos de acabamento/polimento deixaram maior quantidade de resina residual sobre a área adjacente que na área do braquete, com exceção do protocolo Komet Carbide, que teve desempenho semelhante em ambas as áreas. E as quantidades médias de perda e/ou desgaste do esmalte na área do braquete foram: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) e Jet Carbide ( 68,2 m ± 35,7) na área do braquete, enquanto na área adjacente: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) e (Jet Carbide 65,4 m ± 65,0) (Tabela 5.9). Ressalta-se que em ambas as áreas de avaliação, o protocolo (Diamantada FF + Soflex) foi responsável pela maior quantidade de perda e/ou desgaste, diferenciando-se com significância estatística dos demais protocolos. Com base nestes resultados podemos concluir que os protocolos de acabamento/polimento avaliados demonstraram excelente desempenho na remoção dos remanescentes resinosos embora nenhum deles tenha sido capaz de remover totalmente o material de colagem, todos danificaram o esmalte, sendo o protocolo Komet carbide o mais diferenciado. / The objective of this study was to evaluate the quantity of residual resin after removal of brackets and the loss and//or wear-and-tear of enamel occurring during the phases of fixing, detaching and removal of remnant resin in the bracket area and its adjacent. The sample was made up of 150 premolars, divided into two groups in accordance with the type of bracket material used: metal (n=75) and ceramic (n=75), in the two initial phases of study, fixing and removal. Fixing procedures were carried out in accordance with the International Organization for Standardization, (2003), and removal according to orientation advocated by the manufacturer. In the removal of remnant resin phase five groups were considered, all in agreement with the finishing/polishing protocol and prescription of the respective manufacturers: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide and Jet Carbide, and with the aid of telescopic magnifying glass of three-fold magnification Qualitative evaluation (ARIm and ESI) was done by means of digital photographs(stereoscopic magnifying glass Olympus SZ61). Quantitative evaluation was conducted using the coordinate medication method - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - line profile. Possible differences between finishing/polishing protocols were evaluated via variance analysis (ANOVA), and by Tukey Multiple Comparison test. Median quantities of residual resin found in the region below the base of the bracket, following finishing/polishing were: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) and Jet Carbide (22,8 m ± 24,0). In this way, it was confirmed that finishing/polishing protocols, in general, left the major part of residual resin below the adjacent area than in the bracket area, with the exception of Komet Carbide protocol, displaying similar performance in both areas Median quantities of loss and/or wearand- tear of enamel in the bracket area were: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) and Jet Carbide ( 68,2 m ± 35,7) in bracket area, while in adjacent area: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) and (Jet Carbide 65,4 m ± 65,0) (Table 5.9) Standing out in both areas of evaluation, protocol (Diamantada FF + Soflex) was responsible for the major quantity of loss and /or wear and tear, differentiating itself from the other protocols by significant statistics. Based on these results, we can conclude that the finishing/polishing protocols evaluated, displayed excellent performance in the removal of remnant resin, although none have totally been capable of removing fixing material, and all damaged the enamel, with Komet protocol being the most differentiated.

Carbon Fiber Reinforcement Polymer (CFRP) materials are widely used to strengthen reinforced concrete structures because they are light weight, have high strength, and are relatively easy to install. In strengthening applications, CFRP strips are typically attached to the concrete surface using epoxy resin with fibers oriented in the direction needing additional tensile strength. However, if CFRP strips rely exclusively on bond strength with concrete, only 40% to 50% of the CFRP tensile strength can be developed before debonding occurs. In order to fully develop the tensile strength of CFRP strips, some form of anchorage is needed. CFRP anchors can be applied with relative ease and have recently been shown to provide effective anchorage of CFRP strips to concrete members. In many cases, however, current anchorage details may resulting in fracture or failure of CFRP anchors prior to developing the full strength of CFRP strips. Many design parameters, the effects of which are not well understood, can affect the behavior and strength of CFRP anchors. Moreover, previous studies have demonstrated that the quality of installation can influence anchor strength substantially. The objectives of the study presented are to: 1) provide engineers with design guidelines for CFRP anchors, and 2) deliver a reliable test for controlling the quality of installation and materials of CFRP anchorage systems. In all, 39 tests on 6”×6”×24” rectangular concrete beams were conducted to study the influence of five parameters on CFRP anchor strength and effectiveness: 1) the width of the CFRP strip being developed, 2) the material ratio of CFRP anchor to CFRP strip, 3) the concrete strength, 4) the length/angle of anchor fan, and 5) the bond between CFRP strip and concrete (bonded/unbonded). The same tests also served to develop the test methodology for quality control of the CFRP anchorage system. Based on experimental results, guidelines for designing CFRP anchors are proposed. A test specimen and methodology are also proposed for qualifying CFRP materials and anchorage-system installations. A Finite Element (FE) formulation was selected to provide a computational tool that is suited for simulating the behavior of CFRP strips and CFRP anchors. The ability of the selected FE formulation to reproduce the effects on behavior of varying the anchor-material ratio, concrete strength, length of anchor fan, and bond conditions was investigated. Six FE simulations were built by adjusting simulation parameters and comparing results with six experimental tests. Comparisons between experimental and numerical results indicate that the proposed FE formulation and parameter selections reproduced load-deflection and local strain behaviors with high fidelity. / text

No description available.

The performance of smart structures depends on the dynamic electromechanical behavior of piezoelectric sensors/actuators and the bonding condition along the interface. This thesis contents a theoretical study of the coupled electromechanical characteristics of a surface-bonded piezoelectric sensor with interfacial debonding, which is subjected to high frequency mechanical loads. A one dimensional sensor model is proposed. Analytical solutions based on the integral equation method are provided. Numerical simulation is conducted to evaluate the effects of different parameters upon the dynamic load transfer between the sensor and the host medium. The results indicate that, the material combination, the sensor geometry, and the loading frequency, affect the load transfer significantly. The analytical solution of the elastic wave field in the host medium is obtained and used to evaluate the effects of different parameters upon the resulting wave field. The theoretical solution demonstrates the basic properties of wave propagation under current loading conditions.

Depuis quelques décennies, l’élaboration et l’étude des propriétés physiques et mécaniques des microstructures UFG et NC se sont fortement développées. L’intérêt croissant suscité par ces matériaux provient des comportements nouveaux qu’ils présentent et qui ouvrent des perspectives prometteuses d’applications dans divers domaines des sciences et d’ingénieries. Des secteurs d’activité à forte valeur ajoutée et aux enjeux économiques importants tels que la microélectronique, les télécommunications, l’aéronautique, l’énergie et l’armement s’y intéressent. En mécanique, l’intérêt porté à ces microstructures réside dans la possibilité de produire des matériaux ayant à la fois une résistance mécanique et une ductilité élevées. Cependant, ces microstructures ont montré un faible taux d’écrouissage quoiqu’ayant une résistance mécanique élevée. Des mécanismes de déformation nouveaux sont soupçonnés être à l’origine de ce phénomène notamment des mécanismes de déformation aux joints de grains conduisant dans certains cas à une inversion de la loi de Hall-Petch et à un endommagement et/ou rupture précoce. Expérimentalement, des méthodes visant à améliorer le taux d’écrouissage tout en garantissant une résistance mécanique élevée existent et sont de plus en plus nombreuses. De même, des outils numériques de simulation ont permis d’explorer certains phénomènes encore inaccessibles par l’expérience. C’est dans cette optique qu’un modèle micromécanique capable de suivre l’évolution de la texture cristallographique, de caractériser l’influence de la microstructure sur la contrainte d’écoulement et l’endommagement, est proposé dans ce travail. / Since decades, the study of mechanical and physical properties of UFG and NC microstructures has considerably increased as well as processing techniques. The growing interest in these materials comes from new behaviors encountered with wide range of applications perspectives in many scientific and technologic engineering fields, with high added value and important economic issues such as microelectronics, telecommunications, aeronautics, energy and army. In mechanics, the growing interest resides in both the possibility of processing microstructures with high mechanical strength and high ductility. However, these last microstructures have shown a very low strain hardening capacity although they were observed to have a high mechanical strength. New deformation mechanisms are suspected to induce these behaviors namely grain size deformation mechanisms which cause Hall-Petch strain profile inversion and/or early damage. Nowadays, there are many techniques to process UFG and NC microstructures with both high mechanical strength and improved strain hardening capacities. Similarly, simulation numerical tools have helped to understand some phenomenon still not accessible via experiments. Boring in mind this last aspect, a micromechanics modeling was proposed in this work to characterize microstructure influence on yield stress and damage and to study the crystalline texture evolution.

O objetivo deste trabalho foi avaliar a quantidade de resina residual após a descolagem de braquetes e a perda e/ou desgaste de esmalte ocorrido durante as fases de: colagem, descolagem e remoção dos remanescentes resinosos, na área do braquete e adjacente. A amostra foi constituída de 150 pré-molares, dividida em dois grupos de acordo com o tipo de material do braquete utilizado: metálico (n=75) e cerâmico (n=75), nas duas primeiras fases do estudo, colagem e descolagem. Os procedimentos de colagem foram realizados de acordo com a International Organization for Standardization (2003), e a descolagem segundo a orientação preconizada pelo fabricante. Na fase de remoção dos remanescentes resinosos foram considerados cinco grupos de acordo com o protocolo de acabamento/polimento e prescrição dos respectivos fabricantes: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide e Jet Carbide, com auxilio de lupas telescópicas sob a magnificação 3x. A avaliação qualitativa (ARIm e ESI) foi realizada por meio de fotografias digitais (lupa estereoscópica - Olympus SZ61). A avalição quantitativa foi realizada pelo método de medição por Coordenada - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - Perfil de linha. As possíveis diferenças entre os protocolos de acabamento/polimento foram avaliadas pela análise de variância (ANOVA) e pelo teste de comparações múltiplas de Tukey. As quantidades médias de resina residual encontrada na área sob a base do braquete, após acabamento/polimento foram: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5 m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) e Jet Carbide (22,8 m ± 24,0). E na área adjacente: Diamantada FF + Soflex (14,9 m ± 13,0), Pedra Shofu (22,8 m ±19,5), Dentaurum Carbide (21,4 m ±18,5), Komet Carbide (9,6 m ± 7,7), Jet Carbide (27,8 m ± 24,5). Desta forma, constatou-se que, em geral, os protocolos de acabamento/polimento deixaram maior quantidade de resina residual sobre a área adjacente que na área do braquete, com exceção do protocolo Komet Carbide, que teve desempenho semelhante em ambas as áreas. E as quantidades médias de perda e/ou desgaste do esmalte na área do braquete foram: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) e Jet Carbide ( 68,2 m ± 35,7) na área do braquete, enquanto na área adjacente: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) e (Jet Carbide 65,4 m ± 65,0) (Tabela 5.9). Ressalta-se que em ambas as áreas de avaliação, o protocolo (Diamantada FF + Soflex) foi responsável pela maior quantidade de perda e/ou desgaste, diferenciando-se com significância estatística dos demais protocolos. Com base nestes resultados podemos concluir que os protocolos de acabamento/polimento avaliados demonstraram excelente desempenho na remoção dos remanescentes resinosos embora nenhum deles tenha sido capaz de remover totalmente o material de colagem, todos danificaram o esmalte, sendo o protocolo Komet carbide o mais diferenciado. / The objective of this study was to evaluate the quantity of residual resin after removal of brackets and the loss and//or wear-and-tear of enamel occurring during the phases of fixing, detaching and removal of remnant resin in the bracket area and its adjacent. The sample was made up of 150 premolars, divided into two groups in accordance with the type of bracket material used: metal (n=75) and ceramic (n=75), in the two initial phases of study, fixing and removal. Fixing procedures were carried out in accordance with the International Organization for Standardization, (2003), and removal according to orientation advocated by the manufacturer. In the removal of remnant resin phase five groups were considered, all in agreement with the finishing/polishing protocol and prescription of the respective manufacturers: FF diamantada + Soflex; Pedra Shofu; Dentaurum Carbide; Komet Carbide and Jet Carbide, and with the aid of telescopic magnifying glass of three-fold magnification Qualitative evaluation (ARIm and ESI) was done by means of digital photographs(stereoscopic magnifying glass Olympus SZ61). Quantitative evaluation was conducted using the coordinate medication method - Coordinate Measuring Machines (Mitutoyo), mod. Legex CNC 9106 - line profile. Possible differences between finishing/polishing protocols were evaluated via variance analysis (ANOVA), and by Tukey Multiple Comparison test. Median quantities of residual resin found in the region below the base of the bracket, following finishing/polishing were: Diamantada FF + Soflex (10,4 m ±10,5), Pedra Shofu (18,5m ± 12,1), Dentaurum Carbide (11,2 m ± 11,9), Komet Carbide (9,5 m ± 10,8) and Jet Carbide (22,8 m ± 24,0). In this way, it was confirmed that finishing/polishing protocols, in general, left the major part of residual resin below the adjacent area than in the bracket area, with the exception of Komet Carbide protocol, displaying similar performance in both areas Median quantities of loss and/or wearand- tear of enamel in the bracket area were: Diamantada FF + Soflex (-134,9 m ± 56,4), Pedra Shofu ( 39,2 m ± 12,8), Dentaurum Carbide ( 70,5 m ± 27,9), Komet Carbide (-44,8 m ± 14,3) and Jet Carbide ( 68,2 m ± 35,7) in bracket area, while in adjacent area: Diamantada FF + Soflex (-124,7 m ± 133,1), Pedra Shofu (- 37,9 m ± 25,1), Dentaurum Carbide (- 60,1 m ±32,4), Komet Carbide (-36,6 m ± 19,5) and (Jet Carbide 65,4 m ± 65,0) (Table 5.9) Standing out in both areas of evaluation, protocol (Diamantada FF + Soflex) was responsible for the major quantity of loss and /or wear and tear, differentiating itself from the other protocols by significant statistics. Based on these results, we can conclude that the finishing/polishing protocols evaluated, displayed excellent performance in the removal of remnant resin, although none have totally been capable of removing fixing material, and all damaged the enamel, with Komet protocol being the most differentiated.

Ziel der Arbeit war die Bestimmung der Haftfestigkeit und des Debondingverhaltens verschiedener Bracket- und Adhäsivsysteme unter Berücksichtigung eines neu entwickelten Basisdesigns. Hierbei wurden zwei unterschiedliche Testmethoden sowie differierende Untergrundmaterialien verwendet. Zur Prüfung des Verbundes zwischen Bracket, Adhäsiv und Untergrund wurden gemäß der DIN 13990-2 die Brackets Bio Quick (Forestadent), Micro Sprint (Forestadent), Micro Sprint mit neu entwickelter Stotzenbasis (Forestadent), Equilibrium mini (Dentaurum) und In-Ovation mini (Dentsply) im Abscher- und Abzugversuch getestet. Sie wurden mit den Adhäsiven Transbond XT, Kurasper F und GC Ortho Connect auf bovine Zähne sowie auf PMMA-Ringe geklebt und anschließend hinsichtlich ihrer Haftfestigkeit untersucht. Vergleiche konnten außerdem zwischen den Testmethoden der Abscher- und Abzugtests wie auch der Untergrundmaterialien Zahn und Ring angestellt werden. Die Menge des Restadhäsivs auf der Bracketbasis wurde anschließend mikroskopisch bestimmt und anhand des Adhesive Remnant Index (ARI) dargestellt. Im Vergleich der Abscher- und Abzugprüfungen sowie der Untergründe Zahn und Ring konnten beim Abscheren der Brackets und der Anbringung auf Zähnen signifikant höhere Haftwerte erzielt werden. Unabhängig der Brackets ist auf den Zähnen kein signifikanter Unterschied zwischen den Adhäsiven zu erkennen, auf den Ringen hingegen erreicht GC Ortho Connect signifikant geringere Haftfestigkeiten. Die höchsten Haftfestigkeitswerte (in MPa) erreichten beim Abscheren vom Zahn und bei beiden Debondingmethoden vom Ring das Equilibrium mini in Kombination mit den Adhäsiven Kurasper auf dem Ring (Abscher 23,4 MPa/Abzug 8,1 MPa) und GC Ortho Connect auf dem Zahn (23,55 MPa). Beim Abzug vom Zahn erreichte das Micro Sprint mit Stotzenbasis in Kombination mit Transbond XT die höchste Haftfestigkeit (8,02 MPa). In der Untersuchung des ARI verblieb größtenteils mehr als 50% Restadhäsiv auf der Bracketbasis. / The objective of the work was to determine the bond strength and debonding behavior of different bracket and adhesive systems. Hereby, a newly developed basic design was taken into account. Two different test methods and different substrate materials were used. For testing the bond between bracket, adhesive, and substrate, the brackets Bio Quick (Forestadent), Micro Sprint (Forestadent), Micro Sprint with newly developed stotzen base (Forestadent), Equilibrium mini (Dentaurum), and In-Ovation mini (Dentsply) were tested by using shear and tensile tests in accordance with DIN 13990-2. The brackets were bonded to bovine teeth and PMMA rings using the adhesives Transbond XT, Kurasper F and GC Ortho Connect, and subsequently, their bond strength was analyzed. Comparisons could also be made between the test methods of the shear and tensile tests as well as the substrate materials tooth and ring. The residual adhesive on the bracket base was then determined microscopically and presented using the Adhesive Remnant Index (ARI). Comparing the shear and tensile tests and the tooth and ring bases, significantly higher adhesive values were obtained when the brackets were sheared off and attached to teeth. Regardless of the brackets, no significant difference between the adhesives can be seen on the teeth, but GC Ortho Connect achieved significantly lower bond strengths while using rings. In the conducted experiments, the highest bond strength (in MPa) were achieved when shearing from the tooth, and for both debonding methods from the ring by Equilibrium mini in combination with the adhesives Kurasper on the ring (shear bond strength 23.4 MPa/tensile bond strength 8.1 MPa) and GC Ortho Connect on the tooth (23.55 MPa). When pulled off the tooth, the Micro Sprint with stotzen base combined with Transbond XT achieved the highest bond strength (8.02 MPa). Mostly, more than 50% residual adhesive remained on the bracket base in the ARI examination.

The problem of a thin elastomeric layer confined between two stiff adherends arises in numerous applications such as microelectronics, bio-inspired adhesion and the manufacture of soft biomedical products. A common requirement is that the debonding of the elastomeric layer from the adherends be controlled to avoid undesirable failure modes. This level of control may necessitate understanding the collective role of the interfacial adhesion, material properties, part geometries, and loading conditions on the debonding. Analytical and numerical approaches using the finite element method and a cohesive zone model (CZM) for the interfacial debonding are used in this dissertation to delineate the role of the afore-mentioned parameters on the initiation and propagation of debonding for both rigid and non-rigid adherends. Extensively studied in the dissertation is the debonding of a semi-infinite relatively stiffer adherend from an elastomer layer with its other surface firmly bonded to a rigid base. The adherend is pulled upwards by applying normal displacements either on its entire unbonded surface or on the edge of its part overhanging from the elastomer layer. The adherend and the elastomeric layer materials are assumed to be linear elastic, homogeneous and isotropic and the elastomer is assumed to be incompressible. Viscoelasticity of the elastomer is considered in the first part of the work. Plane strain deformations of the system with a bilinear traction-separation (TS) relation in the CZM are analyzed. Two non-dimensional numbers, one related to the layer confinement and the other to the interfacial TS parameters, are found to determine if debonding initiates at interior points in addition to at corner points on the adherend/elastomer interface, and if adhesion-induced instability is exhibited. This work is extended to axisymmetric problems in which debonding can take place at both interfaces. Motivated by an industrial demolding problem, numerical experiments are conducted to derive insights into preferential debonding at one of the two interfaces, including for curved adherends. Results reported herein should help engineers design an elastomer layer sandwiched between two adherends for achieving desired failure characteristics. / Ph. D.