Today’s transportation highly depends on hydrocarbon fuels, and reducing the weight could help a lot in reducing the air pollutants and carbon footprints in the environment to comply with the strict regulations set by reputable standard organizations in the world. Utilizing lightweight materials in automobile parts is one of the key factors to succeed in meeting the goals defined in the standards. Replacing the conventional single material component with a multi-material component having the same geometry but lighter weight could help the automakers to achieve these goals. Compound casting is one of the methods to produce such components. The aluminum alloy/ductile iron bimetal component produced by compound casting was investigated. During the production of the experimental sample of the compound casting, component two parameters were considered, melt-to-solid volume ratio and pre-heat temperature of the solid insert. The results showed that the increasing melt-to-solid volume ratio caused the formation of a stronger metallurgical bond between the two materials compared to the lower melt-to-solid volume ratio. However, pre-heating the solid insert under the atmospheric condition caused the formation of iron oxide layers on the surface, and as a result, no metallurgical bonding was formed, no matter which melt-to-solid volume ratio was used during the production process. So, inspired by AlFin process, the solid inserts were first dipped inside the aluminum alloy bath with the target temperature of 750 °C for two extended periods, 15 minutes and 30 minutes, to ensure that the preliminary metallurgical bonds were formed at the interface surfaces without disturbance by the surrounding atmosphere. To make the experimental components and to develop the metallurgical bonds, the aluminized inserts were then quickly placed inside the sand molds, and the cast alloy was poured inside the molds and around the inserts immediately after placement. In this way, although the formation of the aluminum oxide layer was unavoidable on the surfaces of the aluminized inserts, there was still liquid aluminum alloy melt underneath, which could be easily washed away during the pouring of the cast alloy.Nevertheless, the metallurgical bonds in the compound casting products having a lower melt-to-solid volume ratio didn’t withstand the shear loads and only the product having a higher melt-to-solid volume ratio with the aluminized insert dipped for a longer time could resist against the loads. In addition to the mechanical strength of the experimental products, their metallurgical bonds were specified and characterized using microscopic examination and EDS analysis. The successful results of the experimental product were then proposed to modify the design of a model from the automobile industry, called the truck wheel hub. / Dagens transport beror starkt på kolvätebränslen, och att minska vikten kan hjälpa mycket att minska luftföroreningar och kolavtryck i miljön för att följa de strikta regler som ställts av ansedda standardorganisationer i världen. Att använda lätta material i bildelar är en av de viktigaste faktorerna för att lyckas uppfylla de mål som fastställs i standarderna. Att ersätta den konventionella komponenten med enstaka material med en komponent med flera material som har samma geometri men lättare vikt kan hjälpa biltillverkarna att uppnå dessa mål. Gjutning av föreningar är en av metoderna för att producera sådana komponenter. Aluminiumlegeringen / segjärn-bimetalkomponenten framställd genom sammansatt gjutning undersöktes. Under framställningen av det experimentella provet av gjutning av föreningen beaktades komponent två parametrar, volymförhållandet smält till fast material och förvärmningstemperaturen för det fasta insatsen. Resultaten visade att det ökande smält-till-fasta volymförhållandet orsakade bildandet av en starkare metallurgisk bindning mellan de två materialen jämfört med det lägre förhållandet mellan smält och fast volym. Förvärmning av den fasta insatsen under atmosfäriskt tillstånd orsakade emellertid bildningen av järnoxidskikt på ytan, och som ett resultat bildades ingen metallurgisk bindning, oavsett vilket smält-till-fast volymförhållande användes under produktionsprocessen . Så, inspirerad av AlFin-processen, doppades de fasta insatserna först in i aluminiumlegeringsbadet med måttemperaturen 750 ° C under två långa perioder, 15 minuter och 30 minuter, för att säkerställa att de preliminära metallurgiska bindningarna bildades vid gränsytans ytor utan störningar av den omgivande atmosfären. För att tillverka de experimentella komponenterna och för att utveckla de metallurgiska bindningarna placerades sedan de aluminiumiserade skärmen snabbt inuti sandformarna, och den gjutna legeringen hälldes in i formarna och runt insatserna omedelbart efter placering. På detta sätt, även om bildningen av aluminiumoxidskiktet var oundvikligt på ytorna på de aluminiumförsedda insatserna, fanns det fortfarande flytande aluminiumlegeringssmälta under, vilket lätt kunde tvättas bort under hällningen av den gjutna legeringen.Icke desto mindre tål de metallurgiska bindningarna i de sammansatta gjutprodukterna med ett lägre volym-till-fast volymförhållande inte skjuvbelastningarna och endast produkten med ett högre smält-till-fast volymförhållande med den aluminiumiserade insatsen doppades under en längre tid kunde motstå mot lasterna. Förutom de experimentella produkternas mekaniska styrka specificerades och karakteriserades deras metallurgiska bindningar med mikroskopisk undersökning och EDS-analys. De framgångsrika resultaten av den experimentella produkten föreslogs sedan att modifiera utformningen av en modell från bilindustrin, kallad truckhjulnavet.

<p> A moment resisting frame is one of the most commonly used lateral load resisting system in modem structures because it is suitable for low and medium rise buildings and industrial structures. It can be designed to behave in a ductile manner under seismic loads. </p> <p> Masonry infills have traditionally been used in buildings as partitions and for architectural or aesthetic reasons. They are normally considered as non-structural elements, and their effect on the structural system has been ignored in the design. However, even though they are considered non-structural elements, there is mounting evidence that they interact with the frame when the structures are subjected to lateral loads Infill walls have been identified as a contributing factor to catastrophic structural failures during earthquakes. Frame-infill interaction can induce brittle shear failures of reinforced concrete columns by creating a short column. Furthermore, infills can over-strengthen the upper stories of a structure and when they fail a soft first storey is created, which is highly undesirable from the earthquake resistance standpoint. </p> <p> There is a need for an efficient and accurate computational model to simulate the nonlinear hysteretic force-deformation behaviour of masonry infills, which is also suitable for implementation in time-history analysis of large structures. The aim is to develop a simplified advanced and cost-effective model for nonlinear time history analysis and seismic design of masonry infill frame structures. </p> <p> The objective of this research was to develop a practical and economical technique applicable for global analysis of general three-dimensional reinforced concrete infilled frames under lateral loads. Novel finite element model for the infill and the surrounding frame was developed using a special finite element configuration to represent the masonry panel. Some prescribed failure planes in different directions were defined depending on the common failure mode of masonry panels. Moreover, some of contact elements were used on the failure planes to connect among the panel elements, and between the panel elements and the boundary reinforced concrete frame. Different material models were used to represent the behaviour of concrete, reinforcing steel, mortar joints and inclined saw-tooth cracks in the infill panel. Different material models were used to describe the behaviour through and perpendicular to the prescribed failure planes. The proposed model and the used material models were described in details in the first part of this research. </p> <p> The proposed finite element model was verified against experimental and analytical results previously published by others. Different frames configurations, reinforcing details, boundary conditions and material properties were consider in that section to verify the capability of the proposed model to simulate the behaviour of different frames. The overall behaviour "Load-deflection relationship", failure point and failure mode were compared with the experimental and analytical results. Satisfactory agreement with the previously published results was obtained. </p> <p> The study investigates the capability of the proposed model to simulate the behaviour of infilled frames subjected to cyclic loads. Hysteretic loops obtained by using the new model were verified against experimental and analytical results and good correlation were obtained. The failure modes and crack patterns were compared with the experimental results and good agreements were obtained. The proposed model failed to capture some shear cracks in the RC frames as per the experimental results. </p> / Thesis / Doctor of Philosophy (PhD)

The ability to quickly develop predictions of the time-to-failure under different loading levels allows designers to choose the best polymeric material for a specific application. Additionally, it helps material producers to design, manufacture, test, and modify a polymeric material more rapidly. In the case of polymeric pipes, previous studies have shown that there are two possible time-dependent failure mechanisms corresponding to ductile and brittle failure. The ductile mechanism is evident at shorter times-to-failure and results from the stretching of the amorphous region under loading and the subsequent plastic deformation. Empirical results show that many high-performance polyethylene (PE) materials do not exhibit the brittle failure mechanism. Hence, it is critical to understand the ductile mechanism and find an approach to predict the corresponding times-to-failure using accelerated means. The aim of this study is to develop an innovative rupture lifetime acceleration protocol for PE pipes which is sensitive to the structure, orientation, and morphology changes introduced by changing processing conditions. To accomplish this task, custom fixtures are developed to admit tensile and hoop burst tests on PE pipes. A pressure modified Eyring flow equation is used to predict the rupture lifetime of PE pipes using the measured mechanical properties under axial tensile and hydrostatic pressure loading in different temperatures and strain rates. In total, the experimental method takes approximately one week to be completed and allows the prediction of pipe lifetimes for service lifetime in excess of 50 years. / Master of Science / Steel, cast and galvanized iron, and asbestos cement (AC) pipelines have been historically used in water management services. However, they often experienced deterioration because of corrosion and encrustation, resulting in 23 to 27 bursts per 100 miles of pipeline in the US per year. Therefore, plastic pipes were developed to carry liquids (water and sewage), gases, etc. The Plastic Pipe Institute (PPI) requires a service life of at least 50-years for plastic pipes. Hence, pipe producers and material suppliers continuously attempt to improve the materials and manufacturing processes used for plastic pipes to increase their service lifetimes. However, there is still no plastic pipe that has been in service for 50 years. Therefore, a few techniques have been developed to accelerate the aging process and to predict if the plastic pipe is able to endure the 50-year lifetime without failure. In this work, a combined experimental and analytical framework is presented to develop accelerated lifetime estimates for plastic pipes. Custom axial tensile and internal pressurization fixtures are developed to measure the pipe response; the analytical method is used to extend the results to predict 50-year (and beyond) behavior.

Este trabalho apresenta uma investigação experimental sobre o comportamento à fratura frágil de aços estruturais ferríticos, ASTM A285 Gr C e ASTM A515 Gr 65. Os resultados deste trabalho ampliam a base de dados de propriedades mecânicas utilizadas nas análises de integridade de estruturas pressurizadas tais como vasos de pressão e tanques de armazenamento construídos com esta classe de material. O trabalho tem por objetivo também avaliar a aplicabilidade de corpos de prova de dimensões reduzidas, PCVN, na determinação da temperatura de referência, T0, por meio da metodologia da Curva Mestra, a qual define a dependência da tenacidade à fratura do material em função da temperatura. Os ensaios de tenacidade à fratura foram conduzidos utilizando-se corpos de prova solicitados em flexão três pontos com geometria SE(B), PCVN e PCVN com entalhe lateral, extraídos de chapas laminadas. Os resultados dos ensaios foram obtidos em termos de integral J no momento da instabilidade, denotados por Jc. Dados adicionais de resistência à tração e de Impacto Charpy convencional também foram obtidos para caracterizar o comportamento mecânico dos aços utilizados. Os resultados mostraram uma forte influência da geometria dos corpos de prova sobre os valores de Jc, evidenciada pela grande variação nos valores de tenacidade à fratura. / This work presents an experimental investigation on the cleavage fracture behavior of structural ferritic steels, ASTM A285 Grade C and ASTM A515 Grade 65. One purpose of this study is to enlarge a previously reported work on mechanical and fracture properties for this class of steel to provide a more definite database for use in structural and defect analyses of pressurized components, including pressure vessels and storage tanks. Another purpose is to address the applicability of Precracked V-notch Charpy specimens to determine the reference temperature, T0, derived from the Master Curve Methodology which defines the dependence of fracture toughness with temperature for the tested material. Fracture toughness testing conducted on single edge bend specimens in three-point loading (SE(B), PCVN Plain Side and PCVN Side Grooved) extracted from laminated plates provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, Jc. Additional tensile and conventional Charpy tests produce further experimental data which serve to characterize the mechanical behavior of the tested materials. The results reveal a strong effect of specimen geometry on Jc values associated with large scatter in the measured values of cleavage fracture toughness.

Les déformations élastoplastiques (instantanées) et les mécanismes d'endommagement du sel gemme sont abordés par une étude expérimentale et théorique. Une étude bibliographique présente les mécanismes de déformation du sel gemme, et permet de dégager les différents facteurs physiques régissant le caractère ductile ou fragile du comportement du sel gemme. On situe ainsi le sel gemme par rapport aux autres géomatériaux du point de vue des propriétés mécaniques. On présente également différentes méthodes d'identification de l'endommagement des géomatériaux. Des essais de compression et d'extension axisymétriques sont présentés. La déformation volumique globale est mesurée au cours du chargement déviatorique. Cette mesure est un indicateur d'endommagement et permet en particulier d'identifier les conditions d'initiation de l'endommagement. Le chargement hydrostatique et les phases déviatoriques renseignent sur la rhéologie du matériau et sur la détérioration du sel gemme consécutive au chargement déviatorique. Les variations des paramètres élastiques sont décrites mais, étant de faible amplitude, elles ne sont pas prises en compte dans l'écriture de la loi de comportement. Une analyse des contraintes internes par le truchement d'un modèle micro-macro autocohérent permet d'éclairer les causes de la précocité de l'endommagement en extension. L'usage d'un tel modèle permet aussi de discuter la nature de l'écrouissage. A l'échelle macroscopique, un modèle de comportement élastoplastique est proposé. Il suit un écrouissage isotrope, l'écoulement est non-associé, et sa détermination s'appuie sur l'analyse de l'évolution de l'angle de dilatance en fonction de la contrainte moyenne et du paramètre d'écrouissage (la distorsion plastique). Une généralisation à l'espace tridimensionnel des contraintes (en faisant intervenir trois invariants du tenseur des contraintes) est développé et permet de présenter un résultat de calcul de creusement de galerie axisymétrique.

La Meseta nord-occidentale est un segment de la chaîne hercynienne du Maroc. L'étude lithostratigraphique et structurale de cette région montre que la paléogéographie joue un rôle déterminant au cours de l'évolution tectonique hercynienne : les grands bassins qui se sont individualisés au cours de la sédimentation du Paléozoïque vont gouverner la géométrie et la cinématique de la déformation. La Meseta nord-occidentale se subdivise, d'Ouest en Est, en deux domaines où la sédimentation et le style de la déformation sont très différents : - le Môle côtier ou domaine occidental, qui est marqué par l'ouverture d'un graben intra-continental actif et fortement subsident au Cambrien. Ce domaine est structuré à l'Hercynien par des grands plis concentriques subméridiens. A proximité des principales failles rectilignes, parallèles à la direction de la chaîne, les plis se disposent en échelon et s'accordent avec un coulissage horizontal dextre du bâti. - la Meseta centrale ou domaine oriental, zone haute inactive au Cambrien, sur lequel s'installe au Dévonien supérieur-Carbonifère un bassin marginal dont la bordure occidentale est découpée en panneaux basculés et marquée par une intense activité volcanique de type alcalin à transitionnel. Dans ce domaine la direction des grandes structures plicatives hercyniennes est guidée par les anciennes failles bordières du bassin de direction N20-N30 et N70. Ces deux domaines sont séparés par la Zone de Cisaillement de la Meseta Occidentale (Z.C.M.O.), qui n'est pas une faille unique mais correspond à une succession d'accidents décrochants disposés en relai où se concentrent le métamorphisme et la déformation. Cette zone, qui coïncide à la fois avec la limite orientale du bassin cambrien et avec la limite occidentale du bassin dévono-carbonifère, s'étend depuis la zone faillée de Rabat-Tiflet en Meseta côtière au Nord jusqu'à la faille du Tizi'n Test dans le Haut-Atlas au Sud. Dans la partie centrale du massif des Rehamna, la Z.C.M.O. est une faille peu pentée à l'Est, héritée du dispositif en extension du Carbonifère. Pendant la phase de déformation hercynienne majeure, le compartiment supérieur oriental s'est déplacé vers le SW parallèlement aux structures majeures de la chaîne. La cinématique particulière de cet accident et le métamorphisme mésozonal qui accompagne la déformation ductile s'expliquent par la forte remontée du socle précambrien qui affleure dans ce secteur.

Este trabalho apresenta uma investigação experimental sobre o comportamento à fratura frágil de aços estruturais ferríticos, ASTM A285 Gr C e ASTM A515 Gr 65. Os resultados deste trabalho ampliam a base de dados de propriedades mecânicas utilizadas nas análises de integridade de estruturas pressurizadas tais como vasos de pressão e tanques de armazenamento construídos com esta classe de material. O trabalho tem por objetivo também avaliar a aplicabilidade de corpos de prova de dimensões reduzidas, PCVN, na determinação da temperatura de referência, T0, por meio da metodologia da Curva Mestra, a qual define a dependência da tenacidade à fratura do material em função da temperatura. Os ensaios de tenacidade à fratura foram conduzidos utilizando-se corpos de prova solicitados em flexão três pontos com geometria SE(B), PCVN e PCVN com entalhe lateral, extraídos de chapas laminadas. Os resultados dos ensaios foram obtidos em termos de integral J no momento da instabilidade, denotados por Jc. Dados adicionais de resistência à tração e de Impacto Charpy convencional também foram obtidos para caracterizar o comportamento mecânico dos aços utilizados. Os resultados mostraram uma forte influência da geometria dos corpos de prova sobre os valores de Jc, evidenciada pela grande variação nos valores de tenacidade à fratura. / This work presents an experimental investigation on the cleavage fracture behavior of structural ferritic steels, ASTM A285 Grade C and ASTM A515 Grade 65. One purpose of this study is to enlarge a previously reported work on mechanical and fracture properties for this class of steel to provide a more definite database for use in structural and defect analyses of pressurized components, including pressure vessels and storage tanks. Another purpose is to address the applicability of Precracked V-notch Charpy specimens to determine the reference temperature, T0, derived from the Master Curve Methodology which defines the dependence of fracture toughness with temperature for the tested material. Fracture toughness testing conducted on single edge bend specimens in three-point loading (SE(B), PCVN Plain Side and PCVN Side Grooved) extracted from laminated plates provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, Jc. Additional tensile and conventional Charpy tests produce further experimental data which serve to characterize the mechanical behavior of the tested materials. The results reveal a strong effect of specimen geometry on Jc values associated with large scatter in the measured values of cleavage fracture toughness.

This thesis is focused on creation of mobilization curves, based on data, obtained from standard and detailed monitoring of the load test. The load test was performed on the 9 meters long ductile micropile. The first part of the thesis explains the methods and principles, which was used to construct the mobilization curves. Next there is description of the technologies of ductile micropiles and the load test. In the next part of the thesis is generally explained process, which was applied to the evaluated data. For evaluation was used spreadsheet Microsoft Excel and programming language Matlab, with Kernel Smoothing extension. In the last chapter of the thesis there are interpreted the load transfer function together with skin friction and micropile displacement.

The thesis is focused on the prediction of the fracture toughness temperature dependence through a universal curve of fracture toughness (also known as the master curve). To determine the parameters of the universal curve of fracture toughness, values acquired from the measurement results of fracture toughness and tensile tests of structural steel P91 are used. The theoretical part is based on a summary of the relevant information from the field of fracture mechanics and brittle-ductile fracture behavior of steels that are important for the understanding of fracture-strain response of materials depending on load conditions. The experimental part of the thesis contains the results from practical measurements and analyses, which were used for determining the parameters of a universal curve of fracture toughness as well as for the evaluation of fracture behavior and description of the impact of structural parameters on this behavior in case of steel P91.

No description available.