Surfaces with static contact angle greater than 150 degrees are typically classified as superhydrophobic. Such coatings have been inspired by the lotus leaf. As water flows over a superhydrophobic surface, "slip effect" is produced resulting in a reduction in the skin-friction drag exerted on the surface. Slip flow is caused by the entrapment of a layer of air between water and the surface. Superhydrophobicity could be utilized to design surfaces for applications such as energy conservation, noise reduction, laminar-to-turbulent-transition delay, and mixing enhancement. A popular method of manufacturing a superhydrophobic surface is microfabrication in which well-designed microgrooves and/or poles are placed on a surface in a regular configuration. This method is a costly process and cannot easily be applied to large-scale objects with arbitrary shapes. In this work, we fabricated and characterized simpler low-cost superhydrophobic coatings based on controlling the volume of entrapped air in order to enhance durability (longevity) and the properties of the coating bringing the technology closer to large-scale submerged bodies such as submarines and ships. Two different low-cost fabricating techniques have been utilized: (i) random deposition of hydrophobic aerogel microparticles; and (ii) deposition of hydrophobic polymer micro- and nanofibers using DC-biased AC-electrospinning. The present study is aimed at providing experimental, numerical, and analytical models to characterize the superhydrophobicity and longevity of the coatings depending on the morphology of the surfaces and the concentration of the hydrophobic materials. The surface's micro/nanostructure were observed by field emission scanning electron microscopy. The degree of hydrophobicity of the coatings was estimated using drag-reduction and contact-angle measurements using a rheometer and a goniometer respectively. Furthermore, We have advanced and calibrated a novel optical technique to noninvasively measure the longevity of submerged superhydrophobic coatings subjected to different environmental conditions. We have also modeled the performance of superhydrophobic surfaces comprised of randomly distributed roughness. The numerical simulations are aimed at improving our understanding of the drag-reduction effect and the stability of the air–water interface against pressure in terms of the microstructure parameters. Moreover, we have experimentally characterized the terminal pressure (i.e. the pressure at which the air–water interface completely fails) of aerogel coatings with different morphologies.

My background in clay has emphasized the development of technical considerations in functional ceramics as well as the search for personal images. The past two years have seen an emphasis on the exploration of technical areas chosen to lead to the development of a familiarity with techniques and a solidification of statement. The process has nurtured in me the realization that the objects I produce do not represent an attempt to attain an axiom of art but are personal statements developed through an empirical use of forms and images.

Master´s thesis deals with creating circuit for receiving data from industrial camera. IP Core is designing for FPGA. Theoretical part of the work describes SDI interface, analysis of relevant SMPTE standards and specification of data format. The thesis include general characteristics of multigigabit transceivers. Practical part include VHDL description of SDI receiver. Thesis presents simulations of created circuit, implementation for real application and measurement results for signal transmission over slip ring.

Externally bonding of fibre-reinforced polymer (FRP) strips or sheets has become a popular strengthening method for reinforced concrete structures over the last two decades. For most such strengthened concrete beams and slabs, the failure is at or near the FRP-concrete interface due to FRP debonding. The objective of this thesis is to develop a deeper understanding of the debonding behaviour of the FRP-concrete interface through mesoscale finite element simulation. Central to the investigation is the use of the concrete damaged plasticity (CDP) model for modelling the concrete. The FRP is treated as an elastic material. The numerical simulation is focused on the single shear test of FRP-concrete bonded joints. This problem is known to be highly nonlinear and has many difficulties in achieving a converged solution using the standard static loading procedures. A dynamic loading procedure is applied in this research and various parameters such as time step, loading rate etc. are investigated. In particular, the effect of the damping ratio is investigated in depth and an appropriate selection is recommended for solving such problems. It has been identified that the concrete damage model can have a significant effect on the numerical predictions in the present problem. Various concrete empirical damage models are assessed using cyclic test data and simulation of the single shear test of the FRP-concrete bonded joint and it is proposed that the Birtel and Mark’s (2006) model is the most appropriate one for use in the present problem. Subsequently, the effects of other aspects of the concrete behaviour on the FRP-concrete bond behaviour are investigated. These include the tensile fracture energy, compression strain energy and different concrete compression stress-strain models. These leads to the conclusion that the CEBFIP1990 model is the most appropriate one for the problem. An important issue for recognition is that the actual behaviour of the FRP-concrete bonded joints is three dimensional (3D), but most numerical simulations have treated the problem as two dimensional (2D) which has a number of imitations. True 3D simulation is however very expensive computationally and impractical. This study proposes a simple procedure for modelling the joint in 2D with the 3D behaviour properly considered. Numerical results show that the proposed method can successfully overcome the limitations of the traditional 2D simulation method. The above established FE model is then applied to simulate a large number of test specimens. The bond stress-slip relationship is extracted from the mesoscale FE simulation results. An alternative model is proposed based on these results which is shown to be advantageous compared with existing models. This new model provides the basis for further investigation of debonding failures in FRP strengthened concrete structures in the future.

Master of Science / Department of Architectural Engineering and Construction Science / Kimberly Waggle Kramer / Cold-formed steel framing sheathed with wood structural panels is a common method of construction for wall, roof and floor systems in cold-formed steel structures. Since wood structural panels are attached with screws at relatively close spacing, a certain amount of composite behavior will be present. However, the benefit of composite behavior of this system is currently not being taken advantage of in the design of these structural systems. While composite effects are present, they are not yet being accounted for in design due to a lack of statistical data. To determine the amount of composite action taking place in these systems, the slip modulus between steel and wood is required. The slip modulus reflects the amount of shear force able to be transferred through the screw connection, to either member of the composite system. This thesis presents the results of a study conducted to determine values of the slip modulus for varying thicknesses of cold-formed steel and plywood sheathing. Push tests were conducted and the slip moduli were determined based on ISO 6891 and ASTM D1761. Compared with data from a previous preliminary study performed by others, the values determined from these tests for the slip modulus were deemed reasonable. The determination of the slip modulus will lead to the ability to calculate a composite factor. Determination of a composite factor will allow cold-formed steel wood structural panel construction to become more economical due to the available increase in bending strength.

Microstructure controls many physical properties of a material such as strength, ductility, 1density, conductivity, which, in turn, determine the application of these materials. This thesis work focuses on studying microstructural features (such as grain size, shape, defects, orientation gradients) and mechanical properties (such as hardness and yield strength) of multilayered materials that have undergone different loading and/or operating conditions. Two materials that are studied in detail are 18 nm Cu-Nb nanolaminates and 3D printed Inconel 718. Copper-Niobium (Cu-Nb) nanolaminate is a highly stable, high strength, nuclear irradiation resistant composite, which is destabilized with application of high pressure torsion (HPT). This work focuses on understanding the deformation and failure behavior of Cu-Nb using a novel orientation mapping technique in transmission electron microscopy in (TEM) called Automated Crystal Orientation Mapping (ACOM) and Digistar (ASTARTM) or Precession Electron Diffraction (PED). A new theory is postulated to explain strengthening mechanisms at the nanoscale using a data analytics approach. In-situ TEM compression and tensile testing is performed to image dislocation movement with the application of strain. This experiment was performed by Dr. Lakshmi Narayan Ramasubramanian at Xi’an Jiaotong University in China. Another major aspect of this research focuses on the design, fabrication, and microstructural characterization of 3D printed Inconel 718 heat exchangers. Various heat exchanger designs, machine resolution, printing techniques such as build orientation, power, and velocity of the laser beam are explored. Microstructural and mechanical properties of printed parts (before and after heat treatment) are then analyzed to check consistency in grain size, shape, porosity, hardness in relation to build height, scan parameters, and design. Various tools have been utilized such as scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), x-ray computed microtomography (at Advanced Photon Source at Argonne National Lab), hardness and micro-pillar compression testing for this study.

This project was performed together with ÅF Industry AB in Trollhättan, Sweden. ÅF’s expertise in Trollhättan is oriented towards the automotive industry. It was conducted within the section of CAE and safety where they, for instance, dimension bolt joints in the cars. Bolt joints play an important role in the automotive industry. Slip critical bolt joints are used widely throughout the vehicles. With lack of good test data, the bolt joints need to be dimensioned conservatively. This may lead to that bolt joints are over-dimensioned, adding more mass to the car. On the contrary, the availability of reliable test data enables designers to optimize joint dimensions to achieve a safe design with minimized mass. A mechanical testing configuration has been designed as well as a testing procedure for a test to determine the static friction value between mating surfaces in bolt joints. The testing configuration has been used to perform tests to find the static friction coefficient in different materials. The study contains varied combinations of steel, aluminium and ED-Coated steel. The study resulted in tables with levels of probability. The developed test configuration is robust and relatively simple to use and is recommended for further use. For improved statistical significance, it was noted that more samples should be used than was used in this study. The aluminium has a smoother surface finish and that could be the reason why its coefficient of friction is lower than steel. It is therefore considered important to also include surface roughness when presenting coefficient of friction results.

Lorsqu'un fluide complexe s'écoule à travers un milieu poreux, à la non-linéarité de l'écoulement s'ajoute la spécificité de la structure poreuse, qui est souvent multi-échelle. Il émerge alors un grand nombre de problématiques fondamentales liées à l'interaction entre le fluide et la structure poreuse. L'interprétation et la modélisation de la grande variété des phénomènes physiques à petite échelle ainsi que leurs répercussions à grande échelle soulèvent de nombreuses questions. Dans cette thèse, les fluides étudiés sont des solutions de polymères, et les milieux poreux sont, entre autre, des roches issues de réservoirs pétroliers. Dans le contexte des méthodes de récupération améliorée pour les gisements pétroliers, l’injection d’eau avec polymères fait en effet partie des méthodes couramment utilisées, permettant d’augmenter l’efficacité du balayage et donc la production d’huile sur différents types de réservoirs. De part la rhéologie non-Newtonienne ainsi que les phénomènes particuliers proches de la paroi que développent les molécules de polymères, les fluides modélisés dans cette thèse peuvent être qualifiés de complexes. L'objectif de cette thèse est d'étudier la rhéologie non-Newtonienne ainsi que le comportement des molécules de polymère proches de la paroi. On relie alors ces phénomènes aux propriétés effectives macroscopiques. Pour cela, on simule numériquement les écoulements à travers desimages tomographiques de milieux poreux. Ainsi, on souhaite mieux cerner la physique qui est en jeu et également proposer des pistes d'amélioration des modèles actuellement implémentés dans les simulateurs de réservoirs. Dans une première partie de ce travail de thèse, on s'intéresse à la transition du régime d'écoulement macroscopique, de Newtonien à non-Newtonien, induite parune solution de polymère. Par des simulations numériques de l'écoulement à travers un large panel de milieux poreux, on étudie la transition entre ces deux régimes. Une analyse de la mécanique de l'écoulement permet de proposer un modèle simple et d'évaluer en ordre de grandeur la vitesse moyenne de transition. Ensuite, on étudie le glissement apparent induit par un mécanisme de répulsion des chaînes de polymère à la paroi liquide/solide. On propose un modèle à l'échelle des pores de ce phénomène et, par comparaison avec des données expérimentales,on montre que ce modèle permet de retrouver avec une précision acceptable les comportements macroscopiques observés. Enfin, avec des simulations directes sur des milieux périodiques, on relie les phénoménologies micro- et macroscopiques d'écoulements non-Newtoniens. D'un point de vue fondamental, on étudie notamment la compétition entre la non-linéarité induite par la rhéologie non-Newtonienne et le désordre inhérent à la structure poreuse. Les modèles actuellement utilisés dans les simulateurs de réservoirs sont reconsidérés au vu des résultats. / When a complex fluid is flowing through a porous medium, in addition to the fluid intrinsic physics, the multi-scale properties of the porous structure play a significant role. From the interaction between these features arise a great number of complex physical phenomena. The understandingand the modelling of the variety of these phenomena involved at the small scales and their impact on the large scales is the subject of intense work. In this thesis, the fluids we consider are polymer solutions and the porous media are typical sandstones met in petroleum applications. In petroleumengineering, the injection of a polymer slug into the oil-bearing reservoir is indeed a method commonly used in enhanced oil recovery. This method allows to increase the sweep efficiency, hence to improve the oil production of the reservoir. Due to the non-Newtonian rheology induced by the polymer molecules as well as specific mechanisms occurring at the liquid/solid interface, a polymer solution may be qualified as a complex fluid. The goal of this thesis is to investigate the non-Newtonian rheology and the behaviour of the polymer molecules near the liquid/solid interface. These phenomena are related to macro-scale effective properties. To thoroughly address this goal, we perform numerical simulations of flows through porous media. The goal is to obtain a better understanding of the underlying physics and, furthermore, we wish to propose possible improvements of the models that are currently used in reservoir simulators. Primarily, we are interested in the macro-scale transition from a Newtonian to a non-Newtonian flow. This transition is induced by the non-Newtonian rheology. By simulating flows through a wide panel of porous media, we study the macro-scale transition. An analysis of the fluid mechanics involved allows us to propose a simple model for the critical average velocity at which the transition occurs. In addition, we study the apparent slip induced by a repulsive mechanism of the polymer chains from the liquid/solid interface. We propose a pore-scale model to this mechanism. By performing comparisons with experimental datasets, we show that the model allows for a good description of the observed macro-scale behaviour. Finally, with direct simulations over periodic media, we link the phenomenology at the micro- and macro-scale for the flow of non-Newtonian fluids. On a fundamental level, we study the competition that emerges between the nonlinearity induced by the rheology and the disorder inherent to the porous structure. The results are related to modelscommonly used in reservoir simulators.

Trata-se uma análise elastoplástica de tensões planas nos métodos de conformação em forjamentos com matriz aberta ou fechada e trefilação. Emprega-se o método das linhas de fluência, desenvolvido por Hencky e Prager. O estudo visa a determinação das tensões na região plástica e do campo de velocidades na região deformada, utilizando o método de Prager aplicado a um processo analítico. / An elastoplastic analysis of plane strain in axisymmetric flat and closed punch die and wiredrawing was made using the slip lines method, developed by Hencky and Prager. Studies were made to determine the strains in the plastic zone and the velocities in deformed zone using the Prager\'s method applyed in an analytical process.

L’explosion du nombre et de la variété des données géodésiques, sismologiques et tsunami disponibles est une opportunité exceptionnelle pour produire de nouveaux modèles de la source sismique. Mais ces données n’apportent pas toutes la même information et sont soumises à différentes sources d’incertitudes, rendant la solution au problème inverse non-unique. Dans cette thèse, nous utilisons une méthode d’échantillonnage bayésien pour produire de nouveaux modèles de glissement moins assujettis au sur-ajustement des données et permettant une estimation réaliste de l’incertitude associée aux paramètres estimés. Nous l’appliquons à l’étude du glissement dans trois contextes tectoniques différents : le séisme de Landers (1992, Mw=7.3), la zone de subduction équato-colombienne où s’est produit le séisme de Pedernales (2016, Mw=7.8), et le séisme intra-plaque de Tehuantepec (2017, Mw=8.2). À travers ce travail, nous démontrons l’importance de la considération rigoureuse des incertitudes et les atouts de l’approche bayésienne pour l’étude des différentes phases du cycle sismique. / The explosion in the amount and variety of available geodetic, tsunami, and seismological observations offers an outstanding opportunity to develop new seismic source models. But these data are sensitive to different sources of uncertainty and provide heterogeneous information, which makes the solution of the inverse problem non-unique.In this thesis, we use a Bayesian sampling method to propose new slip models, which benefit from an objective weighting of the various datasets by combining observational and modelling errors. These models are less affected by data overfit and allow a realistic assessment of posterior uncertainties. We apply this method to the study of slip processes occurring in three different tectonic contexts: the Landers earthquake (1992, Mw=7.3), the Ecuador-Colombia subduction zone which hosted the Pedernales earthquake (2016, Mw=7.8), and the intraslab Tehuantepec earthquake (2017, Mw=8.2). Through these analyses, we demonstrate how the study of the seismic cycle can benefit from rigorous uncertainty estimates and Bayesian sampling.