Abstract is secret.

O objetivo deste trabalho é apresentar uma nova formulação direta do Método dos Elementos de Contorno (M.E.C.) para análise de placas, utilizando a teoria de Kirchhoff, admitindo três parâmetros nodais de deslocamentos para sua representação integral: deslocamento transversal e suas derivadas nas direções normal e tangencial ao contorno. Dois valores nodais são usados para os esforços, momento fletor normal mn e força cortante equivalente Vn. Desta forma são escritas três equações integrais de contorno por nó, obtidas a partir da discretização da placa, segundo a forma usual do método. A vantagem mais perceptível desta formulação é a possibilidade de se fazer a ligação da placa analisada pelo M.E.C. com elementos lineares, representados por três valores nodais de deslocamentos que passam a ser compatibilizados diretamente, para a análise de edifícios. São apresentados exemplos numéricos da formulação e das ligações para comprovação da formulação. / The aim of this work is to present an alternative formulation for plate bending analysis, using Kirchhoff\'s theory, in wich the boundary equation for displacements and its derivative in tangential and normal directions to the boundary for each boundary node are used. The efforts, according to Kirchhoff\'s theory, are the normal bending mn and the equivalent shear force Vn. This formulation is adequate for the analysis of plates coupled with flexible colunms and beams because these structural elements have three nodal displacement values at its nodes. Many examples of single plates and buildings slab are presented using the formulation proposed in this work.

An investigation of IsoTruss structures in bending and torsion was conducted. A model was developed in ANSYS APDL where bay length and longitudinal member to helical member cross-sectional area ratio could be varied while holding the diameter constant. The model was validated using previously reported values from analytical models and empirical data. The model was used to make predictions of a specific geometry that was manufactured, tested and compared against the model. 12 specimens were built and tested. In flexure, empirical data had a percent error with respect to the model ranging from 10.9 to 65.4% with one outlier at 94.1%. In torsion, the empirical data had a percent error with respect to the model ranging from 0.4 to 34%. The test data exhibited similar trends compared to the model. An IsoTruss structure built to maximize torsional rigidity should have a diameter and bay length such that its helical angle is between 55 and 60 degrees. The inclusion of longitudinal members has a negligible impact on rigidity. Flexural rigidity is maximized with longitudinal members and with a minimal helical angle, placing helical members more in the direction of the longitudinal members. In order to minimize flexural rigidity, the longitudinal members should be removed from the design and the helical member angle should be maximized up to 80 degrees.

abstract: Weevils are among the most diverse and evolutionarily successful animal lineages on Earth. Their success is driven in part by a structure called the rostrum, which gives weevil heads a characteristic "snout-like" appearance. Nut weevils in the genus Curculio use the rostrum to drill holes into developing fruits and nuts, wherein they deposit their eggs. During oviposition this exceedingly slender structure is bent into a straightened configuration - in some species up to 90° - but does not suffer any damage during this process. The performance of the snout is explained in terms of cuticle biomechanics and rostral curvature, as presented in a series of four interconnected studies. First, a micromechanical constitutive model of the cuticle is defined to predict and reconstruct the mechanical behavior of each region in the exoskeleton. Second, the effect of increased endocuticle thickness on the stiffness and fracture strength of the rostrum is assessed using force-controlled tensile testing. In the third chapter, these studies are integrated into finite element models of the snout, demonstrating that the Curculio rostrum is only able to withstand repeated, extreme bending because of modifications to the composite structure of the cuticle in the rostral apex. Finally, interspecific differences in the differential geometry of the snout are characterized to elucidate the role of biomechanical constraint in the evolution of rostral morphology for both males and females. Together these studies highlight the significance of cuticle biomechanics - heretofore unconsidered by others - as a source of constraint on the evolution of the rostrum and the mechanobiology of the genus Curculio. / Dissertation/Thesis / Doctoral Dissertation Evolutionary Biology 2009

According to a 2009 study, 68% of American households played video games (Entertainment Software Association). With this number continually on the rise, video games and their cultures are in need of further scholarly exploration. A video game of particular interest is a massive online game known as World of Warcraft, drawing over twelve million players worldwide (Blizzard Entertainment, 2010). With a cyberspace-based culture, World of Warcraft exposes its players to phenomenon that are unique to it, and thereby not easily understood through the same measures and evaluations offered by society at large. One such phenomena is that of gender, or more specifically the bending of gender by which players assume characters of the opposite gender. Although a common practice in video games like World of Warcraft, its motivations have yet to receive adequately scholarly attention. The present study seeks to explore the process of gender selection in the massive online game World of Warcraft through qualitative methods utilizing interviews, texts, and field notes. The data is then analyzed using Kellner's (2003) methods of critical analysis of media and Langian's (1975) work on thematization.

Bakgrund: Rullsulor används för att kompensera för ledstelhet, förbättra avveckling av steget, minska höga tryck plantart och minska böjningen vid tålederna.  Det finns dock få studier som undersöker om rullsulan verkligen minskar ledrörlighet i framfoten. Det saknas även information för betydelsen av rullsulans styvhet för böjmomentet av framfoten, vid avvecklingen av steget.   Metod: Fem friska kvinnor (n=5) gick med tre olika par skor, två par var modifierade med en likadan rullsula med olika styvheter och ett par utan rullsula. Fem upprepade mätningar för de tre olika skorna samlades in för alla deltagare. Det dorsala böjmomentet analyserades med sensorsulan (VebitoSCIENCE) som ersatte skons innersula.   Resultat: Det dorsala böjmomentet minskade för samtliga deltagare med en rullsula. Signifikant minskning av det dorsala böjmomentet vid MTP 1, för alla deltagare, när den styva rullsulan jämfördes med utan rullsula (94,4 – 20,1 Nmm) och mellan styv och flexibel rullsula för deltagare 1,2, 4 & 5 (68 – 22,2 Nmm).   Konklusion: Det dorsala böjmomentet minskade signifikant för MTP1 och MTP5 när en rullsula användes av friska kvinnor. Studien har också visat att en styv rullsula har en betydelse för att uppnå ett minskat dorsalt böjmoment vid MTP. / Background: Rocker soles are used to compensate for joint stiffness, reduce high plantar pressure and reduce the bending of the toe joints. Despite this, few studies have investigated if the rocker shoe really reduce the joint movement at the forefoot. There is also a lack of information regarding the importance of the rocker shoes stiffness for the bending moment of the forefoot, at the third rocker.   Method: Five healthy women (n=5) walked with three different pairs of shoes, two pairs were modified with the same rocker shape with different stiffness and one pair without a rocker. Five repeated measurements for the three different shoes were collected for all the participants. The dorsal bending moment was analyzed with a sensor sole (VebitoSCIENCE) that replaced the shoes insole.   Result: The dorsal bending moment was reduced for all participants with a rocker shoe. Significant reduction of the dorsal bending moment at MTP1, for all participants, when the stiff rocker was compared to the shoe without rocker (94,4 – 20,1 Nmm) and between the stiff and flexible rocker for participants 1,2,4 and 5 (68 -22,2 Nmm).   Conclusion: The dorsal bending moment was significantly reduced for MTP 1 and MTP 5 when a rocker shoe was used by healthy women, the study has also shown that the stiffness has an importance in order to achieve a reduction of the dorsal bending moment at MTP.

High energy pulse laser peening (HEPLP) is a manufacturing process, in which a strong shock wave is produced and induces high pressures on the surface of the target material. Generally, this process is used to improve material properties such as the hardness and fatigue life. First a 2D multi-physics model for the process was investigated, which simulates the pressure induced on the surface of the target material. The model can be coupled with commercial finite element software, such as ABAQUS, to more accurately simulate the HEPLP process to find stresses and deformations on the surface. Next two novel applications using the HEPLP process were investigated. The first, laser shock bending is a sheet metal micro-forming process using HEPLP to accurately bend, shape, precision align, or repair micro-components with bending angles less than 10°. Negative bending angle (away from laser beam) can be achieved with the high-energy pulsed laser, in addition to the conventional positive laser bending mechanism. In this thesis, various experimental and numerical studies on aluminum sheets were conducted to investigate the different deformation mechanisms, positive and negative. The experiments were conducted with the sheet thickness varying from 0.25 to 1.75 mm and laser pulse energy of 0.2 to 0.5 J. A critical thickness threshold of 0.7-0.88 mm was found that the transition of positive negative bending mechanism occurs. A statistic regression analysis was also developed to determine the bending angle as a function of laser process parameters for positive bending cases. The second application studied used HEPLP to imprint complex two-dimensional (2D) patterns dental implant material of cpTi. Pure titanium (commercial pure cpTi) is an ideal dental implant material, without the leeching of toxic alloy elements. Evidence has shown that unsmooth implant surface topologies may contribute to the osteoblast differentiation in human mesenchymal pre-osteoblastic cells, which is helpful to avoid long-term peri-abutment inflammation issues for the dental implant therapy with transcutaneous devices. Studies have been conducted on the grit blasted, acid etched, or uni-directional grooved Ti surface, however, for these existing approaches the surface quality is difficult to control or may even damage the implant. The strong shock wave generated by HEPLP is used to press a stainless steel grid, used as a stamp, on Ti foils to imprint a 2D pattern. In this study, the multiple grid patterns and grid sizes were applied to test for cell-attachment improvements. Then, the cell culture tests were conducted with the patterned surface to investigate the contribution of these 2D patterns, with the control tests of the other existing implant surface topography forming approaches. The micro-patterns proved successful in increasing the cell-attachment, increasing the number of cells attaching to the material and also contributing to the cell-growth within the grooved areas.

When using Finite Element Analysis (FEA) to model notched composite panels, the values of certain material properties can have a great effect on the outcome of the simulation. Progressive damage modeling is used to model how a composite structure will fail, and how that failure will affect the response of the structure. Many different progressive damage models exist, but the formulation known as Hashin damage is used to model failure in tension and out-of-plane bending in this study. This model has ten different material properties that are used to define the damage response of the material. Each of these material properties must be calculated experimentally in a time consuming and expensive process. A method of determining which properties will have the greatest effect on the model, and therefore, which to spend the most money on accurate tests, is a factorial analysis sensitivity study. Studies of this nature have been used in many different situations regarding material properties testing and optimization. The work presented in this study uses several factorial analysis designs to perform a sensitivity study on the ten Hashin damage parameters in a variety of situations. Five different ply layups are used in modeling specimens that are loaded in tension and out-of-plane bending. The results of this study show that the significant factors depend on the ply layup and loading scenario, but there are generally less than three factors that play a significant role in modeling the failure of the panels. This means that in most cases, rather than spending substantial money on finding ten different material properties, the time and money can be focused on a small subset of the properties, and an accurate model can still be achieved. While the results of the scenarios presented may not apply to all scenarios, the methods presented can be used to perform a similar study in other specific scenarios to find the significant factors for that case. / Graduation date: 2013

Anodisation has been studied for almost eighty years, primary in the field of corrosion science, as a simple and efficient way of producing thick protective oxide coatings on Al, Ti or Zr alloys. Anodisation is an electrochemical oxidation process which relies on the migration of ions across solid films under the action of a large electric field. From the fundamental point of view, many aspects regarding the growth of anodic films have been studied extensively. However, so far, little interest has been devoted to the mechanical aspects involved in the growth process, despite their considerable importance both from an applied as well as from a fundamental point of view. A solid understanding of internal stresses development is indeed crucial in order to guarantee the durability of anodic coatings, their structural and functional properties. In addition, the stress evolution directly reflects the motion of the ions in the film and therefore provides a unique means to investigate in situ the growth mechanisms of anodic films. In this thesis, we have studied the evolution of the internal stresses in anodic TiO2 films in situ during their growth. The stresses have been obtained from changes in the curvature of cantilevered anode samples, measured using a high-resolution multi-beam optical sensor. We demonstrate, for the first time, the capability of this type of curvature sensor for monitoring processes in liquid environments. Experimental data on the internal stresses developing in anodic TiO2 films is provided, and trends regarding the influence of the experimental conditions on the stress evolution are identified. In particular, the evolution of the internal stresses is shown to be strongly correlated with the evolution of the electrochemical variables, which directly demonstrates the interest of curvature measurements as a fundamental technique for investigating the details of the growth process of anodic oxide films. The reversible and irreversible stress contributions associated, respectively, with electrostriction and with growth-related ionic transport have been separated from one another and quantified. A novel constitutive model for the electrostriction stress has been proposed which explicitly takes into account the effect of dielectrostriction.

The bending of an orthotropic cusped plate in energetic and weighted Sobolev spaces has been considered. The existence and uniqueness of generalized and weak solutions of admissible boundary value problems (BVPs) have been investigated.