Traditional methods of control allocation optimization have shown difficulties in exploiting the full potential of controlling a large array of control surfaces. This research investigates the potential of employing artificial intelligence methods like neurocomputing to the control allocation optimization problem of Hybrid Wing Body (HWB) aircraft concepts for minimizing control power, hinge moments, and actuator forces, while keeping the system weights within acceptable limits. The main objective is to develop a proof-of-concept process suitable to demonstrate the potential of using neurocomputing for optimizing actuation power for aircraft featuring multiple independently actuated control surfaces and wing flexibility. An aeroelastic Open Rotor Engine Integration and Optimization (OREIO) model was used to generate a database of hinge moment and actuation power characteristics for an array of control surface deflections. Artificial neural network incorporating a genetic algorithm then performs control allocation optimization for an example aircraft. The results showed that for the half-span model, the optimization results (for the sum of the required hinge moment) are improved by more than 11%, whereas for the full-span model, the same approach improved the result by nearly 14% over the best MSC Nastran solution by using the neural network optimization process. The results were improved by 23% and 27% over the case where only the elevator is used for both half-span and full-span models, respectively. The methods developed and applied here can be used for a wide variety of aircraft configurations. / Master of Science

Cette thèse présente une étude sur les rotations dans les espaces discrets en 2 dimensions et en 3 dimensions. Dans le cadre de l'informatique, l'utilisation des nombres flottants n'est pas recommandée du fait des erreurs de calculs que cela implique. Nous avons donc fait le choix de nous concentrer sur les espaces discrets. Dans le domaine de la vision par ordinateur, la rotation est une transformation requise pour de nombreuses applications. L'utilisation de la rotation continue discrétisée donne des résultats de mauvaise qualité. Pour cette raison, il est nécessaire de développer de nouvelles méthodes de rotation adaptées aux espaces discrets. Nous nous sommes principalement intéressés aux angles charnières qui représentent la discontinuité de la rotation dans les espaces discrets. Dans ces espaces, deux rotations d'une image avec deux angles très proches peuvent donner le même résultat, ce qui est capturé par les angles charnières. L'utilisation de ces angles permet de décrire une rotation qui donne les mêmes résultats que la rotation continue discrétisée tout en n'utilisant que des nombres entiers. Ils permettent aussi de définir une rotation incrémentale qui décrit toutes les rotations possibles d'une image digitale donnée. Les angles charnières peuvent être étendus dans les espaces discrets en trois dimensions. Pour cela, on définit les multi-grilles qui sont des plans de rotations contenant trois ensembles de droites parallèles. Elles représentent les discontinuités de la rotation en 3D. Les multi-grilles permettent d'obtenir les mêmes résultats en 3D que ceux obtenus en 2D / This thesis presents a study on rotation in 2 dimensional and 3 dimensional discrete spaces. In computer science, using floating numbers is problematic due to computation errors. Thus we chose during this thesis to work only in discrete space. In the field of computer vision, the rotation is a transformation required for many applications. Using discretized Euclidean rotation gives bad results. Then, it is necessary to develop new rotation methods adapted to the discrete spaces. We mainly studied the hinge angles that represent the discontinuity of the rotation in the discrete space. Indeed, it is possible to perform two rotations of the same digital image with two angles that are slightly different and obtain the same result. This is captured by hinge angles. Using these angles allow us to describe a discrete rotation that gives the same results than the discretized Euclidean rotation without using floating numbers. They also allow describing an incremental rotation that performs all possible rotations of a given digital image. Using hinge angles can also be extended to the rotations in 3 dimensional discrete spaces. The extension requires the multi-grids that are rotation planes containing three sets of parallel lines. These parallel lines represent the discontinuities of the rotation in 3D discrete space. Thus they are useful to describe the hinge angles in rotation planes. Multi-grids allow obtaining the same results in 3D discrete rotations than the results obtained in 2D discrete rotations. This thesis presents a study on rotation in 2 dimensional and 3 dimensional discrete spaces. In computer science, using floating numbers is problematic due to computation errors. Thus we chose during this thesis to work only in discrete space. In the field of computer vision, the rotation is a transformation required for many applications. Using discretized Euclidean rotation gives bad results. Then, it is necessary to develop new rotation methods adapted to the discrete spaces. We mainly studied the hinge angles that represent the discontinuity of the rotation in the discrete space. Indeed, it is possible to perform two rotations of the same digital image with two angles that are slightly different and obtain the same result. This is captured by hinge angles. Using these angles allow us to describe a discrete rotation that gives the same results than the discretized Euclidean rotation without using floating numbers. They also allow describing an incremental rotation that performs all possible rotations of a given digital image. Using hinge angles can also be extended to the rotations in 3 dimensional discrete spaces. The extension requires the multi-grids that are rotation planes containing three sets of parallel lines. These parallel lines represent the discontinuities of the rotation in 3D discrete space. Thus they are useful to describe the hinge angles in rotation planes. Multi-grids allow obtaining the same results in 3D discrete rotations than the results obtained in 2D discrete rotations

Considering the deficiencies frequently observed in the existing reinforced concrete buildings, detailed assessment and rehabilitation must be conducted to avoid significant life and value loss in seismic zones. In this sense, performance based evaluation methods suggested in the regulations and codes must be examined and revised through experimental and analytical research to provide safe and economical rehabilitation solutions. In this study, seismic behavior of three reinforced concrete frames built and tested in Middle East Technical University Structural Mechanics Laboratory is examined. The specimens are extracted from a typical interior frame of 3-story 3-bay reinforced concrete structure. One of the specimens has compliant design according to Turkish Earthquake Code (2007) and each of the other two specimens represents different types of deficiencies in terms of material strength and detailing. The test specimens were modeled using different modeling approaches and nonlinear dynamic analyses were conducted on the numerical models. Results of continuous pseudo-dynamic testing of three ground motions are presented and compared with the numerical simulations on models. Calibrated finite element models were used for evaluation of performance assessment procedure of Turkish Earthquake Code (2007) and further investigation on local deformation components in light of experimental findings and observations. Deformation sources of columns and joints were studied in terms of their interaction and contributions to the total drift. Estimated plastic hinge lengths of columns were compared with the experimental observations and the proposed expressions in the literature.

Made available in DSpace on 2015-03-26T13:28:05Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3306173 bytes, checksum: 78f6502185ffad0df1f3c37bb1c66aad (MD5) Previous issue date: 2011-07-15 / Alveolar beams are usually made from rolled shapes cut in half in a zigzag way, displaced and welded again to obtain profiles with greater height and same weight. This work presents the results of a non-linear numerical analysis performed with alveolar steel beams using the software ABAQUS. The main focus of this work was to study the formation of plastic hinges. The experimental test results obtained by Toprac e Cooke (1959) were used to validate the numerical models. The results of numerical analysis were also used in the validation of analytical models presented in this work. In design of alveolar steel beams few studies in literature presented consistent analytical models as Delesques (1968.1969) and Cimadevila (2000). But these works were proposed for a single castellation standard. In this work analytical models have been adapted for various types of holes. Considerations were also made as to the total yielding of the cross section of the webpost, which allowed a closer approximation to the results of numerical models. The study represents a contribution to the establishment of criteria for design of alveolar steel beams according to the standards of design and calculation of structures. / Vigas alveolares são normalmente obtidas a partir de perfis laminados cortados ao meio em zigue-zague, deslocadas e soldadas novamente de forma a obter perfis com maior altura e mesmo peso. Neste trabalho são apresentados os resultados de uma análise numérica não-linear realizada com vigas alveolares de aço utilizando o programa ABAQUS. O enfoque principal do trabalho foi o estudo da formação de rótulas plásticas. A validação dos modelos numéricos foi realizada com resultados experimentais obtidos por Toprac e Cooke (1959). Os resultados da análise numérica também foram utilizados na validação de modelos analíticos apresentados nesse trabalho. Poucos trabalhos na literatura apresentaram modelos analíticos tão consistentes como os de Delesques (1968, 1969) e Cimadevila (2000) para o dimensionamento de vigas alveolares. Porém esses trabalhos foram propostos para apenas um único padrão de castelação. Neste trabalho os modelos analíticos foram adaptados para diversos tipos de aberturas. Também foram feitas considerações quanto à plastificação total da seção transversal do montante de alma, o que permitiu uma aproximação maior com os resultados dos modelos numéricos. O estudo representa uma contribuição para o estabelecimento de critérios de dimensionamento de vigas alveolares de acordo com as normas vigentes de projeto e cálculo de estruturas metálicas.

Master's thesis treat of optical connection. The aim of this work was also the practical implementation and successful testing. Communications signal is low frequency in the range of 20 to 15 kHz and intended length of the coupling is approximately 200 m. The first is the work carried out theoretical analysis issues. Then is described the design and implementation of its own facility. In conclusion, the measurement is done and evaluate the parameters. I have dealt the optical connection with using a laser beam that is modulated frequency modulation. This optical signal is converted in the receiver using a PIN photodiode (type PIN) back to the electrical signal. Then there is the demodulation and amplification. The frequency modulator and demodulator is phase lock loop. It realizes the type of circuit CMOS 4046. The work is designed properly functioning equipment. It serves for the transmission of speech and audio signal line. It has good properties that match the criteria. The connection can be used outdoors due to the use of cover. The scope of communication may be even greater than 200 meters

In this two-part study, developments in finite element technology and the application thereof to topology optimization are investigated. Ultimately, the developed finite elements and corresponding topology optimization procedures are aimed at, but not restricted to, aiding the design of piezoelectrically driven compliant mechanisms for micropositioning applications. The objective is to identify and exploit existing, or to develop new, finite element technologies to alleviate the numerical instabilities encountered in topology optimization. Checkerboarding and one-node connected hinges are two commonly encountered examples which can directly be attributed to inadequacies or deficiencies in the finite element solution of structural problems using 4-node bilinear isoparametric finite elements (denoted Q4). The numerical behaviour leading to checkerboard layouts stems from an over-stiff estimation of a checkerboard patch of Q4 elements. The numerical model of a one-node connected hinge using Q4 elements, on the other hand, possesses no (or very little) stiffness in rotation about the common node. In the first part of the study, planar finite elements with in-plane rotational (drilling) degrees of freedom are investigated. It is shown that the skew-symmetric part of the stress tensor can directly be used to quantitatively assess the validity of the penalty parameter ã, which relates the in-plane translations to the rotations. Thereafter, the variational formulations used to develop these planar finite elements with drilling degrees of freedom are extended to account for the piezoelectric effect. Several new piezoelectric elements that include in-plane rotational degrees of freedom (with and without assumed stress and electric flux density) are implemented, evaluated and shown to be accurate and stable. Furthermore, the application of alternative reduced order integration schemes to quadratic serendipity (Q8) and Lagrangian (Q9) elements is investigated. Reduced or selective reduced integration schemes are often used to enhance element accuracy by `softening' higher order deformation modes. However, application of reduced integration schemes to Q8 and Q9 elements is usually accompanied by element rank deficiencies. It is shown how the application of five and eight point modified integration schemes preserve the accuracy benefits of reduced integration, while preventing element rank deficiencies. In the second part of the investigation, the salient features of elements with drilling degrees are utilized in two schemes to prevent, or improve the modelling of, one-node connected hinges. In principle, the first scheme uses the rotations computed at interior nodes to detect excessive rotations at suspect nodes. The second scheme essentially replaces planar elements forming a one-node hinge, where appropriate, with a more realistic beam model of the material layout while other elements in the mesh are modelled using planar elements as usual. Next, the dependence of optimal topologies on element formulation is demonstrated. Attention is especially paid to plate and shell applications. It is shown that Mindlin-Reissner based elements, which employ selective reduced integration on shear terms, are not reliable in topology optimization problems. Conversely, elements based on an assumed natural strain formulation are shown to be stable and capable of reproducing thin plate topology results computed using shear-rigid elements. Furthermore, it is shown that an ad hoc treatment of rotational degrees of freedom in shell problems is sensitive to the related adjustable parameter, whereas optimal topologies, using a proper treatment of drilling degrees of freedom are not. Finally, the use of reduced order integration schemes as a strategy to reduce the stiffness of a checkerboard patch of elements is considered. It is demonstrated that employing the five and eight point integration schemes, used to enhance the accuracy of Q8 and Q9 elements, also significantly reduce the stiffness of a checkerboard patch of elements, thereby reducing the probability of observing checkerboard layouts in optimal topologies. / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / PhD / unrestricted

Thanks to the advancement of additive manufacturing, periodic metallic lattice structures are gaining more and more attention. A major attraction of them is that their design can be tailored to specific applications by changing the basic repetitive pattern of the lattice, called the unit cell. This may involve the selection of optimal strut diameters and orientations, as well as the connectivity and strut lengths. Numerical simulation plays a vital role in understanding the mechanical behavior of metallic lattices and it enables the optimization of design parameters. However, conventional numerical modeling strategies in which each strut is represented by one or more beam finite elements yield prohibitively time­ consuming simulations for metallic lattices in engineering­ scale applications. The reasons are that millions of struts are involved, as well as that geometrical and material nonlinearities at the strut level need to be incorporated. The aim of this thesis is the development of multi­scale quasicontinuum (QC) frameworks to substantially reduce the simulation time of nonlinear mechanical models of metallic lattices. For this purpose, this thesis generalizes the QC method by a multi­-field interpolation enabling amongst others the representation of varying diameters in the struts’ axial directions (as a consequence of the manufacturing process). The efficiency is further increased by a new adaptive scheme that automatically adjusts the model reduction whilst controlling the (elastic or elastoplastic) model’s accuracy. The capabilities of the proposed methodology are demonstrated using numerical examples, such as indentation tests and scratch tests, in which the lattice is modeled using geometrically nonlinear elastic and elastoplastic beam finite elements. They show that the multi­scale framework combines a high accuracy with substantial model reduction that are out of reach of direct numerical simulations. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

This thesis introduces lamina emergent mechanisms (LEMs) and presents components that can be used as building blocks to create LEMs capable of more complex motion. As the name suggests, lamina emergent mechanisms are fabricated out of planar materials (the lamina) but their motion is out of that plane (emergent). Lamina emergent mechanisms can provide benefits that include reduced manufacturing costs and minimal volume when in the planar state. The compact initial state of LEMs is beneficial in reducing shipping costs, especially in volume critical applications. LEMs also exhibit the potential benefits of compliant mechanisms, namely increased precision, reduced weight, reduced wear, and part count reduction. The LEM components presented in this thesis include flexible segments, fundamental mechanisms, and a new complaint joint, the lamina emergent torsional (LET) Joint. The flexible segments are developed through changes in geometry, boundary/loading conditions, and material. The fundamental mechanisms presented have motion similar to planar change-point four-bar and six-bar mechanisms, and spherical change-point mechanisms. The LET Joint is presented as a compliant joint suited for applications where large angular rotation is desired, but high off-axis stiffness is not as critical. The joint is introduced and the equations necessary for determining the force-deflection characteristics and stress are presented. Since the LET Joint can be fabricated from a single planar layer, it is well suited for macro and micro applications. Illustrative examples of the LET Joint are provided with devices fabricated from materials as diverse as steel, polypropylene, and polycrystalline silicon.

Detta projekt gick ut på att undersöka möjligheterna för integrerade gångjärn till köksluckor samt att försöka ta fram en möjlig lösning. Under projektets inledande fas faktainsamlingen undersöktes dagens lösningar, diverse material och tillverkningsmetoder samt tribologi. Kundkrav identifierades som sedan låg till grun-den för funktionsanalysen, dessa funktioner rangordnades. De tre högst prioriterade egenskaperna var dold öppning, monteringsmöjlighet och justeringsmöjlighet. Dessa rangordnade funktionerna användes till idégenereringen och olika koncept togs fram, bland dessa koncept valdes ett som sedan bearbetades i flera iterationer med hjälp av CAD-program och prototyping till ett förfinat koncept som blev projektets resultat. / This project intended purpose was to examine the possibilities with integrated hinges for kitchen cabinet doors and try to develop a plausible solution. The project started with benchmarking and thereafter researching different materials, manufacturing methods and lubricants. Customer demands was also identified and these demands where used for the function analysis. These functions where the backbone of the morphological matrix used in the concept generating process that led to sex different concept ideas, one concept idea was chosen and developed in to one nearly finished product.

Résumé : Plusieurs tremblements de terre passés ont montré que face aux séismes, les ponts peuvent être les points faibles d’un réseau de transport. Néanmoins, les retours des expériences postsismiques ainsi que les études théoriques et expérimentales effectuées par les chercheurs et les ingénieurs de la pratique ont permis de faire évoluer les règles de l'art relatives au comportement sismique des ponts. Un des résultats de cette évolution est le dimensionnement basé sur la performance sismique (DBPS). En bref, le DBPS tente de concevoir des structures qui atteindront un état limite de performance déterminé lorsqu’ils sont soumis à un séisme d’une intensité donné. Toutefois, dans l'optique du DBPS, il est primordial de situer les états limites des composantes principales des ponts, principalement des piliers, de manière mesurable plutôt que phénoménologique. Lors du développement de courbes de fragilité des ponts au Québec, il est apparu que les états limites des piliers de ponts n'étaient pas clairement définis. Un programme de recherche expérimental a donc été conçu pour déterminer les états limites des piliers de pont en béton armé. Le projet comprend l’essai d’un poteau en béton armé à échelle réelle soumis à des cycles de chargement latéral en plus d’une charge axiale constante représentative du niveau de chargement réel. Le poteau reproduit les propriétés exactes des piliers du pont Chemin des Dalles (Trois-Rivières, Québec). Ce projet de recherche vise à améliorer l’évaluation de la fragilité sismique des ponts actuels du réseau routier québécois et à optimiser le dimensionnement sismique des futures structures selon l’approche basée sur la performance sismique. En particulier, le projet cherche à répondre aux incertitudes importantes qui subsistent sur la description quantitative des états limites des piliers de ponts en béton armé, particulièrement au niveau des déformations associées. / Abstract : Several past earthquakes have shown that bridges can be the weak points of a transport network. Nevertheless, returns of the post-seismic experiences as well as theoretical and experimental studies made by researchers and practice engineers allowed the art rules evolution related to the seismic behavior of bridges. One result of this evolution is the seismic performance based design (DBPS). In brief, the DBPS tries to design structures which will reach a certain limit state of performance when they are submitted to an earthquake of a given intensity. However, in the optics of the DBPS, it is essential to define the limit states of the main components of bridges, mainly for columns, in a measurable way rather than phenomenological. During the development of the fragility curves of bridges in Québec, it seemed that the limit states of the bridges columns were not clearly defined. An experimental research program was thus designed to determine the limit states of the reinforced concrete bridge columns. The project includes the testing of a large-scale reinforced concrete bridge column submitted to lateral cycles load in addition to a constant axial load which represented the real dead load level. The column reproduces the exact properties of the Chemin des Dalles bridge columns (Trois-Rivières, Québec). This research project aims to improve the evaluation of the seismic fragility of existing bridges of Québec road network and optimize the seismic design for future structures according to the performance based seismic approach. In particular, the project seeks to address the significant uncertainties which remain on the quantitative description of the limit states of the reinforced concrete bridge columns, particularly at the associated deformations level.