Non-Destructive Testing of industrial components carries vital importance, both financially and safety-wise. Among all Non-Destructive techniques, Long Range Ultrasonic Testing utilizing the guided wave phenomena is a young technology proven to be commercially valid. Owing to its well-documented analytical models, Ultrasonic Guided Waves has been successfully applied to cylindrical and plate-like structures. Its applications to complex structures such as multi-wire cables are fairly immature, mainly due to the high complexity of wave propagation. Research performed by the author approaches the long range inspection of overhead transmission line cables using ultrasonic guided waves. Existing studies focusing on guided wave application on power cables are extremely limited in inspection range, which dramatically degrades its chances of commercialization. This thesis consists of three main chapters, all of which approaches different problems associated with the inspection of power cables. In the first chapter, a thorough analysis of wave propagation in ACSR (most widely used power cable) cables is conducted. It is shown that high frequency guided waves, by concentrating the energy on the surface layers, can travel much further in the form of fundamental longitudinal wave mode, than previous studies have shown. Defect detection studies proved the system’s capability of detecting defects which introduce either increase or decrease in cross sectional area of the cable. Results of the chapter indicate the detectability of defects as small as 4.5% of the cross sectional area through a 26.5 meter long cable without any post-processing. In the second chapter, several algorithms are proposed to increase the inspection range and signal quality. Well-documented wavelet-denoising algorithm is optimized for power cables and up to 24% signal-to-noise ratio improvement is achieved. By introducing an attenuation correction framework, a theoretical inspection range of 75 meters is presented. A new framework combining dispersion compensation and attenuation correction is proposed and verified, which shows an inspection range of 130 meters and SNR improvement up to 8 dBs. Last chapter addresses the accurate localization of structural defects. Having proven the optimum excitation and related wave propagation in ACSR cables, a system having a more complex wave propagation characteristics is studied. A new algorithm combining pulse compression using Maximal Length Sequences and dispersion compensation is applied to multi-modal signals obtained from a solid aluminum rod. The algorithm proved to be able to improve signal quality and extract an accurate location for defects. Maximal Length Sequences are compared to chirp signals in terms of SNR improvement and localization, which produced favourable results for MLS in terms of localization and for chirp in terms of SNR improvement.

A low-order, dynamical systems approach is applied to the modeling of flow induced vibrations of flexible cables. By combining a coupled map lattice wake model with a linear wave equation cable model, both the free response of the cable as well as the resulting wake structures are examined. This represents an extension of earlier coupled map lattice models that only modeled the wake of forced cable vibration. The validity of the model is assessed through comparisons with both Computational Fluid Dynamics models (NEKTAR spectral element code) and wake experiments. The experimental wake data was collected through the use of hot-film anemometry techniques. Eight hot-film probes were placed along the span of a flexible cable mounted in the test section of a water tunnel. Through the use of frequency domain correlation algorithms, the phase of vortex shedding was calculated along the cable span from the hot-film velocity data. Results for an elastically mounted rigid cylinder showed that the freely vibrating CML model predicted behavior characteristic of a self-induced oscillator; the maximum amplitude of vibration was found to occur at a cylinder natural frequency that did not coincide identically with the natural shedding frequency of the cylinder. Furthermore, the variation of the frequency of cylinder vibration with its natural frequency was seen to be linear. For standing wave cable responses, the freely vibrating CML model predicted lace-like wake structures. This result is qualitatively consistent with both the NEKTAR simulations and experimental results. Little difference was found between the wakes of forced and freely vibrating cables at the Reynolds number of the study $Re=100$. Finally, it was found that the freely vibrating CML could match numerical predictions of cross-flow amplitude as the cable mass-damping parameter was varied over an order of magnitude (once the CML was tuned to match results at a specific mass-damping level). In addition to providing wake patterns for comparisons with the freely vibrating CML, experimental data was supplied to a self-learning CML scheme. This self-learning CML was able to estimate the experimental wake data with good accuracy. The self-learning CML is seen as the next extension of the freely-vibrating CML model, capable of estimating unmodeled wake dynamics through the use of experimental data.

The reliability of the main cable of a suspension bridge is crucial to the reliability of the entire bridge. Throughout the life of a suspension bridge, its main cables are subject to corrosion due to various factors, and the deterioration of strength is a slowly evolving and dynamic process. The goal of this research is to find the pattern of how the strength of steel wires inside a suspension bridge cable changes with time. Two methodologies are proposed based on the analysis of five data sets which were collected by testing pristine wires, artificially corroded wires, and wires taken from three suspension bridges: Severn Bridge, Forth Road Bridge and Williamsburg Bridge. The first methodology is to model wire strength as a random process in space whose marginal probability distribution and power spectral density evolve with time. Both the marginal distribution and the power spectral density are parameterized with time-dependent parameters. This enables the use of Monte Carlo methods to estimate the failure probability of wires at any given time. An often encountered problem -- the incompatibility between the non-Gaussian marginal probability distribution and prescribed power spectral density -- which arises when simulating non-Gaussian random processes using translational field theory, is also studied. It is shown by copula theory that the selected marginal distribution imposes restrictions on the selection of power spectral density function. The second methodology is to model the deterioration rate of wire strength as a stochastic process in time, under Ito's stochastic calculus framework. The deterioration rate process is identified as a mean-reversion stochastic process taking non-negative values. It is proposed that the actual deterioration of wire strength depends on the deterioration rate, and may also depend on the state of the wire strength itself. The probability distribution of wire strength at any given time can be obtained by integrating the deterioration rate process. The model parameters are calibrated from the available data sets by matching moments or minimizing differences between probability distributions.

A indústria eletro-eletrônica vem aumentando a quantidade de sucatas geradas anualmente. Por este motivo necessita-se de reciclagem, para que se evite o desperdício de matérias-primas e de recursos naturais não-renováveis. A maioria dos produtos eletro-eletrônicos não recebe tratamento pós-consumo sendo depositada em aterros sanitários junto com o resíduo doméstico.Os resíduos eletro-eletrônicos são caracterizados pela presença de metais distribuídos em placas de circuito impresso, fios e cabos elétricos e componentes eletrônicos em geral. No caso da reciclagem de fios e cabos ainda persistem práticas incorretas, como a queima do plástico para aproveitamento do metal, que elimina o polímero em vez de aproveitá-lo. A solução para este problema está no reaproveitamento destes metais e polímeros contidos nos resíduos eletro-eletrônicos. Assim, deixarão de ser perdidas quantidades de alumínio, cobre, e polímeros presentes nos cabos, os quais poderão gerar receitas para o processo, já que estes são indispensáveis ao processo de fabricação. O objetivo deste trabalho é estudar a reciclagem dos cabos tipo cordão paralelo e flexível através de operações unitárias de Tratamento de Minérios. O tratamento da sucata iniciou-se com a seguinte seqüência: moagem, separação granulométrica, separação em meio denso, separação eletrostática, atrição, bateamento e elutriação. Ao final destes processos observou-se que as operações unitárias utilizadas na pesquisa obtiveram concentrados de cobre com baixo grau de contaminação, porém com exceção da elutriação, todas precisam de uma outra técnica para complementá-las. Com os resultados obtidos, concluiu-se que a moagem em moinho de facas com grelha de 3mm seguida de elutriação possibilita a separação do material polimérico, assim como, a obtenção de um concentrado de cobre. / The electro-electronics industry follows increasing the amount of scraps annually generated. For this reason it is necessary to recycle, so that it prevents the waste of raw materials and not renovable natural resources. The majority of the electro-electronic products do not receive any treatment after use and is disposed in municipal landfills together with solid wastes (MSW). The electro-electronic wastes are characterized by metal presence distributed in printed circuits, wires and cables and electronic components in general. In the case of the recycling of wires and cables incorrect practices still persist, as the burning of the plastic for recovery of the metal, thus eliminating the polymer instead of using it to advantage. The solution for this problem is in the recovery of the metals and polymers contained in the electro-electronic wastes. Thus, amounts of aluminum, copper, and polymers contained in the cables will not be lost, that way they will be able to generate resources for the process, since these substances are indispensable to the manufacture process. The objective of this work is to study the recycling of the parallel and flexible cables through Mineral Processing unit operations. The treatment of the scrap was initiated with the following sequence: grinding, size classification, density separation, electrostatic separation, attrition, panning and elutrition. To the end of this process concentrate conductor of copper with low degree of contamination were achieved. However, with exception of elutrition, all they need another technique to complement them. With the gotten results, it can be concluded that the milling in knives mill with 3mm grate followed of elutrition makes possible the separation of the polymeric material, as well as, the attainment of a copper concentrate.

As pontes estaiadas vêm sendo cada vez mais utilizadas no país, seja pela competitividade alcançada em função do domínio da tecnologia por parte dos empreiteiros e calculistas, seja pelo apelo estético. Os cabos, principais componentes deste sistema estrutural, que conferem o caráter altamente hiperestático e o comportamento não linear da estrutura são, em muitos modelos, numericamente simulados como um elemento de treliça, com a sua rigidez calculada em função da geometria e nível de carregamento do cabo. No presente trabalho é verificada a influência da componente tangencial do peso próprio do cabo, desprezada por Dishinger no cálculo da rigidez equivalente do elemento de cabo, comparada com o método proposto por Hajdn. Os resultados também são comparados com os da modelagem do cabo discretizado em elementos de treliça, seguindo a Formulação Posicional dos Elementos Finitos, que se mostrou bastante eficaz para simulação do cabo isolado, onde a capacidade de representar o comportamento do cabo foi verificada através de exemplos que mostram aspectos do comportamento não linear do mesmo. / Cable stayed bridges are being increasingly used in Brazil due to the recent master on this technology by the builders and designers and because of its aesthetics appealing. The principal components of this type of bridge, the cables, responsible for high non-linear behavior of the structure, are frequently modeled as truss element with its stiffness evaluated according to the tension and horizontal projection of the span of the cable. On the present paper the influence by neglecting the tangential component of the weight of the cable on Dishingers formula is investigated. The results are compared with the formula by Hajdn and with a model in which the cable is discretized in truss bars in a program based on the Positional Finite Element Method which has presented good results to describe the non-linear behavior of the cable.

Tubos flexíveis e cabos umbilicais têm sido bastante utilizados pela indústria petrolífera em aplicações offshore nos últimos anos. Os primeiros consistem num tipo de tubulação usada para o transporte de vários tipos de fluidos, geralmente trabalhando a alta pressão. Já os cabos umbilicais são usados para permitir o controle e a comunicação entre equipamentos submersos e de superfície. Quanto à concepção estrutural, os dois tipos de produto são muito semelhantes, apresentando diversas camadas metálicas combinadas com camadas plásticas concêntricas de modo a formar uma estrutura com grande rigidez axial e torcional, porém baixa rigidez flexional. O escopo deste trabalho é o estudo de modelos analíticos para a previsão do comportamento estrutural de tubos flexíveis e cabos umbilicais. Inicialmente são propostos modelos para a análise local destas estruturas, sob a ação de carregamentos de tração, torção, pressão interna, externa e flexão, agindo isoladamente ou combinados. São propostos modelos analíticos consistentes para cada camada, resultando num sistema de equações algébricas que, ao ser resolvido, fornece os valores de tensões e deformações nas diversas camadas, bem como os valores de rigidez equivalente axial, flexional e torcional do tubo/cabo. São feitas várias comparações entre os resultados obtidos analiticamente e resultados experimentais obtidos na literatura para diversos tubos e cabos. A importância dos modelos desenvolvidos fica evidente numa análise do comportamento global para a previsão de instabilidade de linhas sob carregamento combinado de torção e compressão dinâmica. Através de uma análise consistente, mostra-se que a clássica equação de Greenhill também pode ser utilizada para a determinação das cargas críticas de flambagem em barras curvas de grande comprimento, sendo o comprimento de flambagem da barra estimado a partir da relação de dispersão de onda flexional numa viga reta. Vários exemplos de determinação da carga crítica de flambagem são abordados, envolvendo tanto risers rígidos quanto flexíveis. Uma atenção especial ao estabelecimento e discussão de hipóteses é dada em todos os modelos propostos. / Flexible pipes and umbilical cables have been largely used by the oil industry in offshore applications in these last years. The former are a kind of pipeline structure used for conducting several fluids, often working at high pressure, while the latter are cables used to provide control and communication links between seafloor and surface equipments. Regarding their structural design, both flexible pipes and umbilicals are quite similar, presenting a number of steel armour layers combined with polymeric layers disposed in such a way to form a structure which is stiff under torsion and traction, but compliant under bending. The aim of this work is the study of analytical models to predict the structural behaviour of flexible pipes and umbilicals. At first, local analysis of such structures is undertaken, considering combined loadings of traction, torsion, internal and external pressures and bending. Consistent analytical models, proposed for each layer, are then combined to result in a system of algebraic equations that is solved for the stresses and deformations in the layers. Equivalent axial, torsional and flexural stiffness values for the pipe/umbilical are also obtained. Several comparisons between analytical results and experimental results obtained in the literature are also made, involving both flexible pipes and umbilicals. The importance of the developed models is highlighted in an analysis of the global structural behaviour made to predict the instability condition of flexible lines under the action of dynamic compression and twisting moment. Through a consistent analysis, it is shown that the classical Greenhill formula can also be used to determine critical buckling loads for long curved rods. In this case, an estimate for the buckling lenght is given by the flexural wave dispersion relation of a straight beam. Several examples, involving both SCRs and flexible pipes, illustrate the method of critical buckling load determination. Emphasis is also given in the establishment and discussion of hypotheses for all proposed models.

[pt] Torres estaiadas são, em geral, estruturas bastante leves e esbeltas e que apresentam comportamento eminentemente não - linear. Assim, a análise de sua estabilidade sob cargas estáticas e dinâmicas é essencial para se ter um projeto econômico e seguro. Neste trabalho estuda-se a estabilidade estática e dinâmica de um modelo plano de torre estaiada. Especial atenção é dada à modelagem dos estais, que são modelados como elementos de mola (linear ou não -linear) ou como cabos inextensíveis. Faz-se, com base no princípio da energia potencial mínima, um estudo da carga crítica e do caminho pós-crítico. Um estudo paramétrico minucioso permite analisar a influência dos diversos parâmetros físicos e geométricos na estabilidade da torre e chegar às melhores configurações para os estais. Na análise dinâmica atenção especial é dada ao estudo paramétrico da freqüência natural. Com base nos resultados da análise estática, analisa-se também o comportamento global da torre em vibração livre e forçada. Em virtude das não linearidades, verifica-se que a torre pode apresentar diversos comportamentos típicos de sistemas não -lineares tais como saltos, bifurcações de período e caos. / [en] Guyed towers are in general very light and slender structures and their behavior under static and dynamic loads is eminently nonlinear. Thus the analysis of its stability under static and dynamic loads is an essential step in obtaining an economic and safe project. In this work the static and dynamic stability analysis of a plain model of a guyed tower is studied. Special attention is given to the modeling of the stays; here they are modeled as spring elements (linear or nonlinear) or as inextensible cables. A study of the critical load and the postcritical nonlinear equilibrium paths is conducted based on the principle of the minimum potential energy A detailed parametric analysis is performed to identify the influence of the physical and geometric parameters of the system on the stability of the tower. This allows one to choose the best configurations for the stays. In the dynamic analysis special attention is given to the parametric study of the system natural frequencies. Based on the results of the static analysis, the global behavior of the tower under free and forced vibration is also analyzed. Due to the inherent nonlinearities, the tower may present dynamic responses typical of nonlinear systems such as jumps, period bifurcations and chaos.

The dynamics of a tether cable for a flying wind generator, employed to generate electricity by utilising the high velocity jet-stream winds in the troposphere, is analysed. A non-linear mathematical model for the study of the dynamics of the cable is described by a partial differential equation, which is solved analytically without damping. For unsteady and damped states, ordinary differential equations are obtained by adopting a discrete analysis approach, which are solved numerically with the aid of MATLAB software. Solutions are found for a range of lumped masses to represent the cable and each solution is verified against a previous case. Likewise, the result for the three masses is checked against the cable using a single lumped mass. The analysis is extended to seven discrete masses. This research highlights the dynamic behaviour of the cable subjected to wind gusts on the rotors and it also represents an appreciable input to the flying wind generator concept. The dynamic behaviour of the cable is critical for a flying electric generator. / Master of Engineering (Hons)

<p>Current cabling systems in cars are about to be, completely or partially, replaced by a cabling technology called flexible flat cables, FFCs. This new technology requires tools that can assist engineers in the design process of the cable layouts. The aim of this thesis is to develop a software demonstrator of a concept tool for this purpose. </p><p>The task is divided into three problem areas. Topology modeling, optimization and visualization. An editor is to be implemented which handles creation and modification of topologies which represents FFC harnesses. The optimization is performed using global and local routing. The global routing handles optimization on topology level, defining net paths in the topology. Local routing handles the exact net placement on each bus cable. Finally, the local routing solutions should be graphically presented to the user. </p><p>The topology modeling requirement was implemented as a graph layouteditor. Global routing is performed using graph search techniques and local routing is based on VLSI channel routing methods. Visualization is implemented for the local routing solutions using the SVG format. </p><p>The developed application handles most of the requirements. The editor has support for an XML netlist which is used for specifying connectors and nets used in the topology. Global routing and local routing can be performed on the topology. Prerouting of nets can be performed on both global and local level. Support for assigning specific cables, from a library, to bus cables is possible.</p>

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