In this thesis, store separation from two different configurations are solved using computational methods. Two different commercially available CFD codes / CFD-FASTRAN, an implicit Euler solver, and an unsteady panel method solver USAERO, coupled with integral boundary layer solution procedure are used for the present computations. The computational trajectory results are validated against the available experimental data of a generic wing-pylon-store configuration at Mach 0.95. Major trends of the separation are captured. Same configuration is used for the comparison of unsteady panel method with Euler solution at Mach 0.3 and 0.6. Major trends are similar to each other while some differences in lateral and longitudinal displacements are observed. Trajectories of a fueltank separated from an F-16 fighter aircraft wing and full aircraft configurations are found at Mach 0.3 using only the unsteady panel code. The results indicate that the effect of fuselage is to decrease the drag and to increase the side forces acting on the separating fueltank from the aircraft. It is also observed that the yawing and rolling directions of the separating fueltank are reversed when it is separated from the full aircraft configuration when compared to the separation from the wing alone configuration.

The objective of this thesis is to accomplish the three dimensional parallel thin-layer Navier-Stokes solutions for low aspect ratio rectangular flat wings in compressible flow. Two block parallel Navier Stokes solutions of an aspect ratio 1.0 flat plate with sharp edges are obtained at different Mach numbers and angles of attack. Reynolds numbers are of the order of 1.0E5-3.0E5. Two different grid configurations, the coarse and the fine grids, are applied in order to speed up convergence. In coarse grid configuration, 92820 total grid points are used in two blocks, whereas it is 700,000 in fine grid. The flow field is dominated by the vortices and the separated flows. Baldwin Lomax turbulence model is used over the flat plate surface. For the regions dominated by the strong side edge vortices, turbulence model is modified using a polar coordinate system whose origin is at the minimum pressure point of the vortex. In addition, an algebraic wake-type turbulence model is used for the wake region behind the wing. The initial flow variables at the fine grid points are obtained by the interpolation based on the coarse grid results previously obtained for 40000 iterations. Iterations are continued with the fine grid about 20000-40000 more steps. Pressures of the top surface are predicted well with the exception of leading edge region, which may be due to unsuitable turbulence model and/or grid quality. The predictions of the side edge vortices and the size of the leading edge bubble are in good agreement with the experiment.

In this thesis a 3-D Euler flow solver is coupled with a finite element program in order to solve static aeroelastic problems involving aircraft wings. A loosely coupled solution approach based on an iterative solution procedure is used to solve the coupled field problem. Because of the deformation of the underlying surface over which the flow is solved, Computational Fluid Dynamics mesh has to move at each computational aeroelastic iteration in order to comform to the new shape of the aerodynamic surface. As a part of this work, a procedure is developed in order to move fluid grid points, which views the whole computational domain as an isotropic elastic medium and solves it using finite element method. A matching discrete interface is defined / displacement and pressure data exchange is accomplished at this interface. AGARD Wing 445.6 and an elastic supercritical wing is modelled and solved with the developed computational aeroelastic procedure and the obtained results are compared with numerical and wind tunnel data.

In this thesis, optimal placement of adhesively bonded piezoelectric patches on laminated plates and the determination of geometry of the bonding area to maximize actuation effect are studied. A new finite element model, in which each layer is considered to be a separate plate, is developed. The adhesive layer is modeled as a distributed spring system. In this way, relative transverse normal and shear motion of the layers are allowed. Effect of delamination on the adhesive layer stresses is also studied and investigated through several case studies. Optimization problems, having single and multiple objectives, are investigated for both actuator placement and selective bonding examples. In these case studies, 2D and 3D Pareto fronts are also obtained. &amp / #8216 / Hide and Seek Simulated Annealing&amp / #8217 / method is adapted for discrete problems and used as the optimization technique for single-objective problems. Finally, Multiple Cooling Multi Objective Simulated Annealing optimization algorithm is adapted and used in multi-objective optimization case studies.

The purpose of this thesis is to implement Finite Volume Weighted Essentially Non-Oscillatory (FV-WENO) scheme to solution of one and two-dimensional discretised Euler equations with different flux algorithms. The effects of the different fluxes on the solution have been tested and discussed. Beside, the effect of the grid on these fluxes has been investigated. Weighted Essentially Non-Oscillatory (WENO) schemes are high order accurate schemes designed for problems with piecewise smooth solutions that involve discontinuities. WENO schemes have been successfully used in applications, especially for problems containing both shocks and complicated smooth solution structures. Fluxes are used as building blocks in FV-WENO scheme. The efficiency of the scheme is dependent on the fluxes used in scheme The applications tested in this thesis are the 1-D Shock Tube Problem, Double Mach Reflection, Supersonic Channel Flow, and supersonic Staggered Wedge Cascade. The numerical solutions for 1-D Shock Tube Problem and the supersonic channel flow are compared with the analytical solutions. The results for the Double Mach Reflection and the supersonic staggered cascade are compared with results from literature.

Le développement dans l'industrie aéronautique des composites à matrices organiques renforcés par des fibres de carbone se justifie entre autres par leur très bonne capacité à transférer les efforts mécaniques élevés en rapport de leur faible masse. Les matrices Poly-EtherEtherCétone (PEEK) sont des candidates idéales pour les applications structurales en raison de leurs bonnes propriétés chimiques, mécaniques, ainsi que d'une stabilité thermique supérieure à d'autres polymères. Cependant celles-ci présentent des inconvénients majeurs pour la phase de mise en peinture, à savoir une faible réactivité de surface et une inertie chimique importante qui impliquent le développement d'un procédé d'activation de surface avant toute étape de revêtement. Ce travail se concentre sur une technologie de plasma froid à la pression atmosphérique développée par la société AcXys Technologie(r) : le module ULS en post-décharge. Cette technologie, choisie sur la base de considérations industrielles et environnementales, vise à garantir une activation de surface efficace, sans détérioration des propriétés intrinsèques de la matrice polymère. L'objectif de ce travail est alors d'améliorer la compréhension des mécanismes d'activation par plasma menant à une meilleure adhésion à l'interface composite PEEK/revêtement industriel. Des caractérisations électriques et optiques de la décharge et de la post-décharge nous permettront de mieux comprendre le fonctionnement intrinsèque de l'équipement. Tandis que la caractérisation des modifications de surface (de nature chimiques, physiques et/ou physico-chimiques), notamment au travers de la mouillabilité et de l'acido-basicité, permet d'appréhender l'influence des paramètres opératoires et du gaz plasmagène utilisé. Dans la perspective de mieux spécifier les conditions optimales d'utilisation industrielles, nous évaluons dans cette étude la pertinence de l'utilisation de la notion de dose plasma pour ce procédé, notion représentative de l'ensemble des paramètres opératoires. Cette notion, communément rencontrée dans d'autres procédés, est revue et développée pour correspondre à notre cas d'étude. Son utilisation permet une juste comparaison entre des configurations d'activation différentes puisqu'elle rend compte à la fois de la puissance dissipée sur le substrat et du temps d'interaction plasma/surface. Afin de valider la dose plasma exprimée pour notre équipement, nous introduisons des mesures d'adhérence effectuées entre le composite activé et le revêtement. Les résultats laissent entrevoir des perspectives d'améliorations dans les procédés industriels d'activation de surface. / Carbon Fiber Reinforced Polymer (CFRP) using thermoplastic polymer matrices as Poly-EtherEtherKetone (PEEK) for example, are increasingly being used in structural engineering due to their light weight coupled with good mechanical properties. In aeronautic industry, the adhesive bonding of these composites is often required. However, their low surface energy motivates the development of robust and reliable surface activation treatments aiming at increasing the surface reactivity before painting. For this reason, we have used an atmospheric pressure plasma torch developed by AcXys Technologies(r). It is a remote plasma, well known to be an effective process to improve surface reactivity without deterioration of the bulk matrix properties. This easily implementable technology attracts many industries looking for a cost-effective and eco-friendly surface activation process. The aim of this work is to contribute to the understanding of plasma activation mechanisms leading to a greater and a more durable adhesion between PEEK matrix and an industrial painting. This study provides some insight into the effects of process parameters (device power, distance between nozzle and substrate, etc) on adhesion improvement. Mechanisms which are attributed to it are investigated by means of three point bending and crosscut adhesion standard tests. Results are discussed with respect to surface properties characterized by wettability measurements including acid-base approach, X-ray Photoelectrons Spectroscopy and Atomic Force Microscopy. In order to facilitate industrialization of atmospheric pressure remote plasma as surface activation technique, this study proposes a new approach aiming at allowing a better and more equitable comparison between atmospheric pressure plasma processes. This comparison is made through the "plasma dose" expression, similar to the one commonly used in Corona process. It is applicable for one plasma gas and accounts for both received energy and interaction time of the post-discharge with the surface. Mechanisms assigned to improvement of adhesion will be more appreciated and their characterization will contribute to a greater definition of industrial surface preparation range by remote plasma.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-24Bitstream added on 2014-06-13T18:55:43Z : No. of bitstreams: 1 franco_vr_me_ilha.pdf: 5148348 bytes, checksum: 722b347f89e5e9a0aa5c379afe0dadba (MD5) / Financiadora de Estudos e Projetos (FINEP) / Este trabalho apresenta o estudo e desenvolvimento de uma técnica de monitoramento da integridade estrutural, para identificação e caracterização de falhas estruturais através da metodologia das ondas de Lamb utilizando materiais piezelétricos como sensores e atuadores. Ondas de Lamb são uma forma de perturbação elástica que se propaga guiada entre duas superfícies paralelas livres. Ondas de Lamb são formadas quando o atuador excita a superfície da estrutura com um pulso depois de receber um sinal. Quando uma onda propaga na superfície de uma placa, ela chega em um PZT sensor por diferentes caminhos. Um caminho é quando a onda atinge o sensor diretamente, ou seja, sem obstáculos no caminho em que ela se propaga. Outro caminho possível é quando a onda chega ao sensor após se propagar sobre descontinuidades existentes na superfície da estrutura. Com as várias características dos sinais recebidos, e com o uso de certas técnicas de processamento de sinais, essas falhas podem ser identificadas, realizando-se a ação correta tentando evitar a total falha da estrutura. Nesse contexto, diferentes testes experimentais foram realizados em diferentes tipos de estruturas. Redes de sensores e atuadores piezelétricos foram acopladas na superfície dessas estruturas, a fim de se fazer a configuração das ondas de Lamb. Os PZTs atuadores excitaram a estrutura em altas faixas de frequência. Diferentes tipos de falhas estruturais foram simuladas, através do aumento de massa, alteração de rigidez e através de cortes na borda das estruturas. Quatro índices de falha foram utilizados para detectar a presença da falha na estrutura, são eles: Root- Means-Square Deviation (RMSD), Índice de Falha Métrica (IFM), Norma H2 e Correlation Coefficient Deviation Mean (CCDM). Estes índices foram computados através dos sinais de entrada e de saída no domínio da frequência... / This work presents the study and development of a Structural Health Monitoring technique for identification and characterization of structural damages based on Lamb waves methodology using piezoelectric materials as actuators and sensors. Lamb waves are a form of elastic perturbation that remains guided between two parallel free surfaces. Lamb waves are formed when the actuator excites the structure’s surface with a pulse after receiving a signal. When the wave propagates on the structure, it comes in a PZT sensor from different paths. One path is when the wave reaches the sensor directly, i.e. without obstacles in the path in which it propagated. Another possible path is when the wave reaches the sensor after spreads on discontinuities in the structure’s surface. Damages can be detected and located through several features of the received signals and with the use of certain techniques of signal processing. In this context, several experimental tests were performed on different kinds of structures. Piezoelectric actuators and sensors networks were attached on the surface of these structures in order to make the Lamb waves configuration. The PZTs actuators excited the structure in high frequency ranges. Different kinds of structural damages were simulated by increasing mass, reduction of stiffness and cuts through the edge of the structures. Four damage-sensitive indexes were used to detect the presence of the damage in the structure: Root-Means-Square Deviation (RMSD), Metric Damage Index (MDI), H2 Norm and Correlation Coefficient Deviation (CCDM). These indices were computed in the frequency domain. The results showed the viability of the Lamb waves methodology for Structural Health Monitoring system using smart materials as actuators and sensors

Resumo: Este trabalho apresenta o estudo e desenvolvimento de uma técnica de monitoramento da integridade estrutural, para identificação e caracterização de falhas estruturais através da metodologia das ondas de Lamb utilizando materiais piezelétricos como sensores e atuadores. Ondas de Lamb são uma forma de perturbação elástica que se propaga guiada entre duas superfícies paralelas livres. Ondas de Lamb são formadas quando o atuador excita a superfície da estrutura com um pulso depois de receber um sinal. Quando uma onda propaga na superfície de uma placa, ela chega em um PZT sensor por diferentes caminhos. Um caminho é quando a onda atinge o sensor diretamente, ou seja, sem obstáculos no caminho em que ela se propaga. Outro caminho possível é quando a onda chega ao sensor após se propagar sobre descontinuidades existentes na superfície da estrutura. Com as várias características dos sinais recebidos, e com o uso de certas técnicas de processamento de sinais, essas falhas podem ser identificadas, realizando-se a ação correta tentando evitar a total falha da estrutura. Nesse contexto, diferentes testes experimentais foram realizados em diferentes tipos de estruturas. Redes de sensores e atuadores piezelétricos foram acopladas na superfície dessas estruturas, a fim de se fazer a configuração das ondas de Lamb. Os PZTs atuadores excitaram a estrutura em altas faixas de frequência. Diferentes tipos de falhas estruturais foram simuladas, através do aumento de massa, alteração de rigidez e através de cortes na borda das estruturas. Quatro índices de falha foram utilizados para detectar a presença da falha na estrutura, são eles: Root- Means-Square Deviation (RMSD), Índice de Falha Métrica (IFM), Norma H2 e Correlation Coefficient Deviation Mean (CCDM). Estes índices foram computados através dos sinais de entrada e de saída no domínio da frequência... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents the study and development of a Structural Health Monitoring technique for identification and characterization of structural damages based on Lamb waves methodology using piezoelectric materials as actuators and sensors. Lamb waves are a form of elastic perturbation that remains guided between two parallel free surfaces. Lamb waves are formed when the actuator excites the structure's surface with a pulse after receiving a signal. When the wave propagates on the structure, it comes in a PZT sensor from different paths. One path is when the wave reaches the sensor directly, i.e. without obstacles in the path in which it propagated. Another possible path is when the wave reaches the sensor after spreads on discontinuities in the structure's surface. Damages can be detected and located through several features of the received signals and with the use of certain techniques of signal processing. In this context, several experimental tests were performed on different kinds of structures. Piezoelectric actuators and sensors networks were attached on the surface of these structures in order to make the Lamb waves configuration. The PZTs actuators excited the structure in high frequency ranges. Different kinds of structural damages were simulated by increasing mass, reduction of stiffness and cuts through the edge of the structures. Four damage-sensitive indexes were used to detect the presence of the damage in the structure: Root-Means-Square Deviation (RMSD), Metric Damage Index (MDI), H2 Norm and Correlation Coefficient Deviation (CCDM). These indices were computed in the frequency domain. The results showed the viability of the Lamb waves methodology for Structural Health Monitoring system using smart materials as actuators and sensors / Orientador: Vicente Lopes Junior / Coorientador: Michael J. Brennan / Banca: Gilberto Pechoto de Melo / Banca: José Roberto de França Arruda / Mestre

A gestão da Cadeia de Suprimentos (SCM) é hoje parte essencial do nosso dia a dia. Ela tem uma influência crescente sobre um grande número de atividades humanas e econômicas e, portanto, é um assunto crítico para a indústria e para a academia. Existe a necessidade de se entender como as pessoas podem ajudar no sucesso da Cadeia de Suprimentos. No entanto, há uma escassez de investigações empíricas das contribuições das variáveis humanas, em especial a cultura, para a Integração da Cadeia de Suprimentos (SCI). Este trabalho tem por objetivo investigar as relações entre as dimensões culturais e a SCI por meio de um estudo de caso exploratório em uma empresa do setor aeronáutico brasileiro. Estabeleceram-se considerações teóricas que determinadas práticas organizacionais contribuiriam para a maior integração de uma Cadeia de Suprimentos genérica (orientação a resultado, orientação a funcionário, sistema aberto, controle frouxo de trabalho, profissionalismo e pragmatismo) o que foi constatado na investigação empírica. Além disso, levou-se em conta a influência da cultura brasileira sobre as práticas organizacionais, de forma que a alta distância do poder e alta aversão à incerteza, por exemplo, dificultariam a orientação a resultado e de sistema aberto, enquanto o alto coletivismo e a relativa feminilidade facilitariam a orientação a funcionário e controle de trabalho frouxo. Este trabalho contribui para propor novas perspectivas e insights que possam levar ao aprofundamento dos estudos das relações entre a cultura e a Cadeia de Suprimentos, além da consideração de aspectos culturais locais no estudo das práticas gerenciais. / The Supply Chain management (SCM) is an essential part of our daily lives. It has a growing influence on a large number of human and economic activities and therefore is a critical issue for the industry and the academy. There is a need to understand how people can help the effectiveness of Supply Chain, however, there is a lack of empirical investigations of the human variables contributions, especially culture, for the Supply Chain Integration (SCI). This work aims to investigate the relations between cultural dimensions and SCI through an exploratory case study in a company in the aeronautical industry. Theoretical considerations were settled in which certain organizational practices contribute to the further integration of a generic Supply Chain (result orientation, employee orientation, open system, loose work control, professionalism and pragmatism) which was corroborated in the empirical research. In addition, we took into account the influence of Brazilian culture on organizational practices so that high power distance and high uncertainty avoidance, for example, hinder the results orientation and an open system, while the high collectivism and the relative femininity facilitate the employee orientation and the loose work control. This work contributes to propose new perspectives and insights that may lead to deeper studies of the relationship between culture and the Supply Chain, beyond the consideration of local cultural aspects in the study of management practices.

O trabalho visou realizar um estudo sobre o comportamento mecânico e de inflamabilidade de estruturas aeronáuticas de interior fabricadas a partir de compósitos reforçados por fibras naturais, especificamente compósitos de resina fenólica com fibras de algodão e de sisal, verificando assim, a possibilidade de substituir compósitos sintéticos. Num primeiro momento, análises experimentais foram executadas para determinar as propriedades mecânicas dos materiais. Em seguida, análises computacionais foram realizadas, empregando as propriedades referentes aos compósitos sintéticos e reforçados por fibras naturais, utilizando critérios de falha e tendo como referência o desempenho do compósito sintético para uma dada estrutura aeronáutica de interior. Além disso, foram efetuadas análises do seu comportamento quanto à inflamabilidade. A incorporação de retardantes de chama foi necessária para que os compósitos reforçados por fibras naturais atendessem aos requisitos de certificação aeronáutica. Após o processo de aditivação, observou-se um aumento do módulo de elasticidade à flexão (55% para o compósito de algodão, 16% para o compósito de sisal) e a diminuição da tensão de ruptura à flexão dos compósitos reforçados por fibras naturais analisados (45% para o compósito de algodão, 55% para o compósito de sisal). No entanto, com o aumento da espessura da estrutura aeronáutica adotada (5,2% para o compósito de algodão, 10,7% para o compósito de sisal), conclui-se que a substituição do compósito sintético pelo natural seria viável. Isto acarretaria em um aumento de massa em 6,2%, caso a estrutura fosse fabricada em compósito reforçado por fibra de sisal. Finalmente, constatou-se que a fração mássica de aditivo utilizada tem grande potencial de otimização e, que a eficiência dos compósitos reforçados por fibras naturais ainda pode ser melhorada. / This dissertation has aimed to study the mechanical behavior and the flammability of aeronautical interior structures manufactured from composites reinforced by natural fibers, specifically phenolic resin and cotton and sisal fibers composites, verifying the possibility of synthetic composites replacement. Firstly, experimental analyses were performed to determine the mechanical properties of the materials. Then, computational analyses were carried out, using properties of synthetic composites and composites reinforced by natural fibers. Also, failure criteria were applied, considering the synthetic composite performance of an interior aeronautical structure as reference. Furthermore, the behavior regarding flammability was analyzed. The addition of flame retardants was necessary for the composites reinforced by natural fibers in order to attend the aeronautical certification requirements. After the addition of flame retardants, an increase in the flexural modulus of elasticity (55% for the cotton composite, 16% for the sisal composite) and a decrease in the flexural stress at break (45% for the cotton composite, 55% for the sisal composite) were observed. However, with an increase of the thickness of the aeronautical structure (5.2% for the cotton composite, 10.7% for the sisal composite), it was concluded that the replacement would be feasible, which would lead to a increase of the mass equal 6.2% for the sisal fiber composite. Finally, it was evidenced that the used flame retardant mass fraction has a great potential for optimization and that the natural composites efficiency can be improved.