Composite materials have been more and more used in aircraft primary structures such as wing and fuselage. The aim of this thesis is to identify an effective way to optimize composite wing structure, especially the stiffened skin panels for minimum weight subject to stiffness and strength constraints. Many design variables (geometrical dimensions, ply angle proportion and stacking sequence) are involved in the optimum design of a composite stiffened panel. Moreover, in order to meet practical design, manufacturability and maintainability requirements should be taken into account as well, which makes the optimum design problem more complicated. In this thesis, the research work consists of three steps: Firstly, attention is paid to metallic stiffened panels. Based on the study of Emero’s optimum design method and buckling analysis, a VB program IPO, which employs closed form equations to obtain buckling load, is developed to facilitate the optimization process. The IPO extends the application of Emero’s method to an optimum solution based on user defined panel dimensional range to satisfy practical design constraints. Secondly, the optimum design of a composite stiffened panel is studied. Based on the research of laminate layup effects on buckling load and case study of bucking analysis methods, a practical laminate database (PLDB) concept is presented, upon which the optimum design procedure is established. By employing the PLDB, laminate equivalent modulus and closed form equations, a VB program CPO is developed to achieve the optimum design of a composite stiffened panel. A multi-level and step-length-adjustable optimization strategy is applied in CPO, which makes the optimization process efficient and effective. Lastly, a composite outer wing box, which is related to the author’s GDP work, is optimized by CPO. Both theoretical and practical optimum solutions are obtained and the results are validated by FE analysis.

Cargas oclusais excessivas podem promover tensões exageradas às estruturas de implantes/pilares/próteses, resultando em deformação, desadaptação ou mesmo fratura dos componentes e do próprio implante. Além disso, tais sobrecargas podem gerar necrose por compressão e perda óssea peri-implantar e, ainda, a ocorrência de microdeslocamentos na interface de conexão implante-pilar (I-P) ocasionando a formação de fendas propícias à colonização bacteriana, o que pode levar ao desenvolvimento de peri-implantite, contribuindo para o insucesso do conjunto. O presente estudo objetivou avaliar, por meio de uma técnica já amplamente utilizada na Engenharia e na Física a Interferometria Eletrônica por Padrões de Speckle (ESPI) as deformações a nível do colar de implantes com conexão cônica interna (cone Morse) de diferentes diâmetros (Kopp 4,3/5,5 mm e Neodent 3,5/5,0 mm), sob dois tipos (cêntrica e excêntrica) e intensidades (50 N e 100 N) de cargas, similares as quais os implantes ficam expostos durante a função mastigatória. Testou-se a hipótese de que a deformação do colar do implante seria inversamente proporcional ao diâmetro do implante. Além disso, discutiu-se vantagens e limitações da técnica ESPI frente a outros métodos comumente utilizados na avaliação de tensões. As maiores deformações foram sempre associadas às cargas excêntricas, com exceção do G1-Kopp. A maior deformação ocorreu no G1-Neodent sob carga excêntrica de 100 N e a menor, no G2-Neodent sob carga cêntrica de 50 N. A técnica ESPI mostrou-se altamente sensível e reprodutível para avaliar deformações a nivel do colar de implantes sendo possível confirmar a hipótese inicial, visto que a maior deformação esteve sempre associada aos implantes de menor diâmetro, em ambos os sistemas de implante pesquisados. / Occlusal overloading may promote excessive stresses to the implants/abutments/prosthesis, resulting in deformation, misfit or fracture of the components, until the implants. Futhermore, strains of the implant-abutment connection can cause the formation of microgaps propitious to bacterial colonization, which leads to the development of peri-implant sites, leading to the failure of the rehabilitation. This study aimed to evaluate, by a technique widely used in the engineering and physics Electronic Speckle Pattern Interferometry (ESPI) the strains related to the implant collar with internal tappered connection (Morse taper) with different diameters (Kopp 4.3/5.5 mm and Neodent 3,5/5,0 mm), under two types (centric and eccentric) and intensities (50 N and 100 N) of loads, similar which implants are exposed during masticatory function. We tested the hypothesis that the strains of the implants collar would be inversely proportional to the diameter of the implant. In addition, the survey discussed the advantages and limitations of the ESPI technique over other methods commonly used to assess strains. The largest strain was always associated with eccentric loads, except for G1-Kopp. The largest strain occurred in the G1-Neodent under the eccentric loads of 100 N and the lowest in the G2-Neodent under the centric loads of 50 N. The ESPI technique was a highly sensitive and reproducible to evaluate the strains at the level of the collar of implants being possible to confirm the initial hypothesis, since most strains was always associated with narrower-diameter implants in both implant systems studied.

Cargas oclusais excessivas podem promover tensões exageradas às estruturas de implantes/pilares/próteses, resultando em deformação, desadaptação ou mesmo fratura dos componentes e do próprio implante. Além disso, tais sobrecargas podem gerar necrose por compressão e perda óssea peri-implantar e, ainda, a ocorrência de microdeslocamentos na interface de conexão implante-pilar (I-P) ocasionando a formação de fendas propícias à colonização bacteriana, o que pode levar ao desenvolvimento de peri-implantite, contribuindo para o insucesso do conjunto. O presente estudo objetivou avaliar, por meio de uma técnica já amplamente utilizada na Engenharia e na Física a Interferometria Eletrônica por Padrões de Speckle (ESPI) as deformações a nível do colar de implantes com conexão cônica interna (cone Morse) de diferentes diâmetros (Kopp 4,3/5,5 mm e Neodent 3,5/5,0 mm), sob dois tipos (cêntrica e excêntrica) e intensidades (50 N e 100 N) de cargas, similares as quais os implantes ficam expostos durante a função mastigatória. Testou-se a hipótese de que a deformação do colar do implante seria inversamente proporcional ao diâmetro do implante. Além disso, discutiu-se vantagens e limitações da técnica ESPI frente a outros métodos comumente utilizados na avaliação de tensões. As maiores deformações foram sempre associadas às cargas excêntricas, com exceção do G1-Kopp. A maior deformação ocorreu no G1-Neodent sob carga excêntrica de 100 N e a menor, no G2-Neodent sob carga cêntrica de 50 N. A técnica ESPI mostrou-se altamente sensível e reprodutível para avaliar deformações a nivel do colar de implantes sendo possível confirmar a hipótese inicial, visto que a maior deformação esteve sempre associada aos implantes de menor diâmetro, em ambos os sistemas de implante pesquisados. / Occlusal overloading may promote excessive stresses to the implants/abutments/prosthesis, resulting in deformation, misfit or fracture of the components, until the implants. Futhermore, strains of the implant-abutment connection can cause the formation of microgaps propitious to bacterial colonization, which leads to the development of peri-implant sites, leading to the failure of the rehabilitation. This study aimed to evaluate, by a technique widely used in the engineering and physics Electronic Speckle Pattern Interferometry (ESPI) the strains related to the implant collar with internal tappered connection (Morse taper) with different diameters (Kopp 4.3/5.5 mm and Neodent 3,5/5,0 mm), under two types (centric and eccentric) and intensities (50 N and 100 N) of loads, similar which implants are exposed during masticatory function. We tested the hypothesis that the strains of the implants collar would be inversely proportional to the diameter of the implant. In addition, the survey discussed the advantages and limitations of the ESPI technique over other methods commonly used to assess strains. The largest strain was always associated with eccentric loads, except for G1-Kopp. The largest strain occurred in the G1-Neodent under the eccentric loads of 100 N and the lowest in the G2-Neodent under the centric loads of 50 N. The ESPI technique was a highly sensitive and reproducible to evaluate the strains at the level of the collar of implants being possible to confirm the initial hypothesis, since most strains was always associated with narrower-diameter implants in both implant systems studied.

Este trabalho se propõe a analisar os efeitos produzidos pela inundação do solo em estacas escavadas, isoladas, submetidas a esforços de compressão. Os resultados obtidos referem-se à execução de três provas de carga lentas em estacas com diâmetros de 0,40 m e 0,50 m (2 provas de carga distintas) e comprimentos de 10,0 m, submetidas anteriormente a uma série de carregamentos (duas provas de carga rápidas e duas lentas). Os resultados relativos aos deslocamentos medidos no topo das estacas e os obtidos pela instrumentação instalada ao longo do fuste são então comparados com a sequência dos resultados anteriores, para avaliação do efeito de umedecimento no comportamento \"carga x recalque\" e nos mecanismos de transferência de carga. É feita ainda uma descrição minuciosa do processo utilizado para inundação do solo e uma breve consideração sobre os efeitos da não reposição de cargas em ensaios lentos, de longa duração. / This work intends to analyze the effects produced by the flooding of the soilexcavated piles, isolated, subjected to compression efforts. The results refer to the execution of three slow load tests on piles with diameters of 0.40 m and 0.50 m (2 distinct load tests) and 10.0 m lengths, submitted previously to a number of shipments (two slow and two quick load). The results concerning offsets measured at the top of the stakes and those obtained by the instrumentation installed along the forend are then compared with the sequence of the previous results, to evaluate the effect of damping in behavior \"load x settlement\" and load transfer mechanisms. It was also made a thorough description of the process used to flood the ground and a brief consideration of the effects of non-replacement of loads in slow, long-term trials.

Este trabalho se propõe a analisar os efeitos produzidos pela inundação do solo em estacas escavadas, isoladas, submetidas a esforços de compressão. Os resultados obtidos referem-se à execução de três provas de carga lentas em estacas com diâmetros de 0,40 m e 0,50 m (2 provas de carga distintas) e comprimentos de 10,0 m, submetidas anteriormente a uma série de carregamentos (duas provas de carga rápidas e duas lentas). Os resultados relativos aos deslocamentos medidos no topo das estacas e os obtidos pela instrumentação instalada ao longo do fuste são então comparados com a sequência dos resultados anteriores, para avaliação do efeito de umedecimento no comportamento \"carga x recalque\" e nos mecanismos de transferência de carga. É feita ainda uma descrição minuciosa do processo utilizado para inundação do solo e uma breve consideração sobre os efeitos da não reposição de cargas em ensaios lentos, de longa duração. / This work intends to analyze the effects produced by the flooding of the soilexcavated piles, isolated, subjected to compression efforts. The results refer to the execution of three slow load tests on piles with diameters of 0.40 m and 0.50 m (2 distinct load tests) and 10.0 m lengths, submitted previously to a number of shipments (two slow and two quick load). The results concerning offsets measured at the top of the stakes and those obtained by the instrumentation installed along the forend are then compared with the sequence of the previous results, to evaluate the effect of damping in behavior \"load x settlement\" and load transfer mechanisms. It was also made a thorough description of the process used to flood the ground and a brief consideration of the effects of non-replacement of loads in slow, long-term trials.

This paper presents a non-linear finite element model (FEM) used to predict the behaviour of slender concrete filled steel tubular (CFST) columns with elliptical hollow sections subjected to axial compression. The accuracy of the FEM was validated by comparing the numerical prediction against experimental observation of eighteen elliptical CFST columns which carefully chosen to represent typical sectional sizes and member slenderness. The adaptability to apply the current design rules provided in Eurocode 4 for circular and rectangular CFST columns to elliptical CFST columns were discussed. A parametric study is carried out with various section sizes, lengths and concrete strength in order to cover a wider range of member cross-sections and slenderness which is currently used in practices to examine the important structural behaviour and design parameters, such as column imperfection, non-dimension slenderness and buckling reduction factor, etc. It is concluded that the design rules given in Eurocode 4 for circular and rectangular CFST columns may be adopted to calculate the axial buckling load of elliptical CFST columns although using the imperfection of length/300 specified in the Eurocode 4 might be over-conservative for elliptical CFST columns with lower non-dimensional slenderness.

Während die Zugfestigkeit im Fokus der Forschung am Werkstoff Carbonbeton steht, wurde die Tragfähigkeit des Materials unter Druck bisher kaum untersucht. Aufbauend auf ersten Erkenntnissen zur einaxialen Druckfestigkeit von Carbonbeton werden im Rahmen dieses Projekts scheibenförmige Prüfkörper aus Carbonbeton mit einer kombinierten Einwirkung aus Druck und zusätzlich wirkenden Querdruck- und Querzugbelastungen betrachtet. Dieser Beitrag stellt die ersten Ergebnisse der zweiaxialen Druckbelastungen vor und gibt einen Ausblick auf weiterführende Untersuchungen im Projekt.