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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Behaviour and Inspection of Novel Non-Crimp Dry Thick Reinforcement Fabrics

BU JLDAIN, HAFETH January 2015 (has links)
Aerospace structural components made from polymer matrix composites (PMCs) offer numerous advantages. Their high stiffness and high strength combined with low densities enable lower fuel consumption coupled with higher payloads. As a result, PMCs provide an important economic advantage over typical metallic airframes. Textile reinforcements for PMCs are made by assembling reinforcement fibres, typically carbon. Then, the textile reinforcements are typically cut into smaller pieces, stacked, draped and assembled into a dry assembly called a preform, the shape of which generally approaches that of the PMC part to be made. This manufacturing process is labour intensive and expensive. Novel thick, net-shape, drapable, high vf textile reinforcements used toward manufacturing aerospace PMCs are being developed at the University of Ottawa. The technology enables the manufacturing of flat, drapable multilayered near net-shape preforms. The bending and in-plane shear behaviours of such novel thick reinforcement textiles was investigated to understand and define the behaviour of such thick fabric reinforcements when formed into required shapes. A bending apparatus was developed for investigating the bending behaviour of these novel thick reinforcement fabrics and an articulated frame shear rig was used for investigating the in-plane shear behaviour. A non-destructive inspection method using infrared imaging was used for investigating and identifying flaws and defects in these thick, dry textile reinforcements, aiming at increasing the quality and reproducibility of the final PMC parts made from these reinforcements.
2

Estruturas tipo sanduíche com placas de argamassa projetada / Sandwich-type structures with plates made of projected mortar

Bertini, Alexandre Araújo 22 February 2002 (has links)
Elementos tipo sanduíche, com placas de argamassa projetada, têm sido utilizados na construção de edificações em alguns países, inclusive no Brasil, apresentando boas características de resistência mecânica, térmica e acústica. De maneira geral, a aplicação desse tipo de elemento tem se restringido a obras de edificações, sendo utilizado principalmente como painéis de fechamento, portantes ou não, existindo ainda um potencial a ser explorado em obras de infra-estrutura, tais como: muros de arrimo, canais, galerias e reservatórios de água. Apesar de ser um método utilizado na construção de edificações, existem dúvidas, tais como: resistência efetiva da argamassa projetada, colaboração entre as placas resistentes em função do tipo de núcleo, modo de combater os efeitos de retração da argamassa, etc. Apresenta-se neste trabalho um estudo sobre a resistência efetiva da argamassa projetada, no qual se obteve que a sua resistência é de aproximadamente 80% da resistência à compressão de corpos-de-prova cilíndricos. Realizaram-se ainda ensaios para analisar a ligação entre elementos tipo sanduíche e seu comportamento à flexão, que comprovam o bom desempenho estrutural. Acredita-se que essa técnica de construção sanduíche possa ser aplicada em obras de infra-estrutura de interesse social, trazendo vantagens tecnológicas e econômicas em relação a sistemas tradicionais / Sandwich–type elements, with plates made of projected mortar, have been used in the construction of buildings in some countries, including Brazil, showing expressive thermical, acoustical and mechanical strength characteristics. In general, the application of this kind of element have been limited to buildings, mainly used as cladding panels, with carrying load capacity or not, and have other potential uses in infra-structural works to be explored such as bearing walls, channels, and water reservoirs. Although it is a method that have been conventionally applied in the construction of buildings, there are uncertainties in some parameters, like the effective strength of the projected mortar, interaction between the plates related to the type of core, the mode against shrinkage of the mortar etc. It is showed in this work a study concerning the effective strength of the projected mortar. As a result of a series of tests in walls made of projected mortar, it is determined that the effective strength of the projected mortar is 80% of that one measured from cylindrical specimens in compression tests. As well, some tests have been executed to analise the bending behaviour and the connections between the plates of the sandwich-type specimens, which demonstrated a relatively high structural performance. It is believed that this technical solution can be well applied to public works of social interest, and can offer technological and economical advantages in contrast to the traditional systems
3

Estruturas tipo sanduíche com placas de argamassa projetada / Sandwich-type structures with plates made of projected mortar

Alexandre Araújo Bertini 22 February 2002 (has links)
Elementos tipo sanduíche, com placas de argamassa projetada, têm sido utilizados na construção de edificações em alguns países, inclusive no Brasil, apresentando boas características de resistência mecânica, térmica e acústica. De maneira geral, a aplicação desse tipo de elemento tem se restringido a obras de edificações, sendo utilizado principalmente como painéis de fechamento, portantes ou não, existindo ainda um potencial a ser explorado em obras de infra-estrutura, tais como: muros de arrimo, canais, galerias e reservatórios de água. Apesar de ser um método utilizado na construção de edificações, existem dúvidas, tais como: resistência efetiva da argamassa projetada, colaboração entre as placas resistentes em função do tipo de núcleo, modo de combater os efeitos de retração da argamassa, etc. Apresenta-se neste trabalho um estudo sobre a resistência efetiva da argamassa projetada, no qual se obteve que a sua resistência é de aproximadamente 80% da resistência à compressão de corpos-de-prova cilíndricos. Realizaram-se ainda ensaios para analisar a ligação entre elementos tipo sanduíche e seu comportamento à flexão, que comprovam o bom desempenho estrutural. Acredita-se que essa técnica de construção sanduíche possa ser aplicada em obras de infra-estrutura de interesse social, trazendo vantagens tecnológicas e econômicas em relação a sistemas tradicionais / Sandwich–type elements, with plates made of projected mortar, have been used in the construction of buildings in some countries, including Brazil, showing expressive thermical, acoustical and mechanical strength characteristics. In general, the application of this kind of element have been limited to buildings, mainly used as cladding panels, with carrying load capacity or not, and have other potential uses in infra-structural works to be explored such as bearing walls, channels, and water reservoirs. Although it is a method that have been conventionally applied in the construction of buildings, there are uncertainties in some parameters, like the effective strength of the projected mortar, interaction between the plates related to the type of core, the mode against shrinkage of the mortar etc. It is showed in this work a study concerning the effective strength of the projected mortar. As a result of a series of tests in walls made of projected mortar, it is determined that the effective strength of the projected mortar is 80% of that one measured from cylindrical specimens in compression tests. As well, some tests have been executed to analise the bending behaviour and the connections between the plates of the sandwich-type specimens, which demonstrated a relatively high structural performance. It is believed that this technical solution can be well applied to public works of social interest, and can offer technological and economical advantages in contrast to the traditional systems

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