Thesis (Ph.D.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 213-223) Also available in print.

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Wisconsin. / Includes bibliographical references (leaves 65-66).

Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2006. / Sathya V. Hanagud, Committee Chair ; George Kardomateas, Committee Member ; Xia Lu, Committee Member ; George Simitses, Committee Member ; Massimo Ruzzene, Committee Member ; Ravindra Annigeri, Committee Member.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-26Bitstream added on 2014-06-13T20:26:37Z : No. of bitstreams: 1 franca_ac_dr_guara.pdf: 2067933 bytes, checksum: 2e982cb5e733cfd4d52e5f6583b7d8b8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / É comum serem identificadas trincas em alvenaria de tijolos, não somente depois de um certo tempo da construção, mas também, por vezes, durante a própria construção. Essas trincas, ou deformações estruturais ocorrem por diversos fatores de ordem técnica, dentre os quais, um deles devido à umidade absorvida pelos elementos da parede (tijolos e argamassa). Tal umidade pode vir das condições do ambiente (dia úmido), de chuvas, do solo e até do excesso da quantidade de água contida na argamassa de assentamento. Em contato com os elementos porosos da parede, tijolos e argamassa, a água concorrerá para a percolação capilar, dando origem a consideráveis esforços internos, que virão provocar deslocamentos estruturais, os quais, via de regra, são diferentes para o tijolo e para a argamassa, dessa forma, provocando o aparecimento de trincas. Os fenômenos que dão origem às deformações foram estudados em um trabalho de pesquisa por FRANÇA (2000), analisados e quantificados em laboratório, no qual se confirmou a hipótese de que a somatória dos esforços capilares provocados pelo deslocamento de um fluido em um meio poroso,pode atingir valores elevados ao ponto de causar na estrutura deslocamentos e, conseqüentemente, trincas. Por isso, o deslocamento do fluido por entre os canais existentes entre as partículas do meio poroso, processado sob a forma de uma frente de fluido se deslocando, denominada velocidade de percolação, necessitou ser visualizado e matematicamente tratado. / The identification of cracks in brick masonry is quite common, not only after a certain period of time post-building but also, sometimes, during the building. These cracks or structural deformations are due to several factors of technical order. One of them is related to the moistness absorbed by the elements of the wall (brick and mortar). Such moistness can be the result of the environment conditions (dank day), rain, soil and even of the excess of water in the laid mortar. In contact with the wall porous elements, brick and mortar, the water will facilitate the capillary percolation, giving berth to remarkable internal efforts, which will cause structural dislocation. These dislocations are, usually, different for the brick and for the mortar, so causing the cracks. The phenomena that cause the deformations were studied in a research by FRANÇA (2000), analyzed and quantified in laboratory, which validated the hypothesis that the sum of the capillary efforts caused by the dislocation of a fluid in a porous element can reach high values to a point that causes dislocations and consequently cracks in the structure. Therefore, the dislocation of the fluid through the channels existing among the particles of the porous element, processed in a form of a dislocating front of fluid, named velocity of percolation, needed to be visualized and mathematically treated. This work aimed, as the main objective, to trace the profile of the dislocation and give to the velocity of percolation a mathematical modeling based on the general equation of Navier-Stokes. It was necessary to search for knowledge of micro world of the labyrinths formed by pores among the sand, clay and cement particles. It became indispensable to measure, in an indirect way, the size of the pores and its relation with the size of the particles.

No description available.

The deformation behaviour of copper, reinforced with iron and steel fibres has been investigated. Parameters studied include: fibre diameter, matrix mean free path, and relative strength of fibre and matrix. No strengthening effect has been observed which can be attributed to fibre size alone. However, it is suggested that the strength of metal fibre-reinforced metal, composites are greatly influenced, by a "size effect" in the matrix. A modification of the theory of combined action has been proposed for predicting the strength of a fibre-reinforced composite, viz: [ Equation omitted ] where A is volume fraction, f refers to fibre, m refers to matrix, df is fibre diameter, and K is a constant whose value depends on the hardness of the fibre. Weakening of the matrix-fibre interface in composites of copper and steel fibres has been attributed to segregation of carbon to the interface. Alloys containing 6 to 8 weight per cent copper in iron have been shown to exhibit a martensitic transformation when cooled from the ɣ region of the Fe-Cu phase diagram. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The deformation characteristics of continuous tungsten fibre-reinforced zinc composites have been investigated. Composites with a single crystal matrix containing up to 4.5 volume per cent of tungsten fibres were studied. The stress-strain curves of W-Zn composites showed positive deviations from the "rule of mixture" predictions. Theoretical work attributes the positive deviations to matrix hardening due to either one of the phenomena: (a) the difference in the lateral contractions of the fibre and the matrix; (b) the pile up of dislocations in the matrix at the matrix-fibre interface. In the present work the positive deviations in the elastic-plastic region of the stress-strain curves of the composites have been attributed to both (a) and (b). The positive deviations in the ultimate tensile strengths of the composites have been attributed to (b). Composites containing up to 0.08 volume per cent of the tungsten wires deformed even after the fracture of the fibres. Dissolution of the matrix of these deformed composites showed that multiple necking had occurred in the fibres fractured to 1-5 mms length. Composites containing greater than 0.08 volume per cent of tungsten fibres fractured by cleaving through the basal plane of the matrix. No fibre fracture inside the matrix was seen except at the fracture end of the composite. Multiple necking of the fibres near the fractured end has been seen only in those composites which have deformed more than the free fibres tested individually. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The compression of fairly short solid cylinders under axial load is considered. A preliminary investigation examines the displacements produced by the superposition of a prescribed surface loading. This is followed by the more interesting problem in which the radial displacement is prescribed over part of the surface, the remaining part of the surface being stress free. Two types of elastic materials are considered; firstly, rubber-like materials governed by a strain energy function of the Mooney form, and secondly, metals which have a quadratic strain energy function. In the former case a finite axial compression is permitted prior to imposing any constraint on the outer curved surface of the cylinder. In all cases the irregularities introduced by the constraints are sufficiently small that they can be described by infinitesimal elasticity theory. The analysis utilizes displacement potential functions and the main problem is reduced to solving a set of dual cosine series. The particular case of the contact problem in which the cylinder height is equal to the radius is examined in detail and the contact stresses are given graphically. / Science, Faculty of / Mathematics, Department of / Graduate