Birefringence has been used to study transparent materials since 1815, and is based on the decomposition of a polarized ray of light into two distinct rays when passing through an optically anisotropic material. This thesis uses this phenomenon in a study of phase retardation in crystalline materials. Single and multicrystalline silicon was chosen as the model material. Silicon is an interesting and important material in its own right, and the use of photoelasticity to determine stresses at linear and planar defects can have important consequences in the electrical performance of devices such as electronics and photovoltaic cells. This thesis presents the results of an experimental investigation of residual stresses in multicrystalline silicon wafers using near-infrared (NIR) transmission photoelasticity. NIR transmission through multicrystalline silicon is found to vary with crystallographic orientation and relate to planar atomic density, enabling the assignment of appropriate stress-optic coefficients to different grains. Noise in the data is reduced with the Ramji and Ramesh 10-step phase shifting algorithm when compared to the Patterson and Wang process. Normal stresses at points of zero maximum shear stress can be characterized based on isoclinic behavior around the point. Points at which all normal stresses are zero serve as boundary conditions for shear difference integration and allow for stress separation from a point that is not a free boundary. The second part of this work focuses on residual stresses in silicon wafers subjected to known physical damage such as indentations. Residual stress fields around Vickers indentations in silicon are found to be larger in size than predicted by contact mechanics. Placing Vickers indentations in close proximity creates a secondary stress field surrounding the entire indentation array, and a relationship is developed to explain this behavior. High residual stresses measured at grain boundaries are found to be consistent with models of atomic displacement. Placement of Vickers indentations near grain boundaries results in a change in stress state at the grain boundaries. The results of this study demonstrate the capacity of birefringence as a non-destructive evaluation tool and describe the effects of residual stress concentrations in silicon wafers.

In this thesis work, a novel low level birefringence detection (LLBD) system operating at 1150 nm was set up based on the photoelastic modulation techniques. The noise level of current LLBD system is about 0.03° and the maximum fluctuation of data in ten measurements is 0.05° and close to the noise level of system. With a slit confining the light, the spatial resolution of the system is 10 mum. Optical orientation and retardation can be simultaneously measured by this system, making the stress measurement more convenience than the traditional PE methods. These peculiar features make this system capable of investigating the details of stress distribution in semiconductor structures. / Our solution reveals that the nonlinear stress filed is responsible for the shift of the zero stress point. Further it is indicated that the classical Stoney formula can either overestimate or underestimate the actual film stress due to the process induced nonlinear stress in the substrate. / Stress and strain play an essential role in determining the structural, electrical, and optical properties of semiconductor materials, and, ultimately, the semiconductor device performance. Many methods have been utilized to measure the stress in semiconductors. Among them infrared photoelasticity method is a promising one, which can be used both in the industrial characterization and scientific research. This thesis is an endeavor in this subject matter and will present our research results of studying the stress problems in semiconductor structures by using infrared photoelasticity method. / The LLBD system was applied to measure the stress distributions in the substrates of SiO2/Si structure. Some deviations from the classical film theory were observed in our experiments. For example non-linear stress fields were observed in all samples whatever their process conditions are. Besides the locations of neutral axis (zero stress point) was not located at the depth of 2/3 thickness of the substrate from the interface as expected by the bi-metallic theory. To interpret these deviations, a theoretical analysis was given to investigate the problem of stress distribution in film/substrate structure. A series of solutions were deduced to modify the Stoney formula and bi-metallic strip theory with the consideration of the nonlinear stress in substrate. / by Liu Xianghua. / "Feb 2006." / Adviser: Sai Peng Wong. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6674. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

No description available.

Understanding the relationship between the structure of materials and their properties allows for the development of new applications and technologies. Here the relationship between local structure and optical properties in several binary oxide glass systems containing zinc oxide was examined, in particular the relationship between structure, applied stress and induced birefringence in a glass. The empirical model introduced by Zwanziger and co-workers posits a negative correlation between the ratio of the bond length to coordination number in a glass and the induced birefringence; zinc oxide in this model is predicted to be exactly at the threshold between positive and negative birefringence and is thus of particular interest to investigate. XAFS and Raman spectroscopy were used to determine local structure while the Sénarmont compensator method, Abbe refractometry and spectroscopic ellipsometry were used to measure optical properties.

No description available.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Orientador: José Ricardo de Albergaria Barbosa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-21T13:29:18Z (GMT). No. of bitstreams: 1 Vemba-Cidade_CasteloPedro_M.pdf: 2207209 bytes, checksum: 39e5b4e487713c98b4563a7fbd4d2e2e (MD5) Previous issue date: 2012 / Resumo: A angulação dos implantes convencionais faz parte de uma modalidade de tratamento com implantes dentais ósseos integrados nos quais são aplicados em maxilas severamente absorvidas para que assim não haja necessidade do uso de enxertos ósseos para reconstrução da mesma. A proposta neste estudo foi avaliar por meio de um estudo biomecânico utilizando o sistema fotoelástico, diferentes protocolos de angulações dos implantes posteriores convencionais e comprimento do cantilever. Os implantes de diâmetro 3,5 x 15 mm de comprimento, dispostos de forma que em 3 modelos os implantes foram instalados com angulação de 15º e em outros 3 modelos com angulação de 35º. Os modelos fotoelásticos foram submetidos a teste de forças verticais sobre os implantes e cantilever. As franjas de forças formadas durante os testes foram avaliadas por meio de um polaroscópio de forma qualitativa e em seguida foi realizada a leitura das regiões de maior concentração de tensão. Foram avaliadas tensões submetidas aos implantes, sendo este dividido em tensão total, tensão cervical e tensão apical para cada grupo analisado. Não houve diferença estatisticamente significativa quando comparado os implantes nas diferentes angulações em relação à incidência de tensão total, tanto em cantilever, quanto em pilar e oclusal. Houve diferença estatística significativa em relação à incidência de força no cantilever e no pilar somente quando é analisada a região apical do implante. Em relação à incidência de força na oclusal houve diferença estatisticamente significativa somente na região cervical. Quando comparado à incidência de forças no cantilever nos dois tipos de angulações, o implante 35º apresentou melhor distribuição de forças na região apical, o mesmo ocorreu para incidência de forças na oclusal da região cervical do implante de 35º. Concluiu-se que o implante com angulação de 35º mostrou-se com melhor distribuição de forças quando comparado com o implante de angulação de 15º que apresentou maior concentração de tensão na região apical / Abstract: Introduction: The implants conventional with angulation are used in treatment with dental implants into bone in the jaws heavily absorbed so that there is no need to use bone grafts to reconstruct the same. Objective: To evaluate using a biomechanical study (photoelastic system) using protocols of the angulation different in the posterior implants conventional and length of the cantilever. Materials and Methods: We made 6 models in photoelastic resin from a skull human prefabricated. In these models have been installed 12 implants with diameter 3.5 x 15 mm long cylindrical cone. The implants were placed so those in three models were fitted with implants of angle of 15 ? and other three with models implants of 35 ?. Photoelastic models were subjected to test of vertical forces on the cantilever of the implants. The fringes forces formed during the tests were evaluated through a polariscope qualitatively and then were carried out reading the regions of greatest stress concentration. Was further assessed the total area of tension that the implant was submitted, which was divided into the total stress, tension neck and apical voltage for each group analyzed. Results: No statistically significant difference when compared the implants in different angles in relation to the incidence total tensile strength in both in relation the cantilever, abutment and occlusal. There was a statistically significant difference in the incidence of force in the cantilever when the region of pillar is analyzed only in the apical region of the implant. There was statistically significant to the incidence of occlusal force only in the cervical region. When compared to the effect of forces on the cantilever in both types of angles, the implant 35 ? showed better distribution of forces in the apical region, the same occurred in the incidence of occlusal forces on the neck of the implant of 35 ?. Conclusion: The implant with 35? proved to have better distribution of forces as compared to the implant with 15 ?of angulation / Mestrado / Cirurgia e Traumatologia Buco-Maxilo-Faciais / Mestre em Clínica Odontológica

[pt] Foi desenvolvido um método computacional para a determinação dos fatores de intensidade de tensão, para os modos de abertura I e II, a partir de configurações de franjas isocromáticas. O método se caracteriza pela generalização na formulação do campo de tensões na vizinhança da ponta de trinca, que busca determinar, além dos fatores de intensidade de tensão, alguns parâmetros significativos do campo de tensões não singular, associados a diferentes geometrias, que interferem no campo singular, próximo à trinca. Um programa de computador foi desenvolvido para a obtenção KI, KII e dos demais fatores considerados. O erro das respostas pode ser calculado a partir das diferentes opções de saída do programa. O método foi testado em modelos de barras com trincas a 90 e 45 graus e os resultados comparados com dados experimentais e analíticos disponíveis na literatura. Como fatores de influência na determinação de KI e KII forma estudados: a quantidade e a posição dos pontos de coleta de dados, e o número de parâmetros considerados no campo não singular. Foram analisados ainda, como exemplo de aplicação ainda, como exemplo de aplicação, três modelos de solda de topo com trincas a 45 e 90 graus com diferentes posicionamentos em relação ao reforço de solda. / [en] A computational method has been developed to determine mixed-mode stress intensity factors from isochromatic fringe patterns. The method proposes a general formulation of the stress field around a crack tip. It searches to obtain not only the stress intensity factors but also all the other non-singular stress field parameters, associated to different geometries, which interfere with the singular field near the crack. The method has been tested in bars with 90 and 45 degree cracks and the results, compared to experimental and analytical data found in literature. Three factors influencing in KI and KII determination have been studied: the quantity of data collecting points, its position and number of parameters considered in the non-singular field. Three models of transverse butt welded joints with 45 and 90 degrees cracks placed in different positions relative to weld reinforcement, have been analyzed as application examples.