This thesis describes the modeling and manufacture of bimorph mirrors as well as an example of their application. A general review of adaptive optics is provided, paying particular attention to those technologies which would allow adaptive optics to be employed in non-astronomical situations. The first stage of the theoretical analysis of the bimorph mirror involves developing a mechanical model of the laminated structure. This is carried out using standard thin plate laminate theory; this results in expressions for the overall sensitivity of a bimorph mirror. The mechanical model also leads to an equation describing the response of the surface of the mirror to a given applied voltage. An analytical solution is developed, and its implementation described. Using this analytical solution, the performance of a bimorph mirror under various operating conditions is analysed. Particular attention is paid to the case of correcting phase fluctuations that have a Kolmogorov spectrum. The process of manufacturing bimorph mirrors is described in some detail, and results of this procedure are presented. Results from various bimorph mirrors are analysed, and the comparisons with the theory are presented. A possible use of bimorph mirrors in laser scanner systems is described. A simple demonstration system is described, and results from its operation are presented. A detailed design for a laser printer using adaptive optics is presented, along with the associated deformable mirror requirements.

Laminated composite structures have started to play a very significant role in today's aircraft industry. The application of composite materials has now gone beyond the borders of aircraft design and has entered into such fields as automotive, athletics and recreational equipment, etc. The light weight and high specific strength of composite material helps design vehicles with higher fuel efficiency and longevity. In order to understand the influence of design parameters related to the use of composite materials in these applications, a proper study of the laminated composite structures requires a complete failure analysis, which includes both initiation and propagation of damage. In this work a progressive failure methodology is developed and implemented in the commercial Finite Element software package, Abaqus. Out of the numerous failure criteria available in the literature to study damage initiation and propagation in unidirectional fiber reinforced composites, Puck and Schurmann's failure criteria have been chosen due to their ability to predict results close to those observed experimentally. Key features of the Puck and Schurmann's failure criteria for three-dimensional deformations of unidirectional fiber reinforced composites have been summarized. Failure modes in the matrix and the fiber are considered separately. The failure criteria are simplified for plane stress deformations. Whereas the failure plane can be analytically identified for plane stress deformations, a numerical search algorithm is needed for three-dimensional problems. Subsequent to the initiation of matrix failure, elastic moduli are degraded and values of these degradation parameters and fracture plane angles are found by using a Continuum Damage Mechanics (CDM) approach. It is found that the assumption that the material response remains transversely isotropic even after the matrix failure has initiated requires the degradation of the transverse Poisson's ratio. The Puck and Schurmann's failure criteria and the material degradation process have been implemented as a User Defined Field (USDFLD) subroutine in Abaqus. The implementation has been verified by analytically computing results for simple loadings and comparing them with predictions from using the USDFLD in Abaqus. Subsequently, both two- and three-dimensional problems of more realistic geometries and loadings have been analyzed and computed results compared with either experimental findings or results available in the literature. Major contributions of the work include identifying the degradation parameter for the transverse Poisson's ratio in terms of the matrix degradation parameter for the matrix failure in compression, development of the USDFLD based on Puck and Schurmann's failure criteria, implementing the USDFLD in the commercial finite element software, Abaqus, and verifying that results computing using the USDFLD for various laminates and loadings agree with those from either the analytical solution of the problem or those available in the literature. / Ph. D.

[pt] O emprego de materiais compósitos em estruturas tem ganhado importância na prática da engenharia devido às suas características de alta resistência mecânica, baixa densidade e boa estabilidade a efeitos térmicos. Uma das classes de compósitos, a de laminados fibrosos, pode ser utilizada em tubulações sujeitas às diversas formas de carregamentos, como pressão interna e/ou externa, tração longitudinal, torção, temperatura, etc. O presente Trabalho tem por objetivo propor, implementar e testar a formulação de um modelo de elemento finito axissimétrico, para a representação do comportamento de um tubo laminado por camadas de materiais compósitos fibrosos. A modelagem consiste em representar a seção geratriz de um tubo cilíndrico por um elemento quadrilateral de quatro nós, com três graus de liberdade por nó, com os deslocamentos nodais tomados em relação aos eixos de um sistema cilíndrico de coordenadas. Considera-se a perfeita adesão das camadas, garantindo a continuidade do campo de deslocamentos. Modelos constitutivos de materiais com o comportamento ortotrópico e/ou o transversalmente isotrópico foram implementados, obtendo-se respostas para os campos de deslocamentos, de deformações e de tensões atuantes. Na validação do modelo numérico, considerou-se a comparação de seus resultados com os de soluções analíticas, disponíveis na literatura, e aqueles fornecidos por um programa comercial de elementos finitos, empregando o modelo com elementos sólidos. Foram propostos, para os testes em ambos os casos, exemplos de laminados com uma a quatro camadas, com fibras orientadas em diferentes ângulos. Destas comparações, verifica-se uma boa convergência das soluções numéricas obtidas com o presente modelo, representativo das principais características cinemáticas da classe de problemas representada. / [en] The use of composite materials in structures has grown in the engineering practice due to its characteristics, of high strength, low density and a good stability to thermal effects. A class of composites, the fibrous laminates, is generally used in tubes subjected to many types of loadings as internal and/or external pressure, traction, torsion, temperatures, etc. This work has the objectives to propose, implement and test an axisymmetric finite element model formulation that represents the mechanical behavior of a fibrous laminated composite tube. Modeling consists in representing the cylindrical tube generating section by a quadrilateral element with four nodes and three degrees-of-freedom per node, with three nodal displacements defined in a cylindrical coordinate system. Layers are considered perfectly bonded together, assuring continuity between elements on the displacement fields. Orthotropic and/or transverse isotropic constitutive material models were implemented, allowing solutions for displacement, strain and stress fields. In the element numerical model validation, result comparisons with those from analytical solutions available on literature and those from the use of layered solid elements in a commercial finite element program were considered. Some examples, considering one to four layers, with different fiber angles, were proposed for model testing. It is noted a good numerical convergence for the presenting model solutions which represent the main kinematic characteristics for this class of problems.