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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

Analise de sensibildade topologica em problemas de não-linearidade geometrica e hiperelasticidade não-linear quasi-incompressivel / Topological sensivity analysis in problems with geometric non-linearities and nonlinear nearly-incompressible hiperelasticity

Pereira, Carlos Eduardo Leite, 1975- 24 February 2006 (has links)
Orientador: Marco Lucio Bittencourt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T20:24:00Z (GMT). No. of bitstreams: 1 Pereira_CarlosEduardoLeite_D.pdf: 2868659 bytes, checksum: 90d7fda0b66989796767d36726984af4 (MD5) Previous issue date: 2006 / Resumo: No presente trabalho, tem-se como objetivo realizar a otimizacao topológica em problemas de elasticidade envolvendo não-linearidade geométrica (grandes deslocamentos e rotações) e não-linearidade de material, no caso, hiperelasticidade não-linear quasi-incompressível, aplicando o conceito de Análise de Sensibilidade Topológica (AST) através de uma formulação Lagrangiana total. A AST é caracterizada por uma função escalar, denominada Derivada Topológica, que fornece para cada ponto do domínio de definição do problema a sensibilidade de uma determinada função quando um pequeno furo é criado no domínio. Assim, considerando a impossibilidade em se obter uma solução analítica para os problemas considerados no presente trabalho, uma expressão aproximada da Derivada Topológica é obtida através de uma análise assintótica numérica para o problema envolvendo somente não-linearidade geométrica e posteriormente para o problema envolvendo hiperelasticidade não-linear quasi-incompressível. Resultados numéricos para ambos os tipos de problema e as limitações quanto à aplicabilidade da Derivada Topológica aproximada obtida para tais problemas são apresentados / Abstract: The aim of the present work is to optimize the topology of elasticity problems with geometric nonlinearities (large displacement and rotation) and material nonlinearities, in this case, nonlinear nearly-incompressible hyperelasticity applying the concept of Topological Sensitivity Analysis (TSA) and a total Lagrangian formulation. The TSA results in a scalar function, denominated Topological Derivative, that gives for each point of the domain the sensitivity of a given cost function when a small hole is created. As an analytical solution is impossible for the considered problems in the present work, an approximated expression for the Topological Derivative is obtained by numerical asymptotic analysis first for geometric nonlinearities and after for nonlinear nearly-incompressible hyperelasticity. Numerical results for both problems and the limitations of the approximated Topological Derivative are presented. / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica
2

Interakce proudící tekutiny a elastického tělesa / Fluid-structure interaction

Kosík, Adam January 2016 (has links)
In this thesis we are concerned with the numerical simulation of the in- teraction of compressible viscous flow and an elastic structure in 2D. For the elastic deformation we use a 2D linear model and nonlinear St. Venant- Kirchhoff and neo-Hookean models. The flow is described by the compressible Navier-Stokes equations written in the arbitrary Lagrangian-Eulerian (ALE) form in order to take into account the time-dependence of the flow domain. The discretization of both the flow problem and the elasticity problem is re- alized by the discontinuous Galerkin finite element method (DGM). We focus on testing the DGM applied to the solution of the flow and elasticity prob- lems. Furthermore, we discuss the coupling algorithm and the technique, how to deal with the deformation of the computational domain for the fluid flow problem. Our work is motivated by the biomedical applications. Numerical experiments include numerical simulation of vibrations of human vocal folds induced by the compressible viscous flow.

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