Tesis Doctoral
DOI
https://doi.org/10.11606/T.18.2016.tde-26072016-101122
Documento
Autor
Nombre completo
Mauricio Francisco Caliri Junior
Dirección Electrónica
Área de Conocimiento
Fecha de Defensa
Publicación
São Carlos, 2015
Director
Tribunal
Tita, Volnei (Presidente)
Coda, Humberto Breves
Ferreira, António Joaquim Mendes
Lima, Antonio Marcos Gonçalves de
Ribeiro, Marcelo Leite
Título en portugués
Contribuição para teoria de placas: análises estruturais de compósitos laminados e estruturas sanduíches via formulações unificadas
Palabras clave en portugués
Análise estrutural
Anisotropia
Estruturas sanduíches
Método dos elementos finitos
Métodos de soluções aproximadas
Teorias unificadas de placa
Resumen en portugués
Título en inglés
Contribution to theory of plates: structural analyses of laminated composites and sandwich structures via unified formulations
Palabras clave en inglés
Anisotropy
Approximate solution methods
Continuity C-1
Finite element method
Laminated composites
Sandwich structures
Structural analysis
Unified plate theories
Resumen en inglés
In engineering, the amount of complex geometrical problems, which need to be solved by using plates and shells theories, is remarkable. This is the reason why there are so many plate and shell theories which attempt to simplify three dimensional problems into ones with low computational cost. Additionally, the current increasing use of sandwich structures requires that the two dimensional formulations be accurate enough. First, this thesis compiles most of the plate theories from the literature and quotes the main differences, advantages and weaknesses of each one. The bi-dimensional laminated plate formulations are mainly classified according to the treatment of the variable in the normal direction of the plate surface: Equivalent Single Layer (ESL), Refined ESL (Zig-Zag theories) and Layer-Wise (LW) theories. Each one of these theories is reviewed along with the plate hypotheses which are made for each ply and/or laminate. To solve such complex structural engineering problems, numerical methods are normally used. Second, few solution methods are reviewed and quoted, but focus is given to the Finite Element Method (FEM). The contribution of this work is the implementation of a new solution method for laminated composites and sandwich structures based on a Generalized Unified Formulation (GUF) via FEM. A quadrilateral 4-node element was developed and evaluated using in-house Finite Element program. The C-1 continuity requirements is fulfilled for the transversal displacement field variable. This method is tagged as Caliri's Generalized Formulation (CGF). Results for isotropic plates, laminated composite plates and sandwich structures for thin and thick laminates are compared with literature data and solutions via Abaqus. The through-the-thickness profile results reinforce the need for non-linear plate (laminated or not) solutions. It was shown that the static and dynamic solutions employing the proposed solution method yield coherent results when compared with other solution methods. Among the different case studies investigated, it was verified that it is possible to obtain results with high agreement. For a soft-core sandwich structure, the displacement result for a static loading is reported as high as 99.8% and the result of a modal analysis of the same structure shows an accuracy of 99.5%, comparing to the results from a 3D finite element model built with a commercial software.

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Fecha de Publicación
2016-07-28

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