Due to a European energy concept for reducing energy consumption and also the concept of sustainable development, there is a growing demand for reduced energy consumption during the operation of the building and hence increasing demands on the thermal and mechanical properties of the building envelope. For this reason, it is necessary to look for materials that could meet both thermal and mechanical properties, as well as mechanical resistance and loadability, especially for the application for the foundations of the house, the base of the house and for application to structural details for elimination of the thermal bridges between interior and exterior boundaries. The main motivation for choosing the topic of thesis was to find materials derived from recycled or secondary raw materials that would be suitable for manufacturing composite applicable for structural details in the envelope of the building and for insulating in humid environment. An economic and environmental aspect plays an important role in the choice of material. The main theme of the thesis is the laboratory manufacturing of a composite with a thermoplastic matrix derived from recycled plastic materials and waste foam as a phase. Has been developed a unique Waste-based Particle Polymer Composite (WPPC) made from recycled foam and polypropylene. However, before WPPC can be reliably used by construction designers, physical properties of WPPC must be accurately identified. Therefore, it was designed laboratory manufacturing system and sample testing system, it was studied thermal, mechanical, thermomechanical and moisture absorptivity of WPPC. Application of finished composite material with satisfying thermal insulation properties to structural details to eliminate the thermal bridge, was the next step. These are details of the unloaded, prefabricated balconies, windows, atics, as well as basement constructions and the heel of the central load-bearing wall, the terrain flooring and the staircase wall

A utilização de materiais compósitos tornou-se uma alternativa importante em muitas aplicações dentro de diversas áreas da engenharia, pois seus constituintes podem agregar propriedades mecânicas, térmicas e acústicas ao compósito, garantindo eficiência e baixo custo. Com isso, faz-se necessário um maior conhecimento do comportamento mecânico desses materiais diante das solicitações, principalmente no que diz respeito aos campos de deslocamento, deformações e tensões. O presente trabalho tem por finalidade a análise, em nível macroscópico, de estruturas bidimensionais elásticas constituídas de materiais compósitos particulados, utilizando formulação desenvolvida no contexto do Grupo de Mecânica Computacional (GMEC), do Departamento de Engenharia de Estruturas (SET), da Escola de Engenharia de São Carlos (EESC), da Universidade de São Paulo (USP), no qual se insere a presente pesquisa. A formulação utilizada baseia-se no Método dos Elementos Finitos Posicional (MEFP) e foi desenvolvida em nível mesoscópico por tratar da interação entre matriz e partículas. Tal formulação possibilita a consideração da interação partícula-matriz sem a necessidade de coincidência entre as malhas da matriz e das partículas e sem o aumento do número de graus de liberdade dos problemas, admitindo-se aderência perfeita entre as fases. A formulação considera material isotrópico e comportamento não-linear geométrico das fases. A aplicação da formulação foi aqui proposta com o intuito de avaliar a influência da geometria, tamanho, fração volumétrica, distribuição e propriedades mecânicas das partículas adotadas, no comportamento global da estrutura em nível macroscópico. Foram desenvolvidos e apresentados exemplos de aplicação, com comparação dos resultados numéricos das análises com resultados de ensaios experimentais encontrados na literatura, bem como com resultados de modelos matemáticos de homogeneização e modelos numéricos propostos por outros autores, que utilizaram o método dos elementos finitos e técnicas de homogeneização assintótica. / The use of composite materials has become an important alternative in many applications in different areas of engineering, because their constituents can add mechanical, thermal and acoustic properties to the composite, ensuring efficiency and low cost. Thus, it is necessary a better understanding of the mechanical behavior of these materials, mainly regarding displacement, stress and strain fields. This study aims to analyze, in macroscopic scale, two-dimensional elastic structures made of particulate composite materials, using formulation developed in the context of the Grupo de Mecânica Computacional (GMEC), of Departamento de Engenharia de Estruturas (SET), of Escola de Engenharia de São Carlos (EESC), of Universidade de São Paulo (USP). The formulation is based on the Positional Finite Element Method and was developed in mesoscopic level, considering the matrix-particles interaction and neglecting the interface, by means of kinematic relations used to ensure adherence of the particles to the matrix without introducing new degrees of freedom in the problem. The formulation considers isotropic material and geometric non-linear behavior of the composite phases. The application of the formulation was proposed in this work in order to evaluate the influence of geometry, size, volume fraction, distribution and mechanical properties of the particles adopted in the global behavior of the structure in macroscopic level. Numerical examples were developed and presented in order to compare the numerical results of the analysis with results obtained in experimental studies found in the literature, as well as results of mathematical models and numerical models using finite element method and the asymptotic homogenization technique.

In this thesis, the focus has been on micro-mechanical mechanisms in polymer-based materials and structures. The first part of the thesis treats length-scale effects on polymer materials. Experiments have showed that the smaller the specimen, the stronger is the material. The length-scale effect was examined experimentally in two different polymers materials, polystyrene and epoxy. First micro-indentations to various depths were made on polystyrene. The experiments showed that length-scale effects in inelastic deformations exist in polystyrene. It was also possible to show a connection between the experimental findings and the molecular length. The second experimental study was performed on glass-sphere filled epoxy, where the damage development for tensile loading was investigated. It could be showed that the debond stresses increased with decreasing sphere diameter. The debonding grew along the interface and eventually these cracks kinked out into the matrix. It was found that the length to diameter ratio of the matrix cracks increased with increasing diameter. The experimental findings may be explained by a length-scale effect in the yield process which depends on the strain gradients. The second part of the thesis treats mechano-sorptive creep in paper, i.e. the acceleration of creep by moisture content changes. Paper can be seen as a polymer based composite that consists of a network of wood fibres, which in its turn are natural polymer composites. A simplified network model for mechano-sorptive creep has been developed. It is assumed that the anisotropic hygroexpansion of the fibres leads to large stresses at the fibre-fibre bonds when the moisture content changes. The resulting stress state will accelerate creep if the fibre material obeys a constitutive law that is non-linear in stress. Fibre kinks are included in order to capture experimental observations of larger mechano-sorptive creep effects in compression than in tension. Furthermore, moisture dependent material parameters and anisotropy are taken into account. Theoretical predictions based on the developed model are compared to experimental results for anisotropic paper both under tensile and compressive loading at varying moisture content. The important features in the experiments are captured by the model. Different kinds of drying conditions have also been examined. / QC 20100910

A utilização de materiais compósitos tornou-se uma alternativa importante em muitas aplicações dentro de diversas áreas da engenharia, pois seus constituintes podem agregar propriedades mecânicas, térmicas e acústicas ao compósito, garantindo eficiência e baixo custo. Com isso, faz-se necessário um maior conhecimento do comportamento mecânico desses materiais diante das solicitações, principalmente no que diz respeito aos campos de deslocamento, deformações e tensões. O presente trabalho tem por finalidade a análise, em nível macroscópico, de estruturas bidimensionais elásticas constituídas de materiais compósitos particulados, utilizando formulação desenvolvida no contexto do Grupo de Mecânica Computacional (GMEC), do Departamento de Engenharia de Estruturas (SET), da Escola de Engenharia de São Carlos (EESC), da Universidade de São Paulo (USP), no qual se insere a presente pesquisa. A formulação utilizada baseia-se no Método dos Elementos Finitos Posicional (MEFP) e foi desenvolvida em nível mesoscópico por tratar da interação entre matriz e partículas. Tal formulação possibilita a consideração da interação partícula-matriz sem a necessidade de coincidência entre as malhas da matriz e das partículas e sem o aumento do número de graus de liberdade dos problemas, admitindo-se aderência perfeita entre as fases. A formulação considera material isotrópico e comportamento não-linear geométrico das fases. A aplicação da formulação foi aqui proposta com o intuito de avaliar a influência da geometria, tamanho, fração volumétrica, distribuição e propriedades mecânicas das partículas adotadas, no comportamento global da estrutura em nível macroscópico. Foram desenvolvidos e apresentados exemplos de aplicação, com comparação dos resultados numéricos das análises com resultados de ensaios experimentais encontrados na literatura, bem como com resultados de modelos matemáticos de homogeneização e modelos numéricos propostos por outros autores, que utilizaram o método dos elementos finitos e técnicas de homogeneização assintótica. / The use of composite materials has become an important alternative in many applications in different areas of engineering, because their constituents can add mechanical, thermal and acoustic properties to the composite, ensuring efficiency and low cost. Thus, it is necessary a better understanding of the mechanical behavior of these materials, mainly regarding displacement, stress and strain fields. This study aims to analyze, in macroscopic scale, two-dimensional elastic structures made of particulate composite materials, using formulation developed in the context of the Grupo de Mecânica Computacional (GMEC), of Departamento de Engenharia de Estruturas (SET), of Escola de Engenharia de São Carlos (EESC), of Universidade de São Paulo (USP). The formulation is based on the Positional Finite Element Method and was developed in mesoscopic level, considering the matrix-particles interaction and neglecting the interface, by means of kinematic relations used to ensure adherence of the particles to the matrix without introducing new degrees of freedom in the problem. The formulation considers isotropic material and geometric non-linear behavior of the composite phases. The application of the formulation was proposed in this work in order to evaluate the influence of geometry, size, volume fraction, distribution and mechanical properties of the particles adopted in the global behavior of the structure in macroscopic level. Numerical examples were developed and presented in order to compare the numerical results of the analysis with results obtained in experimental studies found in the literature, as well as results of mathematical models and numerical models using finite element method and the asymptotic homogenization technique.