Um modelo numerico para analise de estruturas de materiais compostos considerando efeitos viscoelasticos e falhas progressivas

Neste trabalho apresentam-se pocedimentos para análise não linear de estruturas de materiais compostos laminados reforçados por fibras. A formulação é baseada em uma descrição cinemática incremental Lagrangeana Total, que permite o tratamento de deslocamentos arbitrariamente grandes com pequenas deformações, utilizando elementos finitos tridimensionais degenerados deduzidos para a análise de cascas. As estruturas são consideradas como submetidas a cargas mecânicas e a ações de temperatura e de umidade. O material é suposto elástico linear com propriedades dependentes, ou não, dos valores da temperatura e da concentração de umidade, ou viscoelástico linear com uma relação constitutiva em integral hereditária , e com comportamento higrotermo-reologicamente simples. As lâminas são consideradas como sujeitas a falhas, as quais são detectadas através de critérios macroscópicos, baseados em tensões ou em deformações. As equações não lineares de equilíbrio são resolvidas através de procedimentos iterativos e as deformações dependentes do tempo são avaliadas pelo método das variáveis de estado. Diversos exemplos numéricos de estruturas submetidas à flexão, flambagem elástica e viscoelástica e falhas são apresentados.

Obtenção e caracterização de fibras poliméricas e cerâmicas pela técnica de “blow-spinning”

Pós-graduação em Ciência dos Materiais - FEIS

Desenvolvimento de técnicas baseadas em filmes de células bacterianas para aplicação em ensaios não destrutivos de materiais de engenharia

Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica

Estudo de compósitos de madeira com reforço em bambu para utilização em mobiliário

Bamboo has been studied because of its peculiar mechanical properties and numerous possibilities of use, besides being a fast-growing grass and short cutting cycle. This study aimed to analyze the mechanical characteristics of wood-bamboo composite material, where the samples were developed from the combination of layers of bamboo as a structural reinforcement in solid pieces of pine and EGP panel parts. The species of wood used was Pinus taeda, and the bamboo species Guadua angustifolia and Dendrocalamus giganteus. All work was conducted at the Universidade Estadual Paulista - UNESP in the laboratory of Physical and Mechanical Properties of Wood. Tests including the density and tension parallel to grain of the bamboo species used and the static bending of composites in order to use this in the furniture industry. For the tests have been used as a basis the requirements of the normative document NBR 7190/97. The values obtained in the tests showed a significant increase in strength and stiffness compared to unreinforced parts, where there was an increase in MOE and MOR in static bending in all specimens used in evidence. The results showed the possibility of reducing sections in furniture components and the possibility of improving the mechanical properties of parts with defects found in wood of Pinus Itapeva region of São Paulo

NZEB e os novos revestimentos

Dissertação de natureza científica para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Edificações

Avaliação dos parâmetros de soldagem para compósitos de PPS/fibras contínuas com aplicações aeronáuticas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desenvolvimento e caracterização de compósitos poliméricos reforçados com fibras lignocelulósicas: HIPS / fibra de casca do coco verde e bagaço de cana de açucar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Obtenção e caracterização de compósitos de fibras de carbono/PEKK com aplicações aeronaúticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da aplicabilidade do sistema pultrudado de fenólica/fibras de carbono em cabos condutores

Pós-graduação em Engenharia Mecânica - FEG

Desenvolvimento e caracterização de compósitos de fibras naturais modificadas e híbridos: fibras da coroa do abacaxi/polipropileno e fibras da coroa do abacaxi/fibras de vidro/polipropileno

The concern with the environment preservation has done with that researchers as well as industries invest in the search for materials that come from renewable sources. Natural fibers, because they are ecologically correct and have low cost, have been studied as a possible substitute, even if partial, of synthetic fibers in the development of polymeric composites. In this context, the hybrid composites (natural/synthetic) increase considerably the range of application of natural composites. The auto industry, in its constant quest for good mechanical properties materials which are developed with sustainability, has in composites with hybrid reinforcement a very viable alternative. In the present work, the nature Crown pineapple fibers and nature Crown pineapple fibers treated with alkaline solution were studied in order to evaluate the influence of chemical treatment in its properties. For this techniques were used x-ray diffractometry, Thermogravimetry and Infrared Spectroscopy (FTIR). Composites have been developed using polypropylene, reinforced with pineapple fibers and pineapple fibers hybrids/glass fibres, both with levels of 5 and 10%. These composites were analyzed by Thermogravimetry techniques and tested by traction. The realization of this work indicated that although the chemical treatment did not affect the thermal stability of the fibers, caused an increase in crystallinity index fibers and decreased its hydrophilic. The tests performed on composite indicated that the composites process was suitable because it provided good dispersion of the polymer matrix. The addition of natural fibers from the pineapple's Crown, in a proportion of 10%, provided the greatest increase in modulus of elasticity (27%) when compared to the pure polymer

Obtenção e caracterização de compósitos via RTM com alta fração de fibras de carbono processados à temperatura ambiente

After confirming the high specific mechanical properties of composite materials by scientific studies conducted over the last decades, one of the challenges of this new class of materials is the ability to achieve mass production at a more affordable cost, which has become indispensable. The Resin Transfer Molding (RTM) is an excellent method for manufacturing composite materials. Despite being a process widely used by international companies in the production of high performance structural composites, only a short time the national aviation industry has shown interest in implementing this type of processing to more complex structures and greater structural responsibility. In aeronautical projects, the reproducibility and the relative low cost of this process, several studies have been performed in Brazil for learning and perfecting this technique. This process is suitable for producing polymer components both simple as complex geometry, and allows to achieve consistent thickness, with high quality finish and without limiting range. Polymeric composite components for the high mechanical stress applications such as aircraft structures, satellites, etc., require a strict control of volume fractions of the composite constituents, beyond the knowledge of their mechanical and thermal properties. Therefore, in this experimental work degree study on the mechanical, thermal and of porosity composites processed by RTM processed characterization was performed. This characterization was performed targeting a possible aerospace application of this composite material. For the production of composites, process equipment (RTM RTM injector Radius 2100cc) was used. The processed carbono/epoxy composites were characterized via flexure tests mechanically and thermally analysis via DMA, DSC and TGA. To determine the volume fraction of fibers, the composite samples were analyzed via matrix digestion (ASTM D3171) ... (Complete abstract click electronic access below)

Reciclagem de poliestireno expandido: compósito com fibras de algodão para a confecção de placas de circuito impresso

In this work polymeric composites reinforced with cotton fibers, from the textile industry, were developed in order to manufacture printed circuit boards. It was used expanded polystyrene (EPS) as a thermoplastic matrix by melting it. For the obtention of 10% and 15% of fiber volume fraction in cotton fibers composites, it was used wasted cotton fibers as an incentive of recycling and reusing of the domestic and industrial wastes as well as for Expanded Polystyrene(EPS). The mechanical properties of the composites were evaluated by tensile and flexural strength from standardized test methods. Composites were characterized by a Scanning Electron Microscopy (SEM), Thermogravimetry (TG/DTG), Differential Scanning Calorimetry (DSC) and dielectric analysis. The analysis of the results showed that fiber in the composite directly influenced in the thermal and mechanical properties

Reciclagem de poliestireno expandido: compósito com fibras de sisal para confecção de placas de circuito impresso

In this work polystyrene composites reinforced with recycled sisal fibers were processed, in order to apply in the manufacture of printed circuit boards. A thermoplastic matrix of recycled polystyrene was used, this material came from waste expanded polystyrene (EPS) used in appliance's packages. Composites were prepared with 15% and 25% of sisal fibers. To obtain the composites, wasted EPS and natural sisal fibers were chosen, to encourage recycling and reuse of household waste and also the use of renewable resources. The composites were analyzed by standard tensile and flexural test, in order to verify the mechanical properties of the material. The characterization of the composite was done by scanning electron microscopy (SEM) , thermogravimetry (TGA / DTG) , differential scanning calorimetry (DSC) and dielectric analysis . The analysis of the results showed that the percentage of fibers in the composite influences directly the thermal and mechanical properties. Plates with a lower percentage of fibers showed superior properties at a higher percentage. The composite material obtained is easy to process and it's use is feasible for the confection of printed circuit boards, considering it's mechanical, thermal and insulative properties

Processamento de peças em materiais compósitos para o projeto BAJA SAE

The weight of a vehicle has always been considered an extreme important factor, because it interferes in the performance, steering, consume, environmental impact, wear of components, among the others. Because of the new demand, consume reduction aim and gases emission increased the necessity to manufacture lighter vehicles, guaranteeing the complying with the gas emission international law. Besides the legal demand, the low weight will certainly be essential for the competitiveness for the next generation of vehicles. It is with this thinking the composite materials have been introduced in the automobilist industry, because those materials show an excellent relation of strength/weight, providing a reduction of consume and the increase of load capacity. Those factors justify the increase of interest of industry and the necessity of optimization of those materials and of their process. For this research, the field of application will be the Baja SAE Project, a project that is fully developed by engineering students, where they build a prototype single seat, off-road category, for use on hilly slopes with obstacle. This research aims to study two key components of the prototype are made of composite materials, analyzing all the processing. In addition, there is the analysis of the viability of this production parts to a Baja SAE vehicle, in order to increase their performance and reduce their weight without reducing the safety and robustness of the prototype. It was possible to achieve weight reduction of the steering subsystem with manufacturing the flywheel hybrid composite (carbon/glass) and the replacement of SAE 1010 steel by hybrid composite (carbon/aramid) in CVT box. The importance of this study is to obtain a good project for the vehicle of technical and scientific manner, contributing to the know-how to the team and providing a basis for optimization for upcoming projects