Artur Camposo Pereira

Charpy Impact Tests in Epoxy Matrix Composites Reinforced with Continuous Sisal Fiber

The objective of this work was to investigate the toughness behavior of epoxy matrix composites reinforced with up to 30% in volume of long, continuous and aligned sisal fibers by means of Charpy impact tests. The addition of sisal fibers results in a visible improvement in the energy absorption ability of the composites. Macroscopic observation of the post-impacted specimens and the SEM fracture analysis showed that longitudinal rupture through the sisal fiber interface with the epoxy matrix is the main mechanism for the higher toughness attended by these composites.

Fique Fabric: A Promising Reinforcement for Polymer Composites

A relatively unknown natural fiber extracted from the leaves of the fique plant, native of the South American Andes, has recently shown potential as reinforcement of polymer composites for engineering applications. Preliminary investigations indicated a promising substitute for synthetic fibers, competing with other well-known natural fibers. The fabric made from fique fibers have not yet been investigated as possible composite reinforcement. Therefore, in the present work a more thorough characterization of fique fabric as a reinforcement of composites with a polyester matrix was performed. Thermal mechanical properties of fique fabric composites were determined by dynamic mechanical analysis (DMA). The ballistic performance of plain woven fique fabric-reinforced polyester matrix composites was investigated as a second layer in a multilayered armor system (MAS). The results revealed a sensible improvement in thermal dynamic mechanical behavior. Both viscoelastic stiffness and glass transition temperature were increased with the amount of incorporated fique fabric. In terms of ballistic results, the fique fabric composites present a performance similar to that of the much stronger KevlarTM as an MAS second layer with the same thickness. A cost analysis indicated that armor vests with fique fabric composites as an MAS second layer would be 13 times less expensive than a similar creation made with Kevlar™.

Dynamic-Mechanical Characterization of Polyester Matrix Composites Reinforced with Eucalyptus Fibers

Recently, the eucalyptus fibers have been investigated as a potential option in composites application, due to some advantages in comparison with synthetic fibers. It is largely cultivated in all Brazilian territory. The present work has as objective to characterize the dynamic-mechanical behavior of eucalyptus fiber composites subjected to thermal and mechanical constraints. In this work, the temperature variation and the dynamic-mechanical parameters of polyester composites incorporated with up to 30% in volume of eucalyptus fibers were investigated by Dynamic Mechanical Analysis (DMA) experiments. The results showed that the incorporation of eucalyptus fibers tends to increase the viscoelastic stiffness of the polyester matrix. It was also observed

Tensile Properties of Epoxy Composites Reinforced with Continuous Sisal Fibers

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of sisal fibers were evaluated. Composites reinforce with up to 30% in volume of long, continuous and aligned sisal fibers were room temperature tested in an Instron machine. The fracture was analyzed by SEM. The results showed significant changes in the mechanical properties with the amount of sisal fibers. These mechanical properties were compared with other bend-tested composites results. The fracture analysis revealed a weak fiber/matrix interface, which could be responsible for the performance of some properties.

Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS). Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM). The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.

Microstructural Evaluation of a 5052 H34 Aluminum Alloy Used in Multilayered Armor

Among the aluminum alloys, the 5052 has been extensively investigated aiming at high rate deformation applications, owing to its high mechanical strength, plasticity and toughness. In this work, the microstructure and microhardness of a 5052 H34 alloy were investigated. This alloy was subjected to ballistic impact with 7.62 mm ammunition as back layer of a multilayered armor system composed of a ceramic and a composite material. An increase in the microhardness was observed. However, changes in the microstructure were not significant. The fracture aspect of the alloy in the high deformation rate was compared to that of a tensile tested sample. A stronger plastic behavior was verified in ballistic tested samples.

Charpy Toughness Behavior of Jute Fabric Reinforced Polyester Matrix Composites

The fique fiber is an important natural fiber, originally from Colombia where it is used for sacks and crafts while its plant is used to contain slopes. However, few studies were realized with the fiber obtained from the fique plant leaf, its mechanical properties are superior in many aspects in comparison to some other lignocellulosic fibers. This work investigated the toughness behavior of polyester matrix composites reinforced with up to 30% in volume of a fabric made of fique fiber by means of Charpy impact tests. It was found that the addition of fique fabric results in a marked increase in the absorbed energy by the composites. Macroscopic observation of the post-impact specimens and SEM fracture analysis showed that transversal rupture through the fique fabric interface with the polyester matrix is the main mechanism for the remarkable toughness of these composites.

Izod Impact Tests in Polyester Matrix Composites Reinforced with Fique Fabric

Jute fibers are among the lignocellulosic fibers with greater potential for use as fabric reinforcing polymer composites. This study evaluated the impact resistance of this type of composite. Specimens were made with up to 30% in volume of jute fabric in an Izod normalized mold. The jute fabric was embedded with polyester resin and cured at room temperature for 24 h. The specimens were tested in Izod impact pendulum and the fracture surfaces were examined by scanning electron microscopy (SEM). The impact resistance of composites increased linearly with the relative amount of jute fabric reinforcing the composite. This performance was associated with the difficulty of rupture imposed by the jute fabric as well as the type of cracks resulting from the interaction jute fiber/polyester matrix that corroborate the energy absorption at the impact test.

DESEMPENHO DO COMPÓSITO DE MATRIZ POLIÉSTER REFORÇADO COM TECIDO DE JUTA EM UM SISTEMA DE BLINDAGEM MULTICAMADA

* Contribuição técnica ao 72o Congresso Anual da ABM – Internacional e ao 17o ENEMET Encontro Nacional de Estudantes de Engenharia Metalúrgica, de Materiais e de Minas, parte integrante da ABM Week, realizada de 02 a 06 de outubro de 2017, São Paulo, SP, Brasil. DESEMPENHO DO COMPÓSITO DE MATRIZ POLIÉSTER REFORÇADO COM TECIDO DE JUTA EM UM SISTEMA DE BLINDAGEM MULTICAMADA* Foluke Salgado de Assis Sérgio Neves Monteiro Fabio Da Costa Garcia Filho Artur Camposo Pereira Édio Pereira Júnior Carlos Luiz Ferreira Resumo O desempenho balístico de compósitos de matriz de poliéster reforçados com tecido de juta foi avaliado como segunda camada em um sistema de blindagem multicamadas (MAS – Multilayered Armor Systems). Diferentes frações volumétricas de tecido de juta, até 30% vol., foram misturadas com poliéster ortoftálica para se fabricar as placas compósitas. Estes compósitos foram ligados a uma camada cerâmica de alumina dianteira e seguidos por uma placa metálica de liga de alumínio como terceira camada do MAS, os testes balísticos foram conduzidos usando munição comercial de alta velocidade de 7,62 mm. A profundidade de penetração causada pela bala em um bloco de plastilina, que simula o corpo humano, foi usada para avaliar o desempenho balístico do MAS de acordo com o padrão internacional. Os materiais fraturados após testes foram analisados por microscopia eletrônica de varredura (MEV). Os resultados indicaram que os compósitos de tecido de juta apresentam um desempenho semelhante ao do tecido de aramida comercialmente utilizado como segunda camada para MAS com mesma espessura, o KevlarTM. O mecanismo que explica este comportamento balístico semelhante, bem como as vantagens econômicas comparativas dos compósitos de tecido de juta foram discutidos. Palavras-chave: Tecido de juta; Compósito de poliéster; Comportamento balístico; Sistema de blindagem multicamada.