Avaliação das condições de processamento através do ensaio de resistência ao cisalhamento em material compósito
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Citações na Scopus
Tipo de produção
Trabalho de Conclusão de Curso
Data
2023-06-27
Autores
Costa, Kadhine Santos da
Orientador
Naville, William
Periódico
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Título de Volume
Citação
Texto completo (DOI)
Palavras-chave
material compósito,ensaio de cisalhamento,processamento,composite material,shear testing,processing
Resumo
A utilização de materiais compósitos continua crescendo na indústria por conta das propriedades superiores resultante da combinação de dois ou mais materiais. Visando o uso desta classe de materiais, este trabalho tem por objetivo determinar a resistência e módulo de cisalhamento em um compósito polimérico reforçado com fibra de carbono, relacionando as diferenças no processamento com a resistência ao cisalhamento. O ensaio de cisalhamento nesta classe de materiais muitas vezes gera uma discussão devido a muitos testes e diferentes procedimentos propostos. Isso ocorre pelo fato de que muitas técnicas não podem fornecer tanto a tensão e o módulo de cisalhamento em um único teste. Neste estudo optou-se pelo teste Iosipescu padronizado pela ASTM D5379, buscando uma inovação no dispositivo com relação a fixação dos corpos de prova e uso simultâneo para ensaio de cisalhamento na direção da espessura do laminado. Os dados de limite de resistência ao cisalhamento e módulo de cisalhamento pesquisados foram usados para análise do desempenho desse dispositivo. Os corpos de prova foram confeccionados a partir do método infusão a vácuo usando resina epóxi e fibra de carbono no formato de tecido, tramada bidimensionalmente. Foram fabricados 2 tipos de compósitos: o primeiro homogêneo com orientação [0/90] e o segundo com fibras curtas com aproximadamente 3 a 7 mm de comprimento distribuídas na orientação aleatória entre as camadas de tecido 0/90 com o uso de cola especial. Cada placa de compósito foi fabricada com aproximadamente 330x250mm e a espessura ficou dependente das camadas e da compactação provocada pelo vácuo. Com os corpos de prova dentro das dimensões, os extensômetros foram instalados para medir a resposta ao cisalhamento em deformação. Com o intuito de avaliar a influência da adição das fibras curtas à resina epóxi, após ensaiados, foi realizada uma análise da estrutura com microscópico óptico. A adição de fibras curtas aumentou o módulo de cisalhamento G12 e a tensão máxima de cisalhamento τ12, na direção da espessura, diminuiu G13 e τ13. Entretanto, apesar das fibras curtas terrem causado este efeito, foram detectados vazios entre as camadas do compósito 0/90. Portanto, não foi possível afirmar que somente a adição de fibras picotadas curtas entre as camadas do laminado conferiu um maior desempenho na direção [12].
The application of composite materials continues to grow in the industry due to its superior properties resulting from the combination of two or more materials. Aiming the use of this class of materials, this work has the objective to determine the shear strength and modulus in a carbon fiber reinforced polymer composite, relating the differences in processing with the shear strength. Shear testing in composites often generates a discussion since multiple tests and different procedures have been proposed. This is due to the fact that most techniques cannot provide both stress and shear modulus in a single test. In present study it is used the Iosipescu test standardized by ASTM D5379, seeking an innovation in device related to the fixation of the specimens and simultaneous use for shear testing in direction of laminate thickness. The shear strength and modulus data researched were used to analyze performance of this device. The specimens were fabricated using vacuum infusion method with epoxy resin and carbon fiber in a fabric format, two-dimensionally weaved. Two types of composites were manufactured: the first homogeneous with [0/90] orientation and the second with short fibers with approximately 3 to 7 mm in length distributed in random orientation between the layers of 0/90 fabric using a special glue. Each composite plate was manufactured with approximately 330x250 mm and thickness depending on layers and compaction caused by the vacuum. With the specimens within the dimensions, strain gauges were installed to measure the shear response in deformation. In order to evaluate the influence of adding short fibers to the epoxy resin, after shear testing, an analysis of structure was performed with the help of an optical microscope. The addition of short fibers increased the shear modulus G12 and its maximum shear stress τ12, in thickness direction, decreased G13 and τ13. However, despite the short fibers caused this effect, through the optical microscope some voids were detected in 0/90 composite layers. Therefore, it was not possible to affirm that only the addition of short perforated fibers between the layers of laminate conferred a higher performance in direction [12].
The application of composite materials continues to grow in the industry due to its superior properties resulting from the combination of two or more materials. Aiming the use of this class of materials, this work has the objective to determine the shear strength and modulus in a carbon fiber reinforced polymer composite, relating the differences in processing with the shear strength. Shear testing in composites often generates a discussion since multiple tests and different procedures have been proposed. This is due to the fact that most techniques cannot provide both stress and shear modulus in a single test. In present study it is used the Iosipescu test standardized by ASTM D5379, seeking an innovation in device related to the fixation of the specimens and simultaneous use for shear testing in direction of laminate thickness. The shear strength and modulus data researched were used to analyze performance of this device. The specimens were fabricated using vacuum infusion method with epoxy resin and carbon fiber in a fabric format, two-dimensionally weaved. Two types of composites were manufactured: the first homogeneous with [0/90] orientation and the second with short fibers with approximately 3 to 7 mm in length distributed in random orientation between the layers of 0/90 fabric using a special glue. Each composite plate was manufactured with approximately 330x250 mm and thickness depending on layers and compaction caused by the vacuum. With the specimens within the dimensions, strain gauges were installed to measure the shear response in deformation. In order to evaluate the influence of adding short fibers to the epoxy resin, after shear testing, an analysis of structure was performed with the help of an optical microscope. The addition of short fibers increased the shear modulus G12 and its maximum shear stress τ12, in thickness direction, decreased G13 and τ13. However, despite the short fibers caused this effect, through the optical microscope some voids were detected in 0/90 composite layers. Therefore, it was not possible to affirm that only the addition of short perforated fibers between the layers of laminate conferred a higher performance in direction [12].