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Authors
Abstract(s)
Um compósito CFRP (carbon fiber reinforced polymer) é uma classe de materiais
amplamente utilizado em aplicações que exigem elevado desempenho mecânico, pois
este exibe propriedades como elevada resistência, durabilidade e rigidez combinado com
baixa densidade.
Assim, qualquer tipo de defeito no seu interior pode resultar numa redução significativa
da sua performance. Os defeitos como as porosidades, rugas e/ou corpos estranhos,
promovem os danos com origem em condições de serviço, podendo ocorrer casos de
deslocamento, delaminação, fissuração da matriz e rotura de fibras.
Para uma análise experimental de laminados CFRP seguiram-se diferentes sequências
de empilhamento, [010] e [02/902/02/902/02], e foram construídas amostras submetidas
a um teste mecânico de flexão em três pontos. Durante a construção do laminado foi
embebido entre camadas um filme em Teflon com diferentes dimensões (5 mm e 10 mm)
e em diferentes posições, isto é, em zonas sujeitas à tração e em zonas sujeitas à
compressão.
De modo a comprovar os resultados experimentais foi desenvolvido um modelo
numérico recorrendo ao método de elementos finitos, com recurso ao Ansys.
A comparação entre dados experimentais e numéricos permite concluir que a
implementação de um defeito em laminados CFRP influencia o seu desempenho em
5,75% para amostras de construção unidirecional e 5,50% nas amostras de construção
cruzada. Fatores como a dimensão do defeito apresentam divergências, sendo que um
defeito de 10 mm apresenta uma maior influência comparativamente ao defeito de 5 mm.
A posição do defeito também é uma variável, sendo que quando este se encontra à
compressão a performance final da amostra será mais prejudicada comparativamente ao
defeito à tração.
O modelo digital foi validado pelos ensaios experimentais e permitiu obter estimativas
de comportamento para diversas condições, tais como: sequência de empilhamento,
número de camadas, espessura da lâmina, geometria do laminado e dimensão do defeito.
CFRP (carbon fiber reinforced polymer) composite is a material widely used in applications requiring high mechanical performance, as it exhibits properties such as high strength and stiffness combined with low density. Thus, any type of defect inside can result in a significant reduction in its performance. Defects include porosity, wrinkles and/or foreign bodies, and damage occurs under service conditions, which can include displacement, delamination, matrix cracking and fiber breakage. For an experimental analysis of CFRP laminates, diferente stacking sequences were followed, [010] and [02/902/02/902/02], and the samples were subjected to a three-point bending test. During the construction of the laminate, a Teflon film with different sizes (5 mm and 10 mm), was implemented in different positions, in areas prone to traction and areas subjected to compression. In order to verify the experimental results, a numerical simulation using finite element analysis was carried out using Ansys. The comparison between experimental and numerical data shows that the implementation of a defect in CFRP laminates influences its performance by 5,75% for unidirectional construction samples and 5,50% for cross construction samples. Factors such as the size of the deffect differ, with a 10 mm defect having a greater impact than a 5 mm defect. The position of the Teflon film is also a variable element, and when it is in compression the final performance of the sample will be more impaired compared to a tensile defect. The digital model was validated by experimental tests and it allowed behavior estimates to be obtained for various conditions such as: stacking sequence, number of layers, lamina thickness, laminate geometry and defect size.
CFRP (carbon fiber reinforced polymer) composite is a material widely used in applications requiring high mechanical performance, as it exhibits properties such as high strength and stiffness combined with low density. Thus, any type of defect inside can result in a significant reduction in its performance. Defects include porosity, wrinkles and/or foreign bodies, and damage occurs under service conditions, which can include displacement, delamination, matrix cracking and fiber breakage. For an experimental analysis of CFRP laminates, diferente stacking sequences were followed, [010] and [02/902/02/902/02], and the samples were subjected to a three-point bending test. During the construction of the laminate, a Teflon film with different sizes (5 mm and 10 mm), was implemented in different positions, in areas prone to traction and areas subjected to compression. In order to verify the experimental results, a numerical simulation using finite element analysis was carried out using Ansys. The comparison between experimental and numerical data shows that the implementation of a defect in CFRP laminates influences its performance by 5,75% for unidirectional construction samples and 5,50% for cross construction samples. Factors such as the size of the deffect differ, with a 10 mm defect having a greater impact than a 5 mm defect. The position of the Teflon film is also a variable element, and when it is in compression the final performance of the sample will be more impaired compared to a tensile defect. The digital model was validated by experimental tests and it allowed behavior estimates to be obtained for various conditions such as: stacking sequence, number of layers, lamina thickness, laminate geometry and defect size.
Description
Keywords
Defeito de Delaminação Ensaios Experimentais de Flexão Gémeo Digital Laminados de Fibra de Carbono Modo
de Ruína