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Abstract(s)
Ao longo das últimas décadas tem-se verificado um elevado crescimento quanto à procura e utilização dos materiais compósitos laminados, na manufaturação dos componentes, que exigem elevados níveis de performance, em inúmeras indústrias, quando os metais habitualmente utilizados não conseguem satisfazer essas necessidades. É nas indústrias aeroespacial e militar onde estes materiais são mais utilizados, uma vez que têm um elevado custo de aquisição. Nestas indústrias existe também uma elevada necessidade de se fabricar componentes com elevados níveis de desempenho no que toca a resistência mecânica, bons níveis de isolamento térmico e acústico, e baixo peso das estruturas, dos componentes ou equipamentos industriais.
A presente dissertação apresenta inúmeros estudos relativos a falha ou ao dano em placas compósitas por materiais compósitos laminados. Para tal, foram desenvolvidos dois modelos: o analítico e numérico, com objetivo de calcular a carga que origina a primeira falha nas placas apresentadas no trabalho, através dos critérios de falha de Tensão Máxima, Tsai-Wu, Tsai-Hill, Hashin e Hashin-Rotem, sabendo previamente que a resistência da placa diminui significativamente a partir do momento em que uma das lâminas apresenta um índice de falha igual ou superior a 1, ou seja, quando um dos laminados falha, a resistência do material diminui consideravelmente. De modo a garantir uma maior precisão nos resultados, os modelos analítico e numérico foram elaborados, em Maple e Ansys respetivamente. Para o modelo analítico, a precisão dos resultados foi aumentada através do código desenvolvido e das pesquisas realizadas, enquanto para o modelo numérico através do refinamento da malha nas placas estudadas foi possível aumentar a precisão dos resultados.
Para o estudo dos critérios de falha foram considerados 10 casos de estudo, com diferentes distribuições de empilhamento, diferentes espessuras das lâminas e em alguns casos, diferentes propriedades mecânicas dos materiais considerados. Foi também necessário realizar estudos sobre o fator de intensidade de tensão, numa placa com um furo no seu centro. Os furos apresentam diferentes tamanhos e formas, e na presente dissertação são realizados estudos para furos circulares, furos do tipo elipse e do tipo semi-elipse.
Over the past few decades there has been a high growth in demand and use of laminated composite materials, in the manufacture of components, which require high levels of performance, in numerous industries, when the metals commonly used are unable to meet these needs. It is in the aerospace and military industries where these materials are most used, since they have a high acquisition cost. In these industries there is also a large need to manufacture components with large levels of performance in terms of mechanical resistance, good levels of thermal and acoustic insulation, and low weight of structures, components, or industrial equipment. The present dissertation presents numerous studies related to the failure or damage in composite plates by laminated composite materials. To this end, two models were developed: the analytical and numerical, with the objective of calculating the load that originates the first failure in the plates presented in the work, through the failure criteria of Maximum Tension, Tsai-Wu, Tsai-Hill, Hashin and Hashin - Rotate, knowing in advance that the strength of the plate decreases significantly from the moment when one of the blades has a failure index equal to or greater than 1, in other words, when one of the laminates fails, the material strength decreases considerably. In order to ensure greater precision in the results, the analytical and numerical models were developed in Maple and Ansys, respectively. For the analytical model, the precision of the results was increased through the developed code and the researches carried out, while for the numerical model through the refinement of the mesh in the studied plates it was possible to increase the precision of the results. For the study of failure criteria, 10 study cases were considered, with different stacking distributions, different blade thicknesses and in some cases, different mechanical properties of the materials considered. It was also necessary to carry out studies on the stress intensity factor, on a plate with a hole in its center. The holes have different sizes and shapes, and in this dissertation, studies are made for circular holes, ellipse-type and semi-ellipse-type holes.
Over the past few decades there has been a high growth in demand and use of laminated composite materials, in the manufacture of components, which require high levels of performance, in numerous industries, when the metals commonly used are unable to meet these needs. It is in the aerospace and military industries where these materials are most used, since they have a high acquisition cost. In these industries there is also a large need to manufacture components with large levels of performance in terms of mechanical resistance, good levels of thermal and acoustic insulation, and low weight of structures, components, or industrial equipment. The present dissertation presents numerous studies related to the failure or damage in composite plates by laminated composite materials. To this end, two models were developed: the analytical and numerical, with the objective of calculating the load that originates the first failure in the plates presented in the work, through the failure criteria of Maximum Tension, Tsai-Wu, Tsai-Hill, Hashin and Hashin - Rotate, knowing in advance that the strength of the plate decreases significantly from the moment when one of the blades has a failure index equal to or greater than 1, in other words, when one of the laminates fails, the material strength decreases considerably. In order to ensure greater precision in the results, the analytical and numerical models were developed in Maple and Ansys, respectively. For the analytical model, the precision of the results was increased through the developed code and the researches carried out, while for the numerical model through the refinement of the mesh in the studied plates it was possible to increase the precision of the results. For the study of failure criteria, 10 study cases were considered, with different stacking distributions, different blade thicknesses and in some cases, different mechanical properties of the materials considered. It was also necessary to carry out studies on the stress intensity factor, on a plate with a hole in its center. The holes have different sizes and shapes, and in this dissertation, studies are made for circular holes, ellipse-type and semi-ellipse-type holes.
Description
Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia Mecânica
Keywords
Carga da primeira falha Load of the first failure Índice de falha Failure index Índice de resistência Resistance index Critérios de falha Failure criteria Fator de concentração de tensão Stress concentration factor Materiais compósitos laminados Laminated composite materials
Citation
MULA, Samuel Nordina - Estudo sobre falha e fadiga em materiais compósitos laminados. Lisboa: Instituto Superior de Engenharia de Lisboa, 2020. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa