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Abstract(s)
No desenvolvimento de projetos de engenharia, a seleção dos materiais é cada vez mais um critério decisivo e de elevada importância no resultado final dos mesmos. A correta ou errada escolha do material a utilizar tem influência direta na eficácia e eficiência do produto, bem como no preço final do mesmo. De modo a ser possível proceder à sua escolha, é necessário ter todas as informações sobre o comportamento do mesmo. Assim sendo, é necessário caracterizar e documentar cada uma das propriedades dos materiais disponíveis no mercado. A presente dissertação estuda o comportamento mecânico de várias concentrações de fibra de vidro no Sheet Moulding Compound (SMC), quando sujeito a ensaios Bulk (ensaio de tração) e Block Shear (ensaio de corte). Nestes ensaios obtêm-se dados como os módulos de elasticidade à tração (E) e ao corte (G). Além dos anteriores, ainda é possível determinar a tensão máxima, tensão cedência e tensão de rotura, novamente, para cada uma das concentrações de fibra. Através de ensaios Double-Cantillever Beam (ensaio de fratura à tração) e End-Notched Flexure (ensaio de fratura ao corte) é possível determinar a tenacidade à fratura, ou seja, a resistência à propagação de fendas do material. Com estes ensaios são obtidos valores como a taxa de libertação de energia de deformação à tração (GIc) e ao corte (GIIc). Terminada a fase experimental, os ensaios descritos anteriormente foram simulados num software de modelação numérico, ABAQUS®, com o objetivo de comparar valores. Em conclusão, com os ensaios realizados foi possível determinar que as propriedades do material no sentido da direção das fibras são tanto melhores quanto maior a concentração das mesmas.
During project engineering development, the material’s choice is one of the most decisive and with the highest importance criteria to achieve the best final product. The correct or wrong material’s choice has a direct impact on the efficiency and product performance, and even on its final price. To choose, it is necessary to have all the information regarding the material behavior. For this, it is necessary to determine and record all the material properties. This thesis studies the material’s mechanical behavior in different amount of fiber glass present on the Sheet Moulding Compound (SMC), when subjected to Bulk (tensile test) and Block Shear (shear test). In these tests, it is possible to obtain the tensile modulus (E) and shear modulus (G). Even more, it is possible to determine the maximum stress, the yield stress and the strength, for all the different fiber concentrations. By DoubleCantilever Beam (tensile fracture test) and End-Notched Flexure (shear fracture test), it is possible to determine the fracture toughness, i.e., the material resistance to crack propagation. With these tests, the tensile strain energy release rate (GIc) and shear deformation energy release rate (GIIc) can be obtained. With the experimental stage finished, the described tests were simulated in a numerical modeling software, ABAQUS®, with the goal to compare results. In conclusion, it was possible to determine that the material’s properties according with the fiber’s orientation can be improved with the increase of the amount of fiber.
During project engineering development, the material’s choice is one of the most decisive and with the highest importance criteria to achieve the best final product. The correct or wrong material’s choice has a direct impact on the efficiency and product performance, and even on its final price. To choose, it is necessary to have all the information regarding the material behavior. For this, it is necessary to determine and record all the material properties. This thesis studies the material’s mechanical behavior in different amount of fiber glass present on the Sheet Moulding Compound (SMC), when subjected to Bulk (tensile test) and Block Shear (shear test). In these tests, it is possible to obtain the tensile modulus (E) and shear modulus (G). Even more, it is possible to determine the maximum stress, the yield stress and the strength, for all the different fiber concentrations. By DoubleCantilever Beam (tensile fracture test) and End-Notched Flexure (shear fracture test), it is possible to determine the fracture toughness, i.e., the material resistance to crack propagation. With these tests, the tensile strain energy release rate (GIc) and shear deformation energy release rate (GIIc) can be obtained. With the experimental stage finished, the described tests were simulated in a numerical modeling software, ABAQUS®, with the goal to compare results. In conclusion, it was possible to determine that the material’s properties according with the fiber’s orientation can be improved with the increase of the amount of fiber.
Description
Keywords
SMC Tenacidade Bulk Block Shear (BS) Double-Cantilever Beam (DCB) End-Notched Flexure (ENF) Modelos de dano coesivo Análise de tensões Análise de elementos finitos Fracture toughness Cohesive damage models Tensile distribution analyses Finite element analysis