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Abstract(s)
No presente trabalho foi abordado a determinação da curva de resistência à fractura (“Curva R”), em materiais metálicos, através dos métodos de curva de resistência e de normalização descritos na ASTM E 1820.
O método de curva de resistência consiste na obtenção da curva de resistência à fractura (expressa em integral J ou CTOD), através de uma única amostra de material, recorrendo à técnica de elastic compliance.
O método normalização consiste na obtenção da curva de resistência (expressa em integral J) directamente do diagrama de força deslocamento, e da medição do comprimento inicial e final da fenda na superfície de fractura.
Foram ensaiados dois conjuntos de provetes (6+8) de dois materiais metálicos distintos. Dois provetes de cada conjunto foram ensaiados através do método de normalização. Os restantes foram submetidos ao método de curva de resistência, através do ensaio desenvolvido no software Wavematrix baseado no procedimento da ASTM E 1820. Foram confrontados os resultados entre cada um dos métodos dentro de cada material e ainda foram comparadas as curvas de resistência entre os dois materiais metálicos. Com as curvas de resistência obtidas foram ainda aplicados os procedimentos do anexo A9 da ASTM E 1820 para se obterem os valores de iniciação à fractura JIC.
In the present work, a study is made about the experimental determination of the fracture resistance curve (R curve) of metallic materials, through the methods: resistance curve and normalizantion, present on ASTM E 1820. The resistance curve method consists in obtaining the “R curve” (Expressed in integral J or CTOD) through a single specimen.Within this method, the elastic compliance technique was used to obtain crack extension values. The normalization method consists in obtaining the resistance curve (expressed in integral J) directly from the force vs displacement diagram and the initial and final crack lengths, measured at the fracture surface. Two sets of specimens (6+8) of two metallic materials were tested. Two specimens from each set were submitted to the normalization method, while the remaining were studied with the resistance curve method, developed in the Instron Wavematrix software based on the procedure of ASTM E 1820. Within each material, the respective resistance curves were compared using both methods. The procedures of Annex A9 of ASTM E 1820 were also applied to obtain the fracture initiation values, JIC.
In the present work, a study is made about the experimental determination of the fracture resistance curve (R curve) of metallic materials, through the methods: resistance curve and normalizantion, present on ASTM E 1820. The resistance curve method consists in obtaining the “R curve” (Expressed in integral J or CTOD) through a single specimen.Within this method, the elastic compliance technique was used to obtain crack extension values. The normalization method consists in obtaining the resistance curve (expressed in integral J) directly from the force vs displacement diagram and the initial and final crack lengths, measured at the fracture surface. Two sets of specimens (6+8) of two metallic materials were tested. Two specimens from each set were submitted to the normalization method, while the remaining were studied with the resistance curve method, developed in the Instron Wavematrix software based on the procedure of ASTM E 1820. Within each material, the respective resistance curves were compared using both methods. The procedures of Annex A9 of ASTM E 1820 were also applied to obtain the fracture initiation values, JIC.
Description
Trabalho final de mestrado para obtenção do grau de mestre em Engenharia Mecânica.
Keywords
Resistência à fractura Fracture toughness Ensaios de fractura Fracture testing Materiais metálicos Metallic materials Curva de resistência Resistance curve Integral J J Integral JIC ASTM E 1820
Citation
BALHANA, Adriano Jorge Santos - Determinação da curva de resistência à fractura em materiais metálicos: "curva R". Lisboa: Instituto Superior de Engenharia de Lisboa, 2017. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa