نوع مقاله : مقاله پژوهشی
نویسنده
گروه مهندسی معدن، دانشگاه صنعتی همدان
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسنده [English]
In rock mechanics/engineering problems, the propagation and initiation of induced cracks in rock specimens subjected to external stresses can be studied in detail by rock fracture mechanics. The concept of fracture toughness, as one of the most important definitions in fracture mechanics, can be expressed as the capacity of a material to resist fracture propagation. The main objective of the present study is to find a possible relationship between tensile strength and fracture toughness (mode I) of gypsum. For this purpose, the edge-slotted specimen (ENS) is proposed as a new experimental configuration to evaluate the mode I fracture toughness of brittle specimens. After a review of the geometry and testing methods of conventional specimens, a detailed explanation of the characteristics and advantages of using the new specimen will be provided. In the following, the experimental investigation of gypsum specimens in terms of mixture, specimen preparation, and test program will be discussed. Also, the Brazilian Notched Disk (NBD) experimental test was employed to validate the accuracy of the results obtained with the ENS approach. In addition, the measured experimental results were compared with the results estimated using PFC2D. In this paper, the fracture toughness (mode I) of gypsum specimens was obtained using edge-slotted specimens. Brazilian slotted discs were also used to validate the new test results. In addition, a numerical analysis was performed on the edge-slotted specimen test to verify the accuracy of the measured fracture toughness values compared to the numerically obtained values. The slot lengths in the new specimen were set to 15, 25, and 35 mm. However, the slot lengths in the Brazilian slotted discs were set to 5, 10, 20, 30, 40, and 50 mm. The findings show that the flat bond model can accurately predict the potential crack growth path and crack initiation stress compared to the experimental results. It was inferred that the fracture toughness remains almost the same with increasing crack length. Furthermore, the tensile strength and fracture toughness of the gypsum samples are significantly correlated (σt = 5 KIC). It was also found that the fracture propagation patterns obtained from the laboratory investigations are in good agreement with the outputs of the numerical simulations.
کلیدواژهها [English]
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