Fracture mechanics analysis of rock cracked discs using the boundary element method

Document Type : research - paper

Authors

1 Isfahan University of Technology, Mining Engineering Department

2 Malek Ashtar University of Technology, passive Defense Department

Abstract

Fracturing of rock structures occurs usually under mixed mode I-II loading. The determination of the complete fracture toughness envelopes (KI-KII) for rocks is essential since it may serve as a fracture criterion for crack initiation under mixed mode I-II loadings. A number of methods have been developed to determine the fracture toughness of these modes using different specimen configuration. The Brazilian disk specimens with a central crack is proposed by many researchers for investigating modes I, II, and mixed fracture toughness in brittle materials. In this study, the numerical program (2DFPM) was developed based on the boundary element method (displacement discontinuity method) for studying the fracture propagation on Central Straight through Crack Brazilian Disk (CSCBD) specimens. In-order to enhance the capability and accuracy of the numerical program, special elements (crack tip, and quadratic element) were used. The validity of the program was verified by different analytical and numerical results. The results from numerical analysis show that the inclination angle of the crack with respect to the diametrical load and the crack length have the most important impact on the SIFs (Stress Intensity factor) and fracture propagation path.

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