Mixed-Mode Fracture Toughness Testing of Coal
Editor(s)
Hartman, Howard L.
Abstract
An extensive mixed-mode fracture toughness testing programme was conducted on coal from three coal fields. A special mixed-mode testing fixture for coal and other geologic materials was developed together with reliable specimen preparation procedures. Dynamic modulus measurements made on each of the 116 fracture toughness specimens showed that these coals exhibit certain degrees of anisotropy. The fracture toughness testing programme systematically varied the loading rate, specimen orientation and fracture loading mode. Loading rate did not significantly effect the fracture toughness over the quasi-static range tested. Orientation did have a significant effect on measured fracture toughness. In the coals tested, the divider orientation and arrester orientation had higher fracture toughness than the short transverse orientation. Data showed that one orientation could have almost twice the fracture toughness as another. The fracture toughness testing enabled certain evaluations of three mixed-mode fracture theories: maximum tangential stress, maximum energy release rate and strain energy density theory. Due to the extreme heterogeneity of the coals tested, definitive conclusions regarding the best mixed-mode fracture theory are not possible; however, data do tend to support the strain energy density theory. © 1990.
Recommended Citation
R. K. Zipf and Z. T. Bieniawski, "Mixed-Mode Fracture Toughness Testing of Coal," International Journal of Rock Mechanics and Mining Sciences, Elsevier, Jan 1990.
The definitive version is available at https://doi.org/10.1016/0148-9062(90)91000-W
Department(s)
Mining Engineering
International Standard Serial Number (ISSN)
1365-1609
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 1990 Elsevier, All rights reserved.
Publication Date
01 Jan 1990
