J-integral measurement in geological materials
The path-independent J-integral introduced by Rice can be viewed as the derivative of the psuedo-potential energy of a cracked body with respect to crack length. It has been shown that the derivative is related to the work done in loading a deeply notched specimen subjected to pure bending. Thus, J can be obtained experimentally, on a single specimen, by measuring the work done in loading to the critical load at which unstable crack propagation occurs. A technique for accomplishing this measurement in geologic materials, in which the machining of a notch for a conventional clip gage is difficult and costly, has been developed. The resulting load vs. load-point displacement data are fitted to a linear plus power-law relation and integrated analytically to obtain J. It is found that for Barre granite, the onset of unstable crack growth is easily detected by noting the point at which departure from the power-law relation occurs. 21 references.
- OSTI ID:
- 6237210
- Report Number(s):
- CONF-780509-
- Journal Information:
- Nevada Univ, Reno, et al Rock Mech Symp; (United States), Vol. 1; Conference: 19. symposium on rock mechanics, Lake Tahoe, NV, USA, 1 May 1978
- Country of Publication:
- United States
- Language:
- English
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