TY - JOUR
T1 - Fracture process zone in crystalline rock
T2 - effect of specimen size and shape
AU - Mishaan Lilienthal, Gabriel
AU - Zhong, Yi
AU - Makhnenko, Roman Y.
N1 - The authors declare no conflict of interest. The experimental data is available upon request. We thank Kiseok Kim for assistance with the experiments and Ali Tarokh for insightful comments. This work was supported by the UIUC-ZJU Research Collaboration program (grant # 083650) and the Department of Civil and Environmental Engineering at the University of Illinois.
PY - 2023/12
Y1 - 2023/12
N2 - Ability to predict fracture properties of granular materials based on their size and loading conditions needs rigorous experimental evidence. Charcoal granite specimens of various sizes and geometries are tested under three- and four-point bending to investigate the effect on the fracture toughness of rock and size of the fracture process zone calculated using Digital Image Correlation (DIC), with validation provided by Acoustic Emission (AE). Two different methods to evaluate the length of the fracture process zone using DIC are adopted: the first one assumes that a traction free crack does not propagate in the pre-peak regime, while the second one hypothesizes that a cohesionless crack may exist at peak load before unstable crack growth. The effects of specimen size, geometry, and loading conditions are found to be more prominent for the specimen sizes used in the laboratory but are predicted to become less significant and eventually negligible as the specimen size increases. DIC results are in general agreement with localization of AE events, but the former technique is suggested due to greater resolution and ability of continuous measurements of the fracture process zone dimensions.
AB - Ability to predict fracture properties of granular materials based on their size and loading conditions needs rigorous experimental evidence. Charcoal granite specimens of various sizes and geometries are tested under three- and four-point bending to investigate the effect on the fracture toughness of rock and size of the fracture process zone calculated using Digital Image Correlation (DIC), with validation provided by Acoustic Emission (AE). Two different methods to evaluate the length of the fracture process zone using DIC are adopted: the first one assumes that a traction free crack does not propagate in the pre-peak regime, while the second one hypothesizes that a cohesionless crack may exist at peak load before unstable crack growth. The effects of specimen size, geometry, and loading conditions are found to be more prominent for the specimen sizes used in the laboratory but are predicted to become less significant and eventually negligible as the specimen size increases. DIC results are in general agreement with localization of AE events, but the former technique is suggested due to greater resolution and ability of continuous measurements of the fracture process zone dimensions.
KW - Acoustic emission (AE)
KW - Cohesive zone model
KW - Digital image correlation (DIC)
KW - Fracture toughness
KW - Granite
UR - http://www.scopus.com/inward/record.url?scp=85174337553&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85174337553&partnerID=8YFLogxK
U2 - 10.1016/j.tafmec.2023.104118
DO - 10.1016/j.tafmec.2023.104118
M3 - Article
AN - SCOPUS:85174337553
SN - 0167-8442
VL - 128
JO - Theoretical and Applied Fracture Mechanics
JF - Theoretical and Applied Fracture Mechanics
M1 - 104118
ER -