Article
Mechanics
Xiaoran Wang, Pouyan Asem, Chen Hu, Joseph F. Labuz
Summary: Acoustic emission and digital image correlation were used to monitor mode I fracture, revealing local mixed-mode dominance due to oblique microcrack planes within a tortuous fracture. Mechanisms in the global coordinate system mainly indicated mode I opening.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Mechanics
Huilan Ren, Shuizhou Song, Jianguo Ning
Summary: The acoustic emission technique and moment tensor inversion were used to study and quantify the damage evolution process and intensity of microcracks in Brazilian and flattened Brazilian concrete tests. The results showed that microcracks gradually propagate from the zones between the loading points and center to the center and loading points in the Brazilian test. In the flattened Brazilian test, the initiation positions of microcracks were random and crack accumulation occurred near the center of the specimen when the first peak load was reached.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Geological
Longjun Dong, Yihan Zhang, Shuijin Bi, Ju Ma, Yihao Yan, Heng Cao
Summary: Classification of rock micro-fractures by acoustic emission (AE) parameters is crucial, but the criteria are not well-established. This study investigated the uncertainties of the commonly used rise angle (RA) and average frequency (AF) method through experiments. The results showed that the RA-AF distribution range increased with the reduction of the AE source scale and was influenced by the experimental environment. The uncertainties were attributed to the distortion caused by wave attenuation, dispersion, and measurement error. The study provides theoretical and experimental guidance for improving the RA-AF method.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Geological
Ghasem Shams, Patrice Rivard, Omid Moradian
Summary: This study investigated the microcracking processes in granite specimens under indirect (Brazilian) and direct tensile loadings. It was found that the ultimate tensile macro-fracture was predominantly composed of shear microcracks in Brazilian tests and tensile microcracks in direct tension tests. The different contributions of shear and tensile microcracks explain the difference in tensile strengths. The findings of this study have implications for rock fracture applications such as hydraulic fracturing for geothermal energy extraction.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Mechanics
Qi Zhang, Xiao-Ping Zhang, Sheng-Qi Yang
Summary: The study conducted uniaxial compression tests using the bonded-particle model to understand the acoustic emission characteristics and failure mechanisms of specimens containing hole-like flaws. Results showed stress drops in the stress-strain curve corresponded to sudden increases in AE counts, due to micro-crack propagation and coalescence. The shape of the flaw did not significantly impact the magnitude distribution of AE events, and different regions of the flaw experienced different forces and fracture paths.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Aerospace
Yue Kong, Weimin Chen, Ning Liu, Boqi Kang, Min Li
Summary: This study proposes a moment tensor inversion method based on the acoustic emission phenomenon for evaluating the health condition of aircraft structures. A new correlation function is introduced by considering the inherent similarity between signals induced by one source and recorded by different sensors. Synthetic tests demonstrate that the inversion method based on the new correlation function significantly improves accuracy compared to the commonly used amplitude method. This approach does not require knowledge of noise spectra or complex calculation processes, providing a new way to improve inversion accuracy of cracking mechanisms with minimal additional computational consumption.
Article
Mechanics
Guotao Yuan, Mingwei Zhang, Kai Zhang, Hongyue Duan, Lei Jia, Baolin Liu
Summary: An acoustic emission (AE) monitoring test was conducted to investigate the correlation between sandstone fracture evolution characteristics and strain rate during uniaxial compression. The results showed that the peak strength, elastic modulus, and peak strain of sandstone specimens exhibited an exponential relationship within the set strain rate range. The AE monitoring results revealed consistent curve evolution trends for different AE parameters, with a decrease in the cumulative AE count as the strain rate increased. The strain rate also influenced the proportion of different fracture sources and the overall strength of the fracture source inside the sample.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Construction & Building Technology
Haoran Li, Shirong Meng, Dongping Shi, Qun Wei, Zhuang Xu, Weigang Zhao
Summary: This study aimed to improve the safety of concrete structures by investigating the mechanical properties and failure mechanism of concrete specimens with different moisture contents. Uniaxial compression tests were conducted on concrete specimens with moisture contents of 0%, 2%, 4%, and 5.5%. The results showed that crack initiation stress and compressive strength initially increased and then decreased with increasing moisture content, while elastic modulus and Poisson's ratio initially decreased and then increased. The study also analyzed the ultrasonic propagation, acoustic emission characteristics, and deterioration mechanism of bearing capacity in water-saturated concrete. The findings can be applied to health monitoring and safe operation of concrete structures in water environments.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Computer Science, Interdisciplinary Applications
Mengyang Zhai, Lei Xue, Fengchang Bu, Baicun Yang, Hao Ding
Summary: This study numerically examines the microcracking behaviors of Alxa porphyritic granite under direct shear. The results show that the shear fracture systems primarily consist of linked tensile crack arrays, and the proportion of shear cracks increases with an increase in normal stress. Additionally, the strengthening grain inter-locking effect leads to the formation of additional intra-grain cracks and an increase in the thickness of the shear band.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Engineering, Mechanical
Mengyang Zhai, Lei Xue, Fengchang Bu, Baicun Yang, Xiaolin Huang, Ning Liang, Hao Ding
Summary: This study investigates the progressive failure process and acoustic emission characteristics of shales using the bonded-particle model and moment tensor algorithm. The results show that layer orientation affects the failure type and fracture complexity, which can be reflected by acoustic emission characteristics.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Petroleum
Yongzan Liu, Ge Jin, Kan Wu, George Moridis
Summary: A new inversion algorithm is proposed to characterize fracture geometries using LF-DAS strain data, with the method utilizing least-squares and MCMC simulations to quantify uncertainties. The study demonstrates that LF-DAS data can provide important constraints on fracture segments near the monitor well, aiding in the accurate estimation of fracture width and potential calibration of hydraulic-fracturing models.
Article
Engineering, Mechanical
Ghasem Shams, Patrice Rivard, Omid Moradian
Summary: The complexity of the fracture network and the roughness of the generated fractures play a crucial role in determining the hydraulic conductivity of rock masses in rock engineering structures. This study investigated the characteristics of the fracture process zone (FPZ) and the surface roughness of fractures in granite under tension at different loading rates using acoustic emission (AE) and digital image correlation (DIC) techniques. The results showed that the loading rate significantly influenced the extent of the FPZ and the tensile strength of the specimens. Lower loading rates resulted in larger FPZ and higher roughness of the fractures. AE and DIC data were in good agreement, with AE providing slightly wider process zones.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Geochemistry & Geophysics
Guang-an Zhu, Bo-ru Su, Hai-yang Liu, Qi-peng Jiang, Huan Liu
Summary: The study reveals that under true triaxial loading, the number of ring counts representing coal sample damage is influenced by loading level, individual differences, and loading rates. As true triaxial loads increase, the damage process transfers from loading phase to packing phase.
Article
Construction & Building Technology
Shahzad Ashraf, Suliman Khan, Vipin Kumar Oad
Summary: This study investigates the impact of graphene nanoplatelets (GNPs) on cement composites by monitoring the micro-cracking pattern and structural applications using acoustic emission (AE) monitoring. The results show that GNPs content has a significant effect on the absorbance rate and microstructural characteristics of the composites. The flexural capacity, compressive strength, and resistance to fracture of the composites are improved with the addition of GNPs.
CASE STUDIES IN CONSTRUCTION MATERIALS
(2023)
Article
Engineering, Geological
Zihua Niu, Bing Qiuyi Li, Omid Moradian
Summary: We examine the accuracy and reliability of moment tensor (MT) and stress inversion solutions based on acoustic emissions (AEs) during the fracturing of Barre granite samples in the laboratory. The experimental results show that there are different distributions of double-couple (DC) and non-DC events in different loading conditions, and most DC and tensile non-DC events cluster around pre-cut flaws. The stress orientations derived from experiments are consistent with numerical simulations.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Mechanics
Vito Diana, Joseph F. Labuz, Luigi Biolzi
ENGINEERING FRACTURE MECHANICS
(2020)
Editorial Material
Energy & Fuels
Joseph F. Labuz
GEOMECHANICS FOR ENERGY AND THE ENVIRONMENT
(2021)
Article
Engineering, Geological
Roman Y. Makhnenko, Chunwei Ge, Joseph F. Labuz
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2020)
Article
Mechanics
Xiaoran Wang, Pouyan Asem, Chen Hu, Joseph F. Labuz
Summary: Acoustic emission and digital image correlation were used to monitor mode I fracture, revealing local mixed-mode dominance due to oblique microcrack planes within a tortuous fracture. Mechanisms in the global coordinate system mainly indicated mode I opening.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Geological
Pouyan Asem, Heloise Fuselier, Joseph F. Labuz
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Pouyan Asem, Xiaoran Wang, Chen Hu, Joseph F. Labuz
Summary: Three-point bending experiments were conducted to observe mode-I fracture in Sioux quartzite, with detailed observations showing that small specimens follow a size effect law, while Linear Elastic Fracture Mechanics (LEFM) can explain crack growth in larger specimens, indicating a small process zone.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Energy & Fuels
Jinwei Fu, Joseph F. Labuz, Huixiang Cheng, Rongbin Hou, Weishen Zhu
Summary: A novel coupled model involving fluid pressure and mechanical damage is developed to study the failure process of rock specimens under seepage. The results show that the failure process under seepage is different from that under dry conditions, with significantly decreased compressive and residual strengths, and the specimen's volume expansion. Moreover, the results are well consistent with dry experiments, demonstrating the feasibility of the method.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Energy & Fuels
Jinwei Fu, Joseph F. Labuz, Mengdi Guo, Huixiang Cheng, Rongbin Hou
Summary: A new transparent resin material with a high compression-tension strength ratio has been developed, which can simulate various engineering rocks. Uniaxial and biaxial hydraulic fracturing experiments were conducted to analyze the effect of water injection on the mechanical properties of the specimens. The results were validated through numerical simulations, indicating the feasibility of the proposed method.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Geological
Ali Tarokh, Jacob D. Sharpe, Joseph F. Labuz
Summary: Experimental investigation of failure behavior of rock at low mean stress states reveals that a failure criterion incorporating tension cut-offs captures failure in this regime. The roughness of fracture surfaces varies with different failure modes.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
A. Fakhimi, J. F. Labuz
Summary: Measuring the tensile strength of quasi-brittle materials such as rock proves to be a challenging task. However, a new apparatus has been introduced in this study that not only accurately measures the tensile strength but also provides information regarding the crack opening behavior.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Materials Science, Ceramics
Chen Hu, Joseph F. F. Labuz, Takaaki Koyanagi, Jia-Liang Le
Summary: Silicon carbide (SiC) fiber-reinforced SiC matrix (SiC/SiC) composites are being considered as potential materials for fuel claddings in light water reactors. This study presents a probabilistic model for the lifetime distribution of SiC/SiC composites, anchored by a multiaxial stress-based failure criterion and subcritical damage accumulation mechanism. The analysis demonstrates the importance of understanding the static fatigue behavior and length effect on the failure probability of the cladding.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Engineering, Geological
Pouyan Asem, Joseph F. Labuz
Summary: Laboratory experiments were conducted to measure the Skempton coefficient of Dunnville sandstone using small and large specimens. The pore volume of the small specimen was comparable to the system volume, while the pore volume of the large specimen was 100 times greater. The calculated Skempton coefficient using the appropriate poroelastic model and material parameters for Dunnville sandstone was found to agree with the measured coefficient.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Computer Science, Interdisciplinary Applications
Daniel V. Kennedy, Bojan B. Guzina, Joseph F. Labuz
Summary: Several hundred high mast light towers in Minnesota may have insufficient foundation capacity, requiring expensive retrofit or replacement. A non-destructive evaluation technique is proposed to determine in situ pile lengths using seismic waves and machine learning algorithms.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Mechanics
Caleb Widstrand, Chen Hu, Xiaoming Mao, Joseph Labuz, Stefano Gonella
Summary: Advances in topological mechanics have revealed the unique mechanical properties of Maxwell lattices, such as the ability to focus stress and protect against damage. This study provides an experimental exploration of using Maxwell lattices with non-ideal hinges for structural design. The experiments show that the lattice can withstand stress concentration and potential failure, demonstrating the effectiveness of the design approach.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2023)
Proceedings Paper
Engineering, Geological
Daniel V. Kennedy, Bojan B. Guzina, Joseph F. Labuz
UNIVERSITY OF MINNESOTA 68TH ANNUAL GEOTECHNICAL ENGINEERING CONFERENCE (GEO-CONGRESS 2020)
(2020)