Effect of thermal treatment on the fracture toughness and subcritical crack growth of granite in double-torsion test

Author(s):  
Diyuan Li ◽  
Jinyin Ma ◽  
Qianrong Wan ◽  
Quanqi Zhu ◽  
Zhenyu Han
Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Gang Ma ◽  
Jiangteng Li ◽  
Huiwen Wang

Elastic parameters and the subcritical crack growth of different bedding angle slate specimens were studied using uniaxial compression testing and the double torsion constant displacement load relaxation method using SANS and MTS Insight machines. To study the relations of the mode-I stress intensity factor K I versus the subcritical crack growth velocity V , the fracture toughness K I C , the stagnation speed, and the threshold values, the double torsion constant displacement load relaxation method was carried out. The related rules between the bedding angles (β) and the uniaxial compressive strength, fracture toughness, and threshold values were investigated. Experimental results show that the uniaxial compression, the fracture toughness, and the threshold value curves move to the bottom then increase with the increase of the β angle. In addition, its fracture toughness is minimal when the β angle of the slates is 45°, and crack initiation and crack propagation are generated under load, which can lead to the failure of the slate. lg K I - lg V relations of transversely isotropic slates measured by this method are in accordance with linear rules, which is in good agreement with the Charles theory. The range of K 0 / K I C for these different bedding angle slates is from 0.511 to 0.789. The test results would provide the basis for studying seepage and time-dependency of rock engineering stability.


2000 ◽  
Vol 15 (6) ◽  
pp. 1377-1388 ◽  
Author(s):  
M. A. H. Donners ◽  
L. J. M. G. Dortmans ◽  
G. de With

The variation of the fracture toughness of MnZn ferrite ceramics with varying loading rate and humidity was determined with the aid of the single edge notched beam (SENB) test. A strong decrease with increasing humidity and decreasing loading rate was observed. A model for subcritical crack growth incorporating kinetic and adsorption effects was formulated to analyze the data. The value of the adsorptioncontrolled fracture toughness was determined independently by double torsion experiments and agreed favorably with the values as determined from the SENB data using the model. The strength of the material was determined, and analysis showed a strength behavior similar to the fracture toughness behavior, as predicted by the model. The analysis presented can be used to assess the subcritical crack growth behavior using a limited number of SENB specimens.


2018 ◽  
Vol 14 (11) ◽  
pp. 155014771881201 ◽  
Author(s):  
Haiping Yuan ◽  
Feng Wang ◽  
Yan Liu ◽  
Hanbing Bian ◽  
Wen Chen ◽  
...  

Time-dependent behavior of subcritical crack growth is one of the main characteristics in rocks. The double-torsion test is commonly used to study the slow crack growth behavior of brittle and quasi-brittle materials. However, double-torsion specimen is difficult to processing, the process of the laboratory test is irreversible, and the current numerical simulation is difficult to consider the time-dependent behavior, and so on. In view of all above problems, an idealized particle model was built, and the crack was identified in this article, based on the theory of particle flow. The numerical model was built using Particle Flow Code in 3 Dimensions, and the macromechanical and micromechanical parameters of the model were calibrated. The process of the macroscopic crack propagation and its evolution were analyzed. The intrinsic relations with the load, the displacement, and the time were established. The results show that the Particle Flow Code in 3 Dimensions can reproduce the time-dependent behavior of subcritical crack growth in double-torsion test. And, the peak and the law of the curves are in good agreement with the laboratory test results. Therefore, the Particle Flow Code in 3 Dimensions numerical simulation can be used as a new effective method to reveal the slow crack growth behavior, to get the relevant parameters such as V, KI, and KIC, and to build the relationship between V and KI. The results of this article will have some reference value for the simulation and application of double-torsion test.


1996 ◽  
pp. 179-186 ◽  
Author(s):  
Mark Hoffman ◽  
Jürgen Rödel ◽  
Martin Sternitzke ◽  
Richard Brook

1997 ◽  
Vol 63 (607) ◽  
pp. 493-498 ◽  
Author(s):  
Kiyohiko IKEDA ◽  
Takaaki INOTANI ◽  
Koichi KAIZU ◽  
Hisashi IGAKI ◽  
Hiroyosi KIHARA

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