Formula for calculating the critical stress intensity factor in rock fracture toughness tests using cracked chevron notched Brazilian disc (CCNBD) specimens

Wang, Q.Z.

doi:10.1016/j.ijrmms.2010.05.005

Cited by 40 publications

(11 citation statements)

References 14 publications

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“…The average values of mode I and mode II fracture toughness were obtained as 1:206MPa ffiffiffiffi ffi m p and 1:435 MPa ffiffiffiffi ffi m p and the fracture toughness ratio K IIc /K Ic as 1.19. It is noteworthy that K Ic was reported as 1:06 MPa ffiffiffiffi ffi m p in [6], but according to the modified formula suggested by Wang [32] for determining mode I fracture toughness using the standard CCNBD specimen, the value of K Ic is corrected to 1:206 MPa ffiffiffiffi ffi m p . Since the tensile strength s t of Yeosan marble was not given in [6], it was taken from Lee et al [33] who reported the tensile strength of Yeosan marble as s t ¼16 MPa.…”

Section: Resultsmentioning

confidence: 99%

Mode ІІ fracture study of rocks using Brazilian disk specimens

Ayatollahi

Sistaninia

2011

International Journal of Rock Mechanics and Mining Sciences

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Section: Resultsmentioning

confidence: 99%

Mode ІІ fracture study of rocks using Brazilian disk specimens

Ayatollahi

Sistaninia

2011

International Journal of Rock Mechanics and Mining Sciences

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“…The use of 1/ √ R term was proposed in Fowell and Xu (1993); Xu and Fowell (1994); Fowell and Xu (1994); Fowell et al (2006); Iqbal and Mohanty (2006); Nasseri and Mohanty (2008) and Cui et al (2010). Using 1/ √ R term in the basic formula and constants u and ν improved by Wang et al (2004b) and Wang (2010) for computation of the dimensionless stress intensity factor, average K Ic becomes 1.62 ± 0.07 MPa √ m for CCNBD tests on andesite rock.…”

Section: Maximum Stress Intensity Factor Computationsmentioning

confidence: 99%

“…Using 1/ √ R term and constants u and ν improved by Wang et al (2004b) and Wang (2010) for computation of the dimensionless stress intensity factor, average K Ic becomes 1.23 ± 0.13 MPa √ m for CCNBD tests on marble rock. Table 2 shows K Ic avg values for different diameters and different 2α ranges together with minimum and maximum loading angles (2α min and 2α max , respectively) of individual specimens in a particular group of tests on andesite rock.…”

Section: Maximum Stress Intensity Factor Computationsmentioning

confidence: 99%

Investigation of proper specimen geometry for mode I fracture toughness testing with flattened Brazilian disc method

Keleş

Tutluoğlu

2011

Int J Fract

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Investigation of geometrical parameters for flattened Brazilian disc method is important, since this is a simple and attractive method for mode I fracture toughness testing on rock cores. Evaluating numerical modeling results, a parametric equation in terms of principal stresses at the center of the disc and the loading angle of the flattened end was developed. An equation was proposed for maximum stress intensity factors at critical crack lengths around stable to unstable crack propagation. Comparing fracture toughness results of flattened Brazilian disc method to the results of the suggested cracked chevron notched Brazilian disc method, geometrical parameters for flattened Brazilian discs were investigated. Diameter, loading angle of flattened ends, and thickness of andesite rock core specimens were changed to obtain comparable results to the suggested method. The closest results to the suggested method were obtained by 54 mm diameter discs with loading angles larger than 32 • , and thicknesses between 19 and 34 mm. Results were confirmed by the flattened Brazilian disc tests on a marble rock. In flattened Brazilian disc tests with smaller loading angles and larger diameters, larger fracture toughness values than the results of the suggested cracked chevron notched were obtained. However, excluding tests with large loading angles over 27 • ; specimen size was less effective on the results of these tests. Critical crack C. Keles (B) · L. Tutluoglu length parameters computed from modeling and experiments were close to each other for the flattened Brazilian disc specimens with smaller loading angles around 20 • and thickness/radius ratio equal or less than 1.1.

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“…(11) and the values of parameters u, v, as suggested by the ISRM [6]. In order to improve the fracture toughness tests using CCNBD, recent research [8,9,16], based on the slice synthesis method [22] and other numerical methods, presented updated values of the two parameters of the exponential function (Eq. (11) (Fig 10).…”

Section: Experimental Results Ans Discussionmentioning

confidence: 99%

“…(5) and (6) In the ISRM suggested methods [6] the mode I fracture toughness IC K of CCNBD specimens [6,14,15,16] can be calculated by the following equation:…”

Section: Fracture Toughness Calculation For Ccnbd Testsmentioning

confidence: 99%

Using acoustic emissions to enhance fracture toughness calculations for CCNBD marble specimens

Kaklis¹,

Mavrigiannakis²,

Saltas³

et al. 2017

Frattura Ed Integrità Strutturale

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ABSTRACT. Rock fracture mechanics has been widely applied to blasting, hydraulic fracturing, mechanical fragmentation, rock slope analysis, geophysics, earthquake mechanics and many other science and technology fields. Development of failure in brittle materials is associated with microcracks, which release energy in the form of elastic waves called acoustic emissions. In the present study, acoustic emission (AE) measurements were carried out during cracked chevron notched Brazilian disc (CCNBD) tests on Nestos marble specimens. The fracture toughness of different modes of loading (mode-I and -II) is calculated and the results are discussed in conjunction with the AE parameters.

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Formula for calculating the critical stress intensity factor in rock fracture toughness tests using cracked chevron notched Brazilian disc (CCNBD) specimens

Cited by 40 publications

References 14 publications

Mode ІІ fracture study of rocks using Brazilian disk specimens

Mode ІІ fracture study of rocks using Brazilian disk specimens

Investigation of proper specimen geometry for mode I fracture toughness testing with flattened Brazilian disc method

Using acoustic emissions to enhance fracture toughness calculations for CCNBD marble specimens

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