Suggested method for determining mode I fracture toughness using Cracked Chevron Notched Brazilian Disc (CCNBD) specimens

Fowell, R.J.

doi:10.1016/0148-9062(94)00015-u

Cited by 383 publications

(146 citation statements)

References 6 publications

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“…All prepared specimens, according to the aforementioned angles experience a constant compressive loading conditions. All tests are also conducted according to the ISRM standard method for the CCNBD specimen with rigid and parallel loading plates (Fowell, 1995). Furthermore, the loading rate was kept at 0.5 MPa/s as considered in the previous studies with the CBD specimen (Ghazvinian et al, 2013;Haeri et al, 2014).…”

Section: Simulation Of Cbd Specimen Using Imts Criterionmentioning

confidence: 99%

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Eftekhari

Baghbanan

Mohtarami

et al. 2017

jtam

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The crack initiation angle and propagation path for two different disc shaped test specimens (i.e., SCB and CBD specimen) are investigated experimentally and theoretically. The Maximum Tangential Stress (MTS) criterion does not calculate the crack initiation angle in SCB and CBD specimens correctly. Moreover, at the angles after occurrence of pure mode II, where the stress intensity factor of mode I becomes negative, this criterion is not applicable. Therefore, in this research work, Improved MTS (IMTS) criterion which has been implemented in the extended finite element method and is applicable under tensile and compressive loading conditions to examine the crack propagation path in the aforementioned disc shaped specimens. Furthermore, an experimental study on a cracked Brazilian disc specimen has been conducted at different angles. Results of IMTS criterion in these specimens show that the crack propagation path and the crack initiation angle can be predicted theoretically by using IMTS criterion.

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Section: Simulation Of Cbd Specimen Using Imts Criterionmentioning

confidence: 99%

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Eftekhari

Baghbanan

Mohtarami

et al. 2017

jtam

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show abstract

“…It was experimentally noticed that crack extension occurred in mode I rather than shear mode or mixed mode. Many investigations were typically focused in opening mode failure for crack growth (Alfano et al, 2009;Erdogan & Sih, 1963;Fowell et al, 1995;Lim et al, 1994;Yoshihara & Kawamura, 2006;Zhang, 2002;Zhou et al, 2012). The cracks in brittle materials are often vulnerable to compressive loading rather than tensile loading (Ke et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of mode I/II SIF of quasi-brittle materials using cracked semi-circular bend specimen

Fayed¹

2018

10.5267/j.esm

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An in-house finite element code was utilized to evaluate mode I/II stress intensity factor (SIF) of an edge cracked semi-circular disc subjected to three-point bending. The specimen was considered as an isotropic and homogeneous material. Relative span length ratios of 0.3 to 0.8 in steps of 0.1 were invoked. Relative crack length ratios of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 were analyzed with crack angles up to 60° in steps of 5°. At the same crack length, mode I SIF decreases with increasing crack angle or decreasing the span length. The range of pure mode II decreases with increasing the span length. For the same crack length, the crack angle corresponding to the transition from a mixed mode I/II to a pure mode II increases with increasing the relative span length ratio. On the contrary, that angle decreases with increasing the crack length for the same span length. Good agreement has been generally obtained with relevant results found in the literature.

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“…Additionally, the CCNBD specimen has a chevron notch. ISRM [6] recommends that the following dimensionless parameters can be used to characterize the geometry of the chevron notch:…”

Section: The Geometry Of the Ccnbd Specimenmentioning

confidence: 99%

“…Both of these tests configurations show great potential for current and future applications and overcome the disadvantages of the CB and SR specimens. The International Society for Rock Mechanics [6] suggested the cracked chevron notched Brazilian disc (CCNBD) for determining the mode I fracture toughness of rock. There are some unique features characterizing the CCNBD specimen: (a) it is closely related to the Brazilian test which is widely used for tensile strength test for rock and concrete, (b) it can be easily used for mode I, mode II and even mixed mode testing, (c) it can sustain higher critical load than other kinds of specimens with comparable size and (d) it also maintains the merit of convenience for specimen preparation from rock cores.…”

Section: Introductionmentioning

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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Suggested method for determining mode I fracture toughness using Cracked Chevron Notched Brazilian Disc (CCNBD) specimens

Cited by 383 publications

References 6 publications

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Determination of crack initiation and propagation in two disc shaped specimens using the improved maximum tangential stress criterion

Numerical evaluation of mode I/II SIF of quasi-brittle materials using cracked semi-circular bend specimen

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

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