Fracture analysis of three‐point bending notched granite beams under prepeak and postpeak cyclic loading by digital image correlation and acoustic emission techniques

Chen, Xudong; Tang, Jianhui; Zhang, Nan; Dai, Feng; Wei, Mingdong

doi:10.1111/ffe.13646

Cited by 16 publications

(10 citation statements)

References 53 publications

(53 reference statements)

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“…The crack types during different stages in the fracture process can be investigated by analyzing the distribution of AE amplitudes, which is known as “ b ‐value analysis.” The b value can be calculated according to the logarithmic function relationship between earthquake magnitude and frequency proposed by Gutenberg and Richter in 1941, as shown in Equation (1). 29

\log_{10} N ((), M) goodbreak= a goodbreak- b ((), \frac{A_{dB}}{20})

where N is the number of AE hits in a particular time window with amplitude greater than A dB , A dB is the peak amplitude of AE events in decibels, M is the earthquake magnitude or Richter magnitude of events, a is an empirical constant, and b is the b value, which indicates the relative proportion of microcracking to macrocracking.…”

Section: Materials and Test Methodsmentioning

confidence: 99%

Experimental study on cracking process and fracture properties of granite under mode I loading by acoustic emission and digital image correlation

Xue

Lin

Wang

2023

Fatigue Fract Eng Mat Struct

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To explore mode‐I fracture process of hard brittle rocks, semi‐circular bending (SCB) experiments were performed with the concurrent monitoring of acoustic emission (AE) and digital image correlation (DIC). Experimental results revealed that all specimens exhibited ductile fracture characteristic and the fracture planes deviated from the ligament plane to different degrees due to interference from mineral crystals or pre‐existing weak surfaces within the intergranular boundaries. The whole cracking process can be divided into four stages: Microcrack initiation preparation, microcrack initiation and stable propagation, macrocrack formation and unstable propagation, and macrocrack coalescence. The onset of the microcrack initiation occurred at about pre‐80% load. The fracture process zone (FPZ) maintained a constant length as the crack propagated and the length of the traction free zone (TFZ) increased. The identified crack lengths based on the AE locations and energy statistical analysis consisted well with the crack lengths obtained from the DIC.

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\log_{10} N ((), M) goodbreak= a goodbreak- b ((), \frac{A_{dB}}{20})

Section: Materials and Test Methodsmentioning

confidence: 99%

Experimental study on cracking process and fracture properties of granite under mode I loading by acoustic emission and digital image correlation

Xue

Lin

Wang

2023

Fatigue Fract Eng Mat Struct

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“…The fixture and testing method are easier to popularize in the laboratory for measuring the LPDs and CMODs of CB specimens. Furthermore, this improved fixture can be applied for displacement measurements in another three-point bending 16,17 and four-point bending specimens. 18 T A B L E 1 The parameters used for the nonlinearity correction of fracture toughness.…”

Section: The Advantages Of the Improved Fixture Systemmentioning

confidence: 99%

An improved fixture for better measuring the displacements and mode‐I fracture toughness of chevron bend specimens

赵子江

Wei

Zhao

et al. 2023

Fatigue Fract Eng Mat Struct

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The load versus load point displacement (LPD) curve is significant for the nonlinearity corrections for the mode‐I fracture toughness of chevron bend (CB) specimens. The testing fixture plays a crucial role in measuring load versus LPD curves. To better measure the LPDs of CB specimens, we developed an improved fixture system consisting of an understructure and a yoke based on the traditional saddle arrangement fixture suggested by ISRM. With the aid of the improved fixture, continuous synchronized LPDs and CMODs are measured, and nonlinearity corrections are conducted. After nonlinearity corrections, the data of mode‐I fracture toughness become more comparable and present a better regularity among different specimen diameters and variant rock types. Repeated tests verify that the improved fixture has the advantages of higher stability and more convenient installation, removal, and adjustment, which can enhance the testing robustness and efficiency.

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“…The crack opening stress was calculated under tension‐compression cyclic load 16 . Chen et al 17 analyzed the fracture mechanisms of three‐point bending notched granite beams during the pre‐peak and post‐peak cyclic loading tests based on AE and digital image correlation (DIC) methods. Elbably et al 18 revealed the deformation and failure patterns of encased steel‐high‐strength concrete columns subjected to axial and cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

“…Meng et al 7 analyzed the loading rate effect on AE and energy dissipation of sandstone under cyclic loading. Chen et al 17 studied the failure mechanisms of three‐point bending notched granite beams subjected to cyclic loading based on AE and DIC methods. Li et al 25 analyzed the strength and AE evolution of coal with a pre‐existing fissure under uniaxial compression.…”

Section: Introductionmentioning

confidence: 99%

Failure characteristic and acoustic emission spatio‐temporal evolution of coal under different cyclic loading rates

Liu

Zhao

Hua

et al. 2023

Energy Science & Engineering

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The coal and rock dynamic disasters occur more and more frequently in deep mining, which is tightly correlated to the instability of coal pillars under high stress and cyclic disturbance load. In this study, the strength, deformation behaviors, and failure mechanism of coal under cyclic loading in a high-stress state were investigated by considering the influence of cyclic loading rate. The experimental results indicate that the compressive strength is positively correlated with the cyclic loading rate, and the deformation patterns, AE amplitude, and spatial evolution are the same under various cyclic loading rates. The damage variable shows the "slow increase→fast increase→slow increase→ fast increase →slow increase→fast increase→rapid increase" trend.The damage growth rate ranges from 9.32 × 10 −5 to 4.86 × 10 −3 , and increases with the cyclic loading rate. The spatial fractal dimensions under various cyclic loading rates are the same, and the distribution ranges from 2.1 to 2.9, showing a general downward trend. The microfailure mechanism under various cyclic loading rates is mixed failure dominated by tensile failure, with a small amount of shear failure. There is a positive correlation between the percentage of shear cracks and the cyclic loading rates.

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Fracture analysis of three‐point bending notched granite beams under prepeak and postpeak cyclic loading by digital image correlation and acoustic emission techniques

Cited by 16 publications

References 53 publications

Experimental study on cracking process and fracture properties of granite under mode I loading by acoustic emission and digital image correlation

Experimental study on cracking process and fracture properties of granite under mode I loading by acoustic emission and digital image correlation

An improved fixture for better measuring the displacements and mode‐I fracture toughness of chevron bend specimens

Failure characteristic and acoustic emission spatio‐temporal evolution of coal under different cyclic loading rates

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