Frequency characteristics of the released stress wave by propagating cracks in brittle materials

Wang, Zonglian; Ning, Jianguo; Ren, Huilan

doi:10.1016/j.tafmec.2018.04.004

Cited by 52 publications

(23 citation statements)

References 48 publications

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“…High-frequency (up to 0.6 MHz) acoustic emissions have been recorded prior to and during failure of rock samples (e.g. Wang et al, 2018;Schiavi et al, 2011;Carpinteri et al, 2012;Michlmayr et al, 2012), confirming the existence of elastic body waves associated with fracture. In fact, there is no literature claiming a lack of elastic strain release during brittle fracture.…”

Section: Discussionmentioning

confidence: 72%

What happens to fracture energy in brittle fracture? Revisiting the Griffith assumption

2019

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Abstract. Laboratory experiments involving unconfined compressive failure of borosilicate glass cylinders quantified the elastic strain energy released at failure and the size distribution of the resulting fragments. The data were carefully assessed for potential inaccuracies in surface-area calculation, the contribution of energy from the compression machine relaxation during specimen failure, and possible variations in the specific fracture energy of the specimens. The data showed that more new surface area was created during the failures than would be possible if the long-standing assumption, which is that all the energy involved in creating new rock surface area in brittle material is taken up by the newly created surfaces as surface potential energy and is not available to do further work, were valid. We therefore conclude that the assumption is false. This conclusion is supported by independent data from a previous investigation whose authors did not pursue this particular application. Our result does not affect the validity of Griffith fracture mechanics and is significant only when large numbers of very fine fragments are created by brittle fracture, as in rock-avalanche motion and earthquake rupture, and are identified in particle-size distributions. In such situations our result is very significant to understanding fracture energetics.

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Section: Discussionmentioning

confidence: 72%

What happens to fracture energy in brittle fracture? Revisiting the Griffith assumption

2019

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“…The AE signals consist of a variety of frequency components, and the waveform frequency and amplitude are different for different AE sources [24][25][26]. The waveform characterization can reflect the crack type, number and scale; therefore, the spectrum (frequency) information can reflect well, the fracture process of the rock.…”

Section: Ae Spectrum Frequency Characteristicsmentioning

confidence: 99%

Geomechanical and Acoustic Properties of Intact Granite Subjected to Freeze–Thaw Cycles during Water-Ice Phase Transformation in Beizhan’s Open Pit Mine Slope, Xinjiang, China

Wang

Feng²,

Wang

et al. 2019

Water

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The deterioration of rock geomechanical behaviors subjected to freeze–thaw (F–T) action is a determining factor for rock engineering and rock structures in cold regions. In this work, taking six groups of granite obtained from an open pit mine as the research object, F–T cycle treatment, in-situ AE (acoustic emission) monitoring and ultrasonic detection techniques were performed to experimentally reveal the effects of F–T fatigue damage on the mechanical and acoustic properties of granite. The results indicate that the F–T action impacts the rock’s mesoscopic structure, deformation, strength, P and S-wave velocities, AE pattern and energy release. The accumulated AE counts and accumulated AE energy show a decreasing trend as the F–T cycle increases. The frequency spectrum revealed that the width of the low frequency band decreases and the high frequency band increases with increasing F–T cycles, indicating that there is an increase in large-scale cracks for a sample with high F–T treatment. In addition, energy balance analysis further illustrates the energy dissipation and release mechanism. The energy proportion used to drive the crack propagation is relatively small with high F–T treatment, and the final released energy becomes the minimum. The energy evolution characteristics analyzed by the energy balance approach is in good agreement with AE results. It is suggested that the F–T fatigue damage influences the rock energy storage and release characteristics and the instability of rock in the cold regions.

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“…AE Spectrum Frequency Characteristics. The AE signals are consisted of a variety of frequency components, and the waveform frequency and amplitude are different for different AE sources [30][31][32]. The waveform characterization can reflect the crack type, number, and scale; therefore, the spectrum (frequency) information can well reflect the fracture process of rock.…”

Section: Geofluidsmentioning

confidence: 99%

Laboratory Investigation on the Effects of Natural Fracture on Fracture Evolution of Granite Exposed to Freeze-Thaw-Cyclic (FTC) Loads

Wang

Gao

et al. 2021

Geofluids

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The natural fractures in rock mass are susceptible to damage evolution when subjecting to repeated freeze-thaw (F-T) weathering in cold regions, which can lead to the instability of rock engineering and even occurrence of geological hazards. Knowledge of how natural fracture impacts the overall fracture evolution of freeze-thawed rock is important to predict the stability of rock structure. In this work, we reported uniaxial experimental measurements of the changes in strength, deformation, acoustic emission (AE) pattern, and Felicity effect during increasing amplitude stress-cycling conditions on granite. The results show that the change of fracture aperture is related to the fracture openness and filling characteristics, open-type fracture is sensitive to F-T treatment, and its aperture increases faster than the close-type and fill-type fracture. In addition, strength decreases, and the damping characteristics first decrease and then increase with increasing natural fracture volume. AE activities also present different responses during sample deformation. The proportion of AE signals having low-frequency characteristics increases with increasing natural fracture volume, and the shear sliding along natural fracture results in the surge of AE activities. Moreover, the Felicity effect indicates that the Felicity ratio presents a fluctuation decreasing trend, and the preexisting fractures alter the stress memory characteristics of rock. It is suggested that the changes of the geomechanical and AE pattern are the interactions between the natural fracture and the newly stimulated fracture. The testing results are expected to improve the understanding of the influence of natural fractures on rock fracture evolution and can be helpful to predict the stability of rock structures and rock mass in cold regions.

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Frequency characteristics of the released stress wave by propagating cracks in brittle materials

Cited by 52 publications

References 48 publications

What happens to fracture energy in brittle fracture? Revisiting the Griffith assumption

What happens to fracture energy in brittle fracture? Revisiting the Griffith assumption

Geomechanical and Acoustic Properties of Intact Granite Subjected to Freeze–Thaw Cycles during Water-Ice Phase Transformation in Beizhan’s Open Pit Mine Slope, Xinjiang, China

Laboratory Investigation on the Effects of Natural Fracture on Fracture Evolution of Granite Exposed to Freeze-Thaw-Cyclic (FTC) Loads

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