Mechanical behavior of unsaturated argillaceous rocks under uniaxial compression through acoustic emission

2020 ◽  
pp. 1597-1603
Author(s):  
J.M. Espitia ◽  
B. Caicedo
Keyword(s):  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Uniaxial Compression ◽  
Argillaceous Rocks

scholarly journals Study on Acoustic Emission Characteristics and Mechanical Behavior of Water-Saturated Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Muhammad Ali ◽  
Enyuan Wang ◽  
Zhonghui Li ◽  
Haishan Jia ◽  
Dexing Li ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Uniaxial Compression ◽  
Engineering Practice ◽  
Slow Increase ◽  
Soaking Time ◽  
Emission Signal ◽  
Secondary Cracks ◽  
Water Saturated ◽  
Ae Counts

In terms of coal’s stability and failure, soaking time and water content play a significant role in geotechnical engineering practice. To determine the soaking time effect on the mechanical behavior of coal samples and the response of AE (acoustic emission) signal throughout loading, the samples with different soaking times (0–120 hours (h)) were prepared and tested under uniaxial compression. AE signals were continuously monitored during loading to examine the AE characteristic response via the AEwin Express-8.0 system. The results revealed that the mechanical characteristics of the coal samples decreased with an increase in soaking time. When coal samples were subjected to uniaxial compression, AE events occurred due to the formation of the cracks, which further propagated to cause coal fracture. AE counts and the accumulative counts fluctuated with time and corresponded very well to the load. Therefore, AE counts and the trend of the accumulative counts of AE qualitatively explained the rupture of the coal under stress. In addition, the variation in trends of AE counts, AE accumulative counts, and load with time at various phases of all samples were obtained. It is concluded that AE counts increase suddenly during a slow increase phase and peak at the active increase phase. During the attenuation phase, the AE counts first decrease significantly with stress drop, but also a slight increase was observed due to the initiation of secondary cracks. These research results are of great significance as a precursor in coal and rock failure.

scholarly journals Mechanical behavior of Ti-6Al-4V lattice-walled tubes under uniaxial compression

2021 ◽  
Author(s):  
Gen-zhu Feng ◽  
Jing Wang ◽  
Xin-yuan Li ◽  
Li-jun Xiao ◽  
Wei-dong Song
Keyword(s):  
Mechanical Behavior ◽  
Uniaxial Compression

scholarly journals Acoustic Emission Characteristics and Joint Nonlinear Mechanical Response of Rock Masses under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 200
Author(s):  
Zhongliang Feng ◽  
Xin Chen ◽  
Yu Fu ◽  
Shaoshuai Qing ◽  
Tongguan Xie
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Modes ◽  
Strain Curve ◽  
Particle Flow Code ◽  
Rock Masses ◽  
Physical Experiments ◽  
Inclination Angles ◽  
Joint Inclination

The joint arrangement in rock masses is the critical factor controlling the stability of rock structures in underground geotechnical engineering. In this study, the influence of the joint inclination angle on the mechanical behavior of jointed rock masses under uniaxial compression was investigated. Physical model laboratory experiments were conducted on jointed specimens with a single pre-existing flaw inclined at 0°, 30°, 45°, 60°, and 90° and on intact specimens. The acoustic emission (AE) signals were monitored during the loading process, which revealed that there is a correlation between the AE characteristics and the failure modes of the jointed specimens with different inclination angles. In addition, particle flow code (PFC) modeling was carried out to reproduce the phenomena observed in the physical experiments. According to the numerical results, the AE phenomenon was basically the same as that observed in the physical experiments. The response of the pre-existing joint mainly involved three stages: (I) the closing of the joint; (II) the strength mobilization of the joint; and (III) the reopening of the joint. Moreover, the response of the pre-existing joint was closely related to the joint’s inclination. As the joint inclination angle increased, the strength mobilization stage of the joint gradually shifted from the pre-peak stage of the stress–strain curve to the post-peak stage. In addition, the instantaneous drop in the average joint system aperture (aave) in the specimens with medium and high inclination angles corresponded to a rapid increase in the form of the pulse of the AE activity during the strength mobilization stage.

scholarly journals Influence of SiC Addition on Mechanical Behavior of Thermal Barriers with the Aid of Acoustic Emission

2021 ◽  
Vol 5 (1) ◽  
pp. 16
Author(s):  
David Jeronimo Busquets ◽  
Carlos Bloem ◽  
Amparo Borrell ◽  
Maria Dolores Salvador
Keyword(s):  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Barrier Coatings ◽  
Wavelet Transforms ◽  
Coefficient Of Thermal Expansion ◽  
Microstructural Analysis ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Barrier Coatings ◽  
Thermal Barriers

The improvement of high temperature materials with lower heat transfer coefficients lead to the development of thermal barrier coatings (TBCs). One of the most widely used materials for thermal barrier coatings is Y2O3 stabilized ZrO2 (Y-TZP) because of its excellent shock resistance, low thermal conductivity, and relatively high coefficient of thermal expansion. The aim of this work is to study the TBCs mechanical behavior with the addition of SiC into the suspension of Y-TZP/Al2O3 by acoustic emission (AE). Additionally, a microstructural analysis and a finite elements model were carried out in order to compare results. The coatings were made by suspension plasma spray (SPS) on metal plates of 70 × 12 × 2 mm3. An intermetallic was deposited as a bond coating, followed by a coating of Y-TZP/Al2O3 with and without 15 wt.% SiC, with thicknesses between 87 and 161 μm. The AE becomes a fundamental tool in the study of the mechanical behavior of thermal barriers. The use of wavelet transforms streamlines the study and analysis of recorded sound spectra. The crack generation arises at very low stress levels.

scholarly journals Acoustic Emission in Snow at Constant Rates of Deformation

1973 ◽  
Vol 12 (64) ◽  
pp. 144-146 ◽  
Author(s):  
W. F. St. Lawrence ◽  
T. E. Lang ◽  
R.L. Brown ◽  
C. C. Bradley
Keyword(s):  
Acoustic Emission ◽  
Brittle Fracture ◽  
Uniaxial Compression ◽  
Laboratory Experiments ◽  
Acoustic Emissions ◽  
Snow Sample ◽  
Frequency Range ◽  
Snow Samples

AbstractAcoustic emissions in the audio spectrum are reported from observations of laboratory experiments conducted on snow samples in uniaxial compression. A number of tests show the pattern of acoustic emissions to be a function of the rate of deformation. Over the frequency range 20 to 7 000 Hz acoustic emissions are associated with rates of deformation corresponding to brittle fracture of the snow sample. Though probably present, no acoustic emissions were detected from samples deforming plastically.

scholarly journals Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2350 ◽  
Author(s):  
Jun Peng ◽  
Sheng-Qi Yang
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Damage ◽  
Strain Curve ◽  
Treatment Temperature ◽  
P Wave ◽  
High Temperature Treatment ◽  
High Porosity ◽  
Compression Tests

High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

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