Research on the AE Characteristic of the Rock with Rockburst Proneness

2014 ◽  
Vol 608-609 ◽  
pp. 689-692
Author(s):  
Mo Xiao Li ◽  
Guang Zhang ◽  
Jing Xi Chen
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Rock Mechanics ◽  
Compression Tests ◽  
Entire Process ◽  
The Relationship ◽  
Ae Signals

In this paper, in order to strengthen the prediction of rockburst and inquire the relationship between the rockburst proneness of rock and its AE characteristic, each kind of typical rock of volcanic, sedimentary and metamorphic were selected to doing indoor rock mechanics experiments. Calculate the rockburst proneness of these rocks by uniaxial compression tests. In uniaxial compression, we collect the entire process of AE signals by using acoustic emission instrument, then we analysis the AE characteristics of different rocks to inquire the relationship between the AE characteristic and its rockburst proneness.

scholarly journals Internal Leakage Predicition of Hydraulic Spool valves Based on Acoustic Emission Technology

2021 ◽  
Vol 2113 (1) ◽  
pp. 012016
Author(s):  
Fei Song ◽  
Likun Peng ◽  
Jia Chen ◽  
Benmeng Wang
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Peak Frequency ◽  
Leakage Rate ◽  
High Frequency Band ◽  
Signal Characteristics ◽  
Spool Valves ◽  
The Relationship ◽  
Ae Signals ◽  
Acoustic Emission Technology

Abstract In order to realize the nondestructive testing (NDT) of the internal leakage fault of hydraulic spool valves, the internal leakage rate must be predicted by AE (acoustic emission) technology. An AE experimental platform of internal leakage of hydraulic spool valves is built to study the characteristics of AE signals of internal leakage and the relationship between AE signals and leakage rates. The research results show the AE signals present a wideband characteristic. The main frequencies are concentrated in 30~50 kHz and the peak frequency is around 40 kHz. When the leakage rate is large, there are significant signal characteristics appearing in the high frequency band of 75~100 kHz. The exponent of the root mean square(RMS) of AE signals is positively correlated with the exponent of the leakage rate only if the leakage rate is greater than 2~3 mL/min. This find could be used to predict the internal leakage rate of hydraulic spool valves.

Acoustic Emission During Athermal Martensitic Transformation in Steels

1990 ◽  
Vol 112 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Xiangying Liu ◽  
Elijah Kannatey-Asibu
Keyword(s):  
Free Energy ◽  
Acoustic Emission ◽  
Martensitic Transformation ◽  
Signal Intensity ◽  
Temperature Derivative ◽  
Process Characteristics ◽  
Ae Signal ◽  
The Relationship ◽  
Ae Signals ◽  
Start Temperature

A relationship developed earlier between acoustic emission signals and the process of athermal martensitic transformation based on the free energy associated with the process is extended and verified experimentally. The relationship is found to model the process characteristics very well. The intensity of AE signal generated during transformation was found to be proportional to the temperature derivative of the fraction of martensite, the cooling rate, and volume of specimen. The AE signal was also found to be related to the carbon content of the steel. During transformation, the signal intensity was found to increase to a peak, and then tail off near the end of the transformation. Values of the martensite start temperature obtained from plots of the total RMS squared AE signals were also found to correlate well with values from the literature.

Quantitative Relationship between Strain and Acoustic Emission Response in Monitoring Fatigue Damage

2013 ◽  
Vol 66 (1) ◽  
Author(s):  
M. Mohammad ◽  
S. Abdullah ◽  
N. Jamaludin ◽  
O. Innayatullah
Keyword(s):  
Acoustic Emission ◽  
Failure Mechanism ◽  
Fatigue Failure ◽  
Quantitative Relationship ◽  
Steel Specimen ◽  
Cyclic Fatigue ◽  
Steel Component ◽  
Specific Data ◽  
The Relationship ◽  
Ae Signals

This study was carried out to investigate the relationship between the strain and acoustic emission (AE) signals, thus, to confirm the capability of AE technique to monitor the fatigue failure mechanism of a steel component. To achieve this goal, strain and AE signals were captured on the steel specimen during the cyclic fatigue test.  Both signals were collected using specific data acquisition system by attaching the strain gauge and AE piezoelectric transducer simultaneously at the specimen during the test. The stress loading used for the test was set at 600 MPa, and the specimens were fabricated using the SAE 1045 carbon steel.  The related parameters for both signals were determined at every 2000 seconds until the specimen failed.  It was found that a meaningful correlation of all parameters, i.e. amplitude, kurtosis and energy, was established. Finally, all AE parameters are correlated with the damage values, which have been estimated using the Coffin-Manson model.  Hence, it was suggested that the AE technique can be used as a monitoring tool for fatigue failure mechanism in a steel component.

scholarly journals Study of Acoustic Emission and Mechanical Characteristics of Coal Samples under Different Loading Rates

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Huamin Li ◽  
Huigui Li ◽  
Baobin Gao ◽  
Dongjie Jiang ◽  
Junfa Feng
Keyword(s):  
Acoustic Emission ◽  
Elasticity Modulus ◽  
Loading Rate ◽  
Peak Stress ◽  
Test System ◽  
Strong Impact ◽  
Peak Strain ◽  
Compression Tests ◽  
Loading Rates ◽  
The Relationship

To study the effect of loading rate on mechanical properties and acoustic emission characteristics of coal samples, collected from Sanjiaohe Colliery, the uniaxial compression tests are carried out under various levels of loading rates, including 0.001 mm/s, 0.002 mm/s, and 0.005 mm/s, respectively, using AE-win E1.86 acoustic emission instrument and RMT-150C rock mechanics test system. The results indicate that the loading rate has a strong impact on peak stress and peak strain of coal samples, but the effect of loading rate on elasticity modulus of coal samples is relatively small. When the loading rate increases from 0.001 mm/s to 0.002 mm/s, the peak stress increases from 22.67 MPa to 24.99 MPa, the incremental percentage is 10.23%, and under the same condition the peak strain increases from 0.006191 to 0.007411 and the incremental percentage is 19.71%. Similarly, when the loading rate increases from 0.002 mm/s to 0.005 mm/s, the peak stress increases from 24.99 MPa to 28.01 MPa, the incremental percentage is 12.08%, the peak strain increases from 0.007411 to 0.008203, and the incremental percentage is 10.69%. The relationship between acoustic emission and loading rate presents a positive correlation, and the negative correlation relation has been determined between acoustic emission cumulative counts and loading rate during the rupture process of coal samples.

scholarly journals Acoustic Emission Multi-Parameter Analysis of Dry and Saturated Sandstone with Cracks under Uniaxial Compression

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1959 ◽  
Author(s):  
Hongru Li ◽  
Rongxi Shen ◽  
Dexing Li ◽  
Haishan Jia ◽  
Taixun Li ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Failure Process ◽  
Parameter Analysis ◽  
Small Scale ◽  
Rock Interaction ◽  
Secondary Cracks ◽  
Ae Signals

In order to study the mechanics and acoustic emission (AE) characteristics of fractured rock under water-rock interaction, dried and saturated sandstone samples with prefabricated double parallel cracks were prepared. Then, uniaxial compression experiments were performed to obtain their AE signals and crack propagation images. The results show that water reduces the strength and fracture toughness of fractured sandstone and enhances plasticity. After saturation, the samples start to crack earlier; the cracks grow slowly; the failure mode is transformed from shear failure along the prefabricated cracks to combined shear and tensile failure; more secondary cracks are produced. The saturated samples release less elastic energy and weaker AE signals in the whole failure process. However, their AE precursor information is more obvious and advanced, and their AE sources are more widely distributed. Compared with dry specimens, the AE frequencies of saturated specimens in the early stage of loading are distributed in a lower frequency domain. Besides, the saturated samples release less complex AE signals which are dominated by small-scale signals with weaker multi-fractal characteristics. After discussion and analysis, it is pointed out that this may be because water makes rock prone to inter-granular fracture rather than trans-granular fracture. The water lubrication also may reduce the amplitude of middle-frequency band signals produced by the friction on the fracture surface. Multi-fractal parameters can provide more abundant precursory information for rock fracture. This is of great significance to the stability of water-bearing fractured rock mass and its monitoring, and is conducive to the safe exploitation of deep energy.

scholarly journals Method Improvement and Effect Analysis of Triaxial Compression Acoustic Emission Test for Coal and Rock

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Yan Zhou ◽  
Chuanxiao Liu ◽  
Depeng Ma
Keyword(s):  
Acoustic Emission ◽  
Rock Mechanics ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Outer Wall ◽  
Test System ◽  
Test Method ◽  
Effect Analysis ◽  
High Confining Pressure ◽  
Ae Signals

In the study of the acoustic emission (AE) characteristics of rock samples or coal samples under triaxial compression conditions, most scholars carry out relevant experiments by placing the AE detector on the outer wall of the triaxial chamber of the rock mechanics test system. Owing to the continuous obstruction of AE signals by hydraulic oil in the triaxial chamber and the frequent interference of external noises, the final experimental data cannot objectively and truly reflect the essential characteristics of AE of rock or coal under triaxial compression conditions. It is difficult to scientifically guide and accurately predict precursory information of rock’s or coal’s rupture and instability. Based on this, a series of improvements and optimizations were made to the original triaxial compression AE test method, which is based on the modification of the communication interface of the rock mechanics test system, a test head which can put the AE detector into the triaxial chamber and withstands high confining pressure, in order to obtain the true, comprehensive, and reliable AE signals. It is of considerable significance to the scientific determination of the precursory characteristics of rock’s or coal’s rupture and instability.

Manufacturing and Analysis of 3-D Woven Sandwich Composite Under Compressive Loading With Acoustic Emission Monitoring

2002 ◽  
Author(s):  
M. Islam ◽  
H. Mahfuz ◽  
M. Motuku ◽  
M. Saha ◽  
E. Ayorinde ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Polyurethane Foam ◽  
Compressive Loading ◽  
Piezoelectric Sensor ◽  
Woven Fabric ◽  
Sandwich Composite ◽  
Displacement Curve ◽  
Compression Tests ◽  
The Time Domain ◽  
Ae Signals

Composite sandwich panel with 3-d woven fabric preform were manufactured through a vacuum assisted resin transfer molding (VARTM) process. The 3-d sandwich fabric preform known as Parabeam, consist of two bi-directional woven E-glass fabric surfaces, which are inter connected mechanically with several vertical woven piles. Parabeam provides a new type of sandwich composite that possess several multifunctional benefits in addition to light weight, bending stiffness and core skin debonding resistance advantages. After consolidation of the panels, polyurethane foam was injected into the core. Conventional sandwich panels were also fabricated with precast polyurethane foam and E-glass face sheet for comparison with the Parabeam sandwich. Edge wise compression tests were conducted and the corresponding acoustic emission (AE) responses were monitored by an advance AE system. Piezoelectric sensor was used to detect the AE signals. On the basis AE signals, the damage source of the specimen were identified, and classified. Furthermore, cracking size were estimated and used to determine the delamination events among the AE signals. Consequently, the AE signals were correlated to the load-displacement curve in the time domain in order to elucidate the types of damage in the specimen. Details of the manufacturing process, the compression tests, and the analysis of the AE signals are presented in this paper.

scholarly journals Dual role of microcracks: toughening and degradation

2001 ◽  
Vol 38 (2) ◽  
pp. 427-440 ◽  
Author(s):  
G M Nagaraja Rao ◽  
C RL Murthy
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inelastic Strain ◽  
Dual Role ◽  
Compression Tests ◽  
Defective Structure ◽  
Heating And Cooling ◽  
Thermally Treated

One of the methods of improving the mechanical properties of ceramics is to introduce a defective structure that acts as a restraint for the propagation of cracks. In the present study a detailed investigation was carried out by introducing a defective structure in rock to determine if there is any improvement in properties similar to ceramics. Granite was chosen for the investigation, and the microcracks were introduced by a heating and cooling cycle. Uniaxial compression tests have shown that granite thermally treated to 200°C shows the highest strength, and the strength of granite treated to 400°C is comparable to that of unheated granite. Both ultrasonic images and acoustic-emission monitoring show that for thermally treated samples the stress-induced microcrack and macrocrack nucleation and their growth are retarded. The variations in mechanical properties are explained based on the concept of toughening and degradation. Uniaxial compression tests on unheated and thermally treated granite samples have clearly established the dual role of microcracks, which operate in the toughening and degradation mechanisms.Key words: thermal treatment, microcrack, inelastic strain, ultrasonic C-scan imaging, acoustic emission, toughening.

scholarly journals Acoustic Emission and Damage Characteristics of Granite Subjected to High Temperature

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
X. L. Xu ◽  
Z.-Z. Zhang
Keyword(s):  
Acoustic Emission ◽  
High Temperatures ◽  
Count Rate ◽  
Shear Failure ◽  
Rock Fracture ◽  
Mechanical Damage ◽  
Strain Curve ◽  
Effect Of Temperature ◽  
Compression Tests ◽  
Ae Signals

Acoustic emission (AE) signals can be detected from rocks under the effect of temperature and loading, which can be used to reflect rock damage evolution process and predict rock fracture. In this paper, uniaxial compression tests of granite at high temperatures from 25°C to 1000°C were carried out, and AE signals were monitored simultaneously. The results indicated that AE ring count rate shows the law of “interval burst” and “relatively calm,” which can be explained from the energy point of view. From 25°C to 1000°C, the rock failure mode changes from single splitting failure to multisplitting failure, and then to incomplete shear failure, ideal shear failure, and double shear failure, until complete integral failure. Thermal damage (DT) defined by the elastic modulus shows logistic increase with the rise of temperature. Mechanical damage (DM) derived by the AE ring count rate can be divided into initial stage, stable stage, accelerated stage, and destructive stage. Total damage (D) increases with the rise of strain, which is corresponding to the stress-strain curve at various temperatures. Using AE data, we can further analyze the mechanism of deformation and fracture of rock, which helps to gather useful data for predicting rock stability at high temperatures.

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