Study of the Damage Evolution of Concrete with Different Initial Defect Rates under Uniaxial Compression with Acoustic Emission Technology

2021 ◽  
pp. 1-27
Author(s):  
Yanlong Li ◽  
Junhao Chen ◽  
Lifeng Wen ◽  
Junzhong Wang ◽  
Kangping Li
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Load Level ◽  
Internal Damage ◽  
Cumulative Impact ◽  
Kaiser Effect ◽  
Initial Defect ◽  
Response Characteristics ◽  
Cumulative Function ◽  
Damage Process

It is important to evaluate the internal damage of concrete under load conditions in order to evaluate its stability and usability for building applications. In this study, the uniaxial compression of concrete with initial defect was performed, and the internal damage of concrete was monitored by acoustic emission(AE) technology in real time to study the damage process and mechanism. The mechanical properties of concrete specimens with different initial defect were determined, and the cumulative impact count of AE was recorded. The response characteristics of AE in the process of concrete compression and damage were obtained. According to the analysis of the influence of the initial defect on the Kaiser effect and since the irreversibility of the AE process is related to the degree of damage caused by the material under the pre-load, it was determined that the initial defect will aggravate the damage inside the concrete under the same load level. Based on the statistics and analysis of the Weibull cumulative function, the correlation between AE parameters and damage variables was discussed.

Acoustic Emission Test for the Gradual Damage Process of Unidirectional Composites

2013 ◽  
Vol 341-342 ◽  
pp. 105-108
Author(s):  
Xiao Tong Fang ◽  
Wei Fang Zhang ◽  
Deng Jiang Wang ◽  
Sheng Wang Liu
Keyword(s):  
Acoustic Emission ◽  
Matrix Crack ◽  
Interface Fracture ◽  
Fiber Breakage ◽  
Cumulative Impact ◽  
Damage Models ◽  
Impact Rate ◽  
Initial Stage ◽  
Damage Process ◽  
Acoustic Emission Test

The gradual damage progress of unidirectional laminate T700/ epoxy 6808 is investigated by acoustic emission test, and impact rate, impact amplitude, cumulative impact and impact energy in different test stages are measured. The results indicate that the sample suffers from diverse damage models in different loading stages. In the initial stage, damage mode is matrix crack, while other modes like matrix crack/ crack propagation, interface fracture and fiber breakage can be successively detected in the test.

Research on Landscape Limestone Damage and Deformation under Uniaxial Compression Based on Acoustic Emission

2013 ◽  
Vol 423-426 ◽  
pp. 914-919 ◽  
Author(s):  
Yong Qin Xiao ◽  
Yi Ping Wan ◽  
Bao Xian Liu
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Detection System ◽  
Damage Model ◽  
Mechanical Damage ◽  
Test System ◽  
Emission Feature ◽  
Internal Damage ◽  
Emission Parameter

In order to establish the relation between acoustic emission parameter and rock mechanical damage mechanism, as well as to better figure out landscape limestone damage and deformation influenced by uniaxial compression, MTS815 rock mechanical electro-hydraulic servo test system and 8CHSPCI-2 acoustic emission and detection system are applied to implement a test and research on damage evolution of limestone under uniaxial compression and the corresponding acoustic emission feature. On this basis, the acoustic emission feature of limestone under uniaxial compression is analyzed. Moreover, based on the damage variable of normalized accumulated emission ringing count, the uniaxial compression limestone damage model based on acoustic emission feature is established, and the damage evolution curve and equation of limestone is figured out as well. Shown by the research, acoustic emission information reflects the internal damage of limestone, and is closely related with densification of inner original fracture, as well as emerging, developing, and merging of new fractures. The acoustic emission feature of limestone perfectly describes its deformation and damage evolution.

scholarly journals Acoustic Emission Response Characteristics of Anthracitic Coal under Uniaxial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Haiyan Wang ◽  
Gongda Wang ◽  
Guojun Zhang ◽  
Feng Du ◽  
Ji Ma
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Wave Velocity ◽  
Coal Sample ◽  
Compression Process ◽  
Deformation And Failure ◽  
Response Characteristics ◽  
Fracture Evolution ◽  
Anthracite Coal ◽  
Coal Deformation

The damage evolution of coal is accompanied by the generation of acoustic emission (AE) signal. Through the analysis and research of the AE response characteristics of coal deformation and failure, it is helpful to reveal the initiation, propagation, and fracture evolution of microcracks in coal. In this work, taking the anthracite coal as research object, the basic mechanical parameters of the coal samples were obtained by ultrasonic tests and uniaxial compression experiments. Meanwhile, the AE response characteristics of coal samples during uniaxial compression were obtained through AE experiments. The results show that when the density is low, the wave velocity of the coal sample decreases with the increase of density. When the density is higher than a certain value, the wave velocity of the coal sample increases with the increase of density. Through the measurement of ultrasonic wave velocity, it is found that there is some nonuniformity and anisotropy in raw coal samples. The ring counts, energy counts, and AE events with time in uniaxial compression process have approximately normal distribution. The AE events are concentrated in the elastic stage and yield stage, and the energy amplitude of AE events is higher in the plastic stage. Compared with the ring counts and energy counts, the AE events have a good positioning function, which can better reflect the evolution of internal cracks of coal samples during uniaxial compression.

scholarly journals Acoustic emission response characteristics of anthracitic coal under uniaxial compression

2020 ◽  
Author(s):  
Feng Du ◽  
Kai Wang ◽  
Guojun Zhang ◽  
Gongda Wang ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Wave Velocity ◽  
Coal Sample ◽  
Compression Process ◽  
Deformation And Failure ◽  
Response Characteristics ◽  
Fracture Evolution ◽  
Anthracite Coal ◽  
Coal Deformation

Abstract The damage evolution of coal is accompanied by the generation of acoustic emission (AE) signal. Through the analysis and research of AE response characteristics of coal deformation and failure, it is helpful to reveal the initiation, propagation and fracture evolution of micro cracks in coal. In this work, taking the anthracite coal as research object, the basic mechanical parameters of coal samples were obtained by ultrasonic tests and uniaxial compression experiments. Meanwhile, the AE response characteristics of coal samples during uniaxial compression were obtained through AE experiments. The results show that when the density is low, the wave velocity of coal sample decreases with the increase of density. When the density is higher than a certain value, the wave velocity of coal sample increases with the increase of density. Through the measurement of ultrasonic wave velocity, it is found that there are some non-uniformity and anisotropy in raw coal samples. The distribution of ring count, energy count and AE events with time in uniaxial compression process is approximately normal distribution. The AE events are concentrated in the elastic stage and yield stage, and the energy amplitude of AE events is higher in the plastic stage. Compared with the ring count and energy count, the AE events have good positioning function, which can better reflect the evolution of internal cracks in coal samples during 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.

Study on Acoustic Emission Signatures during the Process of Edge Chipping for Engineering Ceramics

2011 ◽  
Vol 697-698 ◽  
pp. 93-96 ◽  
Author(s):  
Xiu Jian Tang ◽  
Xin Li Tian ◽  
Jian Quan Wang ◽  
Ya Tao Mao ◽  
F.Q. Li
Keyword(s):  
Acoustic Emission ◽  
Fracture Process ◽  
Static Load ◽  
Average Frequency ◽  
Displacement Curve ◽  
Edge Chipping ◽  
Kaiser Effect ◽  
Engineering Ceramics ◽  
Highly Active ◽  
Fracture Processes

The developments of edge chipping for engineering ceramics are analyzed. An edge chipping experiment under static load is adopted to study the fracture process of edge chipping. The results show that the fracture processes of edge chipping under different edge distances are similar, which can be divided into four stages based on load-displacement curve. There is obviously Kaiser Effect during the fracture processes of edge chipping. Counts, average frequency, RMS, duration, amplitude and inverse calculation can be used to describe the process of edge chipping for engineering ceramics. Amplitude, duration and average frequency become highly active on the eve of fracture, which can be regard as the omens of edge chipping and used to predict the fracture of edge chipping.

Quantitative acoustic emission investigation on the crack evolution in concrete prisms by frequency analysis based on wavelet packet transform

2021 ◽  
pp. 147592172110188
Author(s):  
Zonglian Wang ◽  
Keqin Ding ◽  
Huilan Ren ◽  
Jianguo Ning
Keyword(s):  
Acoustic Emission ◽  
Frequency Band ◽  
Wavelet Packet ◽  
Strain Energy Release ◽  
Crack Size ◽  
Frequency Bands ◽  
Emission Signal ◽  
Damage Process ◽  
Concrete Materials ◽  
Stage 1

To gain an insight into the evolution of micro-cracks in concrete materials, a quantitative acoustic emission investigation on the damage process of concrete prisms subjected to three-point bending loading was performed. Each of the monitored acoustic emission signals was processed by a two-level wavelet packet decomposition into four different frequency bands (AA2, DA2, AD2, and DD2), and the energy coefficients R1, R2, R3, and R4 that parameterize their characteristic frequency bands were calculated. By analyzing variations in energy coefficients of the lowest frequency band (AA2), R1, and the energy coefficients of the highest frequency band (DD2), R4, the whole damage process was divided into three stages: crack initiation, crack growth, and crack coalescence. An inverse relationship between the frequency of the acoustic emission signal emitted by the propagating crack and the crack size in concrete materials was acquired based on the damage theory of brittle materials and the strain energy release theory. The statistical analysis results of the experimental data indicated that the average of R1 increased in turn, and the average of R4 correspondingly decreased in turn from Stage 1 to Stage 3. It revealed that the frequencies of acoustic emission signals decreased gradually with the evolution of the damage of concrete prisms, which is in a good agreement with the theoretical analysis result.

Acoustic emission waveforms for damage monitoring in composite materials: Shifting in spectral density, entropy and wavelet packet transform

2021 ◽  
pp. 147592172110446
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Giovanni Pappalettera ◽  
Vimalathithan Paramsamy Kannan
Keyword(s):  
Acoustic Emission ◽  
Spectral Density ◽  
Flicker Noise ◽  
Wavelet Packet ◽  
Research Work ◽  
Wavelet Packet Transform ◽  
Spectral Energy ◽  
Emission Data ◽  
Cfrp Composites ◽  
Damage Process

Signal-based acoustic emission data are analysed in this research work for identifying the damage modes in carbon fibre–reinforced plastic (CFRP) composites. The research work is divided into three parts: analysis of the shifting in the spectral density of acoustic waveforms, use of waveform entropy for selecting the best wavelet and implementation of wavelet packet transform (WPT) for identifying the damage process. The first two methodologies introduced in this research work are novel. Shifting in the spectral density is introduced in analogous to ‘flicker noise’ which is popular in the field of waveform processing. The entropy-based wavelet selection is refined by using quadratic Renyi’s entropy and comparing the spectral energy of the dominating frequency band of the acoustic waveforms. Based on the method, ‘dmey’ wavelet is selected for analysing the waveforms using WPT. The slope values of the shifting in spectral density coincide with the results obtained from WPT in characterising the damage modes. The methodologies introduced in this research work are promising. They serve the purpose of identifying the damage process effectively in the CFRP composites.

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