Observation of Crack Propagation in Asphalt Mixtures with Acoustic Emission

Crack propagation is the main reason which leads to the invalidity of the metal components. A set of detecting equipment based on the acoustic emission method was designed, and it was mainly composed of acoustic emission sensor, signal operating circuits and signal acquisition system. Specimens of 16MnR material were manufactured and the static axial tension test of them was carried on. Acoustic emission signals from the specimen were detected by acoustic emission equipment by using piezoelectric ceramic sensor. Signal datum were acquired and operated by the acquisition system, as well as the acquisition program written for it. The final results has demonstrated that acoustic emission equipment designed for the test performed well in acquiring the signals induced by the metal crack propagation.

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Progressive Failure and Acoustic Emission Characteristics of Red Sandstone with Different Geometry Parallel Cracks under Uniaxial Compression Loading

Advances in Materials Science and Engineering ◽

10.1155/2021/5569091 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Xizhen Sun ◽

Fanbao Meng ◽

Ce Zhang ◽

Xucai Zhan ◽

He Jiang

Keyword(s):

Acoustic Emission ◽

Crack Initiation ◽

Crack Propagation ◽

Geometric Distribution ◽

Progressive Failure ◽

Fractured Rock ◽

Propagation Mode ◽

Wing Crack ◽

Red Sandstone ◽

Parallel Cracks

The geometric distribution of initial damages has a great influence on the strength and progressive failure characteristics of the fractured rock mass. Initial damages of the fractured rock were simplified as parallel cracks in different geometric distributions, and then, the progressive failure and acoustic emission (AE) characteristics of specimens under the uniaxial compression loading were analyzed. The red sandstone (brittle materials) specimens with the parallel preexisting cracks by water jet were used in the tests. The energy peak and stress attenuation induced by the energy release of crack initiation were intuitively observed in the test process. Besides, three modes of rock bridge coalescence were obtained, and wing crack was the main crack propagation mode. The wing crack and other cracks were initiated in different loading stages, which were closely related to the energy level of crack initiation. The propagation of wing crack (stable crack) consumed a large amount of energy, and then, the propagation of shear crack, secondary crack, and anti-wing crack (unstable crack) was inhibited. The relationship between the crack propagation mode and the geometric distribution of existing cracks in the specimen was revealed. Meanwhile, the strength characteristic and failure mode of fractured rock with the different geometric distributions of preexisting crack were also investigated. The energy evolution characteristics and crack propagation were also analyzed by numerical modeling (PFC2D).

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Research on fatigue crack propagation of micro-alloyed steel by acoustic emission

Materials Research Innovations ◽

10.1179/1432891714z.0000000001122 ◽

2015 ◽

Vol 19 (sup5) ◽

pp. S5-420-S5-422 ◽

Cited By ~ 1

Author(s):

H. W. Wang ◽

H. Q. Xiao ◽

H. Bai ◽

Z. Y. Han ◽

...

Keyword(s):

Acoustic Emission ◽

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Alloyed Steel ◽

Micro Alloyed Steel

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Acoustic Emission Monitoring of Crack Propagation on the Expedited Wing Fatigue Test Article (X993).

10.21236/ada041107 ◽

1976 ◽

Author(s):

William M. Pless ◽

Cliff D. Bailey ◽

James M. Hamilton

Keyword(s):

Acoustic Emission ◽

Crack Propagation ◽

Fatigue Test ◽

Acoustic Emission Monitoring ◽

Test Article ◽

Emission Monitoring

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Evaluation of Low Temperature Cracking of Asphalt Mixture Modified with PPA Using Acoustic Emission Technique

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.20.26415 ◽

2018 ◽

Vol 7 (4.20) ◽

pp. 541

Author(s):

Mojtaba Kodadadi ◽

Ali Khodaii

Keyword(s):

Acoustic Emission ◽

Asphalt Mixture ◽

Asphalt Mixtures ◽

Bending Test ◽

Limestone Aggregate ◽

Failure Energy ◽

Low Temperature Cracking ◽

Spss Software ◽

Non Destructive ◽

Good Agreement

In this study, the behavior of asphalt mixture was studied using non-destructive Acoustic Emission (AE) technique at low temperatures. For this purpose, two types of bitumen 60/70 and 85/100 with two types of limestone and Silica aggregate were used to construct asphalt mixtures. Polyphosphoric acid (PPA) was used to modify the bitumen in the dosage of 0, 0.5, 1.0 and 1.5% of bitumen weight. Semicircular bending test (SCB) under a steady increasing strain at a rate of 3mm/min was conducted at 0, -10-, and -20 °C. Two AE channels were used to record the Sinusoid output around the crack of SCB sample during crack growth. Analysis of the results obtained from this study using SPSS software indicates that there is a significant relationship between the failure energy of SCB samples and the number of impacts received from AEs. Furthermore, AE energy has a good agreement with the sample failure energy. According to the failure criterion, asphalt mixtures containing 85/100 bitumen modified by 1.0% of PPA and limestone aggregate exhibit more crack resistance among other compositions.

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Experimental Research on the Mechanical Characteristics and the Failure Mechanism of Coal-Rock Composite under Uniaxial Load

Advances in Civil Engineering ◽

10.1155/2020/8867809 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Ke Yang ◽

Zhen Wei ◽

Xiaolou Chi ◽

Yonggang Zhang ◽

Litong Dou ◽

...

Keyword(s):

Compressive Strength ◽

Acoustic Emission ◽

Elastic Modulus ◽

Crack Propagation ◽

Failure Mechanism ◽

Poisson’S Ratio ◽

Mechanical Characteristics ◽

Poisson's Ratio ◽

Energy Value ◽

Coal Rock

Due to the influence of the component structure and combination modes, the mechanical characteristics and failure modes of the coal-rock composite show different characteristics from the monomer. In order to explore the effect of different coal-rock ratios on the deformation and the failure law of the combined sample, the RMT rock mechanics test system and acoustic emission real-time monitoring system are adopted to carry out uniaxial compression tests on coal, sandstone, and three kinds of combined samples. The evolution rules of the mechanical parameters of the combined samples, such as the uniaxial compressive strength, elastic modulus, and Poisson’s ratio, are obtained. The expansion and failure deformation characteristics of the combined sample are analyzed. Furthermore, the evolution laws of the fractal and acoustic emission signals are combined to reveal the crack propagation and failure mechanism of the combined samples. The results show that the compressive strength and elastic modulus of the combined sample increase with the decrease of the coal-rock ratios, and Poisson’s ratio decreases with the decrease of the coal-rock ratios. The strain softening weakens at the postpeak stage, which shows an apparent brittle failure. The combined sample of coal and sandstone has different degrees of damages under load. The coal is first damaged with a high degree of breakage, with obvious tensile failure. The acoustic emission energy value presents different stage characteristics with increasing load. Crackling sound occurs in the destroy section before the sample reaches the peak, along with small coal block ejection and the partial destruction. The energy value fluctuates violently, with the appearance of several peaks. At the postpeak stage, the coal samples expand rapidly with a loud crackling sound in the destroy section, and the energy value increases dramatically. The crack propagation induces the damage in the sandstone; when the energy reaches the limit value, the instantaneous release of elastic energy leads to the overall structural instability.

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