Experimental Study on Acoustic Emission and Resistivity Response of Sandstone under Constant Amplitude Cyclic Loading

A lot of engineering practice shows that, during the construction and operation of rock mass projects, in addition to the static load, the rock is more subjected to cyclic load. Constant amplitude cyclic load is one of the simpler cyclic loading methods. The damage of rocks gradually accumulates under the action of periodic cyclic load, and finally, fatigue damage occurs, which affects the stability of the project. Therefore, it is necessary to study the mechanical properties of the rock under the action of constant amplitude cyclic load. Acoustic emission (AE) parameters and resistivity are both sensitive to the damage process of the rock and can well describe the damage evolution law of the rock. Under the action of constant amplitude cyclic loading, different loading conditions, different state specimens, and so on, factors will make a big difference to the AE signal and resistivity, such as the difference in stress amplitude, loading rate, and saturation. Therefore, in this paper, the typical sandstone in the Chongqing area is taken as the research object, the AE characteristics and resistivity characteristics of sandstone under different test conditions such as different stress amplitude, different loading frequency, and different saturation are tested, and the evolution of AE is found. It also has a three-stage rule: in the initial stage, the deformation is faster and the AE signal is strong; in the constant velocity stage, the deformation develops slowly and the AE signal is also stable; in the acceleration stage, the deformation develops sharply and the AE signal also becomes more intense. With the increase of cyclic loading stress amplitude, or the decrease of cyclic loading frequency, or the decrease of rock sample saturation, the acoustic emission signal generated in each cycle will be stronger. The resistivity as a whole shows a rapid decline in the loading phase and a rapid rebound in the unloading phase. The changes in resistivity at different stress amplitudes show differences in the first few cycles; the overall change trend of resistivity at different frequencies is consistent, but the rate of change increases with decreasing frequency, and the variation trend of resistivity is very different under different saturation.

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Experimental investigation of pretensioned bolts under cyclic loading: Damage assessment using acoustic emission

International Journal of Distributed Sensor Networks ◽

10.1177/1550147719849354 ◽

2019 ◽

Vol 15 (5) ◽

pp. 155014771984935 ◽

Cited By ~ 1

Author(s):

Tieliang An ◽

Xigui Zheng ◽

Dengxing Zhu ◽

Deyu Qian ◽

Yu Guo ◽

...

Keyword(s):

Acoustic Emission ◽

Cyclic Loading ◽

Cyclic Load ◽

Loading Path ◽

Loading Frequency ◽

Damage Factor ◽

Acoustic Emission Energy ◽

Pull Out ◽

Anchorage System ◽

The Relationship

Understanding the acoustic emission effects on bolts under cyclic loading is of great significance for the support of roadways. The presented research focuses on the acoustic emission characteristics of bolts under cyclic loading. The following main conclusions were drawn: (1) With a higher loading frequency, the acoustic emission counts rate increases, while the total energy released in a given cyclic loading path decreases. (2) A fitting formula is established according to the relationship between the tension amplitude and cumulative acoustic emission counts, which can analyze the tension magnitude level of the cyclic load. (3) A damage factor for a cyclic load is proposed based on the acoustic emission counts generated during the cyclic and monotonic loading process that can analyze the degree of damage to the anchorage system caused by the cyclic load. (4) Based on the spatial distribution of the acoustic emission orientation points and the acoustic emission energy generated during the pull-out process, the acoustic emission damage evolution process of the anchorage specimens is deduced, and the mechanism of the high stability of the pretension anchorage system after cyclic loading is analyzed. The above conclusions may provide some experimental references for the application of acoustic emission technology in bolts supporting roadways.

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Damage and fractal evolution trends of sandstones under constant-amplitude and tiered cyclic loading and unloading based on acoustic emission

International Journal of Distributed Sensor Networks ◽

10.1177/1550147719861020 ◽

2019 ◽

Vol 15 (7) ◽

pp. 155014771986102

Author(s):

Dongxu Liang ◽

Nong Zhang ◽

Lixiang Xie ◽

Guangming Zhao ◽

Deyu Qian

Keyword(s):

Acoustic Emission ◽

Cyclic Loading ◽

Damage Evolution ◽

Damage Accumulation ◽

Fractal Dimensions ◽

Damage Variable ◽

Constant Amplitude ◽

Kaiser Effect ◽

Cyclic Loading And Unloading ◽

Loading And Unloading

It is of significance to study the damage and destruction of rock under cyclic loading in geotechnical engineering. We determined the trends in damage evolution of sandstone under constant-amplitude and tiered cyclic loading and unloading under uniaxial compression. The results of the study show that (1) the variation of acoustic-emission events was consistent with the stress curves and 89% of all acoustic-emission events occurred during the cycling stages. The observed Kaiser effect was more notable in tiered cycling. (2) The damage variable increased sharply in the cycling stages and its increment was 0.07 higher for tiered cycling than constant-amplitude cycling. Sandstone exhibited greater damage under tiered cyclic loading and unloading. (3) Equations for the evolution of the damage variable under the two cycle modes were obtained by fitting of experimental data. (4) The fractal dimensions of the constant-amplitude cycle were larger than those of the tiered cycle. The process of damage and destruction presents a trend of reducing fractal dimension. The damage accumulation of sandstone under tiered cycling was faster than under constant-amplitude cycling. These results provide references for damage and early warning of rock under both constant-amplitude and tiered cyclic loading and unloading.

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Behavior of saline ice under cyclic flexural loading

The Cryosphere ◽

10.5194/tc-15-2415-2021 ◽

2021 ◽

Vol 15 (5) ◽

pp. 2415-2428

Author(s):

Andrii Murdza ◽

Erland M. Schulson ◽

Carl E. Renshaw

Keyword(s):

Acoustic Emission ◽

Cyclic Loading ◽

Flexural Strength ◽

Stress Amplitude ◽

Back Stress ◽

Lake Ice ◽

Hit Rate ◽

Vertical Location ◽

Dislocation Pileups ◽

Reversed Cyclic

Abstract. New systematic experiments reveal that the flexural strength of saline S2 columnar-grained ice loaded normal to the columns can be increased upon cyclic loading by about a factor of 1.5. The experiments were conducted using reversed cyclic loading over ranges of frequencies from 0.1 to 0.6 Hz and at a temperature of −10 ∘C on saline ice of two salinities: 3.0 ± 0.9 and 5.9 ± 0.6 ‰. Acoustic emission hit rate during cycling increases with an increase in stress amplitude of cycling. Flexural strength of saline ice of 3.0 ± 0.9 ‰ salinity appears to increase linearly with increasing stress amplitude, similar to the behavior of laboratory-grown freshwater ice (Murdza et al., 2020b) and to the behavior of lake ice (Murdza et al., 2021). The flexural strength of saline ice of 5.9 ± 0.6 ‰ depends on the vertical location of the sample within the thickness of an ice puck; i.e., the strength of the upper layers, which have a lower brine content, was found to be as high as 3 times that of lower layers. The fatigue life of saline ice is erratic. Cyclic strengthening is attributed to the development of an internal back stress that opposes the applied stress and possibly originates from dislocation pileups.

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Elastic-Viscoplastic Constitutive Model of Soil under Cyclic Loading

Advances in Civil Engineering ◽

10.1155/2021/1602431 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Yuan Ma ◽

Hua Liang ◽

Yongxue You ◽

Weiguang Zhang ◽

Limin Guo ◽

...

Keyword(s):

Cyclic Loading ◽

Dynamic Stress ◽

Stress Amplitude ◽

Yield Criterion ◽

Case Analysis ◽

Research Field ◽

Constant Amplitude ◽

Bingham Model ◽

Viscoplastic Model ◽

Flow Criterion

The creep problems are often involved in soil under cyclic loading, and its behaviors of soil under cyclic loading sparks many arguments in current research field. To propose one new model to demonstrate these creep behaviors of soil under cyclic loading, the cyclic loading was simplified equivalently, and the elastic-viscoplastic model (EVPM) for soil under cyclic loading was established based on the Bingham model. The yield criterion for soil under cyclic loading with constant amplitude was proposed following the simplified load. A constitutive equation based on the EVPM was constructed by using the flow criterion related to the yield criterion. Meanwhile, the parameters of EVPM were identified and discussed. In addition, the case analysis of the EVPM was also performed. The results indicate that the stable and destructive creep behaviors of soil under cyclic loading could be well described by the recommended EVPM, and the obtained parameters in the model exhibited a clear regularity with the increase of dynamic stress amplitude. Besides, the established model could be selected to predict the stable and destructive creep behavior of soil under cyclic loading.

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Mechanical Behavior Evolution and Damage Characterization of Coal under Different Cyclic Engineering Loading

Geofluids ◽

10.1155/2020/8812188 ◽

2020 ◽

Vol 2020 ◽

pp. 1-19 ◽

Cited By ~ 1

Author(s):

Huajun Wang ◽

Jian Li

Keyword(s):

Cyclic Loading ◽

Stress Amplitude ◽

Early Stage ◽

Peak Stress ◽

Cyclic Stress ◽

Loading Frequency ◽

Porous Rocks ◽

Strength Change ◽

Drastic Increase

The cyclic loading causes the strength change of porous rocks, which can be frequently encountered in underground coal mining. In order to quantify the cumulative damage of porous coal, multilevel uniaxial cyclic compressive tests were carried out considering different loading frequencies. The results show that under cyclic loading, Young’s modulus of coal shows a first drastic increase and then decrease trend in terms of the number of loading-unloading cycles, while the Poisson’s ratio gradually increased at lower peak stress amplitudes and then increased sharply with peak cyclic stress amplitude until losing load bearing capacity, following a stepwise rising trend. At a higher loading frequency, volumetric compressibility-dilatancy transition is shifted to an earlier time. The loading/unloading response ratio (LURR) was used to evaluate the damage of coal under cyclic loading. It is found that LURR is an effective parameter to evaluate the damage of coaly rock under cyclic loading and is also useful in distinguishing different deformation mechanism at different loading stages. The results also show that the damage of coal can initiate at the early stage of cyclic loading at a low loading frequency; however, the increase in frequency of cyclic loading can delay the damage time, requiring a relatively higher level of peak cyclic stress amplitude.

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Using Acoustic Emission Monitoring to Observe the De-Bonding Behavior of Rebar in Cyclic Pull-Out Tests

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.784.377 ◽

2015 ◽

Vol 784 ◽

pp. 377-384

Author(s):

Kuang Chih Pei ◽

Yu Cheng Kan

Keyword(s):

Acoustic Emission ◽

Cyclic Load ◽

Acoustic Emissions ◽

Remaining Life ◽

Bond Behavior ◽

Signal Density ◽

Pull Out ◽

Emission Monitoring ◽

Rc Structure ◽

Ae Signal

This research aimed to reveal the bond behavior and failure mechanism of varying size rebar embedded in concrete with inside pre-crack through a series of quasi-static/cyclic pull-out tests and real-time acoustic emissions monitoring (AE). The obtained AE signal density records of the tests provide potential usage for evaluate the safety of reinforced concrete (RC) structure subjected to cyclic load, as well as quantitative study in the remaining life of RC after earthquake or shake damage.

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Strength and Fatigue Properties of Sandstone under Dynamic Cyclic Loading

Shock and Vibration ◽

10.1155/2016/9458582 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Mingming He ◽

Ning Li ◽

Yunsheng Chen ◽

Caihui Zhu

Keyword(s):

Fatigue Life ◽

Cyclic Loading ◽

Mechanical Characteristics ◽

Stress Amplitude ◽

Dynamic Strength ◽

Fatigue Properties ◽

Loading Frequency ◽

Strength And Deformation ◽

Metal Materials ◽

The Relationship

This paper presents an experimental investigation of strength and fatigue properties of intact sandstone samples subjected to dynamic cyclic loading in the laboratory. Tests were conducted on sandstone samples with loading frequencies ranging in 0.5, 1, 2, and 4 Hz, loading amplitudes of 1, 15, 30, 60, 90, and 120 kN, and loading speeds of 0.5, 1, 2, 4, and 8 kN/s. In this study it was shown that the loading frequency, as well as the amplitude and loading speed, was of great significance and affected the mechanical characteristics of sandstone under dynamic cyclic loading. The fatigue life of sandstone was found to decrease with loading speeds and amplitudes but increase with loading frequencies. It was found that the minimum of the dynamic strength and deformation factor of sandstone was obtained at loading speeds of 2 kN/s but the maximum at loading frequencies of 1 Hz. Finally, it was concluded that the relationship between the fatigue life and loading speed, frequency, and stress amplitude under dynamic cyclic loading would be expressed as theS-Ncurve, which showed that the fatigue characteristic of sandstone was similar to that of metal materials.

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Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

Mechanics & Industry ◽

10.1051/meca/2020061 ◽

2020 ◽

Vol 21 (5) ◽

pp. 505

Author(s):

Yousef Ghaderi Dehkordi ◽

Ali Pourkamali Anaraki ◽

Amir Reza Shahani

Keyword(s):

Residual Stress ◽

Cyclic Loading ◽

Stress Relaxation ◽

Stress Amplitude ◽

Cyclic Plasticity ◽

Mean Stress ◽

Effective Parameters ◽

Perfect Plasticity ◽

Residual Stress Relaxation ◽

Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

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Analysis of Acoustic Emission (AE) Signals for Quality Monitoring of Laser Lap Microwelding

Applied Sciences ◽

10.3390/app11157045 ◽

2021 ◽

Vol 11 (15) ◽

pp. 7045

Author(s):

Ming-Chyuan Lu ◽

Shean-Juinn Chiou ◽

Bo-Si Kuo ◽

Ming-Zong Chen

Keyword(s):

Stainless Steel ◽

Acoustic Emission ◽

Frequency Domain ◽

Monitoring System ◽

Welding Quality ◽

Steel Sheets ◽

Signal Features ◽

Ae Signal ◽

Laser Microwelding ◽

Ae Signals

In this study, the correlation between welding quality and features of acoustic emission (AE) signals collected during laser microwelding of stainless-steel sheets was analyzed. The performance of selected AE features for detecting low joint bonding strength was tested using a developed monitoring system. To obtain the AE signal for analysis and develop the monitoring system, lap welding experiments were conducted on a laser microwelding platform with an attached AE sensor. A gap between the two layers of stainless-steel sheets was simulated using clamp force, a pressing bar, and a thin piece of paper. After the collection of raw signals from the AE sensor, the correlations of welding quality with the time and frequency domain features of the AE signals were analyzed by segmenting the signals into ten 1 ms intervals. After selection of appropriate AE signal features based on a scatter index, a hidden Markov model (HMM) classifier was employed to evaluate the performance of the selected features. Three AE signal features, namely the root mean square (RMS) of the AE signal, gradient of the first 1 ms of AE signals, and 300 kHz frequency feature, were closely related to the quality variation caused by the gap between the two layers of stainless-steel sheets. Classification accuracy of 100% was obtained using the HMM classifier with the gradient of the signal from the first 1 ms interval and with the combination of the 300 kHz frequency domain signal and the RMS of the signal from the first 1 ms interval.

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The duration-energy-size enigma for acoustic emission

Scientific Reports ◽

10.1038/s41598-021-84688-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Blai Casals ◽

Karin A. Dahmen ◽

Boyuan Gou ◽

Spencer Rooke ◽

Ekhard K. H. Salje

Keyword(s):

Acoustic Emission ◽

Mean Field Theory ◽

Mean Field ◽

Maximum Amplitude ◽

Time Profile ◽

Power Law Distribution ◽

Model Predictions ◽

Ae Signal ◽

Strain Signal ◽

Better Than

AbstractAcoustic emission (AE) measurements of avalanches in different systems, such as domain movements in ferroics or the collapse of voids in porous materials, cannot be compared with model predictions without a detailed analysis of the AE process. In particular, most AE experiments scale the avalanche energy E, maximum amplitude Amax and duration D as E ~ Amaxx and Amax ~ Dχ with x = 2 and a poorly defined power law distribution for the duration. In contrast, simple mean field theory (MFT) predicts that x = 3 and χ = 2. The disagreement is due to details of the AE measurements: the initial acoustic strain signal of an avalanche is modified by the propagation of the acoustic wave, which is then measured by the detector. We demonstrate, by simple model simulations, that typical avalanches follow the observed AE results with x = 2 and ‘half-moon’ shapes for the cross-correlation. Furthermore, the size S of an avalanche does not always scale as the square of the maximum AE avalanche amplitude Amax as predicted by MFT but scales linearly S ~ Amax. We propose that the AE rise time reflects the atomistic avalanche time profile better than the duration of the AE signal.

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