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

2019 ◽  
Vol 15 (5) ◽  
pp. 155014771984935 ◽  
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.

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

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Kui Wang ◽  
Xue Li ◽  
Zheng Huang ◽  
Mingjie Zhao
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Cyclic Load ◽  
Stress Amplitude ◽  
Rate Of Change ◽  
Rapid Decline ◽  
Engineering Practice ◽  
Loading Frequency ◽  
Constant Amplitude ◽  
Ae Signal

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.

ACOUSTIC EMISSION BEHAVIOUR OF OVER-REINFORCED CONCRETE BEAMS

2019 ◽  
pp. 4-12 ◽  
Author(s):  
V. V. Bardakov ◽  
A. I. Sagaydak ◽  
S. V. Elizarov
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Cyclic Load ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Emission Data ◽  
Point Bend ◽  
Destructive Processes ◽  
The Relationship

The paper presents the results of the conducted experimental studies on three-point bend testing of over-reinforced concrete beams with incremental cyclic load, up to destruction, using the acoustic emission method. In total 3 RC beams differ from each other in reinforcement type, concrete composition and ultimate load were tested. Special attention is paid to the investigation of the relationship between destructive processes occurring during the testing of reinforced concrete beams and the evolution of acoustic emission data registered during the test. The analysis described in the article makes it possible, on the basis of acoustic emission data, recorded during the tests, to distinguish the stages corresponding to the different technical state of over-reinforced concrete structures.

In-Process Tool Fracture Detection

1984 ◽  
Vol 106 (2) ◽  
pp. 111-118 ◽  
Author(s):  
M. S. Lan ◽  
D. A. Dornfeld
Keyword(s):  
Acoustic Emission ◽  
Fracture Surface ◽  
Signal Analysis ◽  
Cutting Tool ◽  
Fracture Detection ◽  
Acoustic Emission Energy ◽  
Emission Energy ◽  
Ae Signal ◽  
The Relationship ◽  
Carbide Insert

This paper investigates the feasibility of using acoustic emission (AE) signal analysis for the detection of the breakage as well as the chipping of a cutting tool during machining. Experiments were conducted on a lathe using conventional carbide insert tools under realistic cutting conditions. The tangential and feed forces were also measured for comparisons. The sensitivities of the AE signal and cutting forces to insert chipping and fracture are illustrated. The relationship between acoustic emission energy and the combined effect of fracture surface area and cutting load is discussed.

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

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.

CYCLIC NANOINDENTATION OF SEMICONDUCTOR AND METAL THIN FILMS

2009 ◽  
Vol 23 (30) ◽  
pp. 5639-5647 ◽  
Author(s):  
TE-HUA FANG ◽  
WIN-JIN CHANG ◽  
CHAO-MING LIN ◽  
CHUN-CHIN CHANG
Keyword(s):  
Thin Films ◽  
Cyclic Loading ◽  
Young’S Modulus ◽  
Cyclic Load ◽  
Young's Modulus ◽  
Contact Stiffness ◽  
Small Displacement ◽  
Metal Thin Films ◽  
Metal Materials ◽  
The Relationship

The nanoindentation technique was used to measure the hardness and Young's modulus of semiconductor and metal thin films on a Si(100) substrate under cyclic loading. The results showed that in all instances and at a constant cyclic load that the loading curves overlapped the previous unloading curve and had a small displacement after each cyclic nanoindentation. It was observed that the plastic energies of metal materials from the first loading–unloading cycle were much larger than that observed in semiconductor materials. Furthermore, the hardness and Young's modulus of the thin films decreased when the number of cyclic nanoindentations was increased. The effect of the cyclic loading on the hardness and Young's modulus of semiconductor material was much larger than that of the metal material. Young's modulus, the hardness and the contact stiffness of thin films conform to the relationship that Young's modulus was proportional to the contact stiffness and the square root of the thin film's hardness.

scholarly journals Strength and Fatigue Properties of Sandstone under Dynamic Cyclic Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
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.

The influence of ultrasound signal parameters on sonoluminescence light intensity

2013 ◽  
Vol 62 (4) ◽  
pp. 605-612
Author(s):  
Marek Szmechta ◽  
Tomasz Boczar ◽  
Dariusz Zmarzły
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Power Transformer ◽  
Electrical Power ◽  
Partial Discharges ◽  
Research Project ◽  
Insulation Systems ◽  
Secondary Phenomenon ◽  
New Research ◽  
The Relationship

Abstract Topics of this article concern the study of the fundamental nature of the sonoluminescence phenomenon occurring in liquids. At the Institute of Electrical Power Engineering at Opole University of Technology the interest in that phenomenon known as secondary phenomenon of cavitation caused by ultrasound became the genesis of a research project concerning acoustic cavitation in mineral insulation oils in which a number of additional experiments performed in the laboratory aimed to determine the influence of a number of acoustic parameters on the process of the studied phenomenona. The main purpose of scientific research subject undertaken was to determine the relationship between the generation of partial discharges in high-voltage power transformer insulation systems, the issue of gas bubbles in transformer oils and the generated acoustic emission signals. It should be noted that currently in the standard approach, the phenomenon of generation of acoustic waves accompanying the occurrence of partial discharges is generally treated as a secondary phenomenon, but it can also be a source of many other related phenomena. Based on our review of the literature data on those referred subjects taken, it must be noted, that this problem has not been clearly resolved, and the description of the relationship between these phenomena is still an open question. This study doesn’t prove all in line with the objective of the study, but can be an inspiration for new research project in the future in this topic. Solution of this problem could be a step forward in the diagnostics of insulation systems for electrical power devices based on non-invasive acoustic emission method.

scholarly journals Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

2021 ◽  
Vol 11 (6) ◽  
pp. 2673
Author(s):  
Mu-Hang Zhang ◽  
Xiao-Hong Shen ◽  
Lei He ◽  
Ke-Shi Zhang
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Strain Tensor ◽  
Equivalent Strain ◽  
Differential Entropy ◽  
Strain Components ◽  
Deformation Inhomogeneity ◽  
Standard Deviations ◽  
Number Of Cycles ◽  
The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

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