Acoustic Emission Experimental Research of the Damage Characteristics of Raw Coal under Different Loading and Unloading Rates

Zhang, Minbo; Cui, Li; Hu, Wenjun; Du, Jinlei; Zhang, Zhen; Wang, Cuiling

doi:10.1155/2020/9063929

Cited by 6 publications

(6 citation statements)

References 22 publications

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“…The slip lines resulted from high dislocation motion under the applied stress. Q235 steel is a polycrystalline material whose deformation is achieved by the gradual movement of crystals along the slip surface (Zhang et al, 2015). More slip lines were found when the applied load increased or closer to the hardening stage at 514 s, as shown in Fig.…”

Section: Optical Microscopy Analysismentioning

confidence: 97%

“…AE signals are generated from material damages such as twining, dislocation, cavitation, and crystal slip (Heiple, Carpenter, 1987;Bohlen et al, 2004;Trojanová et al, 2010). Previous work has shown that the damage response of Q235B steel can be assessed by the AE method (Zhang et al, 2015) and the defects can be located accurately (Wu et al, 2008;Jiang, Xu, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Archives of Acoustics

Zhang

Lai³

et al. 2019

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Q235 steel is widely used in engineering and construction. Therefore, it is important to identify the damage mechanism and the acoustic emission (AE) response of the material to ensure the safety of structures. In this study, an AE monitor system and an in situ tensile test with an optical microscope were used to investigate the AE response and insight into the damage process of Q235 steel. The surface of the specimen was polished and etched before the test in order to improve the quality of micrographs. Two kinds of AE responses, namely a burst and a continuous signal, were recorded by the AE monitor system during the test. Based on the in situ test, it was observed that the damage of Q235 steel was induced by the crystal slip and the inclusion fracture. Since the crystal slip was an ongoing process, continuous AE signals were produced, while burst AE signals were possibly produced by the inclusion fracture which occurred suddenly with released higher energy. In addition, a great number of AE signals with high amplitude were observed during the yielding stage and then the number and amplitude decreased.

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Section: Optical Microscopy Analysismentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Archives of Acoustics

Zhang

Lai³

et al. 2019

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“…e fuzzy analytic hierarchy process is a systematic analysis method combining qualitative and quantitative analysis. It is a comprehensive application of the analytic hierarchy process and the fuzzy evaluation method [29]. e essence of the analytic hierarchy process is a way of decision-making thinking.…”

Section: Fuzzy Analytic Hierarchy Processmentioning

confidence: 99%

Stability Assessment of Deep Three‐Soft Outburst Coal Seam Roof Based on Fuzzy Analytic Hierarchy Process

Meng

Zhang

et al. 2021

Shock and Vibration

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The stability of deep “three-soft” coal seam roof has always been a key issue in coal mining. There are a lot of factors affecting the stability of deep three-soft coal seam outburst roof. However, there is currently no definite method able to draw an accurate assessment conclusion on roof stability. In order to accurately determine the main influencing factors of the stability of deep three-soft coal seam outburst roof and reduce the loss of coal production, this paper performed three-soft coal seam risk identification on Lugou Mine based on the introduction of the fuzzy analytic hierarchy process theory. 23 main risk factors were identified. Then, it established a hierarchical structure model of coal seam roof stability in accordance with experts’ opinions. The analytic hierarchy process was used to calculate the weights of indicators at all levels. Next, the paper used the fuzzy comprehensive evaluation method and expert scoring to evaluate various risk factors in the indicator system, as well as the overall safety level. The results showed that the deep three-soft coal seam stability of Lugou Mine ranks the third hazard level. The main risk and harmful factors include safety awareness, safety monitoring system, roof weakness, ventilation system, fire-fighting system, and rock bolt quality. In response to the evaluation results, this paper formulated corresponding control measure in terms of ventilation risk, safety monitoring risks, construction personnel risks, and fire protection risk to reduce losses in the mining process, providing a new evaluation method for the stability assessment of deep outburst coal seam roof.

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“…e deflection equation of the thin plate rock mass with both sides simply supported (S-S) along the x direction could be expressed as follows [46][47][48]: e boundary conditions of the thin plate rock mass with both free sides (F-F) along the y direction may be as follows:…”

Section: Deflection Equation Of the In Plate Rock Mass S-f-s-f Under ...mentioning

confidence: 99%

The Dynamic Response and Failure Model of Thin Plate Rock Mass under Impact Load

Dong

Wang

et al. 2021

Shock and Vibration

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The layered rock mass widely exists in mining, construction, transportation, and water conservancy projects, and the damage phenomena of plate crack and spalling often occurs in the process of coal and rock dynamic disaster in deep mining. Therefore, the rock mass nearby excavation surface is usually considered to be composed of layers of thin plate rock mass to reveal the damage and failure mechanism of rock mass. In the whole dynamic process of mining and coal and rock dynamic disaster, rock mass would bear the dynamic disturbance from mine earthquake, and at present, the mechanical characteristics of rock mass are mainly studied under static load, while dynamic mechanical response characteristics and the mechanisms of dynamic damage, failure, and disaster-causing are still unclear. This study mainly focused on the dynamic response characteristic and failure mechanism of rock mass based on a rectangular thin plate model. The frequency equations and deflection equations of the thin plate rock mass with different boundary conditions (S-F-S-F, S-C-S-C, and C-C-C-C) were established under free vibration by the thin plate model and the dual equation of the Hamilton system, and the deflection equations under impact load were derived based on the Duhamel integral. And then, the effective vibration modes of the thin plate rock mass with different boundary conditions and their natural frequencies were obtained by Newton’s iterative method. Based on the third-strength theory and the numerical simulation results by LS-DYNA, the maximum shear of the effective vibration modes and the processes of damage and failure under impact load were analyzed. The research results showed that the initial position of damage and failure may be determined by effective vibration mode with the lowest frequency; the develop tendency of which by the combined actions of other effective vibration modes and the effective vibration modes with lower frequency could have greater influence on the process of damage and failure of the thin plate rock mass, which are beneficial to revealing the mechanism of coal and rock dynamic disaster.

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Acoustic Emission Experimental Research of the Damage Characteristics of Raw Coal under Different Loading and Unloading Rates

Cited by 6 publications

References 22 publications

Archives of Acoustics

Archives of Acoustics

Stability Assessment of Deep Three‐Soft Outburst Coal Seam Roof Based on Fuzzy Analytic Hierarchy Process

The Dynamic Response and Failure Model of Thin Plate Rock Mass under Impact Load

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