期刊
APPLIED SCIENCES-BASEL
卷 12, 期 22, 页码 -出版社
MDPI
DOI: 10.3390/app122211810
关键词
cyclic loading and unloading; strain; elastic modulus; acoustic emission; damage; b value
类别
资金
- Basic Research Funds for the Central Universities [3142022002]
- Natural Science Foundation of Inner Mongolia Autonomous Region [2021BS05002]
- Natural Science Innovation Foundation of Inner Mongolia University of Science and Technology [2019QDL-B25]
This study conducted experimental tests on the mechanical properties and acoustic emission characteristics of low-strength coal specimens during cyclic loading and unloading, providing theoretical support for understanding the damage evolution of coal specimens.
The paper represents a test investigation of the mechanical properties and acoustic emission (AE) characteristics of low-strength coal specimens subjected to cyclic loading and unloading. From the lab tests, the following conclusions can be obtained: (1) The axial strain is very well linear with the loading-unloading cycle number, and the circumferential and volumetric strains are approximately quadratic functions with the loading-unloading cycle number; (2) Under the same loading stress interval, the elastic modulus firstly increases and then remains stable with the loading-unloading cycle number. In addition, the higher the maximum stress of a loading-unloading cycle, the more significant the plastic strengthening effect produced by this cycle; (3) The damage calculated by the cumulative AE hit count can better reflect the fact that the damage has been increasing in the loading phase and keeps basically unchanged in the unloading phase. So, the AE hit count, as a damage variable, can better describe the damage development of coal specimens. (4) The significant fluctuation of the AE b value can be used as the precursor of coal specimen failure. Additionally, the AE b value decreases rapidly at coal specimen failure. (5) The closer to the loading-unloading cycle of coal specimen failure, the more accurate the predicted maximum magnitude at coal specimen failure.
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