An Experiment Monitoring Signals of Coal Bed Simulation under Forced Vibration Conditions

Li, Chengwu; Hu, Po; Gao, Tian-Bao; Sun, Yingfeng; Shao, Shengyang; Wang, Qifei

doi:10.1155/2015/693612

Cited by 3 publications

(1 citation statement)

References 11 publications

(12 reference statements)

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“…According to the existing literature [3][4][5] , the main causes of bolt loosening were as follows: ① There is a deviation in the installation of main operating parts of the fan, which leads to a large vibration during the operation of the fan and the gradual loosening of the nuts of the bolts. ② The bolts are not fastened in place, which leads to the gradual loosening of the nuts under the vibration.…”

Section: Introductionmentioning

confidence: 99%

Bolt loose judging device for offshore wind turbine

Fei

Qin

2020

E3S Web Conf.

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For the problem of bolt loose in the long-term operation of offshore wind turbine, we proposed a bolt loose judging device for offshore wind turbine. The bolt loose judging device for offshore wind turbine included vibration sensor, signal receiving and transmitter, CCD sensor, data analyzer, power supply, the communication line and the power supply line. The combination of data analyzer and CCD sensor was used to analyze whether the prefabricated symbols on the bolts change, so as to judge whether the bolts are loose. The whole system (except vibration sensor) has been in standby and dormant state at ordinary times, which is more simple and reliable under the harsh conditions at sea.

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Section: Introductionmentioning

confidence: 99%

Bolt loose judging device for offshore wind turbine

Fei

Qin

2020

E3S Web Conf.

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Electromagnetic signal characteristics and energy response pattern of briquette hammer fracturing

Zhao

Han

et al. 2020

Journal of Geophysics and Engineering

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Briquette hammer fracturing experiments were conducted with different impact energies and molding pressures to investigate the characteristics of the electromagnetic signals. The response pattern of the electromagnetic radiation energy as a function of the impact energy and the coal firmness during impact fracturing of a coal mass were analyzed. The characteristics of the electromagnetic radiation signals during the uniaxial compression fracture of a coal mass were also used to analyze their source during fracture. The results show that the generation of electromagnetic radiation during coal mass fracturing can be divided into three stages: compaction, crack propagation and sliding friction. Electromagnetic energy is mainly radiated during the sliding friction stage. The electromagnetic radiation during briquette hammer fracturing is characterized by a frequency below 2000 Hz, an amplitude in the range from 0.05 to 0.6 mV, and a total energy on the order of ∼10−14–10−10 J. For coal masses with the same firmness, as the impact energy increases, the total energy of the electromagnetic radiation increases. For the same impact energy, as the firmness of the coal mass increases, the total energy of the electromagnetic radiation first increases and then decreases.

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Experimental Study on Stress Evolution and Microseismic Signals under Vibration Conditions of Coal during Excavation and Subsequent Waiting Time

Wang

Lyu

et al. 2019

Shock and Vibration

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An experiment designed to simulate coal during excavation was conducted. Microseismic signals of coal under vibration conditions during excavation and subsequent waiting time of the coal roadway at different excavation speeds were collected and analyzed. During the excavation and subsequent waiting time, the stress in coal is redistributed, and the concentrated stress is gradually transferred to the deeper section of the coal seam. The Hilbert–Huang transform (HHT) is used to effectively denoise the collected signals. According to the noise-reduced signal, the amplitude and pulse number of the microseismic signals emitted during the excavation process are much larger than those of the waiting time process. During excavation, the energy and event numbers of microseismic signals increase first and then decrease as the excavation speed increases. The faster the excavation speed, the more the energy, and the higher the event numbers of the microseismic signals released during the subsequent waiting time. When the excavation speed is faster, more elastic potential accumulates in the coal seam and the concentration stress is greater. As the concentrated stress moves forward in time without excavation, more coal seams fail, and more microseismic signals are released. The microseismic signal and the stress evolution law can provide a reasonable explanation for the forward movement of the concentrated stress and coal failure during roadway excavation.

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An Experiment Monitoring Signals of Coal Bed Simulation under Forced Vibration Conditions

Cited by 3 publications

References 11 publications

Bolt loose judging device for offshore wind turbine

Bolt loose judging device for offshore wind turbine

Electromagnetic signal characteristics and energy response pattern of briquette hammer fracturing

Experimental Study on Stress Evolution and Microseismic Signals under Vibration Conditions of Coal during Excavation and Subsequent Waiting Time

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