Experimental research on influencing factors of natural frequency of coal

doi:10.16265/j.cnki.issn1003-3033.2021.08.015

Abstract

Abstract: In order to explore dominant frequency of vibration wave increasing permeability of coal, a coal natural frequency test system was built based on knocking method test principle, and coal natural frequency was studied from three aspects: coal size, moisture content, and hole defects. The research results show that Hanning window is better than rectangular window and exponential window in FFT analysis of vibration signal. On this basis, ranges of the first-order and second-order natural frequencies for four different coal groups are 11.1-17.2 Hz and 35.0-40.6 Hz, respectively. Increase of moisture content reduces coal natural frequency, and variation of first-order natural frequency is more sensitive when moisture content is lower. Influence of hole volume on natural frequency of coal has limitations. Variation amplitude of the first and second natural frequencies of coal with different pore volume is within 5.2% and 6.5% respectively. Main influences of vibration wave on coal natural frequency are plastic deformation and evolution of whole defect of coal.

Key words: coal, natural frequency, window function, moisture content, hole volume

CLC Number:

X913.3

REN Yongjie, WEI Jianping, WEN Zhihui, ZHANG Junzhao, YAO Shuai. Experimental research on influencing factors of natural frequency of coal[J]. China Safety Science Journal, 2021, 31(8): 104-111.

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