Study on Ultrasonic Response to Mechanical Structure of Coal under Loading and Unloading Condition

Table 3

The response result of ultrasonic parameters.

Load; (kN)	Ultrasonic amplitude (V)				Amplitude of dominant frequency (mV)				Ultrasonic velocity (m/s)
	Test result			Average	Test result			Average	Test result			Average
0	0.6823	0.6958	0.7282	0.7021	28.5487	32.1258	29.4266	30.0337	2236.8	1875.1	2031.2	2047.7
1.5	0.6537	0.6593	0.6355	0.6495	30.7845	27.6520	31.1345	29.8570	2039.5	2365.3	2241.1	2215.3
4.5	1.3081	1.3879	1.2949	1.3303	104.2894	109.3201	111.6916	108.4337	3058.2	2865.4	3067.1	2996.9
7.5	1.1058	1.2360	1.0452	1.1290	73.3528	80.5934	66.1428	73.3630	2439.7	2647.2	2684	2590.3
9	0.0952	0.0621	0.0614	0.0729	1.0892	0.3568	0.1710	0.5390	2348.1	1823.9	2123.2	2098.4
10	0.0132	0.0189	0.0165	0.0162	0.0165	0.0097	0.0065	0.0109	1784.4	1501.8	1294.8	1527.0
11	0.0028	0.0035	0.0030	0.0031	0.0020	0.0034	0.0030	0.0028	1627.0	1534.9	1468.3	1543.4