Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Table 3

Ф9 mm experimental data of steel strands.

l/m	f1 (kHz)	f2 (kHz)	f3 (kHz)	f4 (kHz)	SD	RE (%)	f (kHz)
6.0	103.813	103.819	103.815	103.805	0.0057	0.0128	103.813
6.5	101.991	102.009	102.035	102.013	0.0180	0.0428	102.012
7.0	102.379	102.378	102.385	102.374	0.0047	0.0111	102.379
7.5	101.660	101.663	101.662	101.653	0.0044	0.0098	101.660
8.0	100.993	101.011	101.023	101.026	0.0149	0.0327	101.013
10.0	99.016	99.044	99.043	99.042	0.0136	0.0283	99.036
10.5	98.125	98.121	98.126	98.132	0.0047	0.0115	98.126
11.0	97.460	97.471	97.473	97.474	0.0068	0.0150	97.470
11.5	95.727	95.715	95.726	95.739	0.0098	0.0251	95.727
12.0	94.963	94.976	94.973	94.981	0.0073	0.0183	94.973
12.5	94.376	94.371	94.378	94.379	0.0035	0.0081	94.376
14.0	93.786	93.790	93.789	93.792	0.0023	0.0060	93.789
14.5	93.520	93.528	93.539	93.534	0.0081	0.0203	93.530
15.0	92.771	92.786	92.774	92.794	0.0106	0.0244	92.781
15.5	92.658	92.655	92.653	92.674	0.0096	0.0227	92.660
16.0	92.415	92.422	92.450	92.434	0.0152	0.0375	92.430