Root Crack Identification of Sun Gear in Planetary Gear System Combining Fault Dynamics with VMD Algorithm

Table 9

Error between the tested IMF central frequency and theoretical value for 3^# crack.

IMF	Theoretical frequency (Hz)	VMD frequency (Hz)	Corresponding feature	Error (%)
IMF1	30	30.06	fs	0.20
IMF2	656	651.3	fm	0.72
IMF3	1944.6	1954	3fm−1/4fsg	0.48
IMF4	2600.6	2615	4fm−1/4fsg	0.55
IMF5	3233.1	3236	5fm−2/4fsg	0.09
IMF6	4568.6	4559	7fm−1/4fsg	0.21