Detection of Cracks in Rotating Shafts by Using the Combination Resonances Approach and the Approximated Entropy Algorithm

Figure 7

FFT of the system vibration responses at node #8 as excited by the diagnostic frequency of 48.7 Hz at node #4 (rotating speed of 1200 rpm and SNR = 1000): (a) 1% crack depth; (b) 3% crack depth; (c) 5% crack depth; (d) 10% crack depth.

(a)

(b)

(c)

(d)