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

Figure 12

Approximated Entropy for different levels of SNR in the FFTs: (a) 1% crack depth; (b) 3% crack depth; (c) 5% crack depth; (d) 10% crack depth.

(a)

(b)

(c)

(d)