Algorithm for Recognition of the Buried Depth of Non-surface Crack Using Pulse Perturbation Electromagnetic Field

Alternating current filed measurement (ACFM) is an emerging electromagnetic for nondestructive testing technology. Because of skin effect, ACFM is highly sensitive to surface open crack, but critical for non-surface defect. In this paper, the pulse excitation is presented for non-surface crack detection based on alternating current field measurement technique. According to the simulation and experimental results, the wavelet entropy theory is proposed for non-surface defect recognition. Results show that the proposed algorithm can distinguish different buried crack depths effectively.