Effect of Single and Multi-Direction Coil for Differential Probe on Depth Crack Defect Measurement with Different Excitation Frequency Selection in Eddy Current Inspection

Abstract

Abstract In recent years, a number of studies in Non-Destructive Evaluation (NDE) have been conducted on the sensitivity of probes in assessing the depth of cracks based on input stimulation. Range frequency and crack depth have been suggested as relevant features for input excitation waveform forms. The construction of an encircling coil for a differential probe (ECDP) and an encircling coil for an absolute probe (ECAP) was discussed in this paper. For the defect, the Multi-Frequency (MF) measuring method was used to compare ECDP with single direction and multi-direction turn coil growth. The measurement method was based on the coupling of ECDP and ECAP. By comparing the resulting signal between the probes, it is clear that the ECDP (with longitudinal and transverse coils) is very effective in measuring the various types of defects in the frequency ranges. The ideal excitation frequencies for inspection testing are 30kHz and 60kHz.