Features extraction and discussion in a novel frequency-band-selecting pulsed eddy current testing method for the detection of a certain depth range of defects

Local wall thinning defects are unavoidable defects in actual engineering structures and in some cases it occurs in a certain depth range of the object structures. In this study, a novel frequency-band-selecting pulsed eddy current testing (FSPECT) has been proposed for the detection of local wall thinning defects in a certain depth range. Feature of peak value has been extracted and analyzed. The results demonstrate that the FSPECT possess the comparable performances in terms of detection sensitivity over the traditional square wave pulsed eddy current testing (PECT). In addition, other fruitful detailed features extraction in the numerical calculation and experimental signals of FSPECT are deeply studied. The features obtained by simulation and experiment mainly include lift-off point of intersection (LOI) and zero-crossing time. Furthermore, the influences of the depth of local wall thinning defect on features of LOI and zero-crossing time have been explored, which enhance the accuracy and reliability of FSPECT method for the evaluation of local wall thinning defects.