Transient response of a driver-pickup coil probe in transient eddy current testing

Comparison of analytical eddy current models using principal components analysis

“…Two different analytical models have been shown to be accurate in approximating PT to CT gap [5], [6]. Both models are derived from closed form solutions to Maxwell's electromagnetic equations.…”

“…Both models are derived from closed form solutions to Maxwell's electromagnetic equations. Figure 2 shows the six modes of inductive coupling between the sample, and driver and pickup coils (denoted by subscripts d and p, respectively) [6]. The Dodd and Deeds model only accounts for normal and lossy mutual inductances of the coils (M and , respectively), while the Desjardins et al model accounts for normal and lossy self-inductances (L and , respectively).…”

“…The Dodd and Deeds model only accounts for normal and lossy mutual inductances of the coils (M and , respectively), while the Desjardins et al model accounts for normal and lossy self-inductances (L and , respectively). In addition, the Dodd and Deeds model [5] uses the coaxial coil approximation, where the Desjardins et al [6] model accounts for the separation between the coils. Recently, the Desjardins et al model has been adapted to the flat plate case for a separated driver-pickup coil configuration [7].…”

“…Excitation frequencies of 4 kHz, 8 kHz and 16 kHz have different responses to PT to CT gap, which provide useful information in making these gap measurements. The factors affecting PT to CT gap have been analytically modelled using Dodd and Deeds solutions [5] as well as a Desjardins et al plate model [6], [7]. These methods have proved useful in modelling the response of eddy currents when considering different factors affecting PT to CT gap, such as PT wall thickness and PT resistivity.…”

“…PCA has also been used with pulsed eddy current, where it was shown to enhance the classification of defects [13], and to detect defects in multilayer aluminum lap joints [14], [15] and aircraft structures [16], [17]. In this work, principal components analysis was performed on the Desjardins et al plate model of the multifrequency PT to CT gap measurement [7], [6]. The results were analyzed and compared to the PCA analysis done on previously published Dodd and Deeds model results along with accompanying experimental data [2].…”