Abstract
The equivalent circuit model of pulsed eddy current testing (PECT) has simple mathematics but its applications are limited to qualitative analysis such as principle illustration and signal interpretation. In this paper, the parameters of equivalent circuit model are estimated using system identification method and quantitative relationships are found between some of the parameters and the size of the defect. The equivalent circuit equations were solved from the perspective of system analysis to yield the system transfer function. An m-sequence of 10 order was selected to excite the system and the probe current was used as the output. A set of experiment input-output data for system identification were obtained by performing experiments on two aluminium alloy 6061 slabs, one of which was machined with five slots of different widths, and the other one was machined with five depth-varied slots. The equivalent circuit parameters were finally estimated based on the identified transfer function parameters. It is found that the values of resistance and self-inductance of the secondary windings decrease greatly and monotonically with the increase of the slot width or depth. The self-inductance is more sensitive to the slot size variation than the resistance. Both of them have the potential to serve as the signal feature for defect evaluation in PECT applications.
Highlights
The pulsed eddy current testing (PECT), which utilizes a repetitive broadband pulse as its excitation, has gained much attention in the family of eddy current testing (ECT) for decades due to its notable characteristics such as deep penetration in the conductive specimen, diverse time-domain signal features and simple electronics for instrumentation.[1]
The probe and the specimen are respectively modelled as the primary and the secondary windings, both consisting of a resistance in series with an inductance, and their coupling is described by a mutual inductance
This paper concerns the estimate of equivalent circuit model parameters and touches on the application of model parameters in aspect of defect evaluation
Summary
The pulsed eddy current testing (PECT), which utilizes a repetitive broadband pulse as its excitation, has gained much attention in the family of eddy current testing (ECT) for decades due to its notable characteristics such as deep penetration in the conductive specimen, diverse time-domain signal features and simple electronics for instrumentation.[1]. The probe and the specimen are respectively modelled as the primary and the secondary windings, both consisting of a resistance in series with an inductance, and their coupling is described by a mutual inductance. All in all, compared with analytical modelling, equivalent circuit model or transfer function based model doesn’t involve complex mathematics, but the model parameters were not thoroughly studied in the application of defect evaluation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
