[1A1] Eddy current defect characterisation using a parametric manifold approach
Robert R. Hughes and Bruce Drinkwater
CAME School of Engineering, University of Bristol, UK
The design and operational lifetime of industrial components is determined by the size, location and orientation of damage in a structure. This is often over-estimated due to inadequate methods of identification and inaccurate characterisation of defect sizes by NDE techniques. The accurate sizing and characterisation of defects is a problem that faces all NDE techniques, with many advanced approaches being developed across disciplines. Multi-frequency eddy-current inspection is one such method that offers a promising way of obtaining enough information to accurately characterise surface-breaking defects. In this study we explore the application of the parametric-manifold technique, developed to evaluate ultrasonic array data, for the sizing and characterising defects from eddy-current inspection data. A bespoke hybrid FE-circuit model was developed to simulate ECT coil impedances over a range of frequencies (1-10 MHz) and used to simulate databases of ECT surface-breaking defect scans in Aluminium (Al) and Titanium 6V-4Al (Ti6-4). The parametric manifold approach was used to characterise defects from experimental scans, demonstrating accurate characterisation of slot depth in Al. This method was applied to characterise finite-width EDM notches in Al and Ti6-4, and a quantitative assessment of the accuracy of characterisation made with respect to inspection noise.
