The service lifetime of industrial components relies on an understanding of the size, location and orientation of defects present in the materials. This is often over-estimated due to inadequate methods of identification and characterisation in NDE techniques. Multi-frequency eddy-current measurement methods offer a promising way of obtaining sufficient information to accurately characterise and size surface-breaking defects. In this study a parametric-manifold database search approach is employed to low-MHz range eddy-current impedance spectra measurements, to characterise such defects. An in-house, air-cored solenoid coil sensor was used to inspect for surface-breaking defects and a hybrid finite-element and equivalent-circuit model was developed to simulate the impedance over a range of frequencies around it’s electrical resonance. The hybrid-model was optimised, calibrated and validated against experimental standoff/thickness measurements demonstrating accuracy over small standoff distances. The model was used to simulate a database of 2D scans of surface breaking notches over a range of frequencies and a principle component parametric-manifold approach was employed to evaluate the sensitivity of the sensor and frequency range. Finally, simulated and experimental defects were characterized in Titanium 6V-4Al and Aluminum.
How to Cite:
Hughes, R. R. & Drinkwater, B. ., (2019) “Exploring parametric-manifolds for eddy-current defect characterisation”, Review of Progress in Quantitative Nondestructive Evaluation .