Computational methods in eddy current crack detection at fastener sites in multi-layer structures

Abstract

Reliable detection of both surface and subsurface cracks around fastener sites continues to be a need for maintaining ageing aircraft structures. In this work, a comprehensive overview of both experimental and modelling work addressing eddy current crack detection around fastener holes in multi-layer structures is presented. This overview consists of a strategy for the application of computational methods along with case studies that demonstrate the role of modelling for this particular class of problems. The state-of-the-art on eddy current modelling applicable to low-frequency eddy current problems is reviewed. The role of modelling in feature extraction algorithm development, crack characterisation, and probability of detection evaluation is highlighted.

Keywords:

• eddy current
• cracks
• modelling
• feature extraction
• parameter estimation

Acknowledgements

The authors would like to acknowledge support for this study provided by Air Force Office of Scientific Research. The authors thank Harold Sabbagh, Elias Sabbagh and R. Kim Murphy for support with VIC-3D^® and Eric Lindgren, Mark Blodgett and Tom Moran for their valuable discussions.