EC-GMR measurements have been applied for detection of sub-surface corrosion and cracks under fastener (CUF) head. Generally, fastener signal amplitude is larger than the amplitude of the crack signal indication, rendering crack detection a challenging task. Also, another challenge in the analysis of field signals is the stitching problem, commonly present in a raster scan of a row of fasteners. We propose a method based on robust sparse coding (RSC) representation to alleviate the stitching problem and enhance defect detection capability. For the dictionary, we simulate multi-layer geometries using finite element (FE) modeling. Results on simulated and field data demonstrate the feasibility and robustness of the proposed algorithm.
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