A model-based approach for estimation of the crack depth on a massive metal structure

This paper deals with the eddy current technique for nondestructive evaluation of the crack depth on a massive specimen used in aeronautical industry. A set of C-scan eddy current images is analyzed to reduce the noise and to select suitable features, which can be used to estimate the crack depth. Based on this study, a method relying on polynomial forward models of the relationship between crack depth and the maximum value of the sensor impedance is proposed. The least square and the non-negative least square techniques are applied to analyze the usability of proposed models. The error of obtained estimations is smaller than 10%, for almost used experimental data.