Identification of an interface crack in bonded dissimilar materials from electric potential distribution

The electric potential CT method was applied to identify an interface crack in bonded dissimilar materials from an electric potential distribution observed on free surface. The distribution of electric potential in bonded dissimilar materials to be compared with the observed one was calculated using the boundary element method. An alternative approximate distribution in a bonded dissimilar plate was obtained by combining Johnson's solution of electric potential distributions for homogeneous materials. The electric potential distribution estimated by this combined Johnson solution showed good agreement with the results obtained by the boundary element method. The electric potential distribution calculated by the combined Johnson solution was applied to the identification of an interface crack using the electric potential CT method. As an inversion scheme the least residual method was applied: the crack giving the smallest value of residual between the calculated and observed electric potential distributions was taken as the most plausible one. Numerical simulations of the estimation of the location and size of two-dimensional interface cracks, i.e. edge cracks and internal cracks, were made. The cracks were estimated reasonably even in the presence of measurement noise, demonstrating the applicability of the proposed method.