Measurement of Surface Cracks Using Data Base of Electric Potential Distribution

Abstract

The present authors proposed the electric potential computed tomography (CT) method for estimating location, shape and size of two- and three-dimensional cracks in conductive bodies from electric potential distribution, based on boundary-element inversion analysis schemes. In the present study, a simplified inverse analysis scheme is proposed to identify surface cracks on back faces by processing the electric potential distribution using a workstation. In this scheme, a hierarchical method is introduced, in which two-dimensional scanning analysis is combined with three-dimensional inverse analysis. To achieve a high-speed computation on the workstation, an analytical expression of electric potential distribution reported by Johnson is used in the two-dimensional scanning analysis, and a data base of electric potential distribution on a three-dimensional cracked body is utilized in the three-dimensional inverse analysis. Numerical simulations and experiments have shown that the proposed scheme is useful for identifying the surface cracks.