Abstract
The direct-current potential difference method (DC-PDM) is an inspection technique to evaluate defects in structures. Although the method needs large direct current and relatively large equipment, many studies on the applicability of DC-PDM to non-destructive inspection have been performed because of low cost, cheap, and good reproducibility of results. DC-PDM has been applied to evaluate general wall thinning. But very few papers deal with the application of DC-PDM to local wall thinning. In this study, approximated solution for electric potential field analysis of a semi-ellipsoidal wall thinning existing on the back surface of a conductive plate was proposed and its validity was examined by comparing with the results by finite element method. The approximated solution agreed with the finite element analysis.