QUANTITATIVE MEASUREMENT OF TWO-DIMENSIONAL INCLINED CRACKS BY THE ELECTRIC-POTENTIAL CT METHOD WITH MULTIPLE CURRENT APPLICATION.

The electric-potential CT method proposed previously by three of the present authors was applied to quantitative measurements of location, angle and size of two-dimensional inclined cracks embedded in steel plates. In this experiment, a D-C current was consecutively supplied between one of five pairs of electrodes placed on the top and bottom ends of the plates. Electric-potential distribution was measured along the side faces of the plate under each of these five current application conditions. Data on electric-potential were processed to reconstruct cracks by a least residual inverse analysis scheme, in which a least residual criterion was employed between the observed potential distributions and the computed ones for various assumed crack locations. When the residual was evaluated using a potential distribution obtained under any single current application condition, this scheme did not always give reasonable results.