Abstract
A newly developed method for estimating shape of a defect in piping using the several frequencies of T(0,1) mode guided waves was presented. The theoretical model calculating reflection coefficient at a defect having an arbitrary distribution along the axial direction was first described in the paper. In the estimation, defect shape was assumed to be constant-cross-section at circumferential direction and to be circular cross-section at axial direction. In the method, the calculation model was recursively applied to obtain reflection coefficients for plural circular shapes. The effect shape was finally decided when one of the calculation results takes the closest value to the experimental result. The principle and verification were shown.
