| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for highly accurately measuring erosion of a pipe with its axial and circumferential positions identified. SOLUTION: The distance of a propagation path between an elastic wave transmission element 1 and an elastic wave reception element 3 is calculated. A propagation time for every frequency component is calculated by referring to a dispersion curve of a Lamb wave, and a transmission signal is formed by applying a delay to each of the frequency components so as to make each of the frequency components arrive at the element 3 at a same time. An elastic wave 11 is excited on the element 1 by an elastic wave transmitter 5. The elastic wave 11 from the element 3 is received by an elastic wave receiver 7. The signal is converted into a digital signal by an A/D converter 9. After the elastic wave signal is divided into a plurality of signal elements and a propagation path is allotted to each of the signal elements, time of appearance of each signal element is measured. The time of appearance is converted into thickness data. The thickness data is subjected to tomography processing to calculate two dimensional wall thickness distribution. COPYRIGHT: (C)2004,JPO
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