Experimental comparison of analytical modeling of a guided-wave interaction with a notch in a pipe

A comparison of the experimentally measured and the simulated waveforms of a guided-wave signal reflected from a notch in a pipe is presented. The simulated waveforms were calculated analytically by using a recently proposed transmission-line model and its modified version that accounted for the wave diffraction at the backend of the notch. Results are shown for longitudinal guided-wave signals reflected from notches of constant circumferential cross-section with the width along the lengthwise direction of the pipe ranging from 6.35 to 101.6 mm. The results of the simulation made with the modified model agree very well with the experimentally measured waveforms and qualitative changes in the reflection coefficients with the notch width. Quantitatively, the calculated reflection coefficients were consistently smaller than the experimental values, in general by about 50 %. The good agreement between the experimentally measured and the simulated waveforms indicates that, for a defect with an abruptly changing cross-section, wave diffraction plays an important role in determining the defect signal waveform.