The Mode Conversion of a Guided Wave by a Part-Circumferential Notch in a Pipe

Abstract

A study of the reflection of mode-converted guided waves from notches in pipes has been carried out. Measurements were made on a 76-mm bore diameter (nominal 3-inch), 5.5-mm wall thickness pipe with circumferentially oriented through-thickness notches of various lengths. In parallel, a finite element model was used to simulate the experiments. The axially symmetric L(0, 2) mode was incident on the notches and the L(0, 2), F(1, 3), and F(2, 3) modes were received in reflection. The results showed excellent agreement between the measurements and the predictions for all three modes. They also showed that the F(1, 3) mode reflects as strongly as the L(0, 2) mode when the notch length is short. Finally, it has been shown that a very simple analysis based on an assumed crack-opening profile may be used to make accurate predictions of the mode conversion.