| 摘 要： | Based on elasticity theory, the multi-modes and disperse characteristics of guided circumferential waves in a pipe were investigated theoretically and experimentally, the disperse curves of guided circumferential waves were gotten by numerical calculations. The relationships between the angle of beam transducer, frequency and guided circumferential modes were analyzed by our guided wave experiment system. Then single guided circumferential mode was excited in the pipe (O.D 88.8 mm, I.D 80.8 mm). An artificial longitudinal defect (25×1×0.7 mm) on the surface of the pipe was detected by use of the single guided circumferential wave. The results show that single guided circumferential mode can be excited in the pipe by choosing special frequency and special angle beam transducer, similar to the excitation of Lamb wave in a plate, and it can be used to find the longitudinal defect on a pipe surface.
|
