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LIU Zenghua
WU Bin
HE Cunfu
YANG Shiming
WANG Xiuyan
College of Mechanical Engineering and Applied Electronics
Technology,
Beijing University of Technology,
Beijing 100022, China |
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DETECTION OF
LONGITUDINAL
DEFECT IN PIPES USING
TORSIONAL MODES*
Abstract:
The multi-modes and disperse characteristics of torsional modes in pipes are investigated theoretically and experimentally. At all frequencies, both phase velocity and group velocity of the lowest torsional mode T(0,1) are constant and equal to shear wave velocity. T(0,1) mode at all frequencies is the fastest torsional mode. In the experiments, T(0,1) mode is excited and received in pipes using 9 thickness shear vibration mode piezoelectric ceramic elements. Furthermore, an artificial longitudinal defect of a 4 m long pipe is detected using T(0,1) mode at 50 kHz. Experimental results show that it is feasible for longitudinal defect detection in pipes using T(0,1) mode of ultrasonic guided waves.
Key words:
Torsional mode Pipe Longitudinal defect Detection Ultrasonic guided waves |