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A Study Of Guided Wave Pipe Inspection : Visualization Of Guided Wave Propagation In A Pipe And Defect Imaging With A Scanning Laser Source Technique

Nor Salim, Muhammad (2010) A Study Of Guided Wave Pipe Inspection : Visualization Of Guided Wave Propagation In A Pipe And Defect Imaging With A Scanning Laser Source Technique. Masters thesis, Nagoya Institute of Technology.

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Guided waves, an ultrasonic mode propagating along a waveguide such as plates, pipes, and bar-like structures, have been widely used for nondestructive testing in industries. It offers rapid inspection for large structures. However, its potential in defect inspections cannot be fully utilized due to its complicated wave propagation. This thesis describes two major contents for drawing out the latent abilities: one is visualization of guided wave propagation in a pipe using a non-contact laser ultrasonic measurement and the other one is defect imaging using a scanning laser source technique. Experimental studies on visualization of guided wave propagation in a pipe were carried out by scanning a laser Doppler vibrometer with a 6-axis robot arm. Guided waves around circumferential and oblique defects in a pipe were visualized to observe the phenomenon of guided wave behavior in the area of the defects. When an incident axisymmetric torsional mode was emitted from magneto-strictive sensors, which is the way used in pipe inspection with guided waves, larger mode conversion was observed in the reflected wave from an oblique defect. It showed that the magneto-strictive sensors for receiving axisymmetric torsional mode are not suitable for detecting oblique defects. Guided wave propagation was also visualized for a pipe with an elbow to investigate the effect of elbow on the guided wave propagation. It showed large mode conversions at the elbow and manifested difficulties for defect inspections behind the elbows in the guided wave inspections using the axisymmetric torsional mode. In the second major topic of the thesis, 'imaging of thickness distributions are carried out using a laser source scanning technique. Suitable mode selections in guided measurements and applying a signal processing to the measured signals enable us to obtain the residual thickness in plates and pipes. The visualization of the selected guided wave mode in plates and pipes show larger amplitude distribution over thinner region of defects than the thicker intact region. This indicated a great potential to provide rapid residual thickness measurement over plate-like structures including oil storage tanks and pipe networks in industries.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Ultrasonic testing, Electromagnetic waves -- Transmission
Subjects: T Technology > T Technology (General)
T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Library > Tesis > FKM
Depositing User: Siti Syahirah Ab Rahim
Date Deposited: 30 Oct 2014 12:40
Last Modified: 28 May 2015 04:29

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