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In guided wave inspection for pipes, defect characterization is performed by echoes from defects. However, since detected signals become very complex due to mode conversion and multiple reflections, wave mechanics in a pipe with defects are not well studied. In this study, therefore, visualization technique for guided waves in a pipe is developed. In order to visualize guided wave propagation in a pipe, we need to scan an ultrasonic probe and measure ultrasonic waves at many points on a surface of a pipe. Position and posture of a laser doppler vibrometer are controlled by a robot arm, and ultrasonic vibration is detected at arbitrary points from arbitrary laser beam direction. Using the laser scanning technique, reflected guided waves from a shallow round defect was observed in the visualization results. From the defect, reflected waves propagated spirally in the oblique direction. From the view point of guided wave, the spiral waves were very high order modes that have not been measured in guided wave inspection. This result shows that such high order guided wave modes should be useful for defect characterization as well as low order modes. [ABSTRACT FROM AUTHOR]

Pipe screening technique with guided waves has become widely applied to pipe inspection in actual industrial plants. In most cases, however, guided wave propagating in a pipe is still difficult for inspection technicians due to its complex characteristics. Authors have developed the fast calculation technique for guided wave propagation using a semi-analytical finite element method (SAFEM). This study is on development of software for guided wave propagation with the SAFE calculation. A parameter input interface was made with Visual C++, and a core execution file was coded with Fortran 90. Visualization of data set obtained by the calculation was carried out with a free visualization tool OPEN DX. Using this software including a preprocessor and a postprocessor, many kinds of guided wave simulation have become feasible even by a non-expert in guided waves. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]