Laser-Generated Acoustic Signal Interaction with Surface Flaws on Rail Wheels
- Authors: KENDERIAN S; CERNIGLIA D; DJORDJEVIC B B; GREEN JR R E
- Publication year: 2005
- Type: Articolo in rivista (Articolo in rivista)
- Key words: Cracks, laser ultrasound, line source, rail wheel, shadow zone, sound field
- OA Link: http://hdl.handle.net/10447/5364
Abstract
Long- and short-range acoustic-signal interaction with surface-breaking cracks and geometric boundaries of the rail-wheel tread area are presented in this article. Ultrasonic signals are generated using a laser-line source of varying length and distance from a crack and are detected with a 1-MHz contact transducer to map the sound field behind the crack in the near, intermediate, and far fields of the insonified region. The factors that affect the behavior of a laser-generated surface acoustic wave propagating along the tread area of a rail wheel are discussed. A signal normalization method is proposed to help in sensing the presence of a crack from the transmitted signal unaffected by the boundary effect of the complicated wheel geometry, diffraction of the acoustic wave around the crack tip, and source-to-crack length ratio and separation distance.