Shear-wave time of flight diffraction (S-TOFD) technique

✍ Scribed by G. Baskaran; Krishnan Balasubramaniam; C. Lakshmana Rao

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 631 KB
• Volume: 39
• Category: Article
• ISSN: 0963-8695
• DOI: 10.1016/j.ndteint.2006.01.003

✦ Synopsis

Ultrasonic time of flight diffraction (TOFD) for sizing defects is based on the time of flight of the diffracted echo that is generated when a longitudinal wave is incident on a crack tip. This technique has the limitation during near-surface inspection due to signal superposition. Here, this limitation is overcome by using the shear wave-diffracted signal (instead of longitudinal wave) and hence called S-TOFD. Experiments were conducted on samples with defect tip closer to the surface of a flat plate sample to illustrate the utility of the S-TOFD technique. An increase in the flaw sizing accuracy, by using the shear wave-diffracted echoes from the tip and through the application of a signal processing technique (ESIT), was demonstrated.