Fractal Characterization of Ultrasonic Signals from Polycrystalline Materials

✍ Scribed by P. Barat

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 259 KB
• Volume: 9
• Category: Article
• ISSN: 0960-0779
• DOI: 10.1016/s0960-0779(97)00191-4

✦ Synopsis

The concept of fractal geometry has been introduced to characterize discrete time domain ultrasonic signals scattered from two di}erent polycrystalline materials\ aluminium and brass\ using the pulse echo method[ The fractal dimensions of these scattered signals were evaluated by box!counting method and Hurst|s rescaled range analysis[ These signals were found to possess unique fractal dimensions\ which remained invariant even with the change in the sampling rate of signal capture[ Observed variations of the fractal dimensions and the Hurst spectra of these scattered ultrasonic signals are interpreted in the light of acoustic scattering[ It is seen that scattered ultrasonic signals from aluminium are self!similar in character and anti!persistent in nature but\ in the case of brass\ they are self!a.ne and persistent in nature[ Hurst|s spectra revealed that scattered ultrasonic signals from brass possess multifractality[