Ultrasonic defect detection in jet-engine alloys is often a hunt for a flaw response in the presence of microstructural noise. Signal-to-noise ratios (S/N) are often used to quantify the extent to which the response from a defect or reference reflector stands out above the competing noise. In many cases of practical interest the microstructural scattering is 'weak' in the sense that single-scattering events dominate and multiple scattering may be ignored. In such cases, independent-scatterer noise models apply and can be used to develop simple, approximate formulas for S/N. For pulse-echo (P/E) inspections, the formulas relate S/N to the response-weighted volume of the incident sonic pulse, and these formulas have proven useful in designing P/E inspections of jet-engine forgings. After briefly reviewing the P/E case, we introduce generalized versions of the formulas which apply to ultrasonic pitch-catch inspections. The use of the new formulas to assess inspections is then discussed, including a treatment of phased-array inspections using so-called dynamic depth focusing.
Estimates of signal-to-microstructural-noise ratios in ultrasonic inspections of metals
Abschätzung des Mikrogefüge-Signal-Rausch-Verhältnisses bei der Ultraschallprüfung von Metallen
2006
8 Seiten, 3 Bilder, 8 Quellen
Conference paper
Storage medium
English
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