A Comparison of Acoustography with other NDE Methods for F.O. Inclusions Detection in Carbon Epoxy Laminates

In this research, the through-transmission ultrasonic (TTU) Acoustography non-destructive evaluation (NDE) method was employed to detect foreign object inclusion (FOI) defects embedded in carbon fiber epoxy composite laminates. The study employed three different test specimen with varied size FOI defects embedded at varying depth within the composite laminates. For validation, Acoustography results were compared with conventional immersion TTU and infrared thermography (IRT) methods. Also, quantitative measurements based on Signal-to-Noise Ratio (SNR), defect sizing, and inspection times were carried out to compare and correlate between different NDE methods that were applied. The Acoustography method, operating at 5MHz, was easily able to detect all FOIs defect and was also able to resolve two Teflon defects placed side by side (separation = 1.5 mm) at different layers within the composite test panels. SNR measurements for Acoustography were more than 6:1 and were in good correlation with TTU UT and IRT results. The defect sizing ability of TTU Acoustography for FOIs defect in graphite epoxy composite laminates were also in strong correlation with the TTU UT and IRT techniques. Finally, TTU Acoustography inspection time was about 1 minute to scan 300 x 300 mm2 (11.81 x 11.81 inch2) area which was faster compared to conventional TTU C-Scan, and IRT techniques. This is a very significant finding because Acoustography is being developed as a faster, more efficient, and affordable alternative to traditional ultrasonic inspection systems for composites.

References
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