Comparison and analysis of Acoustography with other NDE techniques for foreign object inclusion detection in graphite epoxy composites

This paper presents the use of a novel through-transmission ultrasonic (TTU) Acoustography non-destructive evaluation (NDE) method to detect foreign object inclusion (FOI) defects in graphite epoxy composite laminates. The study employed three different composite test standards with varied size FOI defects embedded at varying depth within the composite laminates. For validation, Acoustography results were directly compared with conventional immersion TTU testing and infrared thermography (IRT) methods. From results obtained, it was demonstrated that the Signal-to-Noise Ratio (SNR) measurements for Acoustography were more than 6:1 and were in good correlation with immersion TTU and IRT results. The defect sizing ability of TTU Acoustography for FOI defects in graphite epoxy composite laminates were also in strong correlation with immersion TTU and IRT techniques. Finally, for the three laboratory systems employed in this study, typical panel TTU Acoustography inspection time was just about three minutes to scan a 300 mm × 300 mm (11.8″ × 11.8″) area, which was more than three times faster compared to IRT and sixty times faster to conventional immersion TTU C-Scan techniques. This is a very significant finding for the reason that Acoustography is being developed as a faster, more efficient, and affordable alternative to traditional ultrasonic inspection systems for composite manufacturing quality control and quality assurance (QC/QA) and field maintenance of composite structure applications.