Ultrasonic Analytic-Signal Responses from Polymer-Matrix Composite Laminates

Robert Smith*, Luke Nelson, Martin Mienczakowski, Paul Wilcox

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

41 Citations (Scopus)
591 Downloads (Pure)


Ultrasound has been used to inspect composite laminates since their invention but only recently has the response from the internal plies themselves been considered of interest. This paper uses modeling techniques to make sense of the fluctuating and interfering reflections from the resin layers between plies, providing clues to the underlying inhomogeneities in the structure. It shows how the analytic signal, analyzed in terms of instantaneous amplitude, phase, and frequency, allows 3-D characterization of the microstructure. It is found that, under certain conditions, the phase becomes locked to the interfaces between plies and that the first and last plies have characteristically different instantaneous frequencies. This allows the thin resin layers between plies to be tracked through various features and anomalies found in real composite components (ply drops, tape gaps, tape overlaps, and out-of-plane wrinkles), giving crucial information about conformance to design of as-manufactured components. Other types of defects such as delaminations are also considered. Supporting evidence is provided from experimental ultrasonic data acquired from real composite specimens and compared with X-ray computed tomography images and microsections.

Original languageEnglish
Article number8113596
Pages (from-to)231-243
Number of pages13
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Issue number2
Early online date16 Nov 2017
Publication statusPublished - Feb 2018


  • Analytical models
  • composite materials
  • material and defect characterization
  • phase measurement
  • signal and image processing
  • ultrasonic imaging
  • wave propagation


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