Ultrasonic tracking of ply drops in composite laminates

Robert A. Smith, Luke J. Nelson, Martin J. Mienczakowski, Paul D. Wilcox

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

17 Citations (Scopus)


As the shapes of composite components become more adventurous, tracking internal locations of ply drops and detecting any tape gaps or overlaps will be crucial to assure conformance to design. The true potential of ultrasound has yet to be exploited for this objective due to the apparent complexity of the ultrasonic response and the assumption that interference between signals from plies is random, confusing and of little use. As a result, most ultrasonic inspection of composites targets defects that either attenuate or reflect ultrasound, regarding ply reflections as undesirable 'noise'. The work presented here extends the ply-orientation mapping of the last two decades by introducing a systematic approach to optimizing the ultrasonic response from the plies, minimizing interference between plies and demonstrating that accurate maps of plies through ply-drop regions can be produced. The key to this method is understanding the ultrasonic analytic signal and how it interacts with plies and the resin-rich layers between them. In certain circumstances of frequency and bandwidth, the instantaneous phase locks onto the resin-rich layers and the instantaneous amplitude indicates the validity of this condition. Analytical modelling is used to explain the interaction between ultrasound and composite plies in various ply-drop scenarios, with reference to experimental results. Optimization of ultrasonic data acquisition is also discussed and demonstrated experimentally.

Original languageEnglish
Title of host publicationAIP Conference Proceedings
PublisherAmerican Institute of Physics (AIP)
ISBN (Print)9780735413535
Publication statusPublished - 10 Feb 2016
Event42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE 2015): Incorporating the 6th European-American Workshop on Reliability of NDE - Minneapolis, Minnesota, United States
Duration: 26 Jul 201531 Jul 2015
Conference number: 42


Conference42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE 2015)
Abbreviated titleQNDE 2015
CountryUnited States
CityMinneapolis, Minnesota

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