Ultrasonic detection and sizing of compressed cracks in glass- and carbon-fibre reinforced plastic composites

M.E. Ibrahim, R.A. Smith, C.H. Wang

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

24 Citations (Scopus)
351 Downloads (Pure)


Nondestructive evaluation of compressed cracks is a major challenge. A quantitative study of the effect of crack-tip closure on the pulse-echo ultrasonic sizing of delaminations in fibre-reinforced polymer-matrix composites (FRP) is presented. In particular, this study focuses on the interaction of ultrasound with a closed crack or kissing disbond, and their effect on the ultrasonic inspectability of FRP laminates consisting of carbon and glass plies. The compression of laminar cracks in these two different laminate types is clearly detectable via both pulse-echo and through-transmission ultrasonic measurements, but the reflected ultrasonic pulses in the two material types exhibit markedly different behaviour. The glass-fibre laminates show a drop in the reflected signal for crack openings up to approximately half the crack growth load, whereas the corresponding carbon-fibre laminates show the expected increase in the reflected signal as the crack opens. The origins of the observed effect of crack closure on the reflection and transmission of ultrasound are analysed in detail to ascertain possible mechanisms responsible for these effects.

Original languageEnglish
Pages (from-to)111-121
Number of pages11
JournalNDT and E International
Early online date18 Aug 2017
Publication statusPublished - Dec 2017


  • Nondestructive inspection
  • Pulse-echo ultrasonics
  • Defect characterization
  • Compressed cracks
  • Delamination
  • Fiber-reinforced plastic
  • Polymer-matrix composites

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