Sensors (May 2019)

Delamination Detection in Polymeric Ablative Materials Using Pulse-Compression Thermography and Air-Coupled Ultrasound

  • Stefano Laureti,
  • Muhammad Khalid Rizwan,
  • Hamed Malekmohammadi,
  • Pietro Burrascano,
  • Maurizio Natali,
  • Luigi Torre,
  • Marco Rallini,
  • Ivan Puri,
  • David Hutchins,
  • Marco Ricci

DOI
https://doi.org/10.3390/s19092198
Journal volume & issue
Vol. 19, no. 9
p. 2198

Abstract

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Ablative materials are used extensively in the aerospace industry for protection against high thermal stresses and temperatures, an example being glass/silicone composites. The extreme conditions faced and the cost-risk related to the production/operating stage of such high-tech materials indicate the importance of detecting any anomaly or defect arising from the manufacturing process. In this paper, two different non-destructive testing techniques, namely active thermography and ultrasonic testing, have been used to detect a delamination in a glass/silicone composite. It is shown that a frequency modulated chirp signal and pulse-compression can successfully be used in active thermography for detecting such a delamination. Moreover, the same type of input signal and post-processing can be used to generate an image using air-coupled ultrasound, and an interesting comparison between the two can be made to further characterise the defect.

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