Pixel frequency based railroad surface flaw detection using active infrared thermography for Structural Health Monitoring

Bilawal Ramzan, Muhammad Sohail Malik*, Milena Martarelli, Hafiz T. Ali, Mohammad Yusuf, S. M. Ahmad

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


With rapid increase in operation and development of high-speed trains, inspection of railroad surface flaws has become an important aspect for safe and reliable operation of rail network. Non-destructive testing using active infrared thermography has been useful in determining the structural health of different structures with additional benefit of robustness in overall inspection system. This study is based on detection of artificial surface flaws on an in-service railroad. Transverse and longitudinal flaws of various dimensions were machined on rough and smooth rail surface. The railroad surface was thermally stimulated to a temperature equivalent to practical conditions. Emitted radiations from rail surface were captured by an infrared camera to detect cracks. Results show a comparison between the surface flaws on rough and smooth rail surface. Subsequently, raw infrared images were post-processed by statistical image improvement to quantitatively analyse the results. Significant change in the frequency distribution of pixel intensity is observed as the flaw size and depth changes giving a clear quantification of crack topology. A comprehensive and inexpensive solution for damage diagnosis will be offered to railway authorities for Structural Health Monitoring (SHM) and NDT by the proposed framework.

Original languageEnglish
Article number101234
JournalCase Studies in Thermal Engineering
StatePublished - Oct 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021 The Authors


  • Infrared radiation
  • Non-destructive testing
  • Railroads
  • Structural health and monitoring
  • Surface flaws
  • Thermography

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Fluid Flow and Transfer Processes


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