Chapter 29. Thermal Imaging Detection and Characterization of Normal Cracks

  1. Mrityunjay Singh and
  2. Todd Jessen
  1. J. G. Sun,
  2. C. Deemer,
  3. S. Erdman and
  4. W. A. Ellingson

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294680.ch29

25th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 22, Issue 3

25th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 22, Issue 3

How to Cite

Sun, J. G., Deemer, C., Erdman, S. and Ellingson, W. A. (2001) Thermal Imaging Detection and Characterization of Normal Cracks, in 25th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 22, Issue 3 (eds M. Singh and T. Jessen), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294680.ch29

Author Information

  1. Argonne National Laboratory Argonne, IL 60439

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2001

ISBN Information

Print ISBN: 9780470375730

Online ISBN: 9780470294680

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Keywords:

  • thermal;
  • anisotropic;
  • photographic;
  • energy;
  • temperature

Summary

This paper describes a flash thermal imaging method for detecting and characterizing of normal cracks in flat test specimens. The method is based on measuring distributions of lateral thermal diffusivity in a specimen. During the flash thermal imaging test, pulsed heat energy is applied to a specimen's partially shielded back surface, and the change of temperature distribution on the front surface is monitored by an infrared thermal imaging system. The temperature distribution represents the effect of both normal heat transfer through the specimen's thickness and lateral heat transfer through the interface between the shielded and unshielded back-surface regions. Because normal cracks restrict lateral beat flow in the specimen, the effective lateral thermal diffusivity is reduced. By correlating the diffusivity reduction with the crack depth, the method can be used to characterize normal cracks in ceramic composites. Discussions of the method and experimental results are presented.