Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Thermographic Detection of Surface Crack Using Holomorphic Function of Thermal Field

  • Kim, No-Hyu (Department of Mechatronic Engineering, Korea University of Technology and Education) ;
  • Lim, Zong-Soo (NDE Division, Research Institute of Industrial Science and Technology)
  • Received : 2012.05.11
  • Accepted : 2012.06.08
  • Published : 2012.06.30
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Abstract

This paper describes an analytic method for infrared thermography to detect surface cracks in thin plates. Traditional thermographic method uses the spatial contrast of a thermal field, which is often corrupted by noise in the experiment induced mainly by emissivity variations of target surfaces. This study developed a robust analytic approach to crack detection for thermography using the holomorphic function of a temperature field in thin plate under steady-state thermal conditions. The holomorphic function of a simple temperature field was derived for 2-D heat flow in the plate from Cauchy-Riemann conditions, and applied to define a contour integral that varies depending on the existence and strength of singularity in the domain of integration. It was found that the contour integral at each point of thermal image reduced the noise and temperature variation due to heat conduction, so that it provided a clearer image of the singularity such as cracks.

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References

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  1. Prediction of the Effect of Defect Parameters on the Thermal Contrast Evolution during Flash Thermography by Finite Element Method vol.34, pp.1, 2014, https://doi.org/10.7779/JKSNT.2014.34.1.10