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Proceedings Paper

Research on lock-in thermography for aerospace materials of nondestructive test based on image sequence processing
Author(s): Junyan Liu; Jingmin Dai; Yang Wang
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Paper Abstract

IR Lock in thermography is an active thermography technology based on thermal wave signal processing, especially, it has many advantages for nondestructive test of composite materials and compound structure application and has been applied on aerospace, automotive, mechanics and electric fields. In lock in thermography, given sufficient time for periodic heating, the surface temperature will evolve periodically in a sinusoidal pattern form the transient state to the steady state. In this paper, the principle of lock in thermography is introduced and the heat transferring process is analyzed by the sinusoidal variation heating flow transferred in materials by means of FEM method. In experiment, the modulating optical stimulation is applied to sample, and image sequences are collected by Jade MWIR 550 FPA IR camera. The digital filter algorithm which is Savitzky-Golay digital smoothness filters is used to remove the effects of high frequency noise. A phase image at the frequency of periodic heating can be calculated using a Fourier transform of the periodic heating frequency in transient state for defect detection. The IR lock in thermography processing software is developed by using of visual C++ programmed based image sequence collected. The experimental results show that the developed system reached up to high level of conventional steady state Lock in method.

Paper Details

Date Published: 25 August 2009
PDF: 8 pages
Proc. SPIE 7375, ICEM 2008: International Conference on Experimental Mechanics 2008, 73753U (25 August 2009); doi: 10.1117/12.839269
Show Author Affiliations
Junyan Liu, Harbin Institute of Technology (China)
Jingmin Dai, Harbin Institute of Technology (China)
Yang Wang, Harbin Institute of Technology (China)

Published in SPIE Proceedings Vol. 7375:
ICEM 2008: International Conference on Experimental Mechanics 2008
Xiaoyuan He; Huimin Xie; YiLan Kang, Editor(s)

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