To improve the defect detecting ability of pulsed infrared thermographic nondestructive testing (NDT) of aluminum specimens, the principal component analysis (PCA) method and its application in thermographic signal processing were studied. Some aspects of PCA, such as data preparation, algorithm and processing effects were discussed, based on the pulsed thermographic sequence processing. Experimental studies were carried out to evaluate the validity of the algorithm and detect the defects in an aluminum alloy plate. The results show that the second and third PCA images and a reconstructed image from the first few principal components have the ability to increase the defect contrast and reduce the effects of non-uniform heating, and the detection capability of pulsed thermographic NDT is enhanced. Besides, the minimum detectable corrosion rate decreases by approximately 10 percent by using PCA in detecting the imitative corrosion in the aluminum alloy plate.
Vavilov V. Evaluating the efficiency of data processing algorithms in transient thermal NDT Burleigh D, Cramer K, Peacock G. Proc SPIE Thermosense XXVI. Bellingham,WA:SPIE,2004:336-347
Ibarra-Castanedo C, Gonz lez D, Galmiche F, et al. Discrete signal transforms as a tool for processing and analyzing pulsed thermographic data Miles J J, Peacock G R, Knettel K M. Proc SPIE Thermosense XXVIII. Bellingham,WA:SPIE,2006:620514.1-620514.12
Maldague X, Galmiche, F, Ziadi A. Advances in pulsed phase thermography[J].Infrared Physics & Technology.2002,43:175-181
������,����,����ƽ,��.������������Ȳ���ʱ��ͼ������[J].�������պ����ѧѧ��,2005,31(11):1204-1207 Guo Xingwang,Shao Wei,Guo Guangping,et al. Image processing algorithms for uneven heating in infrared thermographic NDT[J]. Journal of Beijing University of Aeronautics and Astronautics,2005,31(11):1204-1207(in Chinese)
������,�߹���,����ϼ.��������ֵ�ֽ�ĺ�����ͼ�����д���[J].�������պ����ѧѧ��,2006,32(8):937-940 Guo Xingwang,Gao Gongchen, Lü Zhenxia. Infrared image sequence processing based on singular value decomposition[J]. Journal of Beijing University of Aeronautics and Astronautics,2006,32(8):937-940(in Chinese)
Rajic N. Principal component thermography for flaw contrst enchancement and flaw depth characterization in composite structures[J].Composite Structures.2002,58:521-528
Marinettia S, Finessob L, Marsilioa E. Matrix factorization methods: Application to thermal NDT/E[J]. NDT & E International, 2006, 39:611-616