Detection of edge debonding in composite patch using novel post processing method of thermography

In the present work, the step heating thermography technique has been used to detect disbond defects at the edge of the adhered carbon/epoxy patch on the aluminum plate. The four common post-processing algorithms including principle component analysis (PCA), thermal signal reconstruction (TSR), Fourier transform (FT), and one-dimensional wavelet transform (1D WT) have been applied to the infrared thermal images obtained from the composite patch thermography inspection. A novel post processing method based on the area under temperature-time curve (Thermal Signal Area: TSA) has been proposed for the infrared thermal image analysis. The proposed post-processing method is fast and non-sensitive to noise. A comparison of the new proposed method with the four common post-processing methods has been carried out on disbond detection in a composite patch in a quantitative and qualitative manner. Furthermore, a data fusion of the proposed method with the 1D wavelets transform has been applied to disbond defect characterization which improves the accuracy by decreasing noise level.