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Infrared thermography is a fast and illustrative nondestructive testing method, which is widely used for an inspection of metallic and non-metallic materials. Previously it was used mostly for defects indication. However, modern devices and software allow an application of a quantitative estimation of parameters of the defects. This contribution presents a novel infrared thermographic method for quantitative defect depth estimation. The majority of known thermographic techniques is based on a 1D heat transfer model and does not take into account 3D heat transfer. These methods are applicable only for large defects, which lateral size can be assumed as infinite. In contrast, the presented technique takes into account lateral dimension of defects and a finite thickness of a tested material. The method is based on a modification of the 1D analytical solution obtained by Almond et al. and a nonlinear optimization procedure. The algorithm was verified by numerical modelling and flash-pulse thermographic inspection experiments. Applicability of the method for the defect depth evaluation in the duraluminum parts was demonstrated.
Keywords: Flash pulse thermography, defect depth, thermographic inspection, depth estimation© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.