Forming and Recovering of Thermal Wave Images for Multilayered Structures with Defects

Thermal wave imaging using the pulse-echo technique has been recognized as a powerful tool for the nondestructive evaluation (NDE) of materials. We present an an-alytical three-dimensional model for forming thermal wave images that fit multilayered objects with defects or flaws by use of eigenfunctions and integral transforms in math-ematics. The simulated images based on our theory for three- and two-layer-structures with a crossed shape defect located on the bottom of the structure are shown, and also compared with previous work only valid for a non-laminated object. The thermal wave images mixed with a noise recovered by means of on-line blind sources separation algorithm are presented in the last part of this paper. PACS. 81.7O.Pg- Thermal analysis, differential thermal analysis (DTA), differential thermogravimetric analysis. PACS. 44.10.$-i- Heat conduction (models, phenomenological description). I