Inverse thermographic characterization of optically unresolvable through cracks in thin metal plates

The present research explores the feasibility of a novel non-contact means for the detection and characterization of small scale, open crack-like defects within thin metal plate components. The approach employs inexpensive infrared (IR) digital camera technology (e.g. ≈$5000US) and sophisticated numerical and algorithmic means as part of an inverse solution framework aimed at inferring the nature (i.e. presence, size, orientation, etc.) of micro-scale defects that are below the optical resolution capability of the IR imaging system. The current work explores a technique for inferring the presence and character of optically unresolvable flaws penetrating metallic plate components (i.e. through cracks).

► This paper reports on an algorithmic means for characterizing flaws in thin metallic plates. ► Optically unresolved flaws in a given pixel may be inferred from behavior of surrounding pixels. ► MLE estimators within a GA framework are efficient for effecting required inverse solutions. ► Currently available, inexpensive IR cameras seem to be practical for such applications.