Review of pulsed thermal NDT: Physical principles, theory and data processing

•We summarize the history, models and applications of Thermal NDT (TNDT).•TNDT is an established technique in the aerospace and other high-tech industries.•The evaluation of composites in aerospace is the most typical application of TNDT.•IR thermography is a promising technique in determining anisotropic thermal properties.•In one-sided TNDT, reference-free algorithms are under development.

This paper summarizes the basics of pulsed thermal nondestructive testing (TNDT) including theoretical solutions, data processing algorithms and practical implementation. Typical defects are discussed along with 1D analytical and multi-dimensional numerical solutions. Special emphasis is focused on defect characterization by the use of inverse solutions. A list of TNDT terms is provided. Applications of active TNDT, mainly in the aerospace industry, are discussed briefly, and some trends in the further development of this technique are described.