A review of ultrasonic infrared thermography in non-destructive testing and evaluation (NDT&E): Physical principles, theory, and data processing

Ultrasonic Infrared Thermography (UIT) represents a high-efficiency non-destructive testing method that combines ultrasonic excitation and infrared thermography. UIT produces thermoelastic effect or friction heat generation effect through ultrasonic excitation, and uses infrared camera to capture the changes of surface temperature field, achieving the visual detection of defects. The merits of UIT are manifold, including non-contact, high sensitivity, rapidity, and efficiency, as well as the capacity for multi-scale detection and quantitative evaluation. Consequently, it finds wide application in the detection of surface and near-surface defects in metals, composites, and other materials. This study firstly introduces the principles of ultrasonic infrared thermography non-destructive testing technology. Subsequently, the implementation process of UIT in ultrasound excitation source, excitation waveform, feature extraction algorithm, and image processing were described to facilitate understanding of the technology. The paper then goes on to highlight the development status and practical application examples of ultrasonic infrared thermography non-destructive testing technology, and analyses the problems faced by ultrasonic infrared thermography technology. Finally, the paper offers an outlook on future development trends in ultrasonic infrared thermography non-destructive testing technology.