Non-destructive testing using thermography makes it possible to detect near-surface defects in fiber-reinforced composites as part of quality assurance or maintenance. The quality of the measurement and thus also the detectability of the defects decreases continuously with increasing depth and decreasing defect size. Various post-processing methods, such as pulse-phase thermography (PPT) and higher order statistics (HOS) can be used to improve the contrast or the signal-to-noise ratio of defects, whereby it is important to choose the right parameters depending on the characteristics of the defect. This study investigates the theoretical maximum achievable depths and shows the limits of thermography. For active thermography, impulse thermography is investigated and different post-processing methods are compared. As defect types, delamination in form of air inclusions are considered and their position is varied. Furthermore the influence of the measuring equipment was investigated. The results from the simulation are discussed and compared with results from literature and from experiments.

Date Published: 18 March 2019
PDF: 12 pages
Proc. SPIE 10973, Smart Structures and NDE for Energy Systems and Industry 4.0, 109730K (18 March 2019); doi: 10.1117/12.2518226

Published in SPIE Proceedings Vol. 10973:
Smart Structures and NDE for Energy Systems and Industry 4.0
Norbert G. Meyendorf; Kerrie Gath; Christopher Niezrecki, Editor(s)