Repeatability Study of Flash-Pulse Thermographic Inspection of CFRP Samples

Thermographic flash-pulse inspection is one of popular methods of non-destructive testing (NDT) of materials. Despite the automation of the NDT methods, most of them are based on visual inspections and results of these inspections are influenced by the skills of operators. The repeatability and reproducibility (R&R) of these inspections are therefore more important compared to exact gauge-type methods. This study was focused on the statistical evaluation of flash pulse inspection. Space hardware representative carbon-fiber composite samples with 50 artificial defects were used as reference samples, which were independently inspected by three operators in two independent runs. A Gage R&R study was performed based on contrast to noise ratio defects identification. It was determined that at certain conditions, a total R&R variability 29% can be achieved, which can be assumed as acceptable for this application.