With increasing use of carbon fibre reinforced polymers (CFRP) in civil aviation, the need for nondestructive testing (NDT) techniques capable, of large area inspections in short time, has gained significance. In the following work CFRP laminates were inspected using various NDT methods. The main aim was to validate thermography with optical and ultrasonic excitation sources for the inspection of typical damages in composite aircraft structures. Thermography is especially sensitive to the nature of defects. Therefore a systematic approach was chosen to investigate real impact damage. The laminate was built up in a way that resulting delaminations from the impact damage only occurred in a desired depth. Results from these experiments were compared to typical artificial defects such as blind holes. Additionally, the size and defect depth obtained from the thermography images were compared with ultrasonic c-scan and radiography, as these represent widely accepted NDT-procedures in aerospace industry. Microscopic images of the polished cuts through the impact damaged areas were investigated after NDT to grasp the full extent of the damage made. Significant differences between the artificial defects and the impact damages were observed, where blind holes could be detected deeper into the material than the impact damages. This suggests that studies for detection limits with thermography should be conducted with great care and knowledge about the effect of various damage types on the detection system.
Systematic investigation on the detection limit of impact damage with thermography
Systematische Untersuchung der Nachweisgrenze von Stoßschäden mittels Thermographie
2010
10 Seiten, 7 Bilder, 1 Tabelle, 12 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch