Pulse phase thermographic non-destructive evaluation of composite aircraft structures

The emergence of composite materials as a strong contender to metal alloys for use in aircraft structures has been remarkable and their large-scale use in the development of new generation aircraft is quite phenomenal. This trend in the application of composites for aircraft structures indicates their proven capability, reliability and confidence levels in these materials. Consequently, the development of large primary aircraft structures is being dominated by composite co-cured/co-bonded assemblies. However, the quality assurance and structural integrity of these large and complex composite aircraft structures are critical and demand improved and reliable non-destructive evaluation (NDE) methods. In the domain of thermal NDE, pulse phase thermography (PPT) is an advanced technique when compared to conventional pulse and lock-in thermography. The development of PPT was initiated with a view to enhance the thermal contrast and defect definition and to overcome the limitation of pulse thermography to detect deeper defects. PPT was successfully applied to identify a variety of defects in composite aircraft components. This paper demonstrates the potential of PPT for improved defect detection in composites when compared to pulse thermography.