Diagnosis of composite materials in aircraft applications: towards a UAV-based active thermography inspection approach

Diagnosis of defects to maintain aircrafts' integrity are important for complex and safety-critical aircraft structures. Development of non-destructive testing (NDT) techniques to detect damage in composite aircraft structures have been a subject of intensive research over the last decades. Yet, there is still an ongoing need for damage diagnostic tools with higher sensitivities and the ability to rapidly inspect complex composite structures. Such advanced tools will ease the early detection of damage and can aid in predicting damage propagation; thus, allowing for the implementation of preventive maintenance approach, while maintaining the desired level of safety. Furthermore, the use of unmanned aerial vehicles (UAVs) for the remote inspection of large and/or difficult to access areas have significantly grown in the last few years. UAVs that can potentially fly around the aircraft carrying several sensors, e.g. thermal and optical cameras, to inspect the parts of interest without removing them can have potential benefits to reduce cost and inspection time. Therefore, this paper provides a brief literature review of available research on detecting damage in composite materials with the emphasis on the use of active thermography techniques. In addition, the use of UAV-based active thermography approach for the inspection of composite aeronautical structure is also demonstrated.