NDT thermographic techniques on CFRP structural components for aeronautical application

This paper describes the application of active pulsed Thermography (PT) as Non-Destructive Test (NDT) method for the investigation of CFRP aeronautical components. The analyzed specimens include T-shaped stringers, previously monitored by ultrasonic analysis, and laminated flat panels with internal production defects. Several set-up tests allowed to identify optimal configurations for the defects detection according to specimen geometry and defect location. A custom post-processing algorithm has been developed for more precise defects characterization, elaborating thermographic data; whilst a successive full-field contrast mapping construction allowed to propose a reliable defect distribution map and better definition on larger areas. Detection of defects was studied through proper thermal contrast evaluation, with respect to suitable choice of a sound reference area during the transient cooling phase. Influence of Heating time on the thermal contrast has also been studied and the Thermography ability to detect with accuracy and reliable results real small production defects is verified in this work on typical CFRP aeronautical components.