Line scanning thermography for rapid nondestructive inspection of large scale composites

As next generation structures are utilizing larger amounts of composite materials, a rigorous and reliable method is needed to inspect these structures in order to prevent catastrophic failure and extend service life. Current inspection methods, such as ultrasonic, generally require extended down time and man hours as they are typically carried out via point-by-point measurements. A novel Line Scanning Thermography (LST) System has been developed for the non-contact, large-scale field inspection of composite structures with faster scanning times than conventional thermography systems. LST is a patented dynamic thermography technique where the heat source and thermal camera move in tandem, which allows the continuous scan of long surfaces without the loss of resolution. The current system can inspect an area of 10 in2 per 1 second, and has a resolution of 0.05x0.03 in2. Advanced data gathering protocols have been implemented for near-real time damage visualization and post-analysis algorithms for damage interpretation. The system has been used to successfully detect defects (delamination, dry areas) in fiber-reinforced composite sandwich panels for Navy applications, as well as impact damage in composite missile cases and armor ceramic panels.