Detecting low-energy impact damages in carbon-carbon composites by ultrasonic infrared thermography

Composite materials are widely used in aerospace engineering, shipbuilding, and automobile industry due to their high durability, relatively low mass, and corrosion resistance. Composites are vulnerable to impact damages that may occur during production and service (e.g., as a result of dropped tools, bird strikes and luggage hits in aviation, hail, and other similar factors). Often unnoticeable on the affected composite surface, low-energy damages (below 20–40 J) can, however, lead to the emergence of significant flaws (such as complex combinations of cracks, exfoliations, fiber ruptures, etc.) inside the material. Results of applying ultrasonic infrared thermography to the detection of impact damages with an energy of 5–30 J in a carbon-carbon composite are presented.