Fatigue damage detection in graphite/epoxy composites using sonic infrared imaging technique

This paper describes the application of a short ultrasonic pulse thereby infrared surface imaging to assess fatigue damage in graphite/epoxy composites. The technique uses a short pulse of sound wave that infuses to the material and results in frictional heating at the crack surfaces. The heating at the crack defuses into the surface of the sample, and the temperature rise at the crack location is sufficient to be captured by an infrared (IR) camera. In this paper, the ability of sonic infrared imaging technique in detecting fatigue damage in composite materials has been demonstrated. Finite element modeling was performed to better understand the effect of applied sound pulse at the damage locations and to interpret the vibrometer data. The same samples were also tested using thermal wave imaging nondestructive evaluation (NDE) technique.