IR thermographic detection of defects in multi-layered composite materials used in military applications

Multi-layered composites are frequently used in many military applications as constructional materials and light armours protecting personnel and armament against fragments and bullets. Material layers can be very different by their physical properties. Therefore, such materials represent a difficult inspection task for many traditional techniques of non-destructive testing (NDT). Typical defects of composite materials are delaminations, a lack of adhesives, condensations and crumpling. IR thermographic NDT is considered as a candidate technique to detect such defects. In order to determine the potential usefulness of the thermal methods, specialized software has been developed for computing 3D (three-dimensional) dynamic temperature distributions in anisotropic six-layer solid bodies with subsurface defects. In this paper, both modeling and experimental results which illustrate advantages and limitations of IR thermography in inspecting composite materials will be presented.