Damage assessment of impact damages on CFRP with laser shearography

CFRP material becomes widely used in Aviation industry for substituting or complementing conventional material compositions. There are various advantages in comparison to conventional material that has been used so far, but also some disadvantages. Among those there is the difficulty to detect and estimate impact damages by visual inspection, as it has been carried out at e.g. aluminum material. CFRP material with its own particular behavior to impacts, caused by rough environments (e.g. stone, ice or bird impact, tool drop, etc.) makes visual inspection more difficult. Therefore investigation and defect estimation becomes more and more crucial in maintenance of composite material. The typical material behavior to an impact leaves only a small or even no visible indication on the material surface, but there is indeed a deeper damage extended in the material. Shearography full-field inspection method reveals the extension of the impact damages providing a base for decision of repair. This paper shows various impact damage examples on a CFRP stringer material with its extension into the material beyond the visible area. The metric impact determination allows obtaining data for comparison and/ or catalog of the defects.