Speckle Interferometry Applied to the Detection of Defects in Stiffened Panel

Abstract

In accordance with the Damage Tolerance (DT) approach, the structural components of the aircraft must be periodically maintained to improve the durability of airframes. This approach is applied to anticipated loads in the presence of fatigue, corrosion, or accidental damage until detection via inspections. To prevent the catastrophic growth of the damage, it is necessary to proceed with the replacement or repair of the piece itself. Due to the complex damage growth in composites, the DT approach is not as well-established as on metals. Furthermore, in the presence of a crack, its propagation is rapid and the scheduled inspections do not always cover the time from the crack creation to a critical damage size that is dangerous for the structural safety of the aircraft. In this work, it is proposed a non-destructive interferometric investigation technique to identify artificial defects in load-bearing structural parts in non-contact mode. Results have shown that the speckle technique was able to identify the Kapton sheet and other geometrical discontinuities in the structure.