Nondestructive Evaluation of Composite Substrate Below Thick Top Coat Materials

Structural skins and components of the latest generation of advanced military aircraft include carbon fiber composite construction. In operation there can be impacts, such as from foreign objects and debris (FOD) or bird strike during flight. As composite structures become the norm in advanced military aircraft, there is an increased need for regular inspections beyond the usual visual examination of the aircraft. An additional complication in these applications, however, is the presence of a thick outer coating that makes conventional inspection techniques using acoustic methods (i.e. ultrasonic or tap-test) impractical. Therefore, Compass Technology Group (CTG) proposes an advanced non-destructive evaluation method that can work through the thick coatings and interact with the carbon fiber composite underneath. Specifically, the proposed concept uses a probe that also penetrates into the underlying composite so that damage from various defects can be detected. In this effort, CTG will conduct computational modeling to optimize the sensor and then will build a prototype for testing. The prototype will be demonstrated on representative material coupons.