Application of frequency selective surfaces for inspection of layered structures

Structural health monitoring is important to many industries today. In the case of layered structures (such as composite structures found in the infrastructure and aerospace industries), one failure mechanism that is important to detect is that of delaminations. Numerous nondestructive testing (NDT) methods have been developed for this purpose including acoustic, thermography, microwave, etc. This paper presents a new application of frequency selective surfaces (FSS´s) as a potential inspection method for detection of delaminations in layered structures. Simulations and measurements are presented that support the potential of this method to serve as an additional NDT technique for layered structures. The results indicate that FSS´s are sensitive to delaminations occurring in the local vicinity of the FSS, but are less sensitive to delaminations occurring at other layer interfaces.