This paper presents a novel approach for the detection of surface damage in metallic structures, where the electromagnetic waveguide forms a union with the structure to be inspected. The sensing concept in such jointed electromagnetic waveguides will be described here and measurement results will be presented using a hollow metallic waveguide on an aluminium sample. The experimental proof of principle is performed in the frequency band from 20GHz to 40GHz using a network analyzer. It is possible to (i) detect holes as small as 1mm, (ii) discriminate between different hole sizes, and, (iii) localize the axial position of the defect in the waveguide. This approach has great potential to be used for structural health monitoring of complex technical structures and components.
Moll, J. Damage Detection and Localization in Metallic Structures based on Jointed Electromagnetic Waveguides: A Proof-of-principle Study, Journal of Nondestructive Evaluation, 2018 (accepted in August 2018), Link