From structural mechanics to inspection processes: Getting structural health monitoring into application for riveted metallic structures

Structural health monitoring (SHM) has been around now in research for more than 2 decades. However not many SHM applications have been realized so far for various reasons. The paper addresses those reasons for the case of acoustic wave monitoring by discussing state-of-the-art in SHM, the issue of scattered acoustic waves around holes in plates with gradually enhancing the complexity of the structural component considered from an infinite to the finite plate and allowing a crack to start and to grow from the hole. This sequence intends to exemplify in the end a riveted structure and a way on how increased structural complexity enhances the complexity of an acoustic signal sent through these structures for the purpose of monitoring. This is discussed on the basis of numeric and experimental results regarding the size of cracks to be monitored and what strategy of monitoring might be used best such that a reliable monitoring result is obtained for a riveted structure. Finally a procedure is explained that can be applied such that structural components, and in this case riveted structures, can be identified on an aircraft for which SHM is a promising solution in terms of aircraft operability