Shape Sensing and Damage Identification with iFEM on a Double Bottom Structure of a Containership

This study presents an approach for conducting structural health monitoring utilizing the inverse Finite Element Method (iFEM). The iFEM technique hinges on minimizing a weighted least-squares function, which evaluates the dissimilarity between experimental and numerical strains. This facilitates the reconstruction of a structure's strain distribution using a limited sensor array. Subsequently, structural health monitoring is performed by finding disparities between the strains reconstructed via iFEM and those measured. In the present work, this framework is applied successfully to a paradigmatic case study for the marine and naval engineering, that is the double bottom structure of a containership, using numerical strain measures. Furthermore, it is shown how the choice of a good sensor network affects dramatically the iFEM displacement reconstruction and needs to be carefully located in practical ship applications, where a lot of constraints are present. Finally, an anomaly quantity is devised to portray the state condition of the structure by comparing the strain recorded at a designated sensor location with the corresponding strain reconstructed by the iFEM algorithm at the same position when the structure is damaged due to an extreme event like an explosion in air. The present work proposes a preliminary damage diagnosis framework with iFEM that can be exploit in real marine structures applications in a Digital-Twin framework.