Displacement and stress monitoring of a Panamax containership using inverse finite element method

Abstract

The inverse Finite Element Method (iFEM) is a revolutionary methodology for real-time reconstruction of full-field structural displacements and stresses in plate and shell structures that are instrumented by strain sensors. This inverse problem is essential for structural health monitoring systems and commonly referred as ‘displacement and stress monitoring’ or ‘shape- and stress-sensing’. In this study, displacement and stress monitoring of a Panamax containership is performed based on the iFEM methodology. A simple, efficient, and practically useful four-node quadrilateral inverse-shell element, iQS4, is used for the numerical implementation of the iFEM algorithm. Hydrodynamic analysis of the containership is performed for beam sea waves in order to calculate vertical and horizontal wave bending moments, and torsional wave moments acting on parallel mid-body of the containership. Several direct FEM analyses of the parallel mid-body are performed using the hydrodynamic wave bending and torsion moments. Then, experimentally measured strains are simulated by strains obtained from high-fidelity finite element solutions. After that, three different iFEM case studies of the parallel mid-body are performed utilising the simulated sensor strains. Finally, the effect of sensor locations and number of sensors are assessed with respect to the solution accuracy.