Reducing hydroelastic response of pontoon-type very large floating structures using flexible connector and gill cells

Abstract

This paper presents the use of flexible connector and "gill cells" to mitigate the hydroelastic response of pontoon-type, very large floating structure (VLFS) under wave action. Gill cells are compartments in VLFS with holes or slits at their bottom surfaces to allow free passage of water and they are modeled by eliminating the buoyancy forces at their locations. In the hydroelastic analysis, the water is assumed to be an ideal fluid and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an isotropic plate according to the Mindlin plate theory. In order to decouple the fluid-structure interaction problem, the modal expansion method is adopted for the hydroelastic analysis which is carried out in the frequency domain. The boundary element method is used to solve the Laplace equation for the velocity potential, whereas the finite element method is employed for solving the equations of motion of the floating plate. Genetic algorithm is adopted as an optimization tool to optimize the layouts of gill cells. It is found that by appropriately positioning the flexible connector and a suitably distributing the gill cells in the VLFS, the hydroelastic response and stress resultants of the VLFS can be significantly reduced. © 2013 Elsevier Ltd.