2D Discrete Module Beam (DMB) Method Formulation to Simulate Hydro-Elastic Structures With Two Horizontal Bending Axes

Abstract

Abstract The 1D Discrete Module Beam (DMB) discretize hydro-elastic body into multiple independent rigid bodies (modules) connected by beam elements. The technique has proven accurate in representing structures with a large length-to-breadth ratio (L/B), such as floating bridge, barge, and ship structures. Only one horizontal bending axes are typically considered for such structures. Bending stiffness in the other horizontal axis is considered stiff and consequently treated as rigid. However, this assumption is not satisfied for structures with L/B closer to one. This study aims to extend the 1D DMB method into the 2D DMB method in the frequency domain to simulate hydro-elastic structures with two horizontal bending axes by arranging the beam elements into grid-like configurations in both horizontal axes (x and y). The method is then validated through comparisons with published experimental results and other numerical methods for various sea states. The method’s versatility is then demonstrated by incorporating linearized mooring stiffness in the frequency domain, which consequently changes the structures’ hydrodynamic response. It is found that for freely floating bodies, the centerline deformation of both the 1D and 2D DMB methods is the same. However, the 1D DMB method cannot properly capture the breadth-wise elastic-deformation in oblique waves and the moored case. In those cases, the 2D DMB formulation becomes particularly important. The presented 2D DMB method is projected to be a practical tool to simulate floating structures with unconventional configurations such as floating solar panels and other very large floating structures.