A method for linear hydroelastic wave load analysis is established based upon use of standard software for assessing wave loads and three dimensional structural mode shapes found by ABAQUS. The method is validated by comparison against experimental results for a flexible offshore mat. The results show decent agreement with experiments and another available computer code. Moreover, the approach was found to be computationally efficient.
The growing need for larger ocean going vessels and other ocean structures, calls for hydroelastic analysis of these structures. Introduction of Very Large Floating Structures (VLFS) based on interconnected modules has already demanded such this kind of analysis.
For a hydrodynamicist, the term hydroelasticity refers to the satisfaction of the deformable body surface boundary condition of the boundary value problem for the velocity potential mathematical model (MOB project team, 2000). In other words, by hydroelasticity we imply that the fluid flow and the structural elastic reactions are considered simultaneously and that we have mutual interactions (Faltinsen, 2005). Standard ways of computing wave induced forces on vessels rely on combinations of potential flow and semi-empirical coefficient based models accounting for viscous forces. Rankine type sources are distributed along the hull of the structure, which satisfy the free surface boundary condition. Source strength can be computed by satisfying the exact body boundary conditions that no fluid can pass through the hull surface. Discretization of the hull form into a finite set of Hess-Smith type quadrilateral panels allows formulation of algebraic system of equations to be solved for the unknown singularity strengths (Crook, 1995).
When a few modes of the structure contribute to the response, the structural behavior can be described accurately by superposition of a few modes and correspondingly a few degrees of freedom rather thousands of equations required for the dynamic analysis.