Nonlinear hydrostatic analysis of flexible floating structures

In this study, we present an updated Lagrangian Finite Element (FE) formulation for a geometrically nonlinear hydrostatic analysis of flexible floating structures subjected to buoyancy, self-weight, and various external static loads. The nonlinear equation is linearized with respect to a reference configuration and the resulting FE formulation is iteratively solved using the Newton-Raphson method. The initial stress effect, normal vector change, and buoyancy change are comprehensively considered in the tangential stiffness term of the hydrostatic equations. A special numerical integration technique is developed to handle the wet-surface change without re-meshing. Through the proposed numerical method, the hydrostatic equilibrium can be easily calculated considering various static and quasi-static loading conditions and the stress field of elastic bodies can be more accurately evaluated in the case of large displacement. Various nonlinear hydrostatic problems are solved to demonstrate the general capability of the proposed method. In particular, a hydrostatic experimental test was performed and the results are compared with those obtained using the proposed numerical method.