Evaluation of hydroelastic responses of a 180k DWT large bulk carrier

Abstract

The linear hydroelastic theory has been widely used in engineering applications in the past. However, the increasing demand for larger merchant ships makes it necessary to evaluate the influences of second-order nonlinear fluid forces on ship response in seas. In this study, the second-order nonlinear responses induced by sea waves are calculated using generalized second-order wave force theory in the frequency domain. The Fluid-Structure Interaction (FSI) method is presented first in this paper which is used for the assessment of ship response and loads, including both linear and second-order nonlinear methods in the frequency domain. Subsequently, the effects of linear forces on the wave-induced responses and loads for a 180k DWT large bulk carrier with and without forward speed are calculated using pulsating source Green's function and translating-pulsating source Green's function. The second-order nonlinear responses are predicted mainly based on pulsating source Green's function. The numerical results show that the ship responses change significantly at high speed, and there are extra vertical bending moments caused by second-order fluid forces acting on the ship in large-amplitude waves compared to linear results. It indicates that both the speed of the ship and the second-order nonlinear wave forces acting on the ship could amplify the wave-induced responses and vertical bending moments.