Time-domain hydroelastic analysis of nonlinear motions and loads on a large bow-flare ship advancing in high irregular seas

This paper investigates the nonlinear hydroelastic motion and load responses on a large flexible ship advancing in harsh irregular waves. A 3D time-domain nonlinear hydroelasticity theory for the prediction of ship motions, deformations and wave loads in long-crested irregular waves is presented. The nonlinear Froude-Krylov force and hydrostatic restoring force are calculated on the instantaneous wetted hull surface while the linear diffraction force and radiation force are estimated on the static mean wetted surface. The radiation forces are estimated by retardation function method to take account of the wave memory effects and forward speed effects. The slamming loads that were derived by momentum impact theory are also included in the ship motion equation to investigate the whipping responses. The hydrodynamic and structural responses are fully coupled by modal superposition principle to consider the hydroelastic effects including springing and whipping responses. The numerical results are well validated by the experimental data of a segmented model with large flare-bow tested in an ultra-long laboratory tank. The numerical and experimental data of ship responses in different irregular wave conditions are systemically analyzed and compared by time series analysis, spectral analysis, and probability statistics analysis methods.