3DFEM-3DBEM model for springing and whipping analysis of ships

The paper deals with the modeling of the wave induced ship structural vibrations. The presented method is fully integrated in both the linear frequency domain and non-linear time domain seakeeping calculations. Due to the transient non-linear nature of slamming loading, the corresponding whipping response is calculated in the time domain only, while the non impulsive springing response is evaluated both in frequency and time domain. A method based on the full coupling of 3DFEM structural model and 3DBEM hydrodynamic model is presented. The choice of the full coupling with the 3DFEM structural model is necessary due to the particular structural characteristics of the container ships, in particular their open midship section, which is hard to model using non-uniform beam model. In addition, the 3DFEM model gives the direct access to the structural response (stresses and strains) at any required location. The stresses at the structural details are investigated using a so called top-down analysis, and the total stress response is separated into quasi static and dynamic parts in order to improve the convergence.