On the global free vertical vibrations analyses of an 18000 tdw bulk-carrier ship

Abstract

For ships having the hull girder elastic, before the assessment of the vibration responses induced by waves, a preliminary step is the global free vibrations modes analysis. In this study there is considered an 18000 tdw bulk-carrier ship, with elastic hull structure, of 158.9 m overall length and full loading case. The numerical analyses involve 3D-FEM full hull models, with the main structural details, developed by two finite element programs. The analyses are focused on the first two global free vibration modes, with or without the added hydrodynamic masses, structure-fluid interaction. The numerical results provided by the two FEM models are compared with the values obtained by Kumai’s statistical expression, pointing out the accuracy level of each approach.