1985

Hakala, Matti

Fluid-structure and structure-structure interaction in ship vibration are analysed and numerical calculation procedures based on the finite element method are developed.In the fluid-structure interaction analysis both the ship structure and the surrounding fluid are modelled three-dimensionally.The fluid effect is taken into account in the form of an added mass matrix.The coupled vibration problem is solved using the so-called modal approach, i.e. the dry modes of the structure are used as Ritz functions in the final solution.The structure structure interaction problem, involving the coupling of global and local vibration, is treated by first constructing separate models for global and local behaviour.The coupling is taken into account at a later stage using a dynamic coupling matrix and the separately calculated global and local modes.For the global modelling, a novel deck finite element is developed.A parametric study is performed in a case of a simple model resembling a boxlike ship to reveal the relative importance of various parameters in the interaction process.The developed procedures are tested using an example structure, for which experimental results are also available. The accuracy of the global-local approach and the truncation errors in the modal solution are studied.