Proceedings of OMAE 2009 28th International Conference on Offshore Mechanics and Arctic Engineering 31 May - 5 June , 2009, Honolulu, USA OMAE2009-79574 SOME ASPECTS OF HYDRO-STRUCTURE COUPLING FOR COMBINED ACTION OF SEAKEEPING AND SLOSHING ˇ Sime Malenica Research Department Bureau Veritas (France) Franc ¸ ois-Xavier Sireta Research Department Bureau Veritas (France) Fabien Bigot Research Department Bureau Veritas (France) Chao Wang Development Department Bureau Veritas (France) Xiao-Bo Chen Research Department Bureau Veritas (France) INTRODUCTION The techniques for hydrodynamic load transfer from com- bined action of waves (seakeeping) and internal liquid flow (sloshing), onto 3DFEM structural model are discussed. The problem is relevant both for a ship transporting liquids in tanks (LNG carriers, tankers...) as well as for any ship sailing in bal- last conditions. Correct pressure transfer to the FEM model is essential for spectral fatigue assessment of structural details. The methods that are used in practice do not appear to be very clear and different levels of approximations based on some empirical considerations are usually employed. In this paper, a fully con- sistent method is proposed in the context of the linear frequency domain model. Potential theory is adopted and the Boundary Integral Equation method is used for solving both internal (sloshing) and external (seakeeping) boundary value problems. Several technical diffi- culties need to be solved in order to ensure proper balancing of the structural model. These difficulties are discussed in the con- text of coupling the hydrodynamic numerical code Hydrostar and the 3DFEM structural code Nastran. The method which is pro- posed for solving the internal flow problem is compared with the approximate solution which exists in Nastran. GENERAL The overall methodology for dynamic coupling between liq- uid motions in the ship’s tanks (sloshing) and rigid body motions of the ship in waves (seakeeping) was presented in [2]. The prob- lem was formulated under the classical assumptions of the lin- ear potential theory and the Boundary Integral Equations method was used to solve both sloshing and seakeeping parts. However, the main focus of that paper was on the global ship behavior and no interaction with structural response was con- sidered. The purpose of this paper is to extend the above men- tioned analysis in order to properly consider the corresponding structural response of the ship. Before considering the structural aspects in more detail, we first briefly recall the basics of the coupling procedure. BASIC PRINCIPLES OF SEAKEEPING-SLOSHING COUPLING The reference configuration is presented in Figure 1. It was shown in [2] that the final coupled motion equation can be written 1 Copyright c  2009 by ASME Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering OMAE2009 May 31 - June 5, 2009, Honolulu, Hawaii, USA OMAE2009-79574