Structural Analysis of a Multi-Body Wave Energy Converter in the Frequency Domain by Interfacing WAMIT and ABAQUS

In this paper the structural response of a multi-body wave energy converter with power take-off is analyzed in the frequency domain. The device consists of a semisubmersible platform and 21 buoys. The buoys can slide along guides that are attached to the platform. The hydrodynamic and structural problems are solved by using boundary element and finite element software systems WAMIT and ABAQUS. The hydrodynamic analysis is carried out by a linear perturbation approach. A mode expansion method, with total number of 27 modes, is used to describe the dynamic behavior. Moreover, an idealized form of power absorption mechanism is considered herein. A general procedure is established to interface the relevant information between the two software systems. Such information includes the radiation, diffraction and restoring force pressures and inertia loads, etc. In this way, the interaction between the floating bodies is included in the solution in which the dynamic reaction forces are carried as external forces. The structural response is obtained by a quasi-static approach. The objective is to investigate the still water and wave induced internal loads in the column-deck and guide-deck connections in the form of transfer functions. To demonstrate the approach, calculations are made for a following- and oblique-sea wave condition.