Shock spectral analysis of elastic systems impacting on the water surface

In this paper, the hydrodynamic and elastic forces arising in simple discre te and continuous systems impacting on the water surface are investigated. Both the impact of a single rigid wedge and the case of two elastically cou pled bodies, where the lower one is wedge directly plunging the water, are studied. The analysis is performed by a simplified theoretical model and by a numerical simulation of the fluid-structure interaction. The concepts of residual and overall shock spectrum of the slamming force are introduced. The attention is then addressed to the case of a continuous flexural system . By an envelope analysis of the displacement response, related to the hydr odynamic force spectrum, a slamming shock spectral expansion is introduced. This model is able to provide some insight into the structural response du ring the impact. The characteristic maxima in the time histories of the ela stic deformation are theoretically evaluated in terms of the impact quantit ies, such as the deadrise angle of the wedge, the entry velocity and the st ructural parameters. Results obtained by numerical simulations validate the theoretical (C) 2000 Academic Press.