HYDROELASTIC SLAMMING OF COMPOSITE PLATES

When a vessel sails in rough seas, its forefoot can rise above the water surface. As the vessel re-enters the water, impulsive pressures are imparted to the hull structure due to the relative motion of the sea and ship. In these cases the hull literally slams into the water surface. The duration of the slamming event is in the order of milliseconds. The hull slamming problem is of particular interest for shipbuilding industries due to the high impact load that is generated during the water entry. These loads might damage the entire ship or, because of their short duration, excite dynamic response of the local structure of the hull and cause the structure to vibrate. The aim of this work is to investigate the interaction between the fluid and the structure in case of a deformable wedge entering the water. In this case, the pressure at the fluid/structure interface and the fluid motion are influenced by the structural deformation; this phenomenon is known as hydroelasticity. Hydroelastic effects introduce diffculties in the calculation of the structural stresses. Being able of correctly predicting the structural deformations and stresses during the slamming phenomena is a major challenge, and suitable computer-aided design tools still have to be found. Experimental and numerical results on the parameter affecting hydroelasticity are evaluated for deformable wedges with different boundary conditions, showing a dependency of the hydroelasticity from the ratio between the structural natural frequency and the characteristic wetting time.