Hydroelasticity in water-entry problems: Comparison between experimental and SPH results

Hydroelastic impacts are of major interest in naval applications since, due to the mutual interaction between structural deformation and fluid motion, the impact-induced pressure and the impact dynamics can highly differ from a quasi-static solution. Hydroelastic effects are mostly important when the vessels are made with composite lightweight structures, due to the higher impact speed that can be reached. This work present an experimental and numerical study on the hydroelastic phenomena during the water-entry of elastic wedges. The numerical model is based on a coupled FEM and Smoothed Particle Hydrodynamics (SPH) formulation available in the commercial code Ls-Dyna. Results are compared with experiments about slamming of elastic wedges varying thickness, deadrise angle and impact velocity. Special attention is paid to the structural deformations. In particular, it is shown that more than one mode shape dominates the structural deformation in case of high hydroelastic impacts. Very high hydroelastic effects are observed, and the numerical solutions are found to be in good agreement with the measured data. The range of validity of the SPH technique to investigate hydroelastic effects during the water entry of elastic wedges is also outlined.