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The slamming phenomenon often occurs when the bottom of a ship hits the seawater with a relatively high velocity in irregular waves. In extreme sea conditions, the slam-induced dynamic loads can be quite large resulting in local structural damages and/or global deformation of the panels, in particular when ships face head sea waves with high forward speed. In this respect, high-speed vessels are affected by the slamming phenomenon as they are built with thin steel plates or aluminum. The paper presents finite element simulations performed with the explicit ls-dyna solver of an aluminum stiffened plate subjected to extreme slamming loadings so as to evaluate the large plastic deformation and failure of the stiffened plate and the effect of the heat affected zone (HAZ) due to the welding using the mechanical properties of an aluminum alloy grade 5083-H116. The outcomes of this study identify the parameters that have importance when estimating the extent of structural deformation due to slamming loads. [ABSTRACT FROM AUTHOR]

Experimental and numerical results of drop weight impact tests are presented, examining the plastic response and the crack initiation and propagation of small-scale damped rectangular aluminum plates laterally impacted by different indenter shapes. The experiments are conducted using a fully instrumented impact testing machine. The shape of the deformation of the specimens and the process of initiation and propagation of the material fracture are presented. The obtained force-displacement responses show a good agreement with the simulations performed by the LS-DYNA finite element solver. The strain hardening of the material is defined using experimental data of quasi-static tensile tests and the critical failure strain is evaluated by measuring the thickness and the width at fracture of the tensile test pieces. The results show that the absorbed energy to petforate the specimens is highly sensitive to the shape of the striker. Thus, the crack propagation for each striker type is analyzed in terms of the force-displacement response. The failure modes are described by the matrix of the infinitesimal strain tensors and the shape of the deformation of the failing elements. [ABSTRACT FROM AUTHOR]

Experimental and numerical results of drop weight impact test are presented on the plas-tic behavior and fracture of rectangular plates stuck laterally by a mass with a hemi-spherical indent er. Six specimens were tested in order to study the influence of the impact velocity and the diameter of the indenter. The impact scenarios could represent abnormal actions on marine structures, such as ship collision and grounding or dropped objects on deck structures. The tests are conducted on a fully instrumented impact tester machine. The obtained force-displacement response is compared with numerical simulations, performed by the LS-DYNA finite element solver. The simulations aim at proposing techniques for defining the material and restraints on finite element models which analyze the crashworthiness of marine structures. The mesh size and the critical failure strain are predicted by numerical simulations of the tensile tests used to obtain the mechanical properties of the material. The experimental boundary conditions are modeled in order to represent the reacting forces developed during the impact. The results show that the critical impact energy until failure is strongly sensitive to the diameter of the striker. The shape of the failure modes is well predicted by the finite element models when a relatively fine mesh is used. Comments on the process of initiation and propagation of fracture are presented. [ABSTRACT FROM AUTHOR]