ABSTRACT

The purpose of the present study is to investigate slamming impact of ships as well as to investigate applicability of nonlinear explicit finite element code LS-DYNA to simulations of slamming impact of ships. In this study a series of two-dimensional slamming impact simulations were carried out with using LS-DYNA where sea water is modeled by Euler solid elements and wedge is modeled by Lagrange shell elements. Fluid structure interaction (FSI) is taken into account by coupling fluid analysis and structural analysis in each time step of time domain simulations. In order to validate numerical simulation, water entry of rigid wedge is simulated, and pressure distribution and slamming impact estimated by simulations are compared with those by conventional Wagner theory.

INTRODUCTION

Impact of slamming is one of important issues for structural safety of ships. More specifically it is important to accurately estimate global/local structural response of ships against slamming impact under bottom of ship bow. It was thought to be time-consuming and not practical to carry out water impact analysis with coupling both fluid and structure. However as a considerable development of computer technology as well as computational numerical methods, water impact analysis with coupling both fluid and structure is becoming more and more practical in ship building design. Luo et al (2011) carried out water impact analysis of small-scale rigid wedge using LS-DYNA and found its practical applicability. Nakashima et al (2011) also carried out similar analysis for elasticwedge using LS-DYNA and found its applicability not only to rigid wedge but also to elastic wedge where fluid structure interaction (FSA) is taken into account. However these previous studies are mainly for water impact of small-scale structures, which is much smaller than actual large ships. It is noted that these previous studies are very important to validate accuracy and applicability of numerical methods as well as obtain numerical techniques and tips.

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