Over the last decades, the need for overseas transportation of both people and goods has gradually increased. At the same time, several offshore activities as oil and gas exploration, wind power parks as well as fish farms have bloomed. As a consequence of the increased traffic and activities, the risk of accidents became noticeable. This paper presents a study of the collision between a Platform Supply Vessel (PSV) and an oil platform. Even if such accidents are seldom, their consequences are disastrous, for the ship owner as well as the oil-platform company. Beyond the economic consequences, some lives have been lost due to the ship - structure collisions. These problems are inducing to investigate the possibility of developing protective systems in order to save lives of the concerned persons.
Structural impact analyses can be carried out to give a scientific foundation for an evaluation of the consequences of a possible collision. This study is based on Non-Linear Finite Element Analysis (NLFEA) of the interaction between the PSV and the platform. Due to heavy calculations, only the ship section located close to the crash zone has been modelled and additional masses have been included on each side of this section in order to get the correct ship inertia. These additional masses correspond to the mass of the remaining part of the ship structure. Moreover, the sideways ship motion is modelled with a prescribed initial velocity, and does not contain hydrodynamic response calculations. The NLFEA software package HyperWorks is used to perform the numerical simulations.
As a way to reduce the consequences of a ship platform collision, a shock absorber called “crash box” is proposed mounted on the platform column to absorb the kinetic energy and thus decrease the effect in both ship and platform. 4 case studies are performed in order to compare the results with and without the crash box. Presented results are based on the deflection, resultant forces due to the contacts and absorption of the kinetic energy. The results demonstrate that penetration of the oil platform into the ship structure can be decreased by 96% if the crash box is used. Similar systems such as tires are currently used but this crash box should be investigated with an inner structure using “honeycomb” shape in order to maximise the absorption.
