RIASSUNTO
ABSTRACT
The paper compares the crashworthiness of engine room and cargo hold to assess the safety performance in ship collisions. The external dynamics and the internal mechanics are combined to analyze the structural damages. The finite element simulations of ship collisions account for bow and side deformation interaction. The influence of impact locations is also investigated. The numerical simulations are performed with the LS-DYNA finite element solver. The objective of the paper is to verify whether the engine room has sufficient safety margin in accordance with the requirement of cargo hold.
INTRODUCTION
Ship collisions are of particular importance in marine accidents, resulting in severe economic loss, potential environmental damage and loss of human life. The impact of accidental consequences is mitigated by the design of double-hull structure, such as for the oil tanker, bulk carrier, container ship and LNG carrier. Guidance Notes for Collision Assessment for the Location of Low-flashpoint Fuel Tanks (LR, 2016) were developed by the Lloyd's Register to assess the damage extent of double-hull structure in ship side collision. The development of the guidance notes shows clearly the advantage of moving towards accidental limit state design.
As the probability of collision accidents is very low, it is impossible to improve the ship safety by increasing the hull structural weight, because of the ship energy efficiency. Thus, the penetration of inner hull cannot be avoided in severe collision accidents. Nevertheless, it is not acceptable that a ship cannot continue to function after a structural damage caused by collision.
In a collision of ship engine room, the penetration of the inner hull involves flooding and, consequently, loss of propulsion and power systems and even capsizing of ship. This hazard is too serious to be acceptable in the analysis of ship safety. In contrast, the impact at the cargo hold only results in the hull structural damage, and the residual ultimate strength of ship hull is often sufficient to arrive safely at a port. Generally, the damage of cargo holds does not often lead to the ship capsizing and sink.