An analytical model to assess a ship side during a collision

During its lifetime, a ship may encounter collision or grounding and sustain permanent damage after these types of accidents. Crashworthiness has been based on two main methods: simplified plastic analysis and numerical simulation. In this paper, the resistance of a ship side hit by a rigid bow with two different shapes is investigated using the non-linear finite-element software LS-DYNA. All structural components of the ship side are analysed to determine their contribution to the total resistance. It is found that the shape of the striking bow affects the resistance of the ship. The outer shell plating and plate girders contribute significantly to the total ship resistance until a fracture occurs in the outer skin of the ship. The numerical findings are used as the basis of a new simplified procedure. The ship structure is divided into a shell plating and plate girder; the latter is further divided into cruciforms and web girders. A new analytical formula that can be used to calculate the axial force of shell plating loaded by the general shape of a striking bow is introduced, while the resistance of cruciforms and web girders is determined from the existing formula. The analytical calculations are compared with the numerical results, and good agreement is achieved.