Hull girder failure of a container ship and of a bulk carrier under combined global and local loads

Abstract

Nowadays, the ships strength can be very well estimated using developed methods and available tools. To ensure the safety of construction is reached the classification society rules should be followed. To estimate hull ultimate bending capacity by means of ultimate bending moment Smith’s method is used. Although it is well working it was formulated in the seventies of the twentieth century and nowadays the bigger accuracy would be desired. This work is an analysis of ultimate bending moment using advanced modeling tools. The models of a bulk carrier and of a container vessel will be built in Ansys Workbench program. Two midship part of two hulls will be modeled respecting all scantlings of constructions members. The crucial part of the hull will show fined mesh to achieve the desired level of accuracy. Ship’s loading will include hogging bending moment as well as local loads from water pressure and cargo loading condition. The influence of the initial imperfections on the results also will be checked. The progressive collapse analysis will be performed using LS-Dyna solver. Obtained results will be compared with results from Germanischer Lloyd program Poseidon which uses Smith’s method. The comparison could give a better insight in the safety margin used in estimating hull girder bending capacity to ensure its safety.