The methods for the determination of the springing response for inclusion in the fatigue assessment are introduced. Fluid Structure Interaction (FSI) models are used to investigate wave actions and wave induced global loads acting on a large container ship. Frequency domain simulation techniques are employed to investigate effects of springing on design bending moments of a large container ship based on the Lloyd's Register 2015 Rules requirements for container ships that mandate springing fatigue analysis for large container ships. Locations at typical hatch corners and torsional boundaries are examined for the springing fatigue analysis. This paper shows that the fatigue life is significantly reduced due to the inclusion of springing effects acting on the world largest container ship investigated.
As per the demand of efficiency for mega size container ships in terms of operating and environmental merit, ultra large container ships haven being designed and further developed. On the other hand, obviously slenderness of the vessels also has increased rapidly. At the same time, hatch corners located on the deck openings are concerned in terms of fatigue capacity.
When a vessel having a long and slender body operates in high speed, springing is to be investigated regarding fatigue life reduction at the initial design stage of the vessel. In this regards, the springing phenomena are examined for the concerning locations in this paper.
Compared to whipping response, the magnitude of the springing induced bending moments (stresses) is usually low and hence springing is not normally a strength issue. However, the number of cycles is very large and this can make springing important with regards to the fatigue life of ship structures. High springing causes the form of continuous vibration of a hull girder at resonance frequencies and it increases the risk of premature fatigue cracking in the ship structures (Lee et al., 2011 and 2012).
