Advanced backbone deployed to measure bending modes of ultra- large container vessels

MARIN carried out a series of model tests on behalf of the Marine Design and Research Institute of China (MARIC) to assess the flexural response of an ultra-large container ship (ULCS). A 10-segmented model was mounted on an advanced backbone to replicate the vertical and

horizontal bending modes and tested in a range of wave conditions. Patrick Hooijmans,


he demand for cutting operational costs in the maritime industry has led to a substantial increase in containership size over the past 50 years. Operational costs are dominated by fuel costs, thus carrying more containers whilst burning the same amount of fuel, makes the operational costs per transported container decrease. This hopefully leads to a higher profit and better competitiveness.

Although ULCS do represent a substantial reduction in operational costs, the downside of these vessels - of nearly 400 m in length - is the impact of ship motions and slamming on the construction of the vessel. These ULCS need to withstand enormous forces acting on the hull, which are the result of slamming impacts on the bow and aft body, and these cause whipping and springing effects.

Model tests versus FEA and Class rules A containership of 400 m in length has huge cargo holds and a relatively weak construction. So to what extent do Class rules consider the fatigue and extreme loads and how well do they match the actual loads on the vessel? MARIN was asked to compare the model test results with Class rules and Finite Element computations carried out by MARIC.

10-segmented ship model Slamming impacts of high waves cause extreme loading on the hull, but even low wave impacts contribute to damage to the construction, so-called fatigue loading. The response of the hull structure on the wave frequency components is largely understood. However, there is a great deal of uncertainty surrounding the effect of springing and whipping on the lifetime

Figure 1: Shape of the 3-node vertical bending mode

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