Analysis of accidental iceberg impacts with large passenger vessels
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- Institutt for marin teknikk 
The number of collisions between ships and ice are increasing with the increaseof ships sailing in Arctic areas. It is necessary to research on large passenger shipssubjected to iceberg impact, since it may cause huge human life loss.The method to design ice going ship nowadays is presented. The conventionaldesign of ship structures is carried out in the ULS format. But the design of ship-icebergimpact scenario should fall into ALS design, due to its rare and large loadproperty. ULS design for ship-iceberg collision will yield over-designed structures.The method to get the design ice load according to IACS Polar Class rules isintroduced. The design method is based on simplified method and it doesn t takethe ship-iceberg collision into consideration.For engineering calculations it is common to decouple the collision event intoexternal and internal mechanics. The basic ideas about splitting the impact processinto these two parts is introduced. Some numerical simulation cases in Liu s paperare also presented to give a more clear introduction. The internal mechanics dependson the relative strength of the ship structures and Iceberg, so it is necessaryto establish an accurate ice material model. The most important mechanical andphysical properties of ice are described. The material model for iceberg developedby Liu is also presented. The numerical simulation using this ice material is alsopresented to show that this ice material model is validated.The major work in this master thesis is to establish an FE model for both shipstructures and ice floe, and then run impact simulations in Ls-Dyna. The establishmentof FE model of ship structures and Ice floe is introduced in detail. Theimpact analysis setup in Ls-Dyna prepost is also presented. Some key points abouthow to get appropriate numerical simulation results are presented for anyone whowants to do this kind of analysis again.The simulation results are presented in detail. Basically, the ship is designedwith enough resistance against ice floe impact load. The ship can crush the icecompletely without being significant damaged. One simulation was run using rigidmaterial, and the ship shell was easily penetrated. The damage pattern of the shipstructures is analyzed for this simulation. Some simulations were run with an error,which makes the ice uncrushable. In these cases, the ice floe will cause significantdeformation on the ship shell but not penetrate it. The results are also presented tomake a comparison with the crushed ice.