Modeling and Simulation of a flexible Damper during Ice in Propeller Impacts
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- Institutt for marin teknikk 
In the beginning the problematic of ice impacts on a ships drive train and thesimilarity of this work to last year's thesis from Bjørn Eliassen Vik is mentioned.After that the Bond-Graph-Methodology on which this thesis is based in shortlyexplained. Then the modeling of the coupling is explained. Here the couplingis divided into parts and modeled separately. A particular interest is on thedynamic behavior of the springs. These parts are then joined together. Inthe next chapter the coupling model is compared to the values given by themanufacturer. It shows that the model is too stiff. Therefore the thickness ofthe springs and the bulk-modulus of the oil is adjusted until it matches thetemplate.The model is than tested by varying the excitation frequency, the resistance ofthe load and the inertia of the coupling. It shows that the frequency has a greatinfluence on the stiffness of the system, the resistance a limited influence andthe inertia an influence on the nominal frequency of the system.In the end the coupling is inserted into a drive train model. First it is simulatedin open water, than an additional ice load is placed upon the propeller. Theresults are compared to simulations of the drive train with a simpler couplingand without a coupling. The results show that both couplings have dampingcapabilities. However, the ice load is too little to determine the effect of suddenpeak loads properly.