Fatigue design of the connection between ship hull and modular staircase made of steel sandwich
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Helsinki University of Technology |
Diplomityö
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Kul-24
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en
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65 s. + liitt. 25
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Abstract
The purpose of the study is to understand the behaviour and calculate the fatigue lifetime of the connection between the staircase module made of steel sandwich and conventional steel structure. Furthermore the fatigue lifetime is calculated for the connection. The analysis is made for two different connection designs. To get a comparative result the fatigue lifetime is calculated according to the geometrical and effective notch stress approaches. The analysis procedure consists of different stages. First the data from existing global FE analysis ship model is obtained. The data is used in the next stage, where the staircase model made of steel sandwich is modelled for FE analysis with the surrounding bulkheads. From the critical area obtained in the second stage two local FE models with different designs are made. According to local model's results fatigue analysis is carried trough. The comparison of the results obtained with different methods support the need for precise methods when fatigue analysis is under consideration. The difference was several times, though the result received with less precise method was feasible, because the fatigue lifetime received with this was smaller than the result received with the other method. The reason for it is the approximation and linearization of stresses in less precise method. Suggestions for further investigations are also given to understand the behaviour of the whole module if fatigue lifetime is under consideration.Description
Supervisor
Varsta, PetriThesis advisor
Niemelä, AriNaar, Hendrik