Sternship structure analysis for podded RoPax vessel
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Helsinki University of Technology |
Diplomityö
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Author
Date
2007
Department
Major/Subject
Laivanrakennusoppi
Mcode
Kul-24
Degree programme
Language
en
Pages
70 s. + liitt.
Series
Abstract
The purpose of the study is to develop a structural arrangement for the sternship region of a single-podded RoPax ship and additionally the feasibility to use twin-podded and CRP propulsion as an alternative solution in the same construction is studied. In the study a typical RoPax vessel is used. The most efficient way to fit Azipod propulsion into a RoPax vessel is above the maindeck. As twin-podded propulsion is too space-consuming and many lane meters will be lost, it is not used in calculations. As only Azipod region is studied, 18 m of sternship is considered in the analysis. FE-models of sternship are created and the missing structural areas are compensated by boundary conditions. Four different Azipod mounting block stiffening systems and three loading conditions depending on Azipod turning angle are applied to the model. This gives all together 36 different cases, which are studied. Values of equivalent stresses and deflections are calculated by FE-code FINNSAP. The biggest deflection value is obtained in case of CRP propulsion, when 8/45° frames stiffening system was used. It occurs at the mounting block, bottom shell and floors near to the mounting block. Also maximum Von Mises stresses exist in the mounting block region. In single-podded propulsion system with lower strut height (Hs.) all four stiffening systems are fulfilling the requirements for stresses according to class rules. Comparing with single-podded with higher strut height and CRP propulsion, this number is respectively three out of four and two out of four. To find the best stiffening system for CRP and single-podded propulsion system, the weight of mounting block polar arrayed structural elements is calculated and compared with maximum stresses. The bigger the speed is the more polar arrayed structural elements supporting the mounting block are needed. After 12 polar arrayed supports, the most efficient way to reinforce is increasing the bottom and maindeck plating thickness.Description
Supervisor
Varsta, PetriThesis advisor
Hakulinen, PetriNaar, Hendrik
Keywords
Azipod, CPR, finite element analysis, pod, RoPax, forces
