| In recent years,with the rapid development of offshore wind power,offshore wind power ship market has also become stronger.In order to realize the effectiveness and safety of wind farm maintenance,it is necessary to design and build special operation and maintenance ships.At present,most of the ships used for offshore wind power operation and maintenance are conventional catamarans and trimarans,and some drawbacks have been found in the implementation process.This thesis aims at the inherent defects of conventional catamarans,and proposes a new asymmetric catamaran wind power operation and maintenance ship based on the trimaran,which combines the advantages of conventional catamarans and trimarans,and is suitable for wind power operation and maintenance work.Because the asymmetric catamaran has different structural characteristics from the conventional ships,the safety and stability of the structure should be ensured in the process of design and construction,and the key to ensure the safety of the hull structure lies in the correct structural design and strength analysis.Based on the design wave method,the structural design calculation and strength analysis of a new asymmetric two-hull wind power operation and maintenance ship are carried out in this thesis.The main research contents are as follows:First,the determination of wave load is a crucial step in the whole ship finite element calculation.The Hydro D module of SESAM software is used to analyze the ship motion and wave load characteristics under regular waves.Combined with the coastal wave distribution diagram,the long-term prediction results of characteristic loads of typical profiles of asymmetric catamarans are obtained.The advantage of using design wave method to determine ship wave load is that it can simulate the real sea state with less work,which makes the finite element calculation results more real and reliable.Secondly,according to the "Classification and Construction Code for Maritime Highspeed Vessels"(2022),the hull structure design is carried out based on the type diagram and general layout.The main hull and small side body refer to the high-speed conventional catamaran.Due to the asymmetric distribution characteristics,the connection mode between the two hulls should be mainly considered during the design and construction process.Two different structural schemes of the connecting bridge are designed: Scheme one is plate-frame type-single-layer connecting bridge,scheme two is box-type-double-layer connecting bridge.After calculating and determining the structure size,the basic structure drawing and typical cross-section drawing and other structural diagrams are drawn.Then,the finite element model of the whole ship is established by using the SESAM software Geni E module.Seven calculation conditions are designed according to the structural characteristics of the asymmetric catamaran and related specifications.The stress response of the structure is calculated by using the SESAM software Sestra module,and the stress distribution of each working condition is viewed by Xtract.According to the results of stress distribution nephogram,structural scheme 2 is selected.Finally,the optimal design is carried out for the connecting bridge parts with high stress level in the second structural plan.Three optimization ideas are proposed for the connecting bridge,a total of six structural optimization plans for structural adjustment,and the structural strength of the adjustment plans is calculated respectively.Finally,according to the structural quality and stress level,the asymmetric catamaran structure plan with better quality and strength is obtained.The research content of this topic not only has important theoretical significance and practical value for the development of wind power operation and maintenance ship field,but also the research results of this thesis have certain guiding role for the design and practical engineering application of asymmetric catamaran in the future. |
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