| As a new fourth-generation wind turbine installation vessel,the 20 WM wind turbine installation vessel has the characteristics of strong lifting capacity,large loading capacity,and deep working water,which has played a role in promoting the development of the wind power industry in the future.The wind turbine installation vessel is affected by the combined action of wind,wave,and current environmental loads and additional loads in the marine environment,which affects the safety and stability of the operation.Moreover,under the influence of wave load and operation lifting,the key nodes of the leg produce alternating stress,which causes structural fatigue damage and destroys the safety of the structure.In addition,the spudcan is located at the bottom of the leg structure,which reduces the depth of the leg into the mud and ensures the overall safety and stability of the structure.The strength of the spudcan plays a vital role in the operation and safety of the wind turbine installation vessel.Therefore,it is necessary to study the strength and fatigue characteristics of the key structures of the wind turbine installation vessel.In this thesis,the leg and spudcan of a 20 MW wind turbine installation vessel are taken as the research object,and the key structural strength evaluation and fatigue characteristics of a wind turbine installation vessel are studied in combination with the BV specification.The main research contents are as follows:Firstly,the research on the strength of truss leg structure is carried out.The integrated finite element structure model of the wind turbine installation vessel is established,and SESAM software is used to select different working water depth conditions and self-survival conditions.Combined with the empirical formula,the wind load is directly calculated,and the design wave method is used to analyze and calculate the wave current load on the leg structure.By carrying out structural dynamic analysis and static analysis,the dynamic amplification effect is studied,and the calculation of additional load is completed.According to the BV specification,the strength of the leg structure and the anti-overturning stability of the structure are evaluated,and the structural strength and anti-overturning stability are determined to meet the requirements of the specification.Secondly,the fatigue characteristics of key joints of the truss leg structure are studied.Based on the spectral analysis method,the high-cycle fatigue of the leg structure under the conditions of migration,operation,and self-existence is studied.The fatigue damage to the leg is calculated using the fatigue analysis module of SESAM software.The structural refinement study is carried out on the serious fatigue damage areas(the connection area between the leg and the main hull and the splash area in the contact between the leg and the sea level).Combined with the fatigue theory,the direct calculation method is used to study the low-cycle fatigue damage of the leg structure under the influence of lifting operations.By evaluating the fatigue damage degree of the leg structure under different working conditions and different loads,the overall fatigue life of the leg is evaluated.The results show that the fatigue life of the leg meets the design requirements.Finally,the structural strength of the new spudcan under typical working conditions is explored.Combined with the overall strength calculation results of the leg structure,the maximum support reaction force is selected as the external load to study the stress and deformation of the spudcan structure under preloading,pile pulling,and eccentric conditions and complete the structural strength check,which provides reference for the optimization of spudcan structure design in the future. |
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