Yielding And Buckling (FE) Analysis Of Offshore Wind Turbine Installation Ship (OWTIS) As Per ABS And DNV Rules

The trends in ship design process are changing from the Rule Based Design to Analysis BasedDesign due to the fast development in the computers’ hardware and software capabilities.Although the Analysis Based Design Approach; based on Finite Element Analysis of the shipstructures can be totally relied upon, Rules Based Design Approach; for its centuries old in-field and experimental evolution and in-depth inclusion of around the globe ocean knowledgehas its own irreplaceable place. Our goal from the current work is to combine these twoapproaches to account for all the factors affecting the safety and performance of the structurethroughout its life, and a synthesis of this information, together with the goal or objectivewhich the structure is intended to achieve, to produce that design which best achieves theobjective and which provides adequate safety.This present work is aimed to combine Rule Based Approach with Finite Element AnalysisTechniques, wherein the Rules are employed at Load Calculation and Result Evaluationstages, while the FEA is used in Load Application and Analysis stages. Loads including theStructural Weight, Forces due to Cargo (Wind Turbine Equipment) Weights, Static SeaLoads/Pressures and Dynamic Sea Loads/Wave Loads are applied on structure. The structuralanalyses are done using AQWA and ANSYS software. ABS and DNV standards are used forthe purpose of guideline in loading calculations and analysis.Two load scenarios are being considered to be calculated by rules and analyzed with the helpof different FEA techniques. One is at Full Load Condition with maximum draught and thesecond is with no load, Normal Ballast Condition at minimum draught.In the Calculation Phase, extensive calculations are carried out for each load scenario for eachof the load cases for both the ABS and DNV rules.In the Modelling Phase, a Finite Element Model of the complete OWTIS has been built tocapture the Hull Girder Response sufficiently and accurately.In the Load Application Phase ANSYS Parametric Design Language (APDL) has been usedand programs are written for the application of each load scenario’s tabular loads/pressures.In the Evaluation Phase, Analysis of the structure to determine Structural Response i.e.Stresses and Deflections is performed. Subsequent comparison of the results with the givencriteria in the rules and with the allowable material stresses/deflections is performed, and ithas been verified that the ship’s conversion from a bulk carrier to OWTIS can be validated bythe ABS and DNV Rules.