Fatigue Life Analysis Of FDPSO's Typical Structures

FDPSO is an advanced version of FPSO, adding drilling equipments to the moonpool of the FPSO hull and therefore it enhanced the drilling ability. It can go on production in the wake of drilling. FDPSO has a strong ability to work under atrocious surroundings and is more appropriate to work in deep water. Thus as it can be predicted, FDPSO have a bright commercial prospect.Fatigue damage is one of the major causes which lead to the structure failure in the Shipping and Ocean Project, and has long been a hit spot of research. FDPSO, in his full life cycle, is more often a eternal mooring and imporssible to dock for maintenance. Fatigue exists through all the working life. Moreover, the terrible working environment, in addition to the continuous withstanding of the varying tiding effect and constant loading and unloading as well as the extensive usage of higher tensile steel in the hull structures make the problem more serious. As a result, fatigue design should be made more strictly. The average fatigue life span is 20-25 years but that of FDPSO could be expanded to 40-45 years.The paper analyzes the fatigue strength of a big FDPSO according to the regulations about ship hull fatigue strength calculation in DNV Code. It also uses the finite element analysis software ANSYS modeling the moon pool structure and gives assumptions based on consulting references which not given by DNV. Then it validates the assumption's rationality. At the end, the thesis gets meaningful conclusions through researching the fatigue strength and provides reference for construction of FDPSO.