Fatigue Analysis For Jack-up In Later Service Period

Jack-ups always suffered heavy wind and wave loads.Especially for the one which was in its later service period.The strength and fatigue analysis was no longer reflected the true situation of the platform.So it was necessary to calculate the life time of the platform.Now,SACS was always used to compute the fatigue life of the platform but in some cases the results are not accurate.In this paper,a finite element model was built by ABAQUS with aged problems.Based on the simple evaluation of the static strength,the natural vibration characteristics and the dynamic response of the platform,the more dangerous areas are analyzed.And then Used Python to write the method of rain flow counting and the formula of the fatigue calculation.The research shows that the jack-up platforms had the basic ability to meet the requirements of the static strength and the self vibration characteristics.Compared with the models in different age,The aging effect was not obvious in the former service period due to the protective measures.But in the post service period(about 15 years later),the effect of corrosion and aging on the fatigue damage accumulation was significantly increased and had a great influence on the fatigue life.