Study On Fatigue Damage Of Stinger Based On Health Monitoring

The development of offshore oil and gas has received great attention and has gradually developed into deeper and deeper water.The ultra-deep-water pipe-laying ship came into being.As the key equipment of S-Lay pipe-laying,the stinger rack withstands complex environmental loads such as wind,waves and currents,hull motion excitation,laying tension,and non-uniform contact force between the roller and the pipe.With the development of water depth,the stinger continuously lengthens and its dynamic load increases gradually.The structural fatigue problems that need not be considered in shallow water operations are beginning to attract people's attention.In this paper,based on the research project of health monitoring and early warning system of the stinger of "HYSY201" deep-water pipe-laying ship,the fatigue damage of the stinger is analyzed based on the measured data of monitoring points.Therefore,it has very important engineering significance for the safe operation of the stinger.The main research contents and research results include:(1)Introduced the general situation of health monitoring and early warning system,as well as the methods and procedures for the realization of structural fatigue warning;(2)The fatigue damage degree of effective monitoring points is calculated based on the monitoring data,and the response disciplinarian of the stinger structure is analyzed from the statistical eigenvalues,time domain and frequency domain.The results show that the stinger meets the safety requirements in this operation.However,the non-stationarity of stress and fatigue exposed by the stinger structure during the pipe-laying operation needs attention.(3)The time-domain analysis and spectrum analysis of the tension and the non-uniform contact force of the roller were carried out to investigate the effect of the work load on the structural fatigue damage in the pipe-laying operation.The results show that under ideal working condition,both belong to the low frequency dynamic load which is not easy to damage the structure.However,it is necessary to pay attention to the amplification effect of the dynamic loads on the structural fatigue damage in the marine environment.(4)The fatigue spectrum analysis of the stinger and the fatigue analysis based on the monitoring data are compared from the two aspects of principle and calculation,to summarize the advantages,disadvantages and applicable conditions of the two methods.Reasonable suggestions for the safe operation of the stinger are provided.