System Reliability Analysis Of Suction Anchor Under Rare Fault Samples And Common Cause Failure

The suction anchor system is a new type of anchoring foundation.It has many advantages such as convenient installation and recovery,high economy,strong bearing capacity,and reusability.It is widely used in the mooring of offshore mining platforms,water launch platforms,large ships,and other equipment.The suction anchor system is a large-scale complex system that couples mechanical,electrical,and hydraulic systems.Its system components are numerous and most of them work in harsh environments.Once a fault occurs,it will have a serious impact on the safety and stability of the water platform.Therefore,it is necessary to carry out the system reliability analysis of the suction anchor system to reduce its failure probability.The system reliability analysis of suction anchors is gradually carried out under the vigorous development of marine equipment,but it still faces problems such as scarce fault data,unclear understanding of structural principles,and complex failure modes.In this regard,this thesis will start from the key system and fault pattern recognition,weak link identification and reliability prediction,and carry out the system reliability analysis of suction anchor under rare fault samples and common cause failure.The specific results include :(1)Fault tree analysis of suction anchor system based on similar product data is carried out.Based on the multi-source information of the whole life cycle of the suction anchor system,including design parameters,working environment and system structure,the fault tree model of the suction anchor system is built.Aiming at the problem of scarcity of basic fault unit data,the failure rate of basic fault units of similar products is collected,and the quantitative analysis and importance analysis of the fault tree is carried out.Based on the results of fault tree analysis,the weak links under typical working conditions are determined,the fault mechanism of the weak links is identified,and the probability of the whole system and key components is obtained.(2)Bayesian network analysis of suction anchor multi-stage mission system under common cause failure is carried out.Aiming at the common cause failure in the suction anchor system,the common failure causes of the basic fault units of the system are identified,and the Bayesian network model of the common cause failure of the suction anchor system is established.Aiming at the multi-stage characteristics of the working task of the suction anchor,the Bayesian network model of the suction anchor system of each stage task is integrated,and the reliability analysis of the suction anchor multi-stage task system under common cause failure is carried out.According to the Bayesian network reliability analysis results of the suction anchor system,the fault avoidance measures and maintenance suggestions are formulated.(3)The system reliability analysis of suction anchor under the influence of typical external factors is carried out.Aiming at the problem that the suction anchor system is susceptible to external harsh environmental factors,several typical external factors are identified.Based on the failure mechanism of suction anchor system affected by external factors,the reliability analysis method of suction anchor system under the influence of external factors is proposed.The failure probability model of the suction anchor system under the influence of external factors is established to accurately measure the influence of external factors on the reliability of the suction anchor system.The reliability analysis results can provide theoretical support for the reliability verification of the suction anchor system in the design stage.