基于随机过程理论的舰船结构时变可靠性分析

针对疲劳和腐蚀对舰船结构强度的影响,提出一种结构时变可靠性的评估方法.根据舰船在服役期间的载荷环境特点,采用断裂力学及一般腐蚀原理,研究了其在疲劳和腐蚀作用下总纵强度随时间的变化,基于随机过程理论,建立了船体梁截面模量的随机时变模型.然后应用上穿率分析,结合并联系统的可靠性分析方法对舰船结构的时变可靠性进行了计算和分析.该分析方法既能体现疲劳和腐蚀因素导致的船体梁可靠性的时间连续性,又避免了数值积分,因此简单可行.通过算例与年度瞬时可靠性进行比较,表明该方法能更精确地预测在役舰船的时变可靠度从而为服役舰船的可靠性、维修性、保障性决策提供参考.

Time-dependent reliability analysis of ship structure based on random process theory

We propose a method for time-dependent reliability assessment of hull girders affected by fatigue and corrosion.After researching characteristic loading of hull components of ships in service,typical variations in strength over time due to fatigue and corrosion were analyzed by applying fracture mechanics and general corrosion theory.Then a time-variant model for a ship's hull modulus was formulated based on random process theory.The time-dependent reliability of ships was analyzed with up-crossing analysis and the reliability method of parallel systems.This analysis effectively reflects time dependant changes in reliability of ships affected by the joint action of fatigue and corrosion.No numerical integration is necessary,so it is easy to use.Furthermore,results for time-dependent reliability and annual instantaneous reliability were compared with practical examples.The results indicate that the time-dependent reliability of in-service ships' structures can be predicted using the proposed method in a more reliable way,and it can also provide some references for decision-making on the reliability,maintenance,and safety of ships in service.