考虑腐蚀磨损的锚链疲劳损伤评估方法

Fatigue Damage Estimation Method for Mooring Chains Considering Corrosion and Wear

由于风浪流联合作用和海洋平台的周期性往复运动,系泊锚链受到交变循环载荷作用易发生疲劳破坏,同时系泊锚链遭受严重的腐蚀和链间磨损作用,其强度逐渐减弱,因此提出一种系泊锚链全生命期考虑腐蚀和磨损的疲劳损伤评估方法。首先,根据实际海况完成系泊锚链全生命期的损伤演变计算;然后,使用各损伤模型采用热点应力法计算得到热点处应力集中系数;最后,根据张力时程曲线和链间转角时程曲线,采用雨流计数法完成疲劳损伤评估。计算结果表明,腐蚀和磨损导致锚链疲劳损伤程度逐渐加剧。提出的评估方法具有优良的实用价值和工程意义。

It is easy to be fatigue damage of the mooring chains in the marine environment because of alternating cyclic loading,which is caused by the combined action of wind,wave and periodic reciprocating motion of the offshore platform.At the same time,the strength of mooring chains gradually weakens because of suffering from severe corrosion and interlink wear.Therefore,a fatigue damage assessment method of the mooring chains during the lifetime considering corrosion and wear is proposed.Firstly,the cumulative damage of corrosion and wear of the mooring chains during the lifetime is calculated based on actual sea conditions.Then,the hot spot stress method is employed to calculate the stress concentration factor at the hot spot using each damage model.Finally,according to the tension time history curve and interlink angle time histories curve,the rain flow counting method is employed to complete the fatigue damage assessment.The results show that corrosion and wear cause the fatigue damage of the chains to gradually worsen.The assessment method proposed has excellent practical value and engineering significance.