基于断裂力学开发了一种的系泊系统疲劳评估方法，并对某浮式结构进行了基于S-N曲线和断裂力学方法的系泊系统疲劳分析。分析中将低频和波频载荷过程视为两个独立的随机载荷过程，计算了低频和波频运动所激发的系泊张力，并通过双窄带载荷组合方法耦合分析了系泊系统张力范围。随后用两种方法分别估算了系泊系统疲劳损伤，对比认证了基于断裂力学的系泊系统疲劳评估方法的可行性。结果表明，如果将挪威船级社建议的安全系数应用于基于S-N曲线的疲劳评估，则两种方法预测的疲劳寿命具有一定的可比性。然后，将所开发的系泊疲劳评估方法应用于受平面外弯曲（OPB）影响锚链的疲劳问题。结果表明，受平面外弯曲影响后的5袋、7袋和9袋链轮上系泊锚链疲劳寿命分别了降低19%、 11%和9%。

A fracture mechanics based approach for offshore mooring fatigue assessment was developed. Then both S-N curves and fracture mechanics based fatigue analysis for the mooring system of a floating offshore structure were carried out. The low frequency and the wave frequency load processes were regarded as two random load processes for calculating the tensions along mooring lines excited by motions of low frequency and wave frequency. The dual narrow band method was then performed for combining the mooring line tension ranges， and the fatigue damage of mooring lines was estimated by both S-N curves and fracture mechanics based approaches. A comparison between S-N curves based fatigue assessment approaches and the developed fracture mechanics based mooring fatigue assessment approach was made， and the results showed that fatigue lives estimated by these two approaches were generally comparable if the safety factors suggested by DNV were applied to S-N curves based approaches. The developed fracture mechanics based mooring fatigue assessment approach was then applied for mooring chain links subjected to out-of-plane bending （OPB）. The result showed that the fatigue life of mooring chains on 5， 7 and 9 pocket sprockets affected by out-of-plane bending was reduced by 19%， 11% and 9% respectively.