中文摘要：

海洋结构物的疲劳寿命预报是当前的研究热点，文章根据第二作者率领的课题组提出的海洋结构物疲劳寿命预报统一方法比较了疲劳裂纹扩展模拟的三种数值积分方法：逐周数值积分法、△N积分法和△口积分法，并分析了每种方法的适用条件。随后，以中心表面裂纹承受单向交变拉伸载荷的平板为例，分别运用三种方法计算了裂纹扩展寿命和最终裂纹尺寸。同时，研究了△N和△a取值不同对结果的影响。最后，综合考虑计算耗时和计算结果精度，给出了△N积分法和△a积分法的建议值，即△NIN≤1．0％，△a≥O．1mm。

英文摘要：

Based on a unified fatigue life predcition （UFLP） method for marine structures developed by the second author＇s group, three numerical integration methods are compared to simulate fatigue crack propa gation： cycle by cycle integration method, integration method by △N, integration method by △a. The applicable conditions for each method are also discussed. An example of a plate with a center surface crack sub jected to remote fatigue loading is chosen to demonstrate the calculation of crack propagation life and final crack sizes using each method. And, the influence of different values of △N and △a on the calculation re suits is analyzed. Considering the computation time and accuracy comprehensively, suggested values for integration methods by AN and Aa are given, namely ≤NIN≤ 1.0%, ≤a≤0.1 mm.