老龄半潜式钻井平台节点疲劳裂纹扩展寿命预报

Fatigue crack growth life prediction for a welded detail on an ageing semi-submersible platform

通过结合常规谱疲劳分析方法和裂纹扩展分析方法,给出了一种工程实用的评价老龄平台节点裂纹扩展寿命的方法,并以某一平台为例进行了验证计算。首先,基于谱疲劳分析得到各个节点在过去30年的节点疲劳损伤,然后,对损伤接近或大于1.0的节点进行基于单一曲线模型的裂纹扩展分析,以求得该节点在目前状态下裂纹扩展寿命。结果表明,目标平台计算疲劳热点满足继续使用的要求。此外,针对不同初始裂纹尺寸时的裂纹扩展寿命计算结果表明初始裂纹尺寸对疲劳裂纹扩展寿命影响很大。

Based on the traditional fatigue spectral analysis and fracture mechanics analysis, a method to predict the fatigue life of an old drilling platform was provided and applied to a semi-submersible platform. First, the fatigue damage of hot spots during the past 30 years was obtained by using traditional spectral fatigue method, then the fatigue crack growth life was predicted for those hot spots with damage close to or larger than 1.0 by using the unique curve model. The results showed that the fatigue strength of the discussed spots met the requirements. By comparing the fatigue life of welded detail with surface cracks of different initial sizes, the conclusion that the initial size of the crack had a significant impact on the fatigue crack growth life was obtained. The conclusions and method of tatigue life prediction will be heloful for the life-extension of old mobile drillinz units.