基于谱分析法的深水半潜式平台疲劳强度分析

以某新型深水半潜式钻井平台为分析对象,依据三维绕射理论计算单位波幅下波浪诱导载荷,通过建立三维有限元模型计算完成了热点应力响应。运用热点应力的谱分析法计算得到危险节点的疲劳寿命,并进一步分析了各个短期海况和不同浪向对节点总的疲劳损伤度的贡献。研究结果表明,危险节点的疲劳寿命都满足设计寿命要求;在各种中低海况下,疲劳损伤主要来自于平均跨零周期在6 s附近,有义波高转大的短期海况;平台关键连接部位的疲劳损伤主要是在横浪和斜浪状态下产生的,并且对某单一方向的波浪非常敏感。此研究对该类型平台的连接处结构设计和疲劳分析方法有参考意义。

Spectral-based fatigue analysis of a deep-water semi-submersible platform

Fatigue analysis of a deep-water semi-submersible platform is demonstrated.Unit amplitude wave introduced loads are calculated by means of three-dimensional diffraction/radiation method.Hot spot stress response is obtained by calculation based on three-dimensional FEM structural analysis model.Fatigue life of critical joints is evaluated based on spectral-based method,and what’s more,the contribution of short-term waves and wave directions to fatigue damage is evaluated.The results show that the fatigue life of the key spots satisfies the design fatigue life.In the case of lower sea states,the fatigue demage is mainly made by the sea states whose Tz are near 6 s and the Hs are higher.In addition,the fatigue damage is mainly made by transverse waves and oblique waves and is very sensitive to some single-direction waves.The research is helpful for the structural design of the joints and the research on the fatigue analysis method of similar kind of platforms.