基于断裂力学的船型网箱疲劳损伤评估研究

目的 结合断裂力学,通过直接计算方法进行海洋结构物疲劳损伤评估研究。方法 运用有限元方法,并通过谱分析进行结构强度评估,找到结构热点应力。对热点进行局部精细建模,运用断裂力学方法进行疲劳裂纹扩展,进行海洋结构物疲劳损伤评估。结果 通过水动力分析表明,船型网箱在波浪入射角为0°及180°时,运动幅值最大。通过直接强度计算,验证了网箱满足强度要求,但存在明显的应力集中现象。选取3个疲劳热点进行裂纹扩展,得到其疲劳寿命分别为11.3、17.3、33.1 a。结论 实现了基于断裂力学的海洋结构物强度分析与寿命预测,解决了海洋结构物疲劳损伤评估中计算效率与精度的平衡、整体模型与局部裂纹的耦合等问题。

Fatigue Damage Assessment of Ship-shaped Net Cages Based on Fracture Mechanics

The work aims to evaluate the fatigue damage of marine structures through fracture mechanics and direct calculation methods. Structural strength assessment was performed by the finite element method and spectral analysis to find out the hot-spot stress. Local refined modeling was used for these hot-spots, and fatigue crack growth was evaluated by fracture mechanics methods to assess the fatigue damage of marine structures. The results showed that the ship-shaped net cage exhibited maximum motion amplitude when wave incidence angles were 0° and 180° and met the strength requirements but showed significant stress concentration. By selecting three fatigue hot-spots for crack propagation analysis, fatigue lifespans of 11.3 years, 17.3 years, and 33.1 years were obtained. This study successfully achieves strength analysis and lifespan prediction of marine structures based on spectral analysis and fracture mechanics, addressing the balance between computational efficiency and accuracy in fatigue damage assessment of marine structures as well as the coupling of overall models and local cracks.