船舶在恶劣海况下会受到低频波浪载荷的作用，船体主机基座结构常处于交变应力状态，同时持续性工作的主机会对主机基座产生高频主机振动载荷作用，可能会带来主机基座结构的疲劳破坏。为了探究高低频载荷耦合作用下的疲劳损伤计算，提出一种计及主机振动载荷的高低频载荷联合作用下主机基座疲劳强度计算法。首先，采用线性频域的谱分析法直接计算波浪载荷作用下的主机基座结构热点疲劳损伤；然后采用时域分析计算法和S-N曲线计算出主机振动载荷作用下的热点疲劳损伤。最后，结合双峰谱疲劳计算理论，对高低频载荷耦合作用下的应力响应谱进行计算，提出一种计及主机振动载荷的高低频载荷联合作用下主机基座疲劳强度计算法。结果显示，相比较将2种载荷作用下的疲劳损伤直接叠加计算法，考虑2种载荷耦合的计及主机振动载荷的高低频载荷联合作用下主机基座疲劳强度计算法得到的疲劳损伤结果其损伤度约增加了15%～50%。研究表明，对航行在恶劣海况下的船舶局部主机基座结构进行疲劳评估时，使用所提方法可以提高疲劳损伤计算的准确性。
Ships sailing in bad sea conditions will be affected by low-frequency wave load, hull main engine base structure is often in the state of alternating stress, while the continuous operation of the main engine will produce high-frequency vibration load on the main engine base, which may bring fatigue damage to the main engine base structure. In order to investigate the fatigue damage calculation under the coupling action of high and low frequency loads, a new fatigue strength calculation method of the main engine base under the combined action of high and low frequency loads and the vibration load of the main engine is proposed. Firstly, the hot spot fatigue damage of the host base structure under wave load is directly calculated by using linear frequency domain spectral analysis. Then the time-domain analysis and S-N curve are used to calculate the hot spot fatigue damage of the main engine under vibration load. Finally, combined with the bimodal spectrum fatigue calculation theory, the stress response spectrum under the coupling action of high and low frequency loads is calculated, and a fatigue strength calculation method of the host base is proposed, which takes into account the vibration load of the host. The results show that compared with the direct superposition calculation method of fatigue damage under two kinds of loads, the fatigue damage results obtained by the combined calculation method of high and low frequency loads considering the coupling of two kinds of loads and the vibration load of the main engine are about 15%~50% higher. The results show that the proposed method can improve the accuracy of fatigue damage calculation when evaluating the local main engine base structure of a ship sailing in bad sea conditions.
2023,45(21): 137-143 收稿日期：2023-6-13
DOI：10.3404/j.issn.1672-7649.2023.21.025
分类号：U661
基金项目：航运技术与安全国家重点实验室、交通行业重点实验室开放课题基金项目
作者简介：张甫杰(1983-)，男，副研究员，研究方向为风浪流水池试验
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