近海风机支撑结构的谱疲劳分析

Spectral fatigue analysis of a support structure for offshore wind turbines

以某2 MW近海风机单桩式支撑结构为研究对象,采用谱疲劳分析法进行了疲劳分析。首先通过风机正向设计专业软件S4WT对支撑结构进行风浪联合作用下的动力响应分析;其次选取塔架和基础连接处作为疲劳热点位置,在MATLAB中编程得到热点位置处的应力响应谱;然后根据应力响应谱的统计特性得到应力范围短期分布的概率密度函数,结合各短期海况出现的概率得到应力范围的长期分布;最后基于线性疲劳累积损伤理论和S-N曲线计算出结构总的疲劳损伤度和疲劳寿命。结果表明:热点处的疲劳寿命满足风机设计寿命的要求。谱疲劳分析法能够充分考虑风机载荷与波浪载荷的联合效应,对实际工程应用具有一定的指导作用。

Fatigue analysis of a monopole support structure of 2 MW offshore wind turbine is demon- strated. Spectral fatigue analysis approach is adopted. The dynamic response of offshore wind turbine supporting structures due to wind and wave loads is calculated by the professional wind turbine design software S4WT. The joint of tower and foundation is chosed as fatigue hot spot location.The hot spot stress response spectrum is obtained with MATLAB. The probability density function of stress range of short-term distribution is acquired according to the statistical features of the stress response spectrum. Stress range of long-term distribution is acquired based on the short-term seastate probability.The total fatigue damage and fatigue life of structures is computed based on the linear fatigue cumulative damage theory and the S-N curve. The results show that the fatigue life of the hot spot satisfies the design fa- tigue life. This method can give full consideration of the joint effect of the wind turbine loads and wave loads, and it can provide certain guidance for practical engineering applications.