Offshore wind turbines are subjected to cyclic loading conditions during their operational lifespan which is typically between 20 and 25 years. An important issue in fatigue design and integrity assessment of offshore wind turbine foundations is the examination of the long-term fatigue and corrosion-fatigue behaviour of steel structures in the high cycle region. High cycle fatigue tests, particularly at low frequencies in a seawater environment, are time-consuming and costly. Therefore, there is an essential need to perform accelerated tests to predict the long-term behaviour of the structures under realistic operational loading conditions. In this work, the existing fatigue acceleration mechanisms have been reviewed and a novel methodology has been proposed for accelerated testing and analysis of fatigue data in different environments (i.e. air, salt-spray and seawater) at higher temperatures. Two distinct equations have been developed and proposed for the calibration and prediction of S-N fatigue life and crack growth behaviour of steels in different environments. The proposed methodology has been validated through comparison with the existing data in the literature and predictions have been made at operational temperatures using high temperature data. The proposed approach is relatively simple to calibrate for a material of interest and enables accelerating S-N fatigue and crack growth testing of the examined materials by a factor of two and three, respectively. The proposed methodology and the obtained results have been discussed in terms of the need for accelerated testing for fatigue design and integrity assessment of offshore wind monopiles, especially those which are close to the end of initial design life and need a comprehensive engineering analysis for life extension or decommissioning.

海上风力涡轮机在其使用寿命（通常为20到25年）之间会承受周期性的负载条件。海上风力发电机基础的疲劳设计和完整性评估中的一个重要问题是检查高循环区域钢结构的长期疲劳和腐蚀疲劳行为。高周疲劳测试，特别是在海水环境中的低频下，既费时又费钱。因此，迫切需要进行加速测试以预测结构在实际操作载荷条件下的长期行为。在这项工作中，对现有的疲劳加速机制进行了回顾，并提出了一种新颖的方法来加速测试和分析不同环境（例如，空气，盐雾和海水）。已经开发并提出了两个截然不同的方程式，用于在不同环境下对钢的SN疲劳寿命和裂纹扩展行为进行校准和预测。通过与文献中的现有数据进行比较，已验证了所提出的方法，并已使用高温数据在工作温度下进行了预测。所提出的方法相对容易地针对感兴趣的材料进行校准，并且能够将被检查材料的SN疲劳和裂纹扩展测试分别加快2倍和3倍。就加速测试疲劳设计和海上风电单桩完整性评估的需求，讨论了所建议的方法和获得的结果，