风力机塔架基础环疲劳强度分析

FATIGUE STRENGTH ASSESSMENT OF A WIND TURBINE'S FOUNDATION-TOWER TRANSITIONAL RING

为了评估某风力机塔架钢结构基础环穿筋孔细节的疲劳强度,采用中国船级社(CCS)《风力发电机组规范》规定的轧制件简化疲劳分析方法,根据结构的载荷特征、材料的静强度、缺口疲劳系数、尺寸效应和材料表面影响系数等参数,偏保守地人工合成正应力和剪应力应力幅-循环次数曲线(S-N曲线),并根据存活率、腐蚀环境和低应力幅对损伤的贡献等因素,对S-N曲线进行缩减和修正。使用等效恒幅应力幅,根据修正的S-N曲线对结构进行疲劳分析。结果表明,疲劳缺口系数和综合表面影响系数是影响S-N曲线合成的主要因素。相对应力梯度的计算应基于实际应力分布拟合出多项式曲线;综合表面影响系数各分量应根据实际情况取值。基础环穿筋孔细节在设计寿命期内的最大累积损伤为0.042。

To assess fatigue strength of a foundation-tube tower transitional ring＇ s reinforced hole detail which is a rolled steel structure, a simplified fatigue analysis approach according to CCS specification was adopted. The nor- mal stress and shear stress S-N curve was synthesized conservatively by considering the aspect of load characteris- tic, static strength of raw material, fatigue notch factor （FNF）, size effects and integrated surface effect factor （ISEF）, and then the synthetic S-N curve was reduced and modified acco~＇ding to survival probability, corrosion environment and the damage contribution of low stress range. The equivalent stress range, calculated from equiva- lent constant-amplitude load, was used to assess fatigue strength based on modified S-N curve. The results showed that FNF and SEF are the main influence factors of S-N curve＇ s synthesizing process, the relative stress gradient （RSG） of the stress distribution should be based on fitted polynomial curve, the components values of the ISEF should be based on the actual situation. According to the S-N curve, the maximal cumulative damage in design life is 0. 042.