水轮发电机转子疲劳寿命预测分析

Analysis of fatigue life of turbine generator rotor

本文根据全寿命分析理论,在材料实测S-N曲线的基础上,通过数值模拟国标疲劳实验,验证了疲劳寿命数值计算方法的可信度和精度,并分析了各种误差的产生原因。之后将通过验证的数值方法应用于灯泡贯流机组转子中心体的疲劳分析,模拟了机组在额定工况和飞逸工况下的运行情况,以及由静止加载到上述两工况再恢复静止的启停机过程;并对平均应力修正方法进行了校验。数值方法验证结果显示,针对拉伸、弯曲、疲劳三组国标疲劳实验,有效应力范围内各测点计算结果与标准值最大相对误差为6.58%。贯流机组转子中心体数值计算结果显示在两工况下的稳定运转不会造成疲劳损伤,引起机组疲劳破坏的主要原因是频繁的启停机过程。

National standard fatigue experiments were conducted and simulated in this paper based on the total life theory and the measured S-N curve of practical material to validate the credibility and accuracy of numerical method for fatigue life prediction.Factors that may lead to errors were analyzed.The warranted numerical methods were used for fatigue analysis of the rotor center part in a bulb unit.Operations under the rated and runaway conditions and the corresponding start-stop processes were simulated.The commonly used mean stress correction was also validated.In the validation experiments,the maximum error at the testing points in the validated stress range was 6.58%.In the practical cases,the major cause of fatigue damage is frequent start-stop running rather than stable operation.