摘要
采用有限元方法(FEM),计算分析了电站200MW汽轮机中压主汽阀阀壳在冷启、停机、强热启动、极热启动以及事故等工况下的温度场和应力场,得出了阀壳裂纹区各工况下温度场和应力场的变化规律,提出了内壁裂纹区的周向应力是疲劳寿命计算的主要参考量。绘制关键节点周向应力块谱图,应用局部应力应变法估算阀壳的低周疲劳寿命,并将计算结果与阀壳失效调查统计结果进行了比较。研究表明:计算的周向应力极值区与实际调查发现的裂纹萌生区相吻合,进一步预测的裂纹萌生寿命与实际调查统计结果也基本相符;事故工况为裂纹萌生的主导因素,其导致的疲劳损伤比达到12.5。
Based on the FEM,the calculation and analysis were performed for the transient temperature fields and stress fields of the intermediate pressure main steam valve housing under various operating conditions including cold startup,shutdown,strong hot startup,limit hot startup and accidental condition in 200MW unit in power station. Alteration rules of the temperature fields and stress fields were achieved under these conditions.A result which the cracked region's circumferential stress is regarded as the important factor affecting on the fatigue life is presented.The cracked region's load spectrums are plotted and the fatigue life of the valve housing is predicted by local stress-stain approach.The computational results are contrasted to the failure investigation data of the valve housing.The results indicate that the circumferential stress concentration region is corresponded to the cracked region and the credibility of the fatigue life prediction is proved by the investigative data.The accidental condition is the principal reason for the crack initiation and it bring fatigue damage ratio up to 12.5.
出处
《金属热处理》
CAS
CSCD
北大核心
2007年第z1期122-126,共5页
Heat Treatment of Metals
