裂纹对主蒸汽管道弯头强度的影响

为了找出裂纹对主蒸汽管道弯头强度的影响规律，以90°推制弯头为分析对象，模拟主蒸汽管道的实际工况，首先分析了不同长度和深度的单个裂纹对弯头强度的影响，在此基础上，分析了不同间距的两个裂纹对弯头强度的影响，以及裂纹间距对双裂纹应力的叠加效应及影响范围。分析结果表明，当单裂纹深度一定时，裂纹长度越大裂纹承受的最大应力也越大，且应力分布趋于均匀；当单裂纹长度一定时，随着裂纹深度的增大裂纹承受的最大应力越小；对含有两个裂纹的弯头，裂纹间距越大裂纹间应力的叠加效应就越小，缺陷间距不同使得缺陷附近的应力梯度不同，缺陷间距越小应力梯度越大。

Effect of Crack on Main Steam Pipe Elbow Strength

In order to find out the influencing rules of the crack on the elbow strength of the main steam pipe, 90° push elbow is taken as the analysis object to simulate the actual working condition of the main steam pipe. The influence of the single crack with the different lengths and depths on the elbow strength is analyzed. On this basis, the influence of the two cracks with different spacing on the elbow strength is analyzed; meanwhile, the superposition effect and the influence range of the crack spacing on the double crack stress are also analyzed. The results show that when the single crack depth is constant, the longer the crack length is, the greater the maximum stress the crack will bear, and the stress distribution tends to be uniform. When the length of the single crack is constant, the larger the crack depth is, the smaller the maximum stress is. For the elbow with two cracks, the larger the crack spacing is, the smaller the superposition effect of stress between the cracks will be. The different defect spacing makes the stress gradient near the defect different, and the smaller the defect spacing is, the larger the stress gradient will be.