轮盘槽底低周疲劳寿命预测

航空构件要求重量轻,多半采用弹塑性设计,应力集中区域的材料通常是应变循环而不是应力循环,所以局部应变法已成为比较流行的一种寿命预测方法。本文采用了这种方法。鉴于试验更能真实地反映疲劳累积损伤的过程,所以本文除了用局部应变理论估算寿命之外,还利用光滑试样的疲劳试验预测了轮盘槽底的裂纹起始寿命。实践证明这种寿命预测方法比仅用计算公式估算寿命效果要好。对于中值寿命,轮盘和光滑试样的寿命之比仅为1.2倍。 

A LOW CYCLE FATIGUE LIFE PREDICTION FOR DISK GROOVE BOTTOMS

According to the theory of local strain fatigue,the fatigue experiments for the 30CrMnSiA disk have been completed on a multichannel radial loading fatigue rig (“Ferris”whell).A good number of the crack propagation curves of the groove bottoms in the disk have been obtained.The calculations show that the median LCF life to crack initiation is 8642 (cycles).In comparison with cyclic rotating tests,the test period on a multi channel radial loading fatigue test rig can be shortened greatly and the test data can be obtained easily.A smooth round bar specimen experiment method for predicting the LCF life of groove bottom in the disk is provided,which is better than the Morrow method.For the median LCF life,the ratio of the experimental life to the predited life is 1.2.