一种变K_f-Neuber法及疲劳裂纹形成寿命计算

 本文讨论修正Neuber法中疲劳缺口系数K_f可表示为材料性能、理论应力集中系数和局部塑性变形的函数。在此基础上提出了一种变K_f-Neuber法。试验表明此法具有较好的计算精度。

A VARIED Kf-NEUBER'S RULE AND THE PREDICTION OF FATIGUE CRACK INITIATION LIVES

The elasto-plastic stress-strain analysis at notch roots of notched hardwares is discussed in this paper, proceeding from the modified Neuber's rule. The definition of the fatigue notch coefficient Kf is reconsidered and Kf is redefined by the modified Neuber's rule directly. It is pointed out that with the increase of the local plastic deformation, the Kf does not monotonously decrease, but, first decreases gradually and then increases gradually. The Kf would be larger than Kf(theoretical stress concentration coefficient) under greater plastic deformation. A varied Kf-Neuber's rule is presented and discussed. Both the stress-strain experiment analyses and the fatigue life tests indicate that the method presented in this paper is a better crack formation life prediction method with good accuracy.