基于疲劳短裂纹行为的疲劳寿命估算方法

在疲劳短裂纹形成和扩展行为基础上,提出了一种疲劳寿命估算方法。计算结果表明,该方法具有满意的预测精度。

Predicting Fatigue Life Based on the Behavior of Short Fatigue Crack

The process of forming short fatigue crack was divided into short fatigue crack initiation phase and short fatigue crack propagation phase The theory of continuously distributed dislocations of crack was applied to analyze the early growth and the effect of microstructure of short fatigue crack The dislocations model of crack under cyclic stress was built based on the analysis of the equilibrium condition for dislocations when the applied stress was reduced The reverse plastic displacement at the crack tip was adjusted to discribe the growth of fatigue crack The model was used in short fatigue crack initiation with the physical background of the diceleration behavior of early growth of short fatigue crack A fatigue limit diagram of hyperbola was derived from the threshold stress condition of short fatiuge crack determined by the analysis of interactions between early growth of short fatigue crack and grain boundary The equation of short fatiuge crack growth rate was presented from the model related to the threshold stress condition of short fatigue crack The ellipsoidal inhomogeneity method was applied to the study on elastic plastic fractrue problem, and then the analytical expressions of crack tip extension displacement were found The method in which crack tip extension displacement range was utilized to describe the rate of short fatigue crack propagation was presented It was found that the propagation rate of short fatigue cracks Based on the behavior of initiation and propagation of short fatigue cracks, a method of predictiong fatiuge life was proposed The predicting result shows that this method was accurate enough