Discuss on the Life Prediction in Very High Cycle Fatigue Regime

Abstract:

The typical characteristics of S-N curve and the fracture surface in very high cycle fatigue regime were analyzed in this paper. The fatigue lifetime prediction models based on crack growth and dislocation theory were introduced. On the basis of the numerical data of previous researches on very high cycle fatigue, the prediction errors of the two modes were analyzed. The results indicate that the model based on dislocation theory has better prediction ability. The prediction accuracy decreases with the increment of fatigue lifetime. That is to say, the fatigue crack initiation consumes the main fraction of total life. Finally, some possible and prospective topics of future researches on fatigue lifetime prediction in very high cycle fatigue regime are proposed: the competing failure mechanism of surface/internal fatigue fracture modes, the lifetime prediction in very high cycle fatigue regime based on statistical methods by establishing large samples data.