OS15F098 Prediction of Fatigue Crack Growth Life Considered Crack Closure Behavior to Linear Cumulative Damage Rule

Abstract

In this study, a method was proposed to predict the crack growth life from the linear cumulative damage rule considering the change of effective stress range due to load variance. In order to confirm a usefulness of this proposition, a series of fatigue test using round bar specimens with small hole was carried out under several two step loadings with various ratios of high load excursion. The obtained fatigue life was compared with the predicted life by the linear cumulative damage rule. Although a good agreement was recognized from two lives when the ratio of high load excursion was high, there was a difference between two lives when the ratio of high load excursion was small. However, the modified life agreed with the real fatigue life in all ratios of high load excursion when the predicted life was modified by the change of effective stress range under two step loading.