Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
781181 | International Journal of Fatigue | 2011 | 6 Pages |
An equivalent driving force (EDF) model is proposed for the correlation and prediction of crack growth under different stress ratio, R, values. The equivalent driving force defines a completely-reversed stress intensity range that is expected to yield the same crack growth rate as a given stress intensity range ΔK and stress ratio R. Thus, the suggested equivalent driving force (EDF) model seeks to unify the crack growth data into a single master curve for fatigue design.The EDF depends on a single factor known as the mean-stress-sensitivity factor, which can be readily determined from experimental data. Application of the EDF model to the published data of Titanium and Aluminum alloys indicates that there exists an R-value below and above which the mean-stress-sensitivity factor differs. It was found that for −1 ⩽ R ⩽ 0.3 the mean-stress-sensitivity factor was much higher than for 0.3 < R ⩽ 1. This difference in mean-stress-sensitivity to crack growth behavior in the two R-regimes could be explained in terms of the dominant mechanism controlling damage/crack growth rate.