A fatigue crack driving force parameter with load ratio effects

In this paper, a fatigue crack driving force parameter, (Kmax)α(ΔK+)1−α with load ratio effects on crack growth modeling is proposed. This new crack driving force does not invoke disputable crack closure data. Instead, it is calculated solely using the positive part of the range of the applied stress intensity factor (SIF), ΔK+, and the corresponding maximum value of the SIF, Kmax. It unifies the overall crack rate prediction methodology regarding load ratio effects for both the long- and short-crack growth behaviors. The predictions are compared with the experimental data from the literature and the agreement is found to be fairly good.