A fatigue crack growth model considering in-plane constraint effects

Fatigue crack growth rates are influenced by constraint effects. However, existing research has failed to provide a consistent conclusion regarding the influence of in-plane constraints on fatigue crack growth behavior. In this study, we present a comprehensive analysis of the effect of in-plane constraint on fatigue crack growth rates. Then, a fatigue crack growth model based on two-parameter fracture mechanics is proposed. The effective stress intensity factor range is defined as ΔK_α = ΔK(1 + A₃^′b), where b is a geometric influence factor that measure the extent to which geometry affects crack growth rates, A₃ is the third term in Williams series expansion. Experimental validation showed that our model could describe the constraint effect on the fatigue crack growth rates under conditions where C_m exhibits a monotonically increasing relationship with A₃^′.