Abstract: | The prediction of fatigue crack growth at very low ΔK values, and in particular for the threshold region, is important in design and in many engineering applications. A simple model for cyclic crack propagation in ductile materials is discussed and the expression developed. Here, n is the cyclic strain hardening exponent, σyc is cyclic yield, and εf is the true fracture strain. The model is successfully used in the analysis of fatigue data BS 4360-50D steel. |