A New Multiparameter Model for the Prediction of Fatigue Crack Growth in Structural Metallic Materials

A multiparameter model is proposed for the characterization of fatigue crack growth in structural metallic materials. The model assesses the combined effects of identifiable multiple variables that can contribute to fatigue crack growth. Mathematical expressions are presented for the determination of fatigue crack growth rates, da/dN, as functions of multiple variables, such as: stress intensity factor range, ΔK; stress ratio, R; closure stress intensity factor, K c l , and the maximum stress intensity factor, K m a x . A generalized empirical methodology is proposed for the estimation of fatigue crack growth rates as functions of these variables. The validity of the new methodology is then verified by making appropriate comparisons between predicted and measured fatigue crack growth data obtained from experiments on selected structural metallic materials. The multiparameter predictions are shown to be in close agreement with experimental data.