Fatigue crack growth in railway axle specimens – Transferability and model validation

The issue of transferability of crack propagation parameters from small-scale specimens up to real-scale com-ponents is investigated. Crack growth material parameters are determined based on single edge notched bendingSE(B) specimen tests and the crack growth model is validated by 1:3 scaled railway axle experiments as well asfor 1:1 test axles focusing on the steel grade EA4T. Crack propagation assessment is performed with the aid of thesoftware tool INARA demonstrating the importance of considering secondary mean stress states due to residualstresses and press fits. In addition, short crack behavior and the build-up of the fatigue crack growth threshold isconsidered by means of an enhanced NASGRO fatigue crack growth equation, which is of great importance atloads with stress intensity factors in the threshold region. A final comparison with results of a crack growthassessment model based on a previous research project shows the potential of the presented improved approachand highlights the importance to include secondary stress states as well as short crack behavior in order to ensurea proper transferability from small-scale specimens to real-scale components in practice.