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

• Published in: International journal of fatigue 2020-04, Vol.133, p.105421, Article 105421
• Main Authors: Simunek, D., Leitner, M., Rieger, M., Pippan, R., Gänser, H.P., Weber, F.J.
• Format: Article
• Language: English
• Subjects: 1:3 scale specimens; Crack growth testing; Crack propagation; Fatigue failure; Fracture mechanics; Materials fatigue; Mathematical models; Parameters; Railway axle; Residual lifetime assessment; Residual stress; Residual stresses; Shafts (machine elements); Short cracks; Software; Software development tools; Stress intensity factors
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2019.105421

•Experimental and analytical crack growth analysis of railway axle specimens.•Consideration of short crack behaviour and residual stresses for assessment.•Fracture surface analysis and aspect ratio evaluation of semi-elliptical cracks.•Validation and verification of crack growth model based on experiments.•Evaluation of transferability based on experimental results of different specimens. The issue of transferability of crack propagation parameters from small-scale specimens up to real-scale components is investigated. Crack growth material parameters are determined based on single edge notched bending SE(B) specimen tests and the crack growth model is validated by 1:3 scaled railway axle experiments as well as for 1:1 test axles focusing on the steel grade EA4T. Crack propagation assessment is performed with the aid of the software tool INARA demonstrating the importance of considering secondary mean stress states due to residual stresses and press fits. In addition, short crack behavior and the build-up of the fatigue crack growth threshold is considered by means of an enhanced NASGRO fatigue crack growth equation, which is of great importance at loads with stress intensity factors in the threshold region. A final comparison with results of a crack growth assessment model based on a previous research project shows the potential of the presented improved approach and highlights the importance to include secondary stress states as well as short crack behavior in order to ensure a proper transferability from small-scale specimens to real-scale components in practice.