Crack growth under constant amplitude loading and overload effects in 1:3 scale specimens

Assessment of railway axles requires a detailed analysis of the crack driving mechanisms in the component. Therefore, experimental investigations are performed to determine input parameters for analytical and numerical calculations and analyze material behavior at specific load sequences. In this work, results of the current research project entitled “Eisenbahnfahrwerke 3 (EBFW 3)” - 'Probabilistic fracture mechanics concept for the assessment of railway wheelsets' including an overview of the project philosophy are presented. One goal of the project is the transferability of material parameters, determined on standardized small-scale specimens to the real full-scale axle. Amongst others, influences like residual stresses due to manufacturing, scattering of material parameters, geometry and size effects are responsible for deviations of crack propagation and residual lifetime. In addition to these investigations, tests of 1:3 scale specimens are performed as a link between small-scale laboratory and full-scale specimens. Based on the experimental work, crack propagation approaches are validated and modified to improve the accuracy of assessment methods. In this paper, focus of the experimental investigations is laid on crack growth under constant amplitude loading and overload effects. It is shown that, retardation of the crack growth rate can delay the number of load-cycles under constant amplitude loading by a factor of 1.6 up to 3.3.