Residual fatigue lifetime estimation of railway axles for various loading spectra

Abstract

The knowledge of the residual fatigue lifetime of railway axles is very important for the safe operation of trains. The railway axles could include some defects like cracks, scratches or inhomogeneities which could contribute to the fatigue crack initiation and in the final stage to axle failure. The non-destructive testing methods are not reliable for detection of relatively short (circa 1–2mm), but even dangerous cracks. For conservative estimation of residual fatigue lifetime the railway axle containing initial crack should be considered. The residual fatigue lifetime is given by the number of load cycles for fatigue crack growth from the initial size of the crack up to the critical size with consequent fatigue failure of railway axle. Railway axles are used in different types of trains which are used under different conditions (regional trains, urban trains, high speed trains, freight trains, etc.). This work is focused on numerical estimation of residual fatigue lifetime of railway axle while several different load spectra taken from the literature are considered in the performed estimations. This paper also shows the influence of the discretization level of the continuous load spectrum and effect of magnification or diminution of load spectrum on the calculated residual fatigue lifetime of the railway axle.