Integrated Computational Materials, Process and Product Engineering – IC-MPPE 2022

Keywords: residual stress state; finite element modeling; railway axle; cold rolling; corrosion fatigue
Wheelset axles are among the most safety-critical components in the railway area. Mechanical surface treatments like the cold rolling process introduce residual compressive stresses at the surface of such components. Furthermore, it increases the fatigue strength even under the influence of corrosive media and thus the service life 1.
Experimental results on both laboratory specimens and real axles show how cold rolled components have an increased service life compared to not rolled components, even under the influence of corrosive media. Using calculations of the stress intensity factor of the residual stress state and the state under load in combination with the use of the cyclic R-curve, the growth of cracks at the surface and at defects can be predicted [2-3].
One of the difficulties in such calculations is the correct prediction of the residual stress distribution after cold rolling and the subsequent stress redistribution when defects such as notches or cracks appear, as for example shown in Figure 1. Already established calculation methods provide information about the level of stresses on the surface and their penetration depth, but cannot capture the actual distribution of residual stresses. For this reason, a method is needed that provides additional insight into the strain and stress distribution. Finite Element Analyses are the calculation method of choice for finding the application-specific ideal settings of the cold rolling parameters.
To predict the behavior of such critical components even in corrosive environments an integrated computational material and process model is needed that uses a combination of already established computational methods, experiments and simulations.