PSI - Issue 46

T.J. Gschwandl et al. / Procedia Structural Integrity 46 (2023) 17–23 T.J. Gschwandl et al. / Structural Integrity Procedia 00 (2021) 000–000

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Fig. 5 (a) Stress distribution of a rollover simulation after 100 cycles. The location of the arising tensile stress zone in the simulation is similar to the one present in the investigated rail after several years of operation. (b) Residual stress distribution measured with the contour method.

Nevertheless, with this numerical approach a systematic analysis of critical operating conditions will be feasible in the future. Considering the presented measured in-service stresses and more realistic loading conditions will provide more precise predictions.

4. Conclusions Within this work, three approaches to obtain out-of-plane longitudinal residual stresses in rails have been investigated. An FE rollover simulation for a new rail with simplified contact conditions has been conducted and a damaged rail with a squat has been analyzed with X-ray diffraction method and contour method. The applied measurements provide a detailed distribution of the stresses, where XRD is suitable for the near-surface region and CM delivers an overview on the global stress distribution. However, the simplified FE simulation is currently not capable to predict the residual stress state observed in experiments. Hence, to improve the numerical framework the following steps should be considered:  Adaption of the rollover simulation by varying the wheel geometry and position as well as the loading to compute a realistic stress field.  By combining the applied stress measurement methods (XRD and CM), a genuine residual stress distribution of damaged rails can be obtained and further on used as initial stress state in the FE rollover simulations. By making these adjustments, an improved numerical framework to study the squat initiation and growth can be developed. Moreover, the numerical prediction of squats taking residual stresses into account becomes viable, thereby paving the way towards understanding squats and enabling an enhanced virtual assessment.