PSI - Issue 28

C.D.S. Souto et al. / Procedia Structural Integrity 28 (2020) 139–145 Carlos D.S. Souto et al. / Structural Integrity Procedia 00 (2020) 000–000

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of the web-flange corner are tensile stresses, while at the outer surface are compressive stresses. During fatigue cycling, the mean stresses are influenced by the residual stresses. On e ff ect, during the downward loading scenario, the mean stress will increase due to the tensile residual stresses at the inner surface, which is the crack initiation site; for the upward loading scenario, the mean stress will be reduced due to the expected compressive residual stresses at the outer surface. This mean stress di ff erence would impact di ff erently on fatigue damage.

5. Conclusions

In this work, a fatigue testing setup for rail profiles is presented. This setup allows for various configurations of load actuators and it also allows for upward or downward loading scenarios. Within the FASTCOLD European project, this setup as already been used in order to generate S-N curves for the rail profiles. These S-N curves, in conjunction with the work being done at the FASTCOLD project, provide important contributions to design codes, e.g. Eurocode 3, since these do not yet include considerations for thin cold-formed structural elements. These thin cold-formed elements contain residual stresses left over from their fabrication process that can a ff ect their fatigue performance. Although it is an ongoing investigation, simulations of the cold roll-forming process are being carried out to determine the impact of the residual stresses in these structural elements.

Acknowledgements

The authors express their gratitude to the FASTCOLD RFCS European project (Grant Agreement No. 745982). The SciTech (Science and Technology for Competitive and Sustainable Industries) R&D project NORTE-01-0145 FEDER-000022 co-financed by Programme Operational Regional do Norte (“NORTE2020”) through Fundo Europeu de Desenvolvimento Regional (FEDER) and the Portuguese Science Foundation (FCT) through the post-doctoral grant SFRH / BPD / 107825 / 2015 are also acknowledged for their financial support.

References

EN 1993-1-9, 2014. Eurocode 3: Design of steel structures - Part 1-9: Fatigue. European Committee for Standardization, Brussels.