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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24 hours a day, 7 days a week, and as a consequence of this, the rails are subject to cyclic loading caused by the passage of a shuttle. Because of this cyclic loading, the rails experience fatigue phenomena, moreover, cracks due to material fatigue have already been observed in these types of rails. The current situation is also aggravated due to the competitiveness of the European industrial sector, which is pushing the design of these rails to lower thicknesses, further increasing concerns about their fatigue performance. To ensure safety inside a warehouse that contains a racking structure, design codes should include fatigue design curves for these types of structural elements. Currently, the Eurocode 3 (2014) does not cover the fatigue behavior of thin cold-formed elements, like the mentioned rails. These thin cold-formed elements have residual stresses left over from their fabrication process that could play an important role in their fatigue performance. The Eurocode 3 does cover the subject of thick hot-rolled sections, however, the residual stresses are not relevant in these types of structural elements. Within the presented background, the FASTCOLD European project has been carried out, whose research plan consists in developing fatigue design rules for the mentioned applications, which, again, are not covered by existing design codes, e.g. Eurocode 3. Experimental fatigue testing has been carried out backed by numerical simulations of these tests. A new fatigue setup has also been developed in order to generate representative fatigue cracking in the rail due to the shuttle’s cyclic loads. Numerical simulations of the cold roll-forming fabrication process are also being carried out to determine the importance of the residual stresses in the fatigue performance of the rails. Finally, the aim of this work is to present the work being done within the FASTCOLD European project. With the experimental data obtained from fatigue testing backed by numerical simulations, important contributions are made to the design codes in order to deal with the fatigue design of such critical details.

2. Development of a fatigue testing setup for rail profiles

Throughout thoughtful trial and error, and backed by numerical simulations, an experimental setup was developed in order to generate representative fatigue cracking in the rail due to the shuttle’s cyclic loads.

(a) Experimental setup (CAD).

(b) Experimental setup (laboratory).

(c) Loading device to load cell hinged connection.

(d) Smooth load actuator.

(e) Load actuator with integral plate.

Fig. 1: Experimental fatigue testing setup.