PSI - Issue 77

Esteban Cadavid Gil et al. / Procedia Structural Integrity 77 (2026) 248–255 Cadavid et al. / Structural Integrity Procedia 00 (2026) 000–000

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among the stranded conductor wires in the cable cores—could trigger fretting mechanisms (Wang et al., 2020), which in turn initiate and govern fatigue damage (Svensson et al., 2021). In contrast, the bending sti ff ness in the stick regime is more prone to variation due to the low force and displacement levels involved, making it sensitive to measurement uncertainties. 4.1. Captured non-linear reciprocation bending behaviour Fig. 2 shows the non-linear reciprocating bending behaviour of a single post-processed bending test series (TB7), characterised through the bending moment-curvature diagram. Fig. 2(a)–(c) illustrate the evaluation of bending sti ff ness in both the stick and slip regimes, determined from the slopes of the respective regions, as well as the deter mination of the critical curvature (stick-slip transition) from the intersection of the corresponding tangents. The area enclosed by the hysteresis loop is also computed, representing the energy dissipated through internal friction. The cable’s non-linear response was evaluated at three cycle stages: a first intermediate stage, a second intermediate stage, and the end of the bending series. For comparison, Fig. 2(d) summarizes the non-linear reciprocating bending response at these three stages. For visual clarity, only five cycles per tracked cycle stage are displayed, while the reported values represent averages across all monitored cycles.

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(c) (d) Fig. 2. Test block #7 (TB7): non-linear reciprocating bending behaviour