PSI - Issue 75

Benjamin Causse et al. / Procedia Structural Integrity 75 (2025) 205–218 Author name / Structural Integrity Procedia (2025)

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3.3. Experimental results Figure 6 shows experimental results on J2 rosette located on the arch hoop, when the instrumented chairlift pass through the station.

Fig. 6. Stress tensor signals on rosette J2 in station, (a) in the rosette fixed referential, (b) in the eigenreferential. with the annotations needed to use the charts see figures 4 and 5. 4. Discussion 4.1. Multiaxial Fatigue lifetime fast evaluation with charts for proportional signals with low load angle variation As we have already seen (Causse et al. 2024), when passing over towers, chairlift vehicles are subjected not only to variations in first principal stress  I (due to vertical gravity oscillations when passing over roller battery) but also to variations in secondary principal stress  II due to lateral oscillations of the vehicle (this swaying occurring even in the absence of wind). In addition, variations in the loading angle  max remain moderate overall (generally a few degrees or even ± 10°), and in any case are always well below  max ≤ 30°. The angle, as seen previously (3.1), will therefore have only a moderate influence on the variation in service life compared with a conventional uniaxial estimate based on the Eurocodes (-20% service life for  max =20°, see Table 1 and Fig. 4). Thus, we are dealing with quasi-proportional signals that are typical of the hoop arches of loaded cableways vehicles as they pass over line towers. For these typically bi-axial signals with a moderate variation in loading angle (see Fig. 6 (a) and (b)) we assessed the service life using three methods (see Table 2): • uniaxial fatigue according to Eurocode 3 (N E ), • multiaxial fatigue calculated according to Dang Van (N DVcalculated ) (cf. Causse et al. 2024) • in multiaxial fatigue using our charts (Figures. 4 and 5), this service life is called N DVcharts (in number of cycles). For the chairlift hoop in question, as it passed through the station (LC2), the data from the J2 rosette made it possible to determine a variation in angle over the course of the event  max =24° , a biaxiality stress ratio k=   /   =0.72 and