PSI - Issue 75

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

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2.3. Bi-axiality and average stress variation We propose to study the influence of signal biaxiality (k=  II /  I ) and average stress  m on fatigue life. In this case, we assume that the loading angle  is constant throughout the cycle (separation of parameters to better understand the influence of each). As mentioned in §2.1, in order to be representative of the line loads experienced by chairlift lines and hoops, we define proportional signals in phase (see Figure 2).

Fig. 2. Proportional stress tensor signals expressed in the eigen referential for  = 0°, as a function of  m ,  R and k=  II /  I

We calculated N DV for : •

 R = 100 MPa (i.e.  = 200MPa) k =  II /  I varying from -1 to +1,

•

•  m /  R varying from 0 to 3 (i.e. Ratio R =  min /  max = (  m -  R )/(  m +  R ) varying from -1 à +0.5)

2.4. Experimental setup on a LEITNER’s chairlift with detachable grip

On-site stress measurements were carried out during tests on the 18-20 July, 2023 on the LEITNER six-seater ChairLift with Detachble grip (CLD6), known as the "Leppleskofelbahn", located in Sankt Jakob in Defereggen, Austrian Alps. These measurements were carried out by LATIF laboratory (Bortolamedi (2024)), on behalf of LEITNER then studied by both LEITNER (Tonetta et al. (2025)) and STRMTG (Causse and Chatelus (2025)) Notified Body 1267 in charge of the CE certification of the CLD6 according to the European Cableway Installations Regulation (EU) 2016/424. Extensometric measurements at a speed of 6 m/s and fatigue analysis were carried out in compliance with article 6.3.3.2 of EN 13796-1, following three load cases (Load Case 1 (LC1), Load Case 2 (LC2), Load Case 3 (LC3)): • LC1: entry into station guide systems: carrier with eccentric half load (½Q); (100 000 cycles); • LC2: passage through stations: carrier with full load (Q) with no additional swaying, (200 000 cycles); • LC3: full loaded (Q) vehicle in line (meaning passing through all the towers between bottom and top stations); (5 000 000 cycles). 10 strain gauges were distributed over the entire structure of the chairlift vehicle, for a total of 14 acquisition channels. In the present research work, only the following rosette is studied: J2 located on the hoops curve (see Figure 3). The acquisition unit used is an SA 01 with a MT 04 portable thermohygrometer control unit, VARIE 11 Megohmmeter, a TF 34 Dynamometer and the sampling frequency is 800 Hz.