PSI - Issue 75

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Fabrice Deleau et al. / Procedia Structural Integrity 75 (2025) 392–418 Deleau Fabrice, Emmanuel Persent, Guillaume Coudouel, Guillaume Perrin/ Structural Integrity Procedia (2025)

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A tension force is applied to the system, transmitted through the lug contact surfaces. A key feature of the prototype is the lug geometry. The specific shape of the tooth connection has been the subject of numerous finite element calculations. The goal of this elliptical shape is to reduce the maximum stress concentration in the critical section. The chosen geometry is representative of the i-Clip-Riser TM technology and is identical across all lug connections. • Material specification Small sized i-Clip prototypes were built using 10CrMo9-10 alloy. The specifications of the ASTM A182 Gr F22 material and its verified properties are presented in the table below.

Table 1: Material properties for the ASTM A182 Gr F22

Minimum of yield stress [MPa]

Min-Max of ultimate stress [MPa]

Ultimate elongation [%]

ASTM A182 Gr F22

640 660

780-880

18 %

i-Clip materiel properties (10CrMo9-10)

828

18.5 %

These mechanical properties were verified through standard tests.

• Representativeness In order to validate the fatigue methodology proposed for the i-Clip-Riser TM , fatigue tests were conducted on small sized i-Clip samples. As explained, the small-sized i-Clip specimen is a simplified prototype of the i-Clip-Riser TM at 1:5 scale. Therefore, it is designed to exhibit representative behaviour of the i-Clip-Riser TM with respect to the stress distribution in the critical section located at the lug grooves. Fig. 4 compares the stress distribution in the critical section between the small-sized i-Clip prototype and the Clip-Riser ® . It is found that the behaviours are practically identical in this section, confirming that the small-sized i-Clip is appropriately representative of the i-Clip-Riser TM .

Fig. 4: Comparison between stress distribution at critical section in Small-size i-Clip and Clip-Riser ®

Initially, this paper summarizes the main assumptions for fatigue life evaluation according to the relevant standards (API 16F, 2022) (DNV GL RP C203, 2020). A proposed methodology was developed to be more representative of the specific stress state in the i-Clip-Riser TM hot spot. This approach incorporates an experimental SN-curve and a special evaluation of the mean stress with a stress range correction according Gerber consideration. It is shown to be more representative to optimize our design product. Subsequently, specific comprehension tests were developed at IFPEN. Fatigue tests were performed using small-sized prototypes (1:5) equipped with numerous sensors, including Acoustic Emission sensors introduced by the Institut de