PSI - Issue 75

19

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

410

Autocalibrations were also carried out periodically throughout the acquisition to ensure that the sensitivity of the transducers did not drop by more than 3dB. The results were consistent throughout the acquisition. The arrangement of the sensors on the prototype was designed to maximize the probability of detecting cracks in the male part. Two monitoring sensors were coupled to the inside of the male part, in perfect opposition to the lug positioning zone. The microdot cables connecting the internal sensors to the preamplifiers pass through 2 holes machined in the prototype for this purpose. At the same time, 6 sensors were placed at different positions on the outside of both parts of the prototype (Fig. 14), as well as at the connections to the hydraulic jaws, in order to filter out as far as possible any interfering noise from the fatigue test.

Fig. 14: EA sensors on the experimental set-up

4.4. Description test follow-up The primary monitoring objective is to determine the number of cycles required to reach prototype failure. Previous tests and finite element analysis indicate that failure typically begins with a crack near the elliptical-shaped area close to the lug edge. A small-sized i-Clip prototype is employed for dynamic testing under constant loading throughout the test. An initial static load, greater than the maximum load applied during the dynamic test (e.g., the maximum design load of 160 kN), can be applied. All the aforementioned measurements were utilized to monitor the fatigue test. Data recording was carried out at a frequency of 100 Hz throughout the tests. The test is conducted in distinct phases; for example, the first phase consists of 500,000 cycles, followed by additional phases of 100,000 cycles each. These intervals allow for the disengagement of the male and female parts for visual inspections. Crack detection is performed using conventional penetrant and magnetoscopic testing methods. Once a crack is detected, it is opened using brittle fracture techniques. This procedure enables observation of the crack and the fracture surface to identify its origin. Details of these investigations are provided below for the small-sized i Clip reference 987. 5. Fatigue tests monitoring Ten 1:5 small-sized prototypes were available to validate our fatigue methodology design. As previously discussed, one prototype was utilized to refine our experimental setup and mechanical integration. Various upgrades were implemented to ensure the representativeness of our prototypes.