PSI - Issue 38

10

Christophe Grosjean et al. / Procedia Structural Integrity 38 (2022) 94–108 C.Grosjean and al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Residual stress evaluations were performed by X-Ray Diffraction following the EN15305 standard [6] and these results was used in fatigue post-treatment (Area B, Area G). Results of residual stress evaluation could be seen on Fig. 11 and Table 5.

R1

R2

R3

Fig. 11. Measurement points (R1, R2 and R3) for X-Ray diffraction

Table 5. Results of residual stress evaluation.

Point

 L [MPa]

 R [MPa]

R1 (Area B)

-197+/-15

29+/-15

R2 (Area G) -669 +/-20 -620 +/-20 R3 (other sandblasted area) -642 +/-21 -582 +/-24

R1 is located in the groove obtained by a milling operation (Area B). R2 and R3 correspond to sandblasted areas, hence the high compression residual stress measured (Area G). 8.2. Fatigue post-treatment The fatigue analysis was performed from the FEA results using fatigue material data from previous testing at CETIM (see Fig. 12(a)) with a probability of fatigue failure equal to 50% and roughness from measurements (see Fig. 12(b)) performed in critical areas (A to G) using 2D Mahr roughness measuring instrument. Then for each critical location A to G identified previously, residual stress was added by linear superposition assumption: • B: machined surface with residual stress like R1 • F and G: easily sandblasted area with residual stress like R2/R3 • C: area where sandblasting is impossible: no residual stress • A, D and E: sandblasted areas but with a rather complex access: both residual stress like R2/R3 and no residual stress conditions are evaluated