PSI - Issue 3

Jilali Nattaj et al. / Procedia Structural Integrity 3 (2017) 579–587 Jilali NATTAJ/ Structural Integrity Procedia 00 (2017) 000–000

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A comparison between the number of cycles at break N fex (deduced from the experiment) and N fc (calculated by formula (11) ) corresponding to the three applied loading levels (248, 282 and 352 MPa) is given in the curve below:

Δσ Mpa

248

282

352

10000 15000 20000 25000 30000 35000

NFc

Nfex

Nf

0 5000

Figure 2. Comparison of (N fex -σ) et (N fc -σ) curves

Figure 2 shows a very small difference between the two curves, which confirm the correct approach of the curve (σ-N f ) presented in the figure 1 above. The Graphical representation of the damage D i (t) and reliability R (t), of the notched material subjected to the three loading levels applied during the experimental tests, is possible through the equations (12), (13) and (14).     1 i t D t    (14)

Figure 3: Damage & Reliability curves under a load level of (a):∆σ = 248 MPa; (b):∆σ = 282 MPa; (c):∆σ = 352 MPa.