PSI - Issue 46

Przemysław Strzelecki et al. / Procedia Structural Integrity 46 (2023) 99– 104 Przemys ł aw Strzelecki / Structural Integrity Procedia 00 (2021) 000–000

102 4

S355J2+C

a

b

Samples from fatigue tests S-N curve 50%

Stress amplitude S a [MPa] 10 3

300 350 400 500 600

5  10 3 10 4

5  10 4 10 5

5  10 5 10 6

Number of cycles log N

c

d

Fig. 2. S-N curves for S355J2+C steel for (a) 9 specimens and (b) 32 specimens, (c) histogram of yield strength with normal distribution and (d) S-N curves on one diagram for 32 specimens and 9 specimens with standard deviation from the tensile test

The verification of the proposed method was a comparison of the S-N curve obtained for 32 and 30 samples for S355J2+C and 1.4301, respectively, with the S-N curve obtained by the proposed method for 9 and 8 specimens for S355J2+C and 1.4301, respectively. The estimated parameters for the proposed method (for eq. (3)) are shown in Table 1. The S-N curves for the proposed method and standard method were presented in Fig. 2 (d) and 3 (d). It can be seen that the S-N by the proposed method is a bit shifted to the S-N curve acc. standard method for all materials. This is expressed in different values of parameters written in Table 1. It is worth noting that mentioned the shift caused calculating less value of the fatigue strength, so it is conservative results.