PSI - Issue 2_A

T. Borsato et al. / Procedia Structural Integrity 2 (2016) 3150–3157 Author name / Structural Integrity Procedia 00 (2016) 000–000

3153

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3.2 Fatigue Tests Results Fatigue tests results were statistically elaborated by using a log-normal distribution. The mean curve related to a survival probability of 50% and Haibach’s scatter band defined by lines characterized by a survival probability of 10% and 90% were calculated. Results obtained with samples coming from castings A and B are reported in Figure 2 and Figure 3, respectively. It can be noted that the difference between the two fatigue curves are related both to the mean value of the stress amplitude at 2·10 6 cycles, and to the scatter index T  . In particular, the value of σ a, Ps 50% at 2·10 6 cycles related to casting B is about 12% higher than the value of σ a, Ps 50% at 2·10 6 cycles obtained for casting A and the scatter index T  for casting B is 28% lower than that for casting A.

R = 0 ‐1/k = ‐0,1098 Tσ = 1,5 σ a 50% = 120 MPa (N = 2∙10 6 )

200

σ a stress amplitude [MPa]

100

1,00E+04

1,00E+05

1,00E+06

1,00E+07

Number of cycles to failure

Figure 2 Fatigue life of specimens taken from casting A

R = 0 ‐1/k = ‐0,0886 Tσ = 1,079 σ a 50% = 134 MPa (N = 2∙10 6 )

200

σa stress amplitude [MPa]

100

1,00E+04

1,00E+05

1,00E+06

1,00E+07

Number of cycles to failure

Figure 3 Fatigue life of specimens taken from casting B