Issue 36

M. Arsic et alii, Frattura ed Integrità Strutturale, 36 (2016) 27-35; DOI: 10.3221/IGF-ESIS.36.03 31 Specimen class Initial notch Specimen dimensions Number of specimens a [mm] W [mm] B [mm] L [mm] 1 0.250 9.90 9.50 40 6 2 0.351 9.79 9.60 40 6 3 0.591 9.90 9.50 40 6 4 0.723 9.90 9.70 40 6 5 1.125 9.85 9.80 40 6 Table 2 : Geometric characteristics of specimens and sizes of initial notch. Specimen class a [mm] ∆M [N ∙ mm] ∆σ [MPa] R - f [Hz] σ a [MPa] σ m [MPa] S z [MPa] 1 0.250 19200 157.48 0.5 230-240 81.03 236.23 315 2 0.351 16100 141.24 0.5 230-240 70.62 211.86 282 3 0.591 13600 124.41 0.5 230-240 62.21 186.62 249 4 0.723 12200 112.86 0.5 230-240 56.43 169.30 226 5 1.125 9500 97.47 0.5 230-240 48.73 146.20 195 Table 3 : Examination conditions and fatigue strength properties. Figure 4 : S-N Relationship for specimens with initial crack a = 0.25 mm. Figure 5 : S-N Relationship for specimens with initial crack a = 0.351 mm.