Issue 43

L.C.H. Ricardo, Frattura ed Integrità Strutturale, 43 (2018) 57-78; DOI: 10.3221/IGF-ESIS.43.04 73 0 10 20 30 40 50 60 70 80 90 2 3 4 5 6 7 8 9 10 Number of Cycles Crack Open Stress ( MPa) SAE 0.25 mm SAE 0.50 mm SAE 0.75 mm SAE 1.0 mm Figure 13: Crack Opening Stress (σ yy+) [70]. Figure 14 : Crack Closing Stress (σ yy- ) [70]. Figure 15: Crack Opening Stress (σ yy+ ) model SAE0.50 [70]. Surface Crack Crack Tip  y= 103 MPa