MEAN STRESS EFFECT ON FATIGUE LIFE ESTIMATION FOR INCONEL 718 ALLOY

Uniaxial and biaxial fatigue tests related to Inconel 718 specimens are analysed using the critical plane-based multiaxial fatigue criterion by Carpinteri et al. in conjunction with a Smith-Watson-Topper (SWT) type of relationship. More precisely, specimens subjected to proportional and non-proportional loading under strain control are examined, such loadings being characterised by both zero and non-zero mean values. Fatigue life is computed through the novel formulation proposed here and compared with the experimental fatigue life in terms of number of loading cycles needed to form a surface crack whose length is equal to 1 mm