PSI - Issue 77

J.A. Alves et al. / Procedia Structural Integrity 77 (2026) 440–446

442

Fig. 1. Geometries of the DIN 34CrNiMo6 specimens: a) fully reversible loads; b) partially reversible loads.

Table 2. Fatigue test under fully reversible loads σ (MPa)

σ σ uts

(%)

315 405 420 440 460 480 500 540

35 45 47 49 51 53 56 60

Table 3. Fatigue test under partially reversible loads R (-) σ m (MPa)

σ a σ uts

σ a (MPa)

(%)

105 120 133 150 216 240 315 360

315 360 400 450 360 400 315 360

35 40 44 50 40 44 35 40

-0.5

-0.25

0

2.2. Mean stress predictive models

The Goodman, Gerber, Soderberg, and ASME Elliptic models are described in Equations 2, 3, 4 and 5, respec tively. These models were applied to each partially reversible loading condition ( σ m – σ a ) to obtain an equivalent fully reversed stress. Each model was then used to generate a corresponding fatigue life (S–N) curve, which was compared with the experimental fully reversed curve.

σ a 1 − σ m σ uts

b f

= aN

(2)

σ Goodman =

σ a 1 − σ m

b f

= aN

(3)

σ Gerber =

σ uts

2