PSI - Issue 75

Georg Veile et al. / Procedia Structural Integrity 75 (2025) 184–192 Georg Veile / Structural Integrity Procedia (2025)

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4. Effects of different gradient assessment Multiaxiality can influence the precision of common FDP. Notches usually show an increased level of multiaxiality. FDP FFS , FDP RM and FDP FGF take multiaxiality into account by means of shear-gradient ∗ in Eq. (9) and strain gradient ∗ in Eq. (10). ∗ = 1 ( ) (9) ∗ = 1 ( ) (10) Fig. 4 shows the path of stress and strain, determined with an elastic plastic FEA in (Veile et al. 2025) for illustrative purpose. Changes in Δy, used in Eq. ( 9) and (10) lead to different values of gradients. The latter have an impact on the fatigue life prediction.

Fig. 4. Path of stress and strain of the FEA starting orthogonal from the node with maximum stress into the base metal to determine strain- and shear-gradients.

Fig. 5 shows the change in predicted fatigue life due to different Δy.

(a)

(b)

(c)

Fig. 5 . Influence of Δ y for gradient-based FDP with 0.05 mm (a), 0.1 mm (b) and 0.2 mm (c) on the predicted fatigue lifetime.