PSI - Issue 19

Author name / Structural Integrity Procedia 00 (2019) 000 – 000

4

Kai Schnabel et al. / Procedia Structural Integrity 19 (2019) 442–451

445

Figure 2 Finite element model of the investigated small-scale flat specimens and location of the stress gradient Inside the ‘as - built’ specimen, the area with the subsurface pores has an approximate depth of ≈ 0.4 , Figure 1 right. This is roughly the same depth, in which the stresses in the idealized FE model without pores are higher than the nominal stress. The geometrical induced stress peak coincides with the stress peaks of the pores and leads to an even higher stress on potential failure relevant pores. The highly stressed volume, where 90 % of the top peak stress is present, increases with an increase of the notch radius, Figure 4 left, where the highly stressed volume for one notch is given. In a highly stressed volume, the probability is higher that a larger pore is present at which cracks may initiate, Figure 4 left. However, as diametric effect the stress magnitude decreases due to the overall lower stress level.

Figure 3 Influence on stress gradient, left: variation of the notch radius; right: variation of the notch opening angle

On the contrary, the notch opening angle has just a minor influence on the stress concentration factor, the stress gradient (Figure 3 right) as well as the highly stressed volume (Figure 4 right) and is therefore of minor importance for the fatigue strength.