PSI - Issue 19

8

Helen Bartsch et al. / Procedia Structural Integrity 19 (2019) 395–404 Helen Bartsch, Benno Hoffmeister, Markus Feldmann / Structural Integrity Procedia 00 (2019) 000 – 000

402

100 120

0 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 FAT class [MPa] Thickness of end plate [mm] weld toe outside weld toe inside weld root outside weld root inside FAT class acc. To EC 3-1-9

0 20 40 60 80 Stress range in bolt ∆σ [MPa]

outer bolt inner bolt

10 20 30 40 50 60 70 80

Thickness of end plate [mm]

Fig. 8. Influence of thickness of end plate on bending stress range in bolt and fatigue strength of weld details

To exemplarily show another investigation on influences, Fig. 9 presents the effect of changed vertical bore hole spacing on the bolt bending stress ranges and the fatigue strength of the weld details. Again, immoderate dimensions were chosen to better show the influence.

60

0 10 20 30 40 50 60 70 80

0 Stress range in bolt ∆σ [MPa] 20 40

weld toe outside weld toe inside

weld root outside weld root inside FAT class acc. to EC 3-1-9

FAT class [MPa]

outer bolt inner bolt

80

100

120

140

160

80

100

120

140

160

Inner bore hole distance [mm]

Innerer bore hole distance [mm]

Fig. 9. Influence of inner, vertical bore hole distance on bending stress range in bolt and fatigue strength of weld details

For the variation of the hole spacing in vertical direction, the stress range decreases with smaller inner hole spacing. A small hole spacing of the bolts in the tension area has a positive effect on the bolt bending stress ranges. Again, inner and outer bolts have approximately same stress ranges. On the right hand side of Fig. 9, the FAT class in terms of nominal reference fatigue strength Δσ c at 2 ∙ 10 6 cycles of each configuration calculated with the help of effective notch stresses (see section 2.1) are illustrated. The inner weld root is always identified as the decisive detail. Again, all calculated fatigue strengths lie above the FAT class 36* or 40 according to (Eurocode 3-1-9, 2005). A decrease of the vertical inner hole distance causes a decrease of the FAT class of all details. It can be seen that the weld toe, especially the outer one, is less affected by the change in the vertical hole spacing.