Page 26 - Biaxial Multiaxial Fatigue and Fracture

Assessment of Welded Structures by a Structural Multiaxial Fatigue Approach 11

0 B, Fx, R=- 1
0 A, Fx, R=- 1
150
X C, Fx, R=- 1

0 B, Fz, R=- 1
50 H B, Fx, R=-0.5

X D, Fz, R=-2
~
0 200

Fig. 5. Mean fatigue strength at IO6 cycles obtained on elementary arc-welded structures.

250
X C, Fx, R=- I
O A, Fx, R=- 1
B, Fx, R=- 1
200 O B, Fz, R=- 1
A D, Fz, R=- 1
2 + C, Mz, R=- 1
h
3 150 B, Fx, R=-0.5
0
tJ B, Fz, R=-0.5
0 A, Fx, R=O
IO0 A D, Fz, R=-0.2
X D, Fz, R=-2

50
1 E+04 1 E+05 1 E+06 1 E+07
Number of cycles to failure N

Fig. 6. S-N line for continuous arc-welded steel structures where S = 'To. The highest curve
corresponds to high strength steel (oy = 450 MPa), the lower curve to low strength steel (oy =
170 MPa).

Figure 6 shows the 70-N design curve obtained from more than 200 fatigue tests on
elementary structures with different geometry, different materials and different loading modes