Crack Paths 2006

Type (a) web

Type (b) web

Type (cda))fwaeceeb

100

4567890

Type (cbd) face

]

e[]b)mm

m m

e) [

a c k l e n g th ( f a c

twh(

a c k l e n g

300

C340 r

C r

12505050

30

0

20

0

1

2

3

4

5

N u m b e rofcycles[×106]

Figure 9 Simulated crack propagation lives under water pressure.

Type (a) w e b

300

80

Type (cb)) w e b

Type(d)web e (cabd)) faace

12505050

345670

0

20

0

0.5

1

1.5

2

N u m b e orfcycles[×106]

Figure 10 Simulated crack propagation lives under axial force.

In Fig. 9, the crack growth curves under the water pressure loading are illustrated. It

is found that the crack propagation lives are significantly affected by the structural

details. The difference of the crack propagation lives mainly occurs before the complete

break-off of the face-plate. This difference of the crack propagation lives is caused by

the difference of the nominal stress and/or the stress concentration at the initial crack of

each model. In Fig.10, those under the axial force are illustrated, where the structural

detail (a) exhibits the longest fatigue life, because the crack opening displacement may

be strongly constrained compared to the other structural details due to the transverse

girder.

O nthe Welding Residual Stress

Since welding residual stress is not a fluctuating stress, we assume that it simply

changes the stress ratio, R, and the effective ranges of stress intensity factor. In the