Fatigue Crack Paths 2003

(a) Structural detail

(b) Crack-propagation domain

Figure 4. Critical detail at the end of a horizontal girder: (a) a super-element

surrounding the crack-propagating domain, (b) an automatically generated FE-model of

the crack-propagating domain.

560

567890

(m m )

40

a c k l e ng t h

230

2340

100 0 200000 400000 600000 800000 10000001200000 number of cycles N (Cycles) c r

10

10

0

0

20

40

60

80

100

crack length a (mm)

(b) ΔKeff– a relation

(a) a – N curve

Figure 5. Simulated fatigue crack growth and the corresponding stress intensity range.

C O N C L U S I O N S

An advanced simulation system is proposed for the remaining life assessment of curved

crack propagation. The simulation method is based on a step-by-step finite element

analysis. Fatigue crack paths are investigated for welded structural details of a

transverse girder of a ship structure, and their crack propagation lives can be estimated

for the prevention of the break of a compartment during ship operation. The influencing

factors such as geometry of structural details, welding residual stress, structural

redundancy, and crack paths can be taken into account in the simulation, so that realistic