Fatigue Crack Paths 2003

a)

b)

Figure 6. Dependence of the critical crack length on KI value for unstable crack growth

a)p=1, η=0.1,b)A=50η,=0.1.

The model presented at the beginning of this chapter considers the translation of the

damage zone at the propagating crack tip. It is possible to propose an alternative ap

proach considering both: motion of the damage zone and growth of this zone. So, let us

make an assumption that damage growth zone Ω exists at the tension crack tip. The

length of this zone is r0. It is assumed that normal stress and damage are specified, re

spectively, by the mean values

n σ and n ω .

Figure 7. Damagezone growth scheme.