Crack Paths 2006

the magnitude of the plastic strains, and hence the growth rate, and not the shape of the

plastic zone.

34567890

45° slit, R=0.5

45° slit, R=0.17

45° slit, R=0.06

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Crack extension, m m

Figure 3. ModeI+III twist crack orientation in a three point bend fatigue specimen with

an initial 45° slit

90

80

70

60

50

40

60° slit, R=0.5

60° slit, R=0.17

60° slit, R=0.06

30

0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1

Crack extension, m m

Figure 4. ModeI+III twist crack orientation in a three point bend fatigue specimen with

an initial 60° slit