Crack Paths 2006

40

% P b = 0 . 0

% P b = 0 . 1

% P b = 0 . 5

% P b = 1 . 0

m m ]

1230

[ c r a c k s /

1

10

100

1000

Cycles number

Figure 8. Damagelevel (] phase).

40

% P b= 0.0

% P b= 0.1

m m ]

% P b= 0.5

% P b= 1.0

230

[c r a c k s /

10

1

10

100

1000

Cycles number

Figure 9. Cracks that do not propagate from G phase into ] phase.

For Pb wt% equal to 1, damage values are comparable or also lower than the values

obtained for P b %= 0.5. Damageevolution in the two considered phases is similar. This

peculiar behaviour is probably due to different mechanisms: G phase is characterized by

an evident presence of longitudinal cracks, with a consequent decrease of the

importance of the radial cracks nucleation; ] phase looses its columnar character, and,

consequentely, radial cracks are not still the preferential path. This mechanism is

confirmed by the analysis of the evolution of the difference NG – N], that corresponds to