Fatigue Crack Paths 2003

Nf increased. It could suggest that the shear stress influence on the crack propagation

disappeared sooner in the low/medium than in the high cycle fatigue regime.

In any case, shear stress was never negligible up to a distance from the notch tip

equal to L/2. Thus, it can be formed the hypothesis that L/2 is the transition point

between a crack growth under mixed modes (r

mode I governed (it held true especially in the high cycle fatigue regime).

90_05_05

Notchbisector

150500 0 0.1

0.2 0.3 0.4 0.5 0.6

0.7

Normal Stress

Crack

L/2=0.1mm ρ=0.03

2 0 0µ m

Shear Stress

A

A B

Notch tip

B

-500

200µµm

L/2=0.1mm ρ=0.29

2 0 0µ m

l[mm]

90_03_05

B

1-0500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

A

Normal Stress

L/2=0.1mm ρ=12.5

2 0 0µ m

Notch tip

Shear Stress

A B

Crack

Notchbisector

200µµm

l[mm]

60_05_08

Notchbisector

1-0500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Normal Stress

AL/2=0.1mm ρ=0.14

A

2 0 0µ m

Crack

Shear Stress

B

B

Notch tip

200µµm

l[mm]

60_03_06

Notchbisector

10500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Normal Stress

Notch tip

Shear Stress

A

B

A

500

Crack

0

B

200µµm

-500

l [mm]

Figure 3. (Caption on next page)