Crack Paths 2006

a)

b)

= 643050° D

a D M = 7.92 N · m

AlCuMg1 ALUMINIUMALLOY

AlCuMg1 ALUMINIUMALLOY

a M = 7.92 N · m

R = 0

R = - 1

=46350°

(m m )

(m m )

a

200000 N (cycles)

a

0246

0

100000

300000

400000

02468

0

5000

10000

15000

20000

25000

N (cycles)

Figure 5. Fatigue crack growth versus number of cycles under mixed mode (I + III)

loading for D = 30q, 45q, 60q and stress ratio a) R = - 1, b) R = 0

Figs. 6, 7 and 8 show crack growth rate da/dN versus 'J integral range for three angle D equal 30o, 45o, 60o and the three stress ratios R = - 1, -0.5, 0. In these Figs. mixed modes

I+III loading was separated into pure mode I and mode III. From Figs. 6-8 it appears

that the cracking growth rate increases when we increase D from 30q to 60q in the

aluminium alloy.

b)

a)

1E-2 J (MPa·m)

1E-876

1E-3

0.1

-1

-2

'

-5 -6 -7 8

10

10

10

-5

-3

-76 8

d

1E-5

1E-5 110 10

21

10

DModeI=30° 3 - R = 0

ModeIII3=30°- R = 0

D

3

2 - R = - 0.5

2 - R = - 0.5

1 - R = - 1

1 - R = - 1

3

1E-876

(m / c yc le )

( m / c yc le )

10

21

d a / d N

a / d N

-3

-1

-2

'

1E-3 10

1E-2 10

0.1 10

J (MPa·m)

Figure 6. Comparison of experimental results for different stress ratios and D = 30q a)

mode I, b) modeIII