Crack Paths 2012

follows: w = 57.15 mm,D = 38.1 mm, t = 12.7 mm,a0= b0= 0.635 m m[16]. The

material of the lug tackled in this example is the same as in the previos one

(CA=CB=4.68*10-10 for R=0.1).

Based on the known characteristics of material, corner crack geometry and loading,

the values of stress intensity factors are computed by applying Eqs.3-11 for both, depth

and surface directions. Calculated results for stress intensity factors for depth and

surface directions as a function of crack length are shown in Fig.5.a. Thus, obtained

stress intensity factors and corresponding crack increments are used for the crack path

simulation of quarter-elliptical

corner crack. The evaluated crack path for the

considered attachment lug is shown in Fig.5.b.

a

b

12

7075 T651 (R = 0.1)

7075 T651 (R = 0.1)

40

a=0.635 m m a=1.235 m m

a=2.135 m m a=3.035 m m

10

a=3.935 m m a=4.835 m m

30

a=5.735 m m a=6.635 m m

a=7.535 m m a=8.435 m m

8

20

6

4

10

2

0

0

2 14

0

2

4

6

8

10

-3

6 8 10 1 a, b [m] (x10-3)

0

2 4

b [m] (x10

)

a - KIA (Calculated curve)

b - KIB (Calculated curve)

c

d

7075 T651 (R=0.1)

7075 T651 (R=0.1)

0

a - N (Calculated curve) (ABPLC2 )

1246802 0 5 10 15 20 25 30 35

10

8

0 )

12 0 5 10 15 20 25 30 35 N [cycles] (x103) (1x

6

4

2

0

N [cycles] (x103)

b - N (Calculated curve) ABPLC21)

b -N(ABPLC17)

Figure 5. a) Stress intensity factor versus crack length; b) Crack path simulation;

c) Crack length versus number of loading cycles depth direction (exp. from Ref. [16]);

d) Crack length versus number of loading cycles surface direction (exp. from Ref. [16]).

593