Fatigue Crack Paths 2003

0,4

0,4

μ =0.1 θ=70°

a/b =1000(-(+))

μ=0.5θ=70°

0,3

0,3

0,2

0,2

K I I/ K o

K I I/ K o

0,1

0

0,05

0,1

0,15

-0,10

0

a/b=100(+)

-0,21

a/b=100(-)

0,05 0,075

0

0,025

0,1

KI/Ko

KI/Ko

Figure 6. KI vs KII for the two friction conditions μ=0.1 and μ=0.5.

Effects of the Crack Inclination Angle

The effect of crack inclination was analysed in the whole range θ =[ –70° , + 70°] in

which the W Fwas determined with the cylinder moving rightward. The calculated ΔKI

and ΔKII ranges are reported in Fig. 7 as a function of the angle θ. For both ΔKI and ΔKII:

the positive crack inclination is the most critical, for any a/b ratio (including the point

like load), particularly with high friction. The most critical condition for ΔKIis reached at

an angle higher than 60° in dependence of the friction. For crack inclination ranging

between 0° and 20°, the maximumvalues for ΔKII are observed.

0,18 0,16

0,9

point load

μ=0.1

pointloada/b=100

µ=0.1µ=0.1

0,8

a/b=100

a/b=11,75

0,14

a/b=11,75

0,7

a/b=3

0,001,1682

a/b=03,75

0,3 0,456

/ K o

a/b=0,75

D e lat K

0,04

0,2

0,02

0,1

0

0

-70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 θ(°)

-70-60-50-40 -30-20 -10 0 10 20 30 40 50 60 70 θ(°)

0,345678 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70

point load

µ = 0.5 0,001,01246824-70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 θ(°) paoin/t/lobadba=/b==10103,17,575

µ=0.5µ=0.5

a/b=110,075

a/b=3

/ K o

a/b=0,75

D e lt a K

0,120

θ(°)

Figure 7. DeltaKI and DeltaKII vs the crack inclination angle θ for μ=0.1 and μ=0.5.