Crack Paths 2012

R E S U L TASN DDISCUSSION

Crack Path under LC1– Effect of 'K

There are three specimens, i.e. LC1-0.06-90-1, LC1-0.06-90-2, LC1-0.06-90-3, tested

under the loading condition of R = 0.06,

m a x = 90 MPa, which results in the ' K values

in the range of 9~24 M P a mT.wo specimens, i.e. LC1-0.06-170-1, LC1-0.06-170-2,

tested under R = 0.06,

max = 170 M P awith the ' K values in the range of 19~35

M P a mT.he crack paths of the 5 specimens are shown in Fig. 3.

(a)

(b)

m a x = 90 M P afor (a) and

Figure 3. Crack paths of under C A loading of R = 0.06,

m a x =

170 M P afor (b)

Figure 3 indicates that (1) for the loading condition of R = 0.06,

max = 90 MPa, K

values in 9~24 M P a mth,e crack growth paths in macro-level are muchmore ‘ideally’

compared with that of

max = 170 MPa, though the crack paths show meandering to

some extent. Small macro-level crack branching were observed whenthe corresponding

K increased about 16.5 M P a inmLC1-0.06-90-1, marked by circle in Fig. 3(a); (2)

for the circumstance of R = 0.06,

m a x = 170 MPa, K in the range of 19~35 M P a m ,

significant crack path deviations with the angle of about 100 ~135 degree were found in

both the two specimens, see Fig. 3 (b). The crack lengths a at the turning point are about

6~8 mm, and the corresponding K is about 22~26 M P a. m(3) no remarkable crack

bifurcations appeared in the crack path during the propagation, which is quite different

from the crack path under LC2and LC3.

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