Crack Paths 2012

1 B B 6

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10

.

100

A K e q[MPa.vm)

Figure 10: Correlation of crack growthrates with AKIor AKeq, specimenccp5a.

Analysis of crack paths based on the local approach

Figure 11 shows the computed profiles of VonMises equivalent strain range ahead of

the successive crack fronts for tests ccp7a (stress range 34MPa)and ccp5a (40MPa).

Since AKeq increases as the crack grows, so does the equivalent strain range, which is

higher for ccp5a than for ccp7a.

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0,5 1

1,5 2 2,5 3 3,5 4

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depth: y (mm)

depthy ( m m )

Figure 11: Profiles of Aseq ahead of the crack fronts for a) test ccp5a and b) ccp7a

Figure 12 shows the profiles of predicted twist angles for those two specimens. A

progressive increase in twist angle, 0, as the crack grows is predicted near the free

surfaces where the drop in 0 noticed on fig. 2b and 2c is qualitatively captured.

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depth: y ( m m )

depth: y ( m m )

Figure 12: Profiles of predicted twist angles for a) ccp5a and b) ccp7a

The shear lips width, ts, was computedfrom such profiles, as the part in which

49 2 4°. Figure 13 compares the predicted and measured evolutions of ts. The model

qualitatively captures the progressive increase in t5 and the fact that it is larger in the

specimen submitted to a loading range.

85