Crack Paths 2012

3a, ahead of the crack tip a drawn. Figure 3b is a ma results for geomet y G2 aret = 0, cf. Figure 1, taken from Figure 2a an gnification of the M Dvalues in Figure 3 e found in Figure 4 and Figur 5. d Figure 2c, are

a. Corresponding

a.

b.

Figure 3. zz ahead of the [GPa]. + showM Dresults crack tip for G1. The abscissa is in [nm] and and the solid line the L E F Msolutio . b) is a m the M Dvalues in a). the ordinate in

magnification of

First consider the results 3. In general terms the s simulation and the L E F M levels than th square shap obtained f om the M D(+) a 3b is a close-up of th M D for the L E F Msimula ion, crack front is approach d orne f m ng the m lecus concerning the largest geometry, G1, in Fig stress fields agree in shapes and trends be solution. As xpected, the sh rp c ack giv ped rack in the M Dsimulation. The stress an L E F M(__) calculations are seen in Figur D simulat on values. As de from the higher s zz fr m the M Dsimulat on shows a singular as seen from Figure 3b. Th is expected d ular crack fr nt.

ure 2 and Figure

etween the M D

ves higher stress

levels of

zz as

re 3a, and Figure

stress magnitude

r behavior as the

due to the sharp

compared to the L E F Msolutions. As r gard the two corners of the crack front induces ar bove and below he k. The stress fie i ion of two str ss fields, emanat ng from er points, each acting as a crack tip, b t of lo ear stress might act as sites of dislocation nuress distributions

Further it is seen from F ahead of the crack front as stress distribution, each of magni udes of zx, both a composed by superposi concen rations t the corne T e bands enhan ed Fhigure 2 that the boundary is affecting the str

ds the M Dshear

reas of enhanced

eld seems to be

m the two stress

ower singularity.

ucleation.

Turning to the smaller g effects found for G1 ar en and L E F Mstress fields, dramatically. This is also singular behavi close t t to the boundary de re s s. eometry G2 in Figure 4 and Figure 5, it is hanced for G2. Still there is a resemblance b but the inference from the boundaries obvious from Figure 5b, wh r zz, after e crack o t for = 0, eventually increase noticed that all

between the M D

have increased

having shown a

es as the distance

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