Crack Paths 2009

σ ∂

θθ

=

0,

θ

∂

=

o θ θ

16 − −

c T

θ

] (3cos 1 )cos s i2n, 0 3 2 r π θ = 0 0 0 θ θ

K

+

K

(3)

I

II

∴ [

sin

0

where Tis T-stress, rc is the size of the process zone, which must be determined and θ0

is the further crack propagation direction.

There is a non-consistent view in the literature as to how to define parameter rc.

Someauthors consider rc to be a material constant [3, 6], some as a plastic or process

zone [7]. In this work, the rc is connected with the plastic zone size near the crack tip:

2

(4)

1 π σ   =  , I y K

r

c

where σy is the yield stress of the material studied.

E X P E R I M E N TMAELA S U R E M E N T

Experimental measurements on a modified C T specimen were performed to validate the

numerical predictions. A standard C T specimen with two holes was chosen for

experimental work, see Fig. 2. This geometrical configuration induces high level of the

constraint in region where the crack is supposed to propagate.

Figure 2. C T specimen used for experimental measurements

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