Crack Paths 2009

-0.4

0

0.4

0.8

X/Zh

T

0

.

.

.

|

.

.

.

|

.

.

Z _

_‘ Through-the-thickness average I A V

_

q) I 0

Plane strain

0 8 _

\ ~

.

Mid-thickness I M T

predictions , uZ I 0

-

_

\ \ \~

¢ I ()0

_()_4 -

Crack tip

0.6 - 0 4 I

IOIS -

097°)

'

--- FE (MT) [27]

‘

.1” P1

t

d- t

-

_1_2 _

II/ /o’/ ane s ress pre 1c1ons

0.2 — ——FE(AV) [27]

/

.

/

FE 28,30 —-

FE (MT, 0: 5°) [28]

\

_1 6 _

I

_

[

1

0 -

\‘a‘v,

'

/

Exper1mental[29] °

— First-order plate theory [26] “

_

I t

'

E

First-order plate theory [26] —

-0.2

.

.

.

.

112

0.001

0.01

0.1

1 x/2h vKIaPPJF

Fi . 8a. Constraint factor in the vicinit

Fi .8b. Out-of- lane dis lacement,

g

Y

8

P

P

of the crack tip (x is the distance from

uZ, on the free surface, z : ih near

the crack tip)

the crack tip

Crack stressed in mode11

A m o n gvarious results available for cracks stressed in modeII we showthe dependence

of the O-modeas a function of the crack length (Fig. 9a) for through the thickness crack

of length 2a. Fig. 9b shows the variation of the stress intensity factor of modeII in the

vicinity of the plate surface [24] for semi-infinite crack.

KO

KII

Kapp

— First Order plate theory [31]

Kipp

Finite Element result [25,31]

H

.

.

.

.

-

0 Finite Elementresult [25, 32]

16 _

seml'mfimtecrack

VI0.1,0.3,0.5 1_4 -

V I 0.1, 0.3, 0.5

1.2 -

O I

IIIIIII| I

IIIIIII| I

IIIIIII| I

I

I

I

I

I

001

O1

1

10

M, 0.75

0.8

0.85

0.9

0.95 z/h

Fig. 9a. Intensity of O-modeas a function

Fig.9b. Rise of the intensity of shear

of the ratio of the crack length to the plate

mode H In the VlclnltY ofthe P1ate

thickness

Surface

Normally, experimental results correspond to h/a < 1. Fig 9a and 9b indicate a strong

presence of three-dimensional effects and influence of the plate thickness: an increase of

the local stress intensity factor, KILI and a significant magnitude of K 0 in the vicinity of

198