Crack Paths 2012

With the Hutchinson and Suo [9] condition, setting 0/ Itan’1(,u) and where G,c and

G,,C respectively denote modeI and II toughness

G, I G, (1+ tan2(ci//))

if y/=0 G, I G,

(8)

2 if y/Iirr/2 GCIGHCI> cI—tan_1 % — 1

a

G,C

The general form of the criterion can be written

24,-1

_

1-2,

G C

O - C T C

k1 2 k l f: {

2

J

1/q

A1(60) + m0A12(60) + m0 A2 (60)

((S1+m0S2)qTZ+‘l1+m0l2lq 0'3)

(9)

Where G, I%£G,(r)drcorresponds to the mean toughness along the presupposed

crack path and m, I 111%) , [0 being the solution to the implicit equation

2/q 6 ((s 1+m(l)s2)"r;I + ]t,+m(l)t2 ‘q of)

(10)

60273 A1(00)+m(l)A12(00)‘l'm2(l)A2 (00)

A more general form of the criterion (yet slightly heavier to handle) was established by

Garcia and Leguillon [10], it avoids the asymmetrybetween mode I and mode 11 that

appears through the mixity parameter m defined in (4).

E X T E N S ITOONF A T I G ULEO A D I N G S

l"1

10

k

1 m

>2‘

Figure 2. Schematic view of a fatigue loading vs. time t. The load intensity is

characterized by the GSIF k1 of the singularity at the root of the V-notch, k1C is its

critical value under monotonic loading and km the m a x i m urmeached during a cycle.

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