Fatigue Crack Paths 2003

Figure 3: Five crack modes: a) opening and b) sliding due to membraneloads; c)

opening and d) sliding due to bending and torsion loads; e) tearing due to shear

load [6]

where K 1 m and K2m are membranestress resultant intensity factors and K 1b , K2b

and K 3b are bending stress resultant intensity factors. Stress intensity factors are

then evaluated following Dirgantara and Aliabadi [3].

The maximumvalues of the stress intensity factors through the plate thickness

are to be found on the plate surfaces for modeI and modeII, while on the middle

plate for modeIII. They can be related to the stress resultant intensity factors as

follow:

KMaxI= ¯ Kh1m ¯

¯¯¯+6h2|K1b|

KMaxII = ¯ Kh2m ¯

(7)

¯¯¯+6h2|K2b|

3 2h |K3b|

KMaxIII =

Considering the minimumload as zero the { Kis then evaluated as:

{ K= Kmax

(8)

C A S SET U D I E S

The X-core structure proposed is composed of at plates of same material ( Tita

nium alloy,Young modulus E = 0,000Mpa; Poisson ratio v = 0.3) and di erent