Issue 39

S. Seitl et alii, Frattura ed Integrità Strutturale, 39 (2017) 100-109; DOI: 10.3221/IGF-ESIS.39.11

Dimensions of specimens for all four geometry variants are summarized in Tab. 1 (dimensions common to all variants) and in Tab. 2, there are unique dimension of all studied variants (I, II, III and IIIb) with angles.

Width

Breadth B [mm]

Height H [mm]

Load position

Groove depth

W [mm]

h [mm]

d n

[mm]

150

150

130

8

20

Effective width

Groove width

Load position

Eccentricity

W eff

f [mm]

i [mm]

e [mm]

[mm]

142

40 20 Table 1 : Nominal variant dimensions and test geometry parameters, taken from [29]. 10

Depth of bottom notch

Initial crack length

Relative crack length

Geometry variant Specimen set

Depth of top notch

Wedge angle

Length

Span

α = a/W eff [-]

L [mm]

S [mm]

c [mm]

c 1

a [mm]

2 α w

[º]

[mm]

I, α 1 I, α 2

30 30 15 15 15

150 150 300 300 300 600 600 600 600 600

0 0

13 30 15 31 54 13 35 54

- - - - - - - -

25 42 27 43 66 25 47 66 53 81

0.18 0.30 0.19 0.30 0.46 0.18 0.33 0.46 0.37 0.57

II, α 1 II, α 2 II, α 3 III, α 1 III, α 2 III, α 3

270 270 270 540 540 540 540 540

15, 30 15, 30 15, 30 15, 30 15, 30

IIIb, α 1 IIIb, α 2

8 9

53 81

Table 2 : Nominal variant dimensions and test geometry parameters, taken from [29].

T HEORETICAL BACKGROUND

A

ccording to the two-parameter fracture mechanics approach which uses T -stress as a constraint parameter [1, 11, 13, 24, 34], the stress field around the crack tip of a two-dimensional crack embedded in an isotropic linear elastic body subjected to normal mode I loading conditions is given by the following expressions [33]:

K

      2 3 sin 2 3 sin  

     

    



           2 2           

     

   

cos

sin 1

T

I







xx

2

2

 r

(1)

K



cos

sin 1

I





yy

2

2

 r

K

   2 3 cos 





  

  

  

  

  

cos

sin

I





xy

2

2

2

 r

102