Issue 39

S. Seitl et alii, Frattura ed Integrità Strutturale, 39 (2017) 100-109; DOI: 10.3221/IGF-ESIS.39.11 102 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 Height Load position Groove depth W [mm] B [mm] H [mm] h [mm] d n [mm] 150 150 130 8 20 Effective width Groove width Load position Eccentricity W eff [mm] f [mm] i [mm] e [mm] 142 40 10 20 Table 1 : Nominal variant dimensions and test geometry parameters, taken from [29]. Geometry variant Wedge angle Length Span Depth of top notch Depth of bottom notch Initial crack length Relative crack length Specimen set 2 α w [º] L [mm] S [mm] c [mm] c 1 [mm] a [mm] α = a/W eff [-] I, α 1 30 150 0 13 - 25 0.18 I, α 2 30 150 0 30 - 42 0.30 II, α 1 15 300 270 15 - 27 0.19 II, α 2 15 300 270 31 - 43 0.30 II, α 3 15 300 270 54 - 66 0.46 III, α 1 15, 30 600 540 13 - 25 0.18 III, α 2 15, 30 600 540 35 - 47 0.33 III, α 3 15, 30 600 540 54 - 66 0.46 IIIb, α 1 15, 30 600 540 8 53 53 0.37 IIIb, α 2 15, 30 600 540 9 81 81 0.57 Table 2 : Nominal variant dimensions and test geometry parameters, taken from [29]. T HEORETICAL BACKGROUND 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]:                                                                      2 3 cos 2 sin 2 cos 2 2 3 sin 2 sin 1 2 cos 2 2 3 sin 2 sin 1 2 cos 2 I xy I yy I xx                r K r K T r K (1) A